Method for evaluating pruritus improvement effect of cosmetics based on Chinese yam induction
By using a yam-induced cosmetic evaluation method, and employing EEG data and a multiple regression model, the efficacy of cosmetics in improving itching was assessed. This approach resolved the subjectivity issue in cosmetic evaluation and achieved an objective and stable assessment of its effectiveness in reducing itching.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-12
- Publication Date
- 2026-04-10
AI Technical Summary
Existing methods for evaluating itching caused by cosmetics are highly subjective, making it difficult to guarantee objectivity and stability, and they lack effective evaluation methods for non-histamine-induced itching.
This study employed a method for evaluating the itch-relieving effects of cosmetics based on yam-induced irritation. By recording EEG data from the participants' skin surface, calculating the power values of the θ and β bands, and combining this with the relaxation index S, a multiple linear regression or principal component regression model was established to assess the itch-relieving effects of the cosmetics.
It enables an objective and accurate evaluation of the itch-relieving effects of cosmetics, refines the evaluation process, improves the stability of the evaluation and the tolerance of participants, and is applicable to the evaluation of cosmetics for different itch conditions.
Smart Images
Figure CN121817891A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of cosmetic efficacy evaluation technology, specifically to a method for evaluating the itch-relieving effect of cosmetics based on yam-induced efficacy. Background Technology
[0002] Itching is often defined as an unpleasant sensation that triggers the urge to scratch, affecting people's daily lives. Using appropriate cosmetics for skin care can alleviate itching symptoms to some extent. Therefore, establishing suitable evaluation methods is crucial for the development of cosmetics that relieve itching symptoms and for the screening of cosmetic ingredients.
[0003] Itching includes histamine-induced pruritus and non-histamine-induced pruritus. Histamine-induced pruritus is mainly mediated through histamine receptors (H1R, H4R) and TRPV1 pathways, and is mostly associated with acute pruritus; while non-histamine-induced pruritus involves multiple receptors and pathways, such as MrgprA3, PAR2, and NK1R, and is mainly associated with chronic pruritus. Histamine is the main substance that triggers histamine-induced pruritus, and histamine-induced pruritus is often accompanied by wheals, erythema, and flushing. Histamine-induced skin itching has been extensively studied, but it is highly irritating to participants. Currently, there is less research on non-histamine-induced pruritus associated with chronic pruritus. The triggers for non-histamine-induced pruritus are diverse, including neuropeptides, proteases, bile acids, and chloroquine. These substances trigger non-histamine-induced pruritus by activating different receptors and signaling pathways.
[0004] Yam is a traditional Chinese medicinal herb used in both food and medicine. Its juice, when in contact with the skin, can cause intense itching. Related research suggests that allantoin and cysteine proteases (such as CCP2) in yam may be the active ingredients responsible for the itch: allantoin can directly activate dorsal root ganglion (DRG) neurons, inducing calcium influx and inward currents, thereby triggering the transmission of itch signals; CCP2 activates the peripheral itch pathway by activating the protease-activated receptor (PAR). Yam-induced itching is usually not accompanied by symptoms such as skin redness, swelling, blisters, or wheals, and the duration of itching is short, with good tolerance among participants. Although yam is suitable as a material for establishing itch models, there is currently a lack of research on itch evaluation / intervention methods based on yam-induced itch.
[0005] On the other hand, current assessments of pruritus primarily rely on questionnaires, such as the verbal rating scale (VRS), numerical rating scale (NRS), and visual analogue scale (VAS), which directly reflect the severity of pruritus. Secondly, pruritus can also be indirectly assessed through its impact on patients' quality of life, using scores such as itchy quality of life (ItchyQol) and dermatology life quality index (DLQI).
[0006] In subjective assessments, the NRS and VAS are widely used, both of which quantify the degree of itching with a score of 0 to 10 (Pereira MP, Ständer S. Assessment of severity and burden of pruritus [J]. Allergol Int, 2017, 66(1):3-7. doi: 10.1016 / j.alit.2016.08.009.). However, they are highly subjective, with significant differences between individuals and even among the same participant under different conditions, making it difficult to guarantee objectivity and stability. Summary of the Invention
[0007] Based on this, the purpose of this application is to provide a method for evaluating the effect of cosmetics on pruritus that is well tolerated by participants and yields objective and accurate results.
[0008] To achieve the above objectives, this application adopts the following technical solution: A method for evaluating the pruritus-relieving effect of cosmetics based on yam-induced pruritus is provided, including the following steps: S1. Screen participants who are sensitive to yam, and mark two skin test areas of the same size on the participants' skin surface. Randomly select one area as the blank control side and the other as the sample side. S2. Record the effect of applying the test cosmetic during the itch stimulation phase on the participants' EEG data: S21. Apply yam extract to the blank control side to create an itchy stimulus, and collect the EEG data D1 of the participants after application; S22. The blank control side is not coated with the cosmetic to be tested, and the EEG data D2 of the participants continues to be collected; S23. After the participants have been in equilibrium for 20-30 minutes, the same amount of yam extract as the blank control side is applied to the sample side to create an itchy stimulus. After the application is completed, the participants' EEG data D1' is collected. S24. Apply the cosmetic to be tested evenly to the sample side, and collect the EEG data D2' of the participant after application; Steps S22 and S24 are performed during the period when the degree of skin itching is increasing or decreasing after applying the yam extract. S3. Calculate the emotional change parameters of the blank control side and the sample side in each test stage based on the power values of the θ and β frequency bands in the EEG data of the blank control side and the sample side; The emotion change parameter includes the relaxation index S, which is defined as Power(θ) / Power(β). If the sample side shows improved mood change parameters after applying the test cosmetic during the itch stimulation stage, then the test cosmetic is judged to have the effect of improving itch.
[0009] In a preferred embodiment, step S3 further includes assessing the degree of itching caused by the yam extract, thereby evaluating the degree to which the cosmetic product improves itching: A1. Record the participants' subjective VAS score Y at the onset of itching, and denote the physiological indicators related to itching, including the relaxation index S, as X1, X2, ..., X... m ; Calculate each X separately m The correlation with Y and the p-value were determined, and a significance level of α=0.05 was set to screen out physiological indicators with p<0.05. A2. Using Y as the dependent variable and the physiological indicators selected in step A1 as independent variables, establish a multiple linear regression model: ; The coefficients β0, β1, ..., β are estimated using the least squares method. m； A3. Constructing comprehensive indicators: ; A4. Verify the aforementioned comprehensive indicators: Calculate the correlation coefficient between Y and Z. If r(Z, Y) > 0.8, it indicates that the comprehensive index is effective. A5. If the aforementioned comprehensive indicators are effective, then the degree of itching Z is: .
[0010] In another preferred embodiment, step S3 further includes assessing the degree of itching caused by the irritation from the yam extract, thereby evaluating the degree to which the cosmetic product improves itching: B1. Record the participants' subjective VAS score Y at the onset of itching, and denote the physiological indicators related to itching, including the relaxation index S, as X1, X2, ..., X... p The X1, X2, ..., X p Standardized; B2. Let the variable Use the following PCA model: ; in, It is the load vector; The optimal k principal components are selected through cross-validation; B3. Use the following principal component regression model: ; Will Substituting, we get: ;
[0011] B4. Obtain the information from step B3. Combined into a linear combination of the original variables, let Its weight ; B5. The degree of itching (Z) is: ;
[0012] in, =The j-th principal component pair X i The load, =Y to PC j The regression coefficients, =The intercept of principal component regression.
[0013] More preferably, the physiological indicators other than the relaxation index S include potency V, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR.
[0014] Preferably, the yam extract is prepared according to the following steps: M1: Mix yam with purified water and homogenize for 1-5 minutes to obtain a mixed homogenate; M2: Filter the mixed homogenate through a 150-250 mesh filter to obtain the filtrate; M3: The filtrate is centrifuged at 800~1500rpm for 3~8min, and the supernatant is collected to obtain the yam extract.
[0015] More preferably, the two test areas are respectively located on the inner side of the participant's forearm, and the test area is 3cm×3cm in size; The amount of the yam extract applied is 10-30 μL, and the application time is 0.5-1.5 min. The amount of the cosmetic product to be tested applied was 1.5~2.5 mg / cm³. 2 The application time is 1-2 minutes.
[0016] Preferably, before processing the blank control side and the sample side with yam extract, the static electroencephalogram (EEG) data of the participants are also collected respectively.
[0017] Preferably, each EEG data acquisition stage is accompanied by an emotion scale score for auxiliary evaluation, and steps S22 and S24 are accompanied by a self-assessment questionnaire score for auxiliary evaluation.
[0018] More preferably, the emotion scale scoring uses the SAM emotion scale, the evaluation dimensions of which include valence and arousal; In the valence, 1 represents "very unpleasant", 5 represents "moderate", and 9 represents "very pleasant"; in the arousal level, 1 represents "very calm", 5 represents "moderate", and 9 represents "very excited".
[0019] More preferably, the self-assessment questionnaire includes: improved skin discomfort, more pleasant mood, improved anxiety, improved tension, improved irritability, and overall satisfaction with the product's effects; In the self-assessment questionnaire, 1 indicates "strongly disagree", 2 indicates "somewhat disagree", 3 indicates "neutral", 4 indicates "somewhat agree", and 5 indicates "strongly agree". The self-assessment questionnaire's acceptance level is calculated as follows: Acceptance level = Number of participants who selected "Rating > 3 points" / Number of valid participants × 100%.
[0020] The technical solution claimed in this application achieves the following beneficial effects: 1. The established evaluation method can assess the itch-reducing effect of the tested cosmetics during the itch onset or recovery phase of itch stimulation, refining the exploration of the itch-reducing effect of the tested cosmetics. Furthermore, by measuring the electrical activity of the cerebral cortex under itch-related conditions, subtle emotional changes can be accurately recorded. By analyzing indicators such as EEG frequency power, the connection between brain neural activity and different itch-related stimuli can be objectively and accurately reflected, thus reflecting the changes before and after intervention with itch-reducing products and more accurately evaluating the itch-reducing effect of the tested cosmetics.
[0021] 2. Since itch induced by yam is usually not accompanied by symptoms such as skin redness, swelling, blisters, or wheals, and the duration of itching is short, it is well tolerated by participants and is a suitable irritant. Furthermore, establishing an evaluation model for itch induction using yam extract obtained through crude extraction is convenient, quick, and low-cost.
[0022] 3. Based on this yam-induced evaluation model, the degree of itching can be used as a standard to screen and control factors such as mixing ratio, centrifugation parameters, application amount and application time in the yam extraction process to ensure the flexibility and feasibility of the model, and it can be applied to the evaluation of cosmetics with different itching conditions.
[0023] 4. By establishing a computational model, complex evaluation parameters such as the relaxation index S, potency, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR obtained during the itch stimulation phase are transformed into a simple itch severity parameter. This parameter evaluates the itch severity caused by the stimulation of yam extract, thereby further evaluating the degree of itch improvement that the tested cosmetic can improve, achieving a comprehensive, detailed, and accurate assessment of the itch-improving effect of the cosmetic. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0025] Figure 1 This is a schematic diagram of electrode localization for the entire brain.
[0026] Figure 2 This is a schematic diagram showing the correspondence between electrodes and brain regions.
[0027] Figure 3 This is a schematic diagram illustrating the effect of centrifugation conditions on the degree of itching induced by the yam-induced model.
[0028] Figure 4 A schematic diagram of brain topography of participants during the evaluation of the itch-reducing effect of the tested cosmetic. Detailed Implementation
[0029] To make the objectives, technical solutions, and beneficial effects of the embodiments in this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0030] <Example 1> This embodiment provides a method for evaluating the pruritus-relieving effect of cosmetics based on yam-induced pruritus, specifically as follows: (1) Participant selection Selection criteria: 1. Age between 18 and 40 years old, in good health; 2. No allergic diseases, and no history of allergies to cosmetics or other topical preparations; 3. The dominant hand is right, there is no sleep disorder, and there is no head trauma or brain disease; 4. Wash your hair the night before the test and ensure you get enough sleep; 5. Do not consume alcohol or caffeinated beverages for 8 hours prior to the test; 6. Be able to understand the testing process, voluntarily participate in the test and sign a written informed consent form, and comply with the testing procedures.
[0031] Exclusion criteria: 1. Women who are planning to become pregnant, are pregnant, are breastfeeding, or are within six months postpartum; 2. Individuals with severe systemic diseases, immunodeficiency, or autoimmune diseases; 3. Individuals who have used antihistamines within the past week or immunosuppressants within the past month; 4. The skin area to be tested has scars, pigmentation, atrophy, port-wine stains, or other blemishes that may affect the test results; 5. Individuals who have participated in other clinical trials in the target region within the past three months; 6. Patients with respiratory diseases who are currently receiving treatment; 7. People currently undergoing skin treatment; 8. Patients with insulin-dependent diabetes mellitus; 9. Other relevant exclusion criteria.
[0032] (2) Testing process Step S1: Screen participants sensitive to the yam-induced model. In this embodiment, the criteria for sensitivity to the yam-induced model are: having normal perceptual abilities and being able to express them clearly; and being able to feel obvious subjective itching when the yam-induced model is applied to the skin.
[0033] S2, Data Acquisition This step establishes a yam-induced itch evaluation model on the participants' skin surface and records the effect of applying the tested cosmetic during the itch stimulation phase on the participants' electroencephalogram (EEG) data. Specifically, this is done as follows: S21, T base1 Basic phase data collection: 5 minutes of static EEG data were collected from participants; S22, T irritation1 Collection during the stimulation phase: Clean the inside of the participant's forearm and mark a 3cm x 3cm test area at the same location on both arms; The test area of one arm of the participant was randomly selected as the blank control side. Yam extract was applied to complete the pretreatment (the amount applied was 10~30 uL, and the application time was 0.5~1.5 min). Then, the participants' EEG data were collected for 5 minutes. S23, T sample1 Sample collection phase: No cosmetics were applied to the blank control side, and EEG data were collected directly from the participants for 5 minutes. S24, participants balance for 20-30 minutes; S25, T base2 Basic phase data collection: 5 minutes of static EEG data were collected from participants; S26, T irritation2 Collection during the stimulation phase: The test area on the other arm of the participant was the sample side. Yam extract was applied to the sample side in the same way as in step S22 to complete the pretreatment. Then, the participant's EEG data was collected for 5 minutes. S27, T sample2 Sample collection: The cosmetic product to be tested was evenly applied to the sample side manually, with the amount applied controlled at 2.0 ± 0.1 mg / cm³. 2 Latex gloves must be worn during manual application. The cosmetic application time is 1.5 minutes. After the application is completed, EEG data will be collected from the participants for 5 minutes. Steps S23 and S27 are performed during the period when the degree of skin itching increases after applying the yam extract (itching onset period) or during the period when the degree of skin itching decreases (itching recovery period). In this embodiment, the steps are performed during the itching onset period. The complete trend of skin itching after applying the yam extract can be measured in advance by electroencephalography or other methods. The specific relationship between the degree of itching and time after applying the yam extract is related to the amount applied, the treatment method of the yam extract, etc. For example, in some experiments, the period when the degree of itching of the participants increases is about 5 minutes after applying the yam extract, while from about 6 minutes after applying the yam extract, the participants' itching gradually decreases until it disappears. Step S3, Result Analysis: Analyze the power values of the θ and β bands of the recorded EEG data of the participants, and calculate the emotional change parameters of the sample side and the blank control side at each test stage. Compare the emotional change parameters of the sample side and the blank control side at different test stages. If the sample side shows improved emotional change parameters after applying the sample during the itch stimulation stage, and these parameters are better than those of the blank control side, then the tested cosmetic product is judged to have an effect on improving itch; otherwise, the tested cosmetic product does not have an effect on improving itch. Among them, the emotion change parameter includes the relaxation index S, which is calculated by the formula: S = Power(θ) / Power(β).
[0034] In this embodiment, the conditions for establishing the yam-induced pruritus evaluation model are as follows: M1: Peel and wash the yam, mix it with purified water at a ratio of 1:1 (w / w), and homogenize for 3 minutes to obtain a mixed homogenate; M2: Filter the mixed homogenate through a nylon filter screen (200 mesh) to obtain the filtrate; M3: Centrifuge the filtrate at 1000 rpm for 5 min at room temperature, and take the supernatant to obtain yam extract; M4: 20uL of supernatant was manually applied to the marked skin test area to complete the establishment of the yam induction model.
[0035] (3) Results Analysis In this embodiment, a total of 14 participants were enrolled, with 12 valid cases. Among them, there were 0 males and 12 females, with an average age of 37.3±5.2 years and Asian skin type.
[0036] Using the ANT Neuro portable EEG instrument eego™ mylab 32-channel, emotions were reflected through 32 electrodes. The whole brain average was used as the reference electrode. The M1 and M2 electrodes were removed. The high-pass filter was 0.1Hz and the low-pass filter was 50Hz. The power values of the θ and β frequency bands were analyzed and the relaxation index S was calculated. Figure 1 This is a schematic diagram of electrode localization across the entire brain. Figure 2 This shows the correspondence between electrodes and brain regions.
[0037] The relaxation index S of the participants in this embodiment at each test stage is shown in Table 1.
[0038] Table 1: Relaxation Index S of Participants in Each Test Phase
[0039] Note: ° indicates the relationship with T. base The difference was statistically significant (p < 0.05), * indicates that the difference was statistically significant compared to T. irritation The difference was statistically significant (p < 0.05); # indicates a statistically significant difference compared to T. base The differences between the groups were statistically significant (p < 0.05).
[0040] The cosmetic product tested in this embodiment is a cream that claims to improve itchy and uncomfortable skin. Based on the participants' T... base T irritation T sample The brain topography map plotted based on the relaxation index S of the stage is as follows: Figure 4 As shown, the EEG topography reflects the spatial distribution of Power(θ) / Power(β), with colors ranging from blue to red representing increasing ratios, and the redder the color, the greater the relaxation index.
[0041] As shown in Table 1, compared to the resting state in the baseline phase, the relaxation index S decreased in both the sample and control groups during the stimulation phase. In the sample phase, the control group, without the application of the test cosmetic, showed a consistently decreasing and significantly different relaxation index S, indicating an overall non-relaxed trend in the brain. The sample group showed an increase in the relaxation index S, indicating an overall relaxation trend in the brain after applying the test cosmetic. The change in the relaxation index S in the sample group was better than that in the control group. Therefore, compared to the control group, the sample group showed an improved relaxation index after applying the cosmetic during the itch stimulation phase, indicating that the test cosmetic has an effect on improving itch.
[0042] In this embodiment, since the itching caused by yam is usually not accompanied by symptoms such as skin redness, blisters, or wheals, and the duration of itching is short, the participants tolerate it well, making it a suitable irritant. Furthermore, the evaluation model for itch induction is established directly using yam extract obtained through crude extraction, a convenient, quick, and low-cost process. In addition, the degree of itching can be used as a standard to screen and control factors in the yam extraction process, such as mixing ratio, centrifugation parameters, application amount, and application time during model establishment (e.g., Figure 3 The effect of centrifugation conditions on the degree of pruritus induced in the yam-induced model is shown to ensure the flexibility and feasibility of the model, which can be applied to cosmetic evaluations of different pruritus conditions.
[0043] The evaluation method established in this embodiment can assess the itch-reducing effect of the tested cosmetic during the itch onset or itch recovery phase of the itch stimulation stage, thus refining the exploration of the itch-reducing effect of the tested cosmetic. On the other hand, in order to improve the objectivity of itch assessment, existing technologies also use instrument detection methods. Instrument detection starts from physiological indicators, such as the degree of skin redness, skin barrier function (transepidermal water loss rate, etc.), heart rate, etc. For example, Aliotta et al. used the VAS scale and blood perfusion to assess the degree of itch caused by papain; Stefanie H. Meeuwis et al. used heart rate and skin conductivity to assess the degree of itch (Meeuwis SH, van Middendorp H, Pacheco-Lopez G, et al. Antipruritic placebo effects by conditioning H1-antihistamine [J]. Psychosomatic medicine, 2019, 81(9): 841-850.). Studies have found a close correlation between itching sensations and changes in neural activity in specific areas of the cerebral cortex. Emotions play a crucial role in the perception and relief of itching. While existing instrumental tests offer some objectivity, they cannot directly reflect the brain's emotion-related activities during itching, and are even less capable of accurately capturing the emotional changes caused by itching. Compared to existing instrumental tests, this embodiment uses a portable electroencephalogram (EEG) to measure the electrical activity of the cerebral cortex under varying itching conditions. This allows for precise recording of these subtle changes. By analyzing indicators such as EEG frequency power, the connection between brain neural activity and different itching stimuli can be objectively and accurately reflected. This, in turn, reflects the changes before and after intervention with anti-itch products, enabling a more accurate evaluation of the anti-itch effects of cosmetics.
[0044] In the preferred embodiment, to make the evaluation of the cosmetic's effect on improving itching more comprehensive, this embodiment can also use an emotion scale score for auxiliary evaluation at each stage of EEG data acquisition. The emotion scale can be the SAM Emotion Scale (Self-Assessment Manikin), which has two assessment dimensions. One is valence, which measures the positive or negative characteristics of emotion, i.e., the degree of positive or negative emotion. An increase in valence indicates that the participant has a positive emotional tendency (a score of 1 indicates "very unpleasant", a score of 5 indicates "moderate", and a score of 9 indicates "very pleasant"). The other is arousal, which measures the degree of emotional activation, with a score of 1 indicating "very calm", a score of 5 indicating "moderate", and a score of 9 indicating "very excited".
[0045] In T sample1During the sample phase of EEG data acquisition and T sample2 Self-assessment questionnaires can also be used in conjunction with EEG data collection during the sample phase. The self-assessment questionnaire's agreement level is calculated as follows: Agreement Level = Number of participants who selected "score > 3" / Number of valid participants × 100%, where the rating scale is from 1 to 5 (score 1 indicates "strongly disagree," score 2 indicates "somewhat disagree," score 3 indicates "neutral," score 4 indicates "somewhat agree," and score 5 indicates "strongly agree"). Furthermore, the self-assessment questionnaire can include: improved skin discomfort, improved mood, improved anxiety, improved tension, improved irritability, and overall satisfaction with the product's effects.
[0046] <Example 2> This embodiment establishes a calculation module based on Embodiment 1. Using a computer calculation model, it combines the relaxation index S of the participants obtained through the itch evaluation model of Embodiment 1 with other measured parameters such as potency V, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR to evaluate the degree of itch caused by the stimulation of yam extract. This further evaluates the degree of itch that the tested cosmetic can improve, achieving a comprehensive, detailed, and accurate assessment of the itch-improving effect of the cosmetic.
[0047] In one exemplary embodiment, this method is performed according to the following steps: S1. Correlation Analysis After yam-induced skin itching, participants' subjective itch scores (VAS subjective scores, denoted as Y) were recorded.
[0048] Multiple physiological indicators of participants at the onset of itching, such as potency, relaxation index S, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR, were denoted as X1, X2, ..., X m .
[0049] For continuous Y, if it is approximately continuous and normally distributed, use the Pearson correlation coefficient r. If it does not satisfy the normality requirement, use the Spearman rank correlation ρ.
[0050] For each X m Calculate the correlation with Y and the p-value respectively, set the significance level (e.g., α=0.05), and select the physiological indicators with p<0.05.
[0051] The mathematical formula for calculating the Pearson correlation coefficient r is as follows:
[0052] and These are the average values of X and Y, respectively.
[0053] S2. Multiple linear regression Using the subjective pruritus score Y as the dependent variable, the physiological indicators X1, X2, ..., X... selected in step S1 are... m As the independent variable, a multiple linear regression model is established:
[0054] Estimate the coefficients β0, β1, ..., β in the above model using the least squares method. m .
[0055] S3. Constructing comprehensive indicators The comprehensive index Z can be defined as the predicted value:
[0056] S4. Verification Calculate the correlation coefficient between Z and Y. If r(Z,Y) is very high (e.g., >0.8), it indicates that the comprehensive index is effective.
[0057] S5. If the comprehensive indicators are effective, then the degree of itching Z is:
[0058] In another exemplary scheme, if there is strong collinearity among the physiological indicators, this embodiment can also proceed as follows: First, perform principal component analysis (PCA) on X, and take the first k principal components PC1, PC2, ..., PC... k Then, regression analysis is performed on these principal components using the dependent variable Y. The specific steps are as follows: S1': Record the participant's subjective itch score (VAS subjective score) as Y.
[0059] Multiple physiological indicators of participants at the onset of itching, such as potency, relaxation index S, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR, were denoted as X1, X2, ... X p (Standardized)
[0060] S2': Let variable X = [X1,X2,...,X... p ] .
[0061] Use the following PCA model:
[0062] in, It is the load vector (unit length).
[0063] The optimal k principal components are selected through cross-validation.
[0064] S3': Use the following principal component regression model:
[0065] Will Substituting, we get:
[0066] S4': Obtained from S3' The merging of the variables into a linear combination of the original variables, let
[0067] This is a vector with the following components:
[0068] Therefore, the degree of itching Z is:
[0069] Where Z represents the degree of itching, = The j-th principal component pair X i The loads (from the PCA load matrix). =Y to PC j The regression coefficients, = Intercept of principal component regression.
[0070] The embodiments and application examples described above are merely illustrative descriptions of this application and are not intended to limit the scope of this application. Any modifications and improvements made to the technical solutions of this application by those skilled in the art without departing from the spirit of this application should fall within the protection scope defined by this application.
Claims
1. A method for evaluating the pruritus-relieving effect of cosmetics based on yam-induced irritation, characterized in that, Includes the following steps: S1. Screen participants who are sensitive to yam, and mark two skin test areas of the same size on the participants' skin surface. Randomly select one area as the blank control side and the other as the sample side. S2. Record the effect of applying the test cosmetic during the itch stimulation phase on the participants' EEG data: S21. Apply yam extract to the blank control side to create an itchy stimulus, and collect the EEG data D1 of the participants after application; S22. The blank control side is not coated with the cosmetic to be tested, and the EEG data D2 of the participants continues to be collected; S23. After the participants have been in equilibrium for 20-30 minutes, the same amount of yam extract as the blank control side is applied to the sample side to create an itchy stimulus. After the application is completed, the participants' EEG data D1' is collected. S24. Apply the cosmetic to be tested evenly to the sample side, and collect the EEG data D2' of the participant after application; Steps S22 and S24 are performed during a period when the degree of skin itching is increasing or decreasing after applying the yam extract. S3. Calculate the emotional change parameters of the blank control side and the sample side in each test stage based on the power values of the θ and β frequency bands in the EEG data of the blank control side and the sample side; The emotion change parameter includes the relaxation index S, which is defined as Power(θ) / Power(β). If the sample side shows improved mood change parameters after applying the test cosmetic during the itch stimulation stage, then the test cosmetic is judged to have the effect of improving itch.
2. The evaluation method according to claim 1, characterized in that, Step S3 further includes assessing the degree of itching caused by the yam extract, thereby evaluating the degree to which the tested cosmetic product improves itching: A1. Record the participants' subjective VAS score Y at the onset of itching, and denote the physiological indicators related to itching, including the relaxation index S, as X1, X2, ..., X... m ; Calculate each X separately m The correlation with Y and the p-value were determined, and a significance level of α=0.05 was set to screen out physiological indicators with p<0.
05. A2. Using Y as the dependent variable and the physiological indicators selected in step A1 as independent variables, establish a multiple linear regression model: ; The coefficients β0, β1, ..., β are estimated using the least squares method. m； A3. Constructing comprehensive indicators: ; A4. Verify the aforementioned comprehensive indicators: Calculate the correlation coefficient between Y and Z. If r(Z, Y) > 0.8, it indicates that the comprehensive index is effective. A5. If the aforementioned comprehensive indicators are effective, then the degree of itching Z is: .
3. The evaluation method according to claim 1, characterized in that, Step S3 further includes assessing the degree of itching caused by the yam extract, thereby evaluating the degree to which the tested cosmetic product improves itching: B1. Record the participants' subjective VAS score Y at the onset of itching, and denote the physiological indicators related to itching, including the relaxation index S, as X1, X2, ..., X... p The X1, X2, ..., X p Standardized; B2. Let variable X = [X1,X2,…,X] p Using the following PCA model: ; in, It is the load vector; The optimal k principal components are selected through cross-validation; B3. Use the following principal component regression model: ; Will Substituting, we get: ; B4. Obtain the information from step B3. Combined into a linear combination of the original variables, let , Its weight ; B5. The degree of itching (Z) is: ; in, =The j-th principal component pair X i The load, =Y to PC j The regression coefficients, =The intercept of principal component regression.
4. The evaluation method according to claim 2 or 3, characterized in that, The physiological indicators other than the relaxation index S include the potency V, skin color a* value, oxyhemoglobin HbO, and deoxyhemoglobin HbR.
5. The evaluation method according to any one of claims 1 to 3, characterized in that, The yam extract is prepared according to the following steps: M1: Mix yam with purified water and homogenize for 1-5 minutes to obtain a mixed homogenate; M2: Filter the mixed homogenate through a 150-250 mesh filter to obtain the filtrate; M3: The filtrate is centrifuged at 800~1500rpm for 3~8min, and the supernatant is collected to obtain the yam extract.
6. The evaluation method according to any one of claims 1 to 3, characterized in that, The two test areas are respectively set on the inner side of the participant's forearm, and the test area is 3cm×3cm in size; The amount of the yam extract applied is 10-30 μL, and the application time is 0.5-1.5 min. The amount of the cosmetic product to be tested applied was 1.5~2.5 mg / cm³. 2 The application time is 1-2 minutes.
7. The evaluation method according to any one of claims 1 to 3, characterized in that, Before processing the blank control group and the sample group with yam extract, static electroencephalogram (EEG) data of the participants were collected respectively.
8. The evaluation method according to any one of claims 1 to 3, characterized in that, Each EEG data acquisition stage is accompanied by an emotion scale score for auxiliary evaluation, and steps S22 and S24 are accompanied by a self-assessment questionnaire score for auxiliary evaluation.
9. The evaluation method according to claim 8, characterized in that, The mood scale scoring uses the SAM mood scale, whose assessment dimensions include valence and arousal. In the valence, 1 represents "very unpleasant", 5 represents "moderate", and 9 represents "very pleasant"; in the arousal level, 1 represents "very calm", 5 represents "moderate", and 9 represents "very excited".
10. The evaluation method according to claim 8, characterized in that, The self-assessment questionnaire includes: improved skin discomfort, more pleasant mood, improved anxiety, improved tension, improved irritability, and overall satisfaction with the product's effects; In the self-assessment questionnaire, 1 indicates "strongly disagree", 2 indicates "somewhat disagree", 3 indicates "neutral", 4 indicates "somewhat agree", and 5 indicates "strongly agree". The self-assessment questionnaire's acceptance level is calculated as follows: Acceptance level = Number of participants who selected "Rating > 3 points" / Number of valid participants × 100%.