JP2008111834A - Method and device for evaluating ultraviolet radiation protective effect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating an ultraviolet radiation protective effect in vitro measurement reflecting a light deterioration phenomenon of a measuring sample by irradiation light, and showing high correlation with in vivo SPF value even in a measuring sample having a high SPF value, and to provide a device for evaluating an ultraviolet radiation protective effect by using the method. <P>SOLUTION: The method has a first step of measuring a change with time of a spectral transmission spectrum of a measuring sample by light irradiation from a light source including the ultraviolet radiation for a predetermined light irradiation time, a second step of correcting the spectral transmission spectrum of the measuring sample according to the change with time on the basis of the measurement results obtained in the first step, and a third step of calculating the final in vitro SPF estimation value of the measuring sample by using the correction results obtained in the second step. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for evaluating an ultraviolet protection effect.

  An SPF (Sun Protection Factor) value is used as a measure representing the ultraviolet protection effect of cosmetics (so-called sun care products) for preventing sunburn by ultraviolet rays. This SPF value is an index showing the effect of protecting the skin from sunburn caused by ultraviolet rays and preventing sunburn. When using suncare products, the amount of ultraviolet rays necessary to cause a slight redness is not used. In some cases, it is defined by the value divided by the amount of ultraviolet light necessary to cause a slight redness. For example, when a sun care cosmetic product having an SPF value of 10 is used, it means that sunburn (erythema) similar to that of the bare skin occurs when the UV rays are ten times higher than those obtained when the skin is tanned. For the measurement of the SPF value, artificial light (solar simulator) that is very close to the sunlight is used instead of sunlight that may vary depending on the season and location. The measuring method is to irradiate a certain amount of ultraviolet rays to the skin to which the product is not applied and to the skin to which it is applied, and examine whether or not erythema has occurred the next day.

  If the SPF value measured in accordance with the above-described method is used, it is possible to make an objective evaluation of the sun protection product's UV protection effect. However, the above-described method requires a great deal of cost and number of days because the cooperation of subjects with many specific skin types is indispensable. Therefore, for example, in order to evaluate the UV protection effect of a product in the development stage, calculation of an in vitro SPF predicted value that is easily correlated in vitro with the in vivo SPF value obtained by the above method. There has been a desire for a method to be involved.

  Conventionally, as a method for evaluating the ultraviolet protective effect by in vitro measurement, a sample diluted with an organic solvent is put in a quartz cell, and the diluted solution method for measuring the absorbance or transmittance of the ultraviolet light, and the sample on the quartz plate are uniform. There has been known a thin film method for forming a film film having a proper thickness and measuring the absorbance or transmittance of ultraviolet rays. Such a conventional method is meaningful for grasping characteristics such as the absorption maximum wavelength and the protective wavelength region of the ultraviolet absorber, but the SPF value cannot be predicted. This is because these methods for evaluating the UV protection effect are greatly different from the method for measuring the in vivo SPF value. In addition, the biological reaction indicated by the SPF value is dependent on the wavelength of ultraviolet rays, and there is a range from the ultraviolet wavelength at which erythema reaction is likely to occur to the ultraviolet wavelength at which erythema reaction is difficult to occur. There was thought to be.

  Regarding the above two problems, in Non-Patent Document 1, a sample was applied on a medical tape as a skin substitute film, and the spectral transmission spectrum of the sample was measured. This measurement result was calculated by the Diffey & Robson equation, and the SPF value was calculated. This Diffey & Robson equation has succeeded in solving the above-mentioned problem because the wavelength dependence of the erythema reaction as a human biological reaction has been addressed by using the erythema coefficient disclosed in Non-Patent Document 2. Was.

  However, since there are various factors such as individual differences, site differences, age differences, sex differences, and skin type differences in in vivo SPF values, it is not possible to accurately predict SPF values using only an example of the erythema coefficient. In fact, it was a problem that it was very difficult.

Therefore, instead of adopting only the erythema coefficient, an equation that provides a statistically high correlation is derived from the relationship between a large number of samples with known in vivo SPF values and the spectral transmission spectrum, and even for unknown samples. An evaluation method capable of predicting the in vitro SPF value has been proposed (see, for example, Patent Document 1). With this evaluation method, in vitro SPF prediction values were obtained with high accuracy, and the factors of variation caused by individual differences, site differences, age differences, sex differences, skin type differences, and the like were resolved.
Journal of the Society of Cosmetic Chemists (1989) 40:33, 127-133 CIE Journal (1987) 6: 1, 17-22 Japanese Patent No. 3377832

  However, although the method for evaluating the UV protection effect disclosed in Patent Document 1 enables accurate prediction up to an SPF value of about 30, accurate prediction is performed for a sample having an SPF value of 30 or more. There was a problem that I could not. In recent years, products having an SPF value of 50 or more have been mainstream, and it is expected that products having an even higher SPF value will be introduced in the future.

  In recent years, much knowledge about the photodegradation phenomenon of ultraviolet absorbers by ultraviolet light has been clarified. Therefore, in the method of calculating the in vitro SPF predicted value, it is possible to accurately estimate the SPF value decrease equivalent by reproducing the light irradiation conditions similar to the in vivo SPF value measurement conditions. Is considered indispensable.

  The present invention has been made in view of the above points, and reflects in vitro photodegradation of a sample due to irradiation light, and also shows a high correlation with an in vivo SPF value even in a sample having a high SPF value. An object of the present invention is to provide a method for evaluating an ultraviolet protective effect by measurement and an apparatus for evaluating an ultraviolet protective effect using this method.

  In order to achieve the above object, the present invention is characterized by the following means.

  The method for evaluating the ultraviolet ray protection effect of the present invention includes a first step of measuring a temporal change in a spectral transmission spectrum of a measurement sample by light irradiation of a light source including ultraviolet light according to a preset light irradiation time, and the first step. A second step of performing correction according to a change with time of the spectral transmission spectrum of the measurement sample based on the measurement result obtained by the step, and a final result of the measurement sample using the correction result obtained by the second step. And a third step of calculating a predicted in vitro SPF value.

  The ultraviolet protection effect evaluating apparatus of the present invention includes a time-change measuring means for measuring a time-dependent change of a spectral transmission spectrum of a measurement sample by light irradiation of a light source including ultraviolet light according to a preset light irradiation time, and the measurement means Correction means for correcting the spectral transmission spectrum of the measurement sample according to a change over time based on the measurement result obtained by the step, and a final in vitro SPF of the measurement sample using the correction result obtained by the correction means SPF predicted value calculating means for calculating a predicted value.

  According to the present invention, a method for evaluating the UV protection effect by in vitro measurement, which reflects the photodegradation phenomenon of a sample due to irradiation light, and shows a high correlation with an in vivo SPF value even in a sample having a high SPF value, and It is possible to provide an apparatus for evaluating the ultraviolet protection effect using this method.

  Next, the best embodiment of the present invention will be described with reference to the drawings.

  The ultraviolet protection effect evaluation method of this embodiment and the ultraviolet protection effect evaluation apparatus using this method are, for example, a method for measuring the spectral transmission spectrum of a measurement sample over time by light irradiation of a light source including ultraviolet light according to a preset light irradiation time. A first step of measuring a change, a second step of correcting the obtained spectral transmission spectrum according to a change over time, and a third step of calculating a final in vitro SPF prediction value of the measurement sample. This measurement consists of

  In the first step, for example, a step of measuring the spectral transmission spectrum of the measurement sample with ultraviolet rays of 290 to 400 nm every 1 nm, and a step of determining the light irradiation time of the main measurement described below from the obtained spectral transmission spectrum. A preliminary measurement consisting of: Hereinafter, this method and apparatus will be described.

(Schematic configuration example of evaluation device)
FIG. 1 is a diagram illustrating an example of a schematic configuration of an apparatus for evaluating an ultraviolet protection effect according to the present embodiment.

  Referring to FIG. 1, the ultraviolet protection effect evaluation apparatus 10 is roughly composed of a light source 11, a filter 12, an optical fiber 13, an irradiation port 14, a skin substitute film 16, a spectrometer 17, and light detection. It is comprised so that the machine 18 and the computer 19 may be included. The ultraviolet protection effect evaluation apparatus 10 is an apparatus for applying the ultraviolet protection effect evaluation method described below to a measurement sample.

  The light source 11 is preferably a xenon lamp in the present embodiment, but is not limited thereto. The light source 11 is connected to a computer 19 described below, and the computer 19 controls on / off of the light source 11.

  The filter 12 is in the vicinity of the traveling direction of the light from the light source 11 and changes the light emitted from the light source 11 into a predetermined ultraviolet region such as UVB and UVA ultraviolet rays having a wavelength of 290 to 400 nm. This means that the light source at the site of in vivo SPF measurement is reproduced and irradiated. Moreover, as the filter 12 for converting the UVB and UVA ultraviolet light having the wavelength of 290 to 400 nm described above, a WG320 filter and a UG11 filter (both manufactured by SCHOTT) are preferably used, but are not limited thereto. An appropriate filter is used depending on a desired ultraviolet region or the like.

  The optical fiber 13 is in the vicinity of the traveling direction of light from the filter 12. The ultraviolet light transmitted through the filter 12 is guided to the irradiation port 14.

  The above-mentioned ultraviolet rays are irradiated from the irradiation port 14, the irradiation port 14 and the photodetector 18 are fixed at a predetermined interval, and the skin substitute film 16 to which the sample 15 is applied in a predetermined amount and method is fixed from the irradiation port 14. The position of the distance is fixed. In the order in which light travels, the irradiation port 14, the sample 15, the skin substitute film 16, the spectrometer 17, and the photodetector 18 are arranged in this order. In addition, the arrangement | positioning to this skin substitute film | membrane 16 is based on the in vivo SPF measuring method prescribed | regulated by INTERNATIONAL SUN PROTECTION FACTOR (SPF) TEST METHOD, February 2003.

The skin substitute film 16 is applied to the measurement sample 15 and replaces the skin of the living body in in vivo SPF measurement, and is preferably composed of a material that does not absorb ultraviolet rays of 290 to 400 nm. A method of using a medical tape as a skin substitute membrane is disclosed. In the present embodiment, a PMMA (polymethyl methacrylate) resin plate (Plexiglas ^™ , manufactured by Schonberg GmbH & Co. KG) is preferably used, but is not limited thereto.

  The light detector 18 separates light in the range of 290 to 400 nm by the spectroscope 17 at 1 nm intervals, converts each intensity into voltage, further A / D converts it, and outputs it to the computer 19. In the ultraviolet protection effect evaluation apparatus 10, the light detector 18 detects the light beam that has passed through the measurement sample 15 and the skin substitute film 16 described above.

  The computer 19 inputs the spectral intensity for every 1 nm from the light detector 18, performs the processing described below, and calculates the light irradiation time and the final in vitro SPF predicted value in this measurement. Moreover, the computer 19 controls on / off of the light source 11 as mentioned above.

  The computer 19 receives the data from the light detector 18, processes the data so that it can be easily understood by the user based on the contents, displays the result on the screen, puts the result on a recording sheet, The result can be stored in a storage medium. Moreover, the computer 19 can use a general purpose personal computer etc., for example, and can perform each function in the evaluation apparatus 10 mentioned above by the instruction | indication from a user, etc. by an input means.

(Example of functional configuration of evaluation device)
FIG. 2 is a diagram illustrating an example of a functional configuration of the ultraviolet protection effect evaluation apparatus according to the present embodiment.

  Referring to FIG. 2, the ultraviolet protection effect evaluation apparatus 10 is roughly composed of an input unit 21, an output unit 22, a storage unit 23, a spectral transmission spectrum measurement unit 24, an irradiation time setting unit 25, A change measuring unit 26, a correcting unit 27, an SPF predicted value calculating unit 28, and a control unit 29 are included.

  The input means 21 is provided, for example, in the computer 19 and accepts input of various data such as an instruction to start evaluation from a user or the like, and output of measurement results by the output means 22. Note that the input unit 21 includes, for example, a keyboard and a pointing device such as a mouse.

  The output means 22 is provided in the computer 19, for example, and displays / outputs the contents input by the input means 21 and the contents executed based on the input contents. Note that the output means 22 includes a display, a speaker, and the like. Further, the output unit 22 may have a function such as a printer. In this case, simple measurement results and calculation results may be printed on a print medium such as paper and provided to the user.

  Further, the storage means 23 is provided in, for example, the computer 19, and is measured by the result measured by the spectral transmission spectrum measuring means 24, the irradiation time set by the irradiation time setting means 25, and the time-change measuring means 26. As a result, various data such as correction information obtained by the correction means 27 and results calculated by the SPF predicted value calculation means 28 are accumulated.

  Further, the spectral transmission spectrum measuring means 24 measures the spectral transmission spectrum of the measurement sample 15 every 1 nm with ultraviolet rays of 290 to 400 nm, for example, by the photodetector 18 or the like. That is, the spectral transmission spectrum measuring unit 24 performs preliminary measurement for determining the light irradiation time in the main measurement. The irradiation time setting means 25 sets the light irradiation time based on the spectral transmission spectrum obtained by the preliminary measurement in the spectral transmission spectrum measuring means 24 described above as a function of the computer 19. Details of the preliminary measurement will be described later.

  The time-change measuring means 26 measures the time-dependent change of the spectral transmission spectrum of the measurement sample 15 by light irradiation according to the light irradiation time set by the irradiation time setting means 26 as a function of the computer 19. The time change measuring means 26 measures the time change due to light deterioration of the spectral transmission spectrum in the measurement sample 15. This makes it possible to calculate an in vitro SPF predicted value that reflects the photodegradation phenomenon of the sample due to irradiation light.

  Further, the correction means 27 performs correction according to the temporal change of the spectral transmission spectrum of the measurement sample 15 based on the measurement result obtained by the temporal change measurement means 26 as a function of the computer 19. Further, the SPF predicted value calculating means 28 calculates the final in vitro SPF predicted value of the measurement sample using the correction result obtained by the correcting means 27 as a function of the computer 19.

  Furthermore, the control means 30 controls the entire components of the evaluation device 10 as a function of the computer 19. Specifically, for example, based on an instruction from the input means 21 by a user or the like, spectral transmission spectrum measurement, irradiation time setting, light degradation measurement, correction according to temporal change of spectral transmission spectrum, in vitro SPF prediction Controls such as value calculation. In addition, the control means 29 performs on / off control of the light source 11 as a function of the computer 19. Details of this measurement will be described later.

(About preliminary measurement)
Here, as described below, in the preliminary measurement, the photodetector 18 measures a spectral transmission spectrum in an ultraviolet region of 290 to 400 nm, for example, at a predetermined wavelength interval. The predetermined wavelength interval includes, for example, every 1 nm or every 5 nm, but is not particularly limited in the present invention. Accordingly, in the following description, measurement is performed every 1 nm as an example. Further, in order to measure every 1 nm, the photodetector 18 and the spectroscope 17 having sensitivity characteristics matched to this wavelength region are necessary, but are not particularly limited. However, in order to measure the spectral transmission spectrum every 1 nm, the wavelength resolution of the spectroscope 17 needs to be 1 nm or less.

  In the apparatus and method for evaluating the ultraviolet protection effect, since the spectral transmission spectrum of the sample is measured, the higher the SPF value of the sample, the higher the ultraviolet absorption effect by the sample, resulting in a smaller amount of transmitted light. For this reason, in order to accurately predict the SPF value even in a sample having a high SPF value exceeding SPF value of 50, a photodetection device having excellent detection sensitivity for weak light is required. Conventionally, photodiode arrays, CCDs, and the like have been generally used as photodetectors. However, with the recent development of weak light detection technology, photomultiplier tubes with increased detection sensitivity are often used. Although it is apparent from theory that the detection sensitivity is higher than that of the conventional photodiode array and CCD, it is necessary to select the material of the photocathode of the photomultiplier tube depending on the wavelength region of the light to be detected. In the present embodiment, it is possible to measure even a sample having a high SPF value by using a photomultiplier tube having excellent sensitivity characteristics particularly in the ultraviolet region of 290 to 400 nm.

(Preliminary measurement and determination of light irradiation time)
In the present embodiment, prior to the main measurement, a preliminary measurement for measuring the spectral transmission spectrum of the measurement sample is performed. The light irradiation time in the main measurement is determined from the spectral transmission spectrum of the sample obtained in the preliminary measurement. The method for determining the light irradiation time starts by first calculating a provisional in vivo SPF predicted value based on the measurement result of a standard sample whose in vivo SPF value is known.

  Spectral transmission spectra are measured for a plurality of standard samples whose in vivo SPF values are known, and a multivariate analysis is performed on the correlation between this spectrum and the known in vivo SPF values from the transmitted light intensity for each wavelength. Based on a calibration curve composed of point groups plotted with the relationship between the numerical value obtained from this multivariate analysis and the in vivo SPF value, and the result of the spectral transmission spectrum of the measurement sample, a provisional in vitro SPF predicted value close to the in vivo SPF value is obtained. This is an analysis method of obtaining.

  In addition, the multivariate analysis of the present embodiment is characterized by using a PLS (Partial Least Squares) regression analysis method, which is a known analysis method. The commonly used multiple regression analysis method is a method of performing regression analysis using all parameters used for analysis, and can be used in principle for analysis of data including many factors. However, when there are more explanatory variables than objective variables, an appropriate regression equation cannot be obtained because excessive fitting is performed. On the other hand, the PLS regression analysis used as this embodiment is one method for constructing a prediction model when there are a large number of explanatory variables. PLS regression analysis can be a very useful tool when prediction is the ultimate goal and there is practically no need to limit the number of factors to be measured. For example, this is the case when spectral spectrum data is used.

  FIG. 3 is a diagram showing a correlation between an in vivo SPF value and an in vitro SPF predicted value in a standard sample.

  Referring to FIG. 3, the SPF value is predicted by the above-described PLS regression analysis method in a standard sample whose in vivo SPF value is known. The horizontal axis indicates a known in vivo SPF value, and the vertical axis indicates an in vitro SPF predicted value.

In addition, the in vitro SPF predicted value shown on the vertical axis in FIG. 3 is a result predicted by taking into consideration the photodegradation phenomenon of the sample through this preliminary measurement and the main measurement as described below. As shown by (R ² = 0.9743), the prediction accuracy of the in vitro SPF value is high. Therefore, if the spectral transmission spectrum of the measurement sample is obtained by preliminary measurement, the SPF value of the measurement sample can be grasped with a certain degree of accuracy as the provisional in vitro SPF predicted value.

  The light irradiation time of the measurement sample reproduces the conditions of the in vivo SPF measurement site performed using an actual living body, and the light irradiation time becomes longer as the provisional in vitro SPF predicted value is higher. It is set to have a proportional relationship. Therefore, it is calculated based on 1 MED (Minimum Erythema Dose) at the measurement site of the in vivo SPF value. Here, 1 MED is the amount of ultraviolet light required to induce the minimum amount of erythema at the test site of the subject at the measurement site of the in vivo SPF value.

  In an ultraviolet lamp (solar simulator) used in an in vivo SPF measurement site, the light quantity and spectral distribution of the light source are standardized, so 1 MED is mainly expressed in time units. This is confirmed in an in vivo SPF measurement site in a state where no sample is applied at a test site.

  As described above, there are various factors such as human individual differences, site differences, age differences, sex differences, and skin type differences. In this embodiment, 1 MED is changed from 5 seconds (0.083 minutes) to 90 seconds. It is assumed that it falls within the range of (1.5 minutes). From this assumption, the light irradiation time in the main measurement of the present embodiment is set to a provisional in vitro SPF prediction value × 0.08 (minutes) or more and less than a provisional in vitro SPF prediction value × 1.50 (minutes). From the viewpoint of data reproducibility and the like, in the present embodiment, 1 MED is preferably in the range of 10 to 60 seconds, and more preferably in the range of 20 to 50 seconds. When the light irradiation time is calculated by this conversion, the provisional in vitro SPF predicted value by preliminary measurement is 50, and when 1 MED is 30 seconds (0.5 minutes), 50 × 0.5 = 25 minutes of light Irradiation will be performed.

  The calculation of the light irradiation time described above is performed by the computer 19. In the main measurement described below, the computer 19 controls the light source 11 so that a predetermined light irradiation time is reached.

(Correction according to the actual measurement and light degradation)
In the main measurement, the measurement sample is irradiated with ultraviolet rays of 290 to 400 nm continuously for the light irradiation time calculated from the result of the preliminary measurement. At this time, the time-dependent change of the spectral transmission spectrum of the measurement sample is measured, a correction process is performed in accordance with the change in the photodegradation of the measurement sample, and the final in vitro SPF predicted value is calculated.

  Here, the photodegradation phenomenon of the measurement sample means that the original ultraviolet absorbing ability is lowered by causing isomerization or the like when the organic ultraviolet absorber is irradiated with light. That is, it means that the SPF value of the measurement sample is lowered due to the photodegradation phenomenon (see, for example, Photogradation of Sunscreen Chemicals: Solvent Condensation, Cosmetics & Toiletries (1990) 105: 41-44).

  This photodegradation phenomenon is considered to occur also in the sample on the living body skin because light irradiation is continuously performed even at the measurement site of the in vivo SPF value. In this evaluation system, it can be confirmed as a change in the transmission spectrum of the sample accompanying light irradiation, that is, a phenomenon in which the amount of transmitted light increases.

  The purpose of reproducing the photodegradation phenomenon of the sample is by measuring the temporal change of the spectral transmission spectrum under the continuous light irradiation condition and by the photodegradation from the provisional in vitro SPF predicted value that does not reflect the photodegradation obtained in the preliminary measurement It is to calculate a highly accurate final in vitro SPF prediction value in consideration of the decrease equivalent.

  In the main measurement, the time-dependent change in the spectral transmission spectrum of the measurement sample is detected by controlling the light irradiation time obtained from the preliminary measurement in seconds, and the spectral transmission spectrum data at an arbitrary time during the light irradiation time. Is achieved by allowing

  Specifically, in the processing by the computer 19, the light irradiation time condition can be set in units of seconds such as minutes and seconds. In addition, the temporal spectrum change during the light irradiation time can be acquired at any time interval such as every minute or a time interval obtained by equally dividing the irradiation time into ten. Preferably, after dividing the time evenly with respect to a predetermined light irradiation time, it is possible to acquire spectral data at 6 or more locations (including the time when light irradiation starts at zero time), more preferably 11 or more locations. It is. The more spectral data during this period, the more detailed the photodegradation behavior of the sample can be grasped, and therefore the prediction accuracy can be increased.

  At this time, in order to accurately capture the light deterioration phenomenon of the measurement sample during light irradiation, the measurement sample and the entire apparatus must not be moved. It is important to obtain the time change behavior of the same location that is completely fixed as spectrum data in order to improve the prediction accuracy.

  From the detection result of the temporal change in the spectral transmission spectrum of the measurement sample in the main measurement described above, correction processing is performed in accordance with the change in light degradation of the measurement sample. This correction processing is achieved by predicting the in vitro SPF value from the time average spectrum of the spectral transmission spectrum of the sample in the ultraviolet region of 290 to 400 nm.

  As described above in the preliminary measurement, the in vitro SPF prediction value can be determined with a certain degree of accuracy as long as the spectral transmission spectrum of the measurement sample is determined. In other words, after grasping the temporal change behavior of the spectral transmission spectrum accompanying the photodegradation of the measurement sample at the time of the main measurement, which spectral transmission spectrum is adopted for determining the in vitro SPF predicted value of the measurement sample. However, it is very important to perform highly accurate measurement.

  Employing time zero, that is, spectral transmission spectrum data at the start of light irradiation, provides the same value as the provisional in vitro SPF predicted value in the preliminary measurement. However, since this numerical value does not reflect the photodegradation phenomenon of the measurement sample due to continuous light irradiation, it is considered that a numerical value higher than the SPF value that should be predicted is predicted. In addition, if the data of the spectral transmission spectrum of the latest time just before the end of the light irradiation time in this measurement is adopted, the spectrum data after having sufficiently changed due to light degradation, that is, after receiving excessive light irradiation conditions Therefore, it is considered that an SPF value that is lower than the SPF value of the original measurement sample is predicted.

  Therefore, in order to reflect the change over time, the in vitro SPF value is predicted after calculating the total amount of transmitted light by the time integration of the spectral transmission spectrum in the same manner as the phenomenon that the skin is exposed with time. It is preferable.

  However, in view of the complexity of calculation processing and the like, in the present embodiment, a calculation method called a time average spectrum is introduced for time-varying spectral transmission spectrum data. When the in vitro SPF prediction value is calculated using the concept of the time average spectrum, a method for obtaining a final in vitro SPF prediction value having a high correlation with the in vivo SPF value can be constructed.

  The time-average spectrum shown here is the average of the spectral transmission intensity for each wavelength from the spectrum data at the start of light irradiation to the last spectrum data of the light irradiation time acquired at an arbitrary number of times. It has been processed.

  Specifically, the final in vitro SPF prediction value is obtained by measuring a spectral transmission spectrum with respect to a plurality of standard samples whose in vivo SPF values are known, and calculating the spectrum and the known in vivo SPF values. The correlation is calculated from a calibration curve derived by performing analysis by the PLS regression analysis method from the transmitted light intensity for each wavelength, and a result obtained by correcting the spectral transmission spectrum obtained in this measurement to a time average spectrum.

  By introducing the above-described calculation method, the final in vitro SPF value is predicted by the same calculation method from a measurement sample that is easily affected by light deterioration to a measurement sample that is not easily affected by light deterioration phenomenon. It becomes possible.

(Flow of UV protection effect evaluation method)
FIG. 4 is a flowchart of the method for evaluating the ultraviolet protection effect of the present embodiment.

  The above-described method for evaluating the UV protection effect is summarized as a procedure. Referring to FIG. 4A, it is a flow of preliminary measurement performed prior to the main measurement.

  The spectral transmission spectrum of the sample in the ultraviolet region of 290 to 400 nm is measured every 1 nm (S101).

  Preliminary in vitro SPF prediction of a measurement sample from a spectral transmission spectrum using a calibration curve obtained by multivariate regression analysis of the spectral transmission spectrum of a standard sample with a known in vivo SPF value and the in vivo SPF value A value is calculated (S102).

  For the provisional in vitro SPF predicted value [A], the light irradiation time is determined in the range of [A] × 0.08 (min) or more and less than [A] × 1.50 (min) (S103).

  Referring to FIG. 4B, this is a flow of the main measurement performed after the preliminary measurement.

  During the time determined in S103, the measurement sample is continuously irradiated with light, and spectral transmission spectrum data is acquired for each arbitrary time period (S151).

  The obtained spectral transmission spectrum for each elapsed time is subjected to a time averaging process to calculate a time average spectrum in which light degradation of the measurement sample is corrected (S152).

  A final in vitro SPF prediction value is calculated using the obtained time-average spectrum and the calibration curve obtained in S102 (S153).

  Here, in the above-described embodiment, the process of performing the preliminary measurement before the main measurement is described. However, for example, when there is a track record of evaluating a similar sample in the main measurement system in the past, there is no measurement track record. Both can be easily predicted from similar prescription examples with measurement results (for example, when SPF20 is predicted at 10% titanium oxide and SPF10 is predicted at 5%, prescription of 7% titanium oxide is SPF14. Preliminary measurement can be omitted as necessary when the value of the in vivo SPF is empirically known. In other words, preliminary measurement is important in order to perform prediction with high accuracy, but it may be omitted depending on various conditions such as shortening the processing time.

  The embodiment will be described in more detail by way of examples. In the following examples, preliminary measurement is performed.

[Example 1]
(Measurement condition)
In the measurement apparatus shown in the above-described embodiment, the light emitted from the xenon lamp light source is transmitted through the WG320 filter and the UG11 filter (both manufactured by SCHOTT) to obtain light with a wavelength of 290 to 400 nm. As the skin substitute film, a PMMA (polymethyl methacrylate) resin plate (Plexiglas ^™ , manufactured by Schonberg GmbH & Co. KG) is used and disposed so as to have an irradiation distance of 1 to 2 mm from the light source. At this time, the intensity of UV-B is set to 2.0 MED / min. The amount of application of the sample on the PMMA resin plate was 0.75 mg / cm ² , and a predetermined amount of sample was weighed and then applied to the surface of the PMMA resin plate by spreading with a finger for 1 minute. After coating, the sample was dried for 15 minutes at 25 ° C. In preliminary measurement, light irradiation for 30 seconds is performed for 1 MED.

(Sample measurement)
Under the measurement conditions described above, measurement was performed on sample A for which the in vivo SPF value was unknown. As a result of the preliminary measurement, the provisional in vitro SPF predicted value is 29.8, so the light irradiation time in this measurement is determined to be 29.8 × 0.5 = 14.9 minutes (14 minutes 54 seconds). did. In this measurement, continuous irradiation for this light irradiation time was performed. In addition, the light irradiation time of 14 minutes and 54 seconds was equally divided into five equal intervals, and a total of six points of spectral data were acquired including the time of light irradiation start. With respect to the spectrum data of these six points, a time average spectrum was calculated for each wavelength, and a final in vitro SPF predicted value 21.9 was obtained. This final in vitro SPF value approximated the later obtained in vivo SPF value of 22.5. Table 1 shows the in vivo SPF values and the preliminary and final in vitro SPF predicted values for Sample A.

[実施例２]
測定条件については、実施例１と同様の条件において、ｉｎ ｖｉｖｏ ＳＰＦ値が未知である試料Ｂについて測定を行った。予備測定の結果、暫定ｉｎ ｖｉｔｒｏ ＳＰＦ予測値は、７０．５であることから、本測定での光照射時間は、７０．５×０．５＝３５．２５分（３５分１５秒）と決定した。本測定では、この光照射時間の継続照射を行った。また、光照射時間３５分１５秒を等間隔で１０等分し、光照射開始時を含めて計１１点のスペクトルデータを取得した。この１１点のスペクトルデータについて、波長毎に時間平均スペクトルを算出して、ｉｎ ｖｉｔｒｏ ＳＰＦ予測値６２．４を得た。このｉｎ ｖｉｔｒｏ ＳＰＦ予測値は、後に得たｉｎ ｖｉｖｏ ＳＰＦ値６４．５に近似していた。試料Ｂについての、ｉｎ ｖｉｖｏ ＳＰＦ値、並びに、暫定及び最終的なｉｎ ｖｉｔｒｏ ＳＰＦ予測値を表１に示す。

[Example 2]
With respect to the measurement conditions, measurement was performed on Sample B whose in vivo SPF value was unknown under the same conditions as in Example 1. As a result of the preliminary measurement, the provisional in vitro SPF predicted value is 70.5, so the light irradiation time in this measurement is determined as 70.5 × 0.5 = 35.25 minutes (35 minutes and 15 seconds). did. In this measurement, continuous irradiation for this light irradiation time was performed. Further, the light irradiation time of 35 minutes and 15 seconds was equally divided into 10 equal intervals, and a total of 11 points of spectrum data including the time of light irradiation start were obtained. With respect to the 11 points of spectrum data, a time average spectrum was calculated for each wavelength, and an in vitro SPF predicted value 62.4 was obtained. This in vitro SPF predicted value approximated the in vivo SPF value 64.5 obtained later. Table 1 shows the in vivo SPF values and the preliminary and final in vitro SPF predicted values for Sample B.

[Example 3]
As for the measurement conditions, measurement was performed on the sample C in which the in vivo SPF value was unknown under the same conditions as in Example 1. As a result of the preliminary measurement, the provisional in vitro SPF predicted value is 32.9, so the light irradiation time in this measurement is determined as 32.9 × 0.5 = 16.25 minutes (16 minutes 15 seconds). did. In this measurement, continuous irradiation for this light irradiation time was performed. Further, the light irradiation time of 16 minutes and 15 seconds was equally divided into 5 equal parts, and a total of 6 points of spectral data including the time of light irradiation start were obtained. With respect to the 11 points of spectrum data, a time-average spectrum was calculated for each wavelength, and a final in vitro SPF predicted value 32.2 was obtained. This final in vitro SPF predicted value approximated the in vivo SPF value 31.5 obtained later. Table 1 shows the in vivo SPF values and the provisional and final in vitro SPF predicted values for Sample C.

  In Example 3, the provisional and final in vitro SPF predicted values were approximated because the sample C was hardly affected by light deterioration due to continuous irradiation of light. It is considered that the compounding component of Sample C has a small content of an organic ultraviolet absorber that is easily affected by light deterioration, and is mainly composed of inorganic titanium oxide or zinc oxide.

[Comparative Examples 1 to 3]
About the above-mentioned sample A, B, and C, it measured using the measurement conditions of Example 2 in patent document 1 which is a conventional method, and obtained the in vitro SPF predicted value of each sample. Table 1 shows the predicted in vitro SPF values of Samples A, B, and C obtained here.

[Comparative Examples 4 to 6]
About the above-mentioned sample A, B, and C, it measured using the method of the nonpatent literature 1 which is a conventional method, and obtained the in vitro SPF predicted value of each sample. Table 1 shows the predicted in vitro SPF values of Samples A, B, and C obtained here.

  Referring to Table 1, in Examples 1 to 3, the final in vitro SPF predicted value by this evaluation method was very close to the in vivo SPF value obtained later. This result can be said to prove the validity of this evaluation method. In addition, the final in vitro SPF predicted value obtained by this evaluation method is more approximate to the in vivo SPF value than the in vitro SPF predicted value obtained by the conventional evaluation method disclosed in Patent Document 1 and Non-Patent Document 1. It was. Therefore, it can be said that this evaluation method is superior to the conventional method in predicting the in vivo SPF value.

  According to this example, an in vitro SPF showing a high correlation with an in vivo SPF value even in a sample that reflects the photodegradation phenomenon of the sample due to irradiation light and exhibits a high UV protection effect exceeding the SPF value of 50. A predicted value can be obtained.

  In addition, since the in vitro SPF predicted value obtained by this measurement method has a very high correlation with the in vivo SPF value, the SPF value of the sample can be easily and rapidly changed in the development stage of cosmetics having an effect of preventing sunburn. It can be measured by a highly accurate method. Therefore, the development cost is low and many samples can be evaluated at the development stage. Therefore, the use of this evaluation method can further accelerate the development of cosmetics that have a high-performance sun protection effect. I can expect.

  Furthermore, it can be applied to the development and evaluation of nanomaterials and UV absorbers.

  The preferred embodiments and examples of the present invention have been described in detail above, but the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

It is a figure which shows an example of schematic structure of the evaluation apparatus of the ultraviolet protection effect of this embodiment. It is a figure which shows an example of a function structure of the evaluation apparatus of the ultraviolet protection effect of this embodiment. It is a figure which shows the correlation of the known in vivo SPF value in the standard sample of this embodiment, and the estimated in vitro SPF value. It is a flowchart of the evaluation method of the ultraviolet protection effect of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultraviolet rays protection effect evaluation apparatus 11 Light source 12 Filter 13 Optical fiber 14 Irradiation port 15 Sample 16 Skin substitute film 17 Spectrometer 18 Photo detector 19 Computer 21 Input means 22 Output means 23 Accumulation means 24 Spectral transmission spectrum measurement means 25 Irradiation Time setting means 26 Aging measurement means 27 Correction means 28 SPF predicted value calculation means 29 Control means

Claims (10)

A first step of measuring a time-dependent change of a spectral transmission spectrum of a measurement sample by light irradiation of a light source including ultraviolet rays according to a preset light irradiation time;
A second step of performing correction according to a change with time of the spectral transmission spectrum of the measurement sample based on the measurement result obtained by the first step;
And a third step of calculating a final in vitro SPF predicted value of the measurement sample using the correction result obtained in the second step. The first step includes
A spectral transmission spectrum measurement step of measuring a spectral transmission spectrum of the measurement sample in a predetermined ultraviolet region at a predetermined wavelength interval;
2. The method for evaluating an ultraviolet protection effect according to claim 1, further comprising an irradiation time setting step of setting a light irradiation time from the spectral transmission spectrum obtained by the spectral transmission spectrum measurement step. The irradiation time setting step includes:
A correlation is calculated by a multivariate regression analysis method from a known in vivo SPF value of the standard sample and the spectral transmission spectrum of the standard sample, and a temporary in vitro of the measurement sample is calculated from the correlation and the spectral transmission spectrum of the measurement sample. An SPF prediction value is calculated, and the light irradiation time is set to a time that is equal to or longer than the time obtained by multiplying the provisional in vitro SPF prediction value by 0.08 and less than the time obtained by multiplying the provisional in vitro SPF prediction value by 1.50. The method for evaluating an ultraviolet protective effect according to claim 2. The multivariate regression analysis method is:
4. The method for evaluating an ultraviolet protective effect according to claim 3, wherein a PLS (Partial Last Squares) regression analysis method is used. The first step includes
For the time-dependent change of the spectral transmission spectrum of the measurement sample, the light irradiation time is controlled in seconds, and the spectral transmission spectrum data is acquired at any time during the light irradiation time. The method for evaluating an ultraviolet protective effect according to any one of claims 1 to 4. The first step includes
6. The method for evaluating an ultraviolet protection effect according to claim 1, wherein a change with time of the spectral transmission spectrum in the measurement sample due to light deterioration is measured. The second step includes
The method for evaluating an ultraviolet protection effect according to any one of claims 1 to 6, wherein a change with time of the spectral transmission spectrum measured in the first step is corrected as a time average spectrum. The third step includes
The final in vitro SPF prediction value is calculated from the correlation calculated in the irradiation time setting step and the time average spectrum corrected in the third step. Evaluation method of UV protection effect. The spectral transmission spectrum measurement step includes:
3. The spectrum of the ultraviolet ray that has passed through the measurement sample and the skin substitute film is measured by irradiating the ultraviolet ray to the skin substitute film that transmits the ultraviolet ray to which the measurement sample is applied. For evaluating the UV protection effect of selenium. A time-change measuring means for measuring a time-dependent change of a spectral transmission spectrum of a measurement sample by light irradiation of a light source including ultraviolet rays according to a preset light irradiation time;
Correction means for performing correction according to a change with time of the spectral transmission spectrum of the measurement sample based on the measurement result obtained by the measurement means;
And an SPF predicted value calculating means for calculating a final in vitro SPF predicted value of the measurement sample using a correction result obtained by the correcting means.

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