26 JOURNAL OF COSMETIC SCIENCE Table VI Minimum Inhibitory Concentrations of the Four Bacteriostatic Agents Against the Three Tested Microorganisms Bacteriostatic agent Minimum inhibitory concentration (μL mL−1) S aureus C albicans E coli S baicalensis extract 75 100 100 L erythrorhizon extract 50 25 50 S flavescens extract 100 100 100 C reticulata peel extract 75 50 15 Table VII Bacteriostatic Effects of Different Composite Plant Extract Ratios Compound number Combination method Average inhibition zone diameter (mm)a C reticulata peel extract (g) L erythrorhizon extract (g) S aureus C albicans E coli 0b 0.0 0.0 0.00 0.00 0.00 1 1.5 0.0 46.20 48.44 54.86 2 1.2 0.3 46.51 49.82 55.28 3 1.0 0.5 47.83 52.63 55.94 4 0.8 0.7 47.62 53.14 54.73 5 0.7 0.8 46.85 49.85 54.11 6 0.5 1.0 45.93 48.93 53.42 7 0.3 1.2 42.48 48.25 52.53 8 0.0 1.5 42.19 47.37 51.07 a The bacteriostatic effect was determined according to the diameter of the inhibition zone (inhibition diameter: 6 mm) as described in the bacteriostatic performance test section. b Indicates no bacteriostatic agent was added rather, an equal amount of deionized water was added as a blank control. Table V Base Formula and Plant-Based Hand Cream Formulations Phase Raw material Base formula Plant extract hand cream formula A Deionized water 74.85 73.40 Glycerin 8.00 8.00 Allantoin 0.15 0.15 Xanthan gum 0.20 0.15 B Jojoba oil 5.50 5.50 Shea butter 2.50 2.50 Isopropyl palmitate 1.30 1.30 Dimethicone 2.50 2.50 Steareth-2 2.00 2.00 Steareth-21 1.50 1.50 C Tocopheryl acetate 1.50 1.50 Composite plant extract / 1.5 100.00 100.00

27 TESTING OF HAND CREAMS to as “composite plant extract”) with a 2:1 C reticulata peel extract to L erythrorhizon extract ratio had the strongest bacteriostatic effect. Therefore, this composite plant extract was added to the formulation design of the hand cream below, and its bacteriostatic effect and other properties were investigated. HAND CREAM FORMULA DETERMINATION BACTERIOSTATIC EFFECTS Bacteriostatic rate. Three samples were made according to the plant extract hand cream formula in the hand cream formula determination section, and these were tested using the bacteriostatic rate assay described in the bacteriostatic performance test section. The average values from three independent replicates are presented in Table VIII. The average inhibitory rates of the composite plant extract hand cream against S aureus, C albicans, and E coli were 92.46%, 92.33%, and 97.61%, respectively, demonstrating a strong bacteriostatic effect. Comparison of bacteriostatic effects. Four common hand creams and an alcohol-based disinfecting gel were compared with the designed plant extract hand cream using the antibacterial test (Figure 5). Compared with the other four cosmetics, the designed bacteriostatic hand cream exhibited an outstanding bacteriostatic effect that was only slightly less than the alcohol disinfection gel control. Field trials. Field trials were conducted on 10 subjects for each microorganism separately. The results are shown in Figure 6. The killing log values of inactivation for S aureus and E coli were about 3.0, and the inhibition rate was nearly 99.9%. The killing log value of inactivation of C albicans was about 2.0, and the inhibition rate was 99.0%. It can effectively meet the bacteriostasis disinfection. Table VIII Bacteriostatic Rate Assay Results for the Composite Plant Extract Hand Creama Test microorganisms Serial number Inhibition rate (%) Number of microorganisms recovered in positive control (cfu/piece) 2 min 5 min 10 min 20 min S aureus 1 93.19 97.17 98.38 98.50 2.13 × 104 2 92.12 97.42 98.33 98.64 1.98 × 104 3 92.06 96.82 98.36 98.48 1.80 × 104 Average 92.46 97.13 98.36 98.54 1.97 × 104 C albicans 1 92.01 95.60 97.10 97.77 2.04 × 104 2 95.55 95.64 97.50 97.98 1.79 × 104 3 92.49 96.27 97.21 97.89 1.93 × 104 Average 92.35 95.84 97.27 97.77 1.92 × 104 E coli 1 97.77 97.82 98.45 98.81 1.97 × 104 2 97.41 97.98 98.63 98.91 1.83 × 104 3 97.65 98.11 98.53 98.93 2.06 × 104 Average 97.61 97.97 98.54 98.88 1.95 × 104 a Inspection temperature 23.6°C, relative humidity 52%.