JOURNAL OF COSMETIC SCIENCE 10 carcinogenic substance, nitrosamine (R1–N–R2–N=O). However, nitrite scavenging can effectively suppress the formation of these carcinogenic compounds (36). Higher concen- trations of phenolic compounds at lower pH values increase nitrite scavenging, whereas this effect diminishes at high pH (37). Table IV shows that the nitrite-scavenging activity increased from 0.08 ± 0.12% at 0.4 mg/ml to 94.97 ± 0.06% at 50 mg/ml in the MLFE, and from 0.19 ± 0.08% at 0.4 mg/ml to 95.89 ± 0.03% at 50 mg/ml in the MEFE, thereby demonstrated that higher concen- trations of fermentation extracts resulted in enhanced scavenging ability. EM-fermentation imparted a superior effect versus lactobacillus fermentation at all concentrations. The statistically signifi cant differences were observed between the two fermentation agents except at a low concentration level of 0.4 mg/ml, in supporting suppression of nitrosa- mine production by mango leaf extracts. Mango leaves, which are high in phenols, effectively break down nitrites at a low pH of 2.5. CONCLUSIONS We evaluated the concentration-dependent antioxidative properties of lactobacillus and EM fermentations of mango leaf extracts. We measured DPPH-radical inhibitory activity and ROS production to estimate the concentration-dependent activity of lactobacillus and EM fermentations. It was confi rmed that the antioxidative activity signifi cantly increased with increasing concentrations of the sample. Total phenolic and fl avonoid contents also increased in a dose-dependent manner. EM fermentation exhibited higher antioxidative activity than lactobacillus fermentation, as well as the synthetic antioxidant, BHT. Figure 5. Effects of MEFE on the generation of ROS in LPS-stimulated macrophage cells. The data are representative of three independent experiments. Table III Tyrosinase Inhibitory Activity in Percentage for MLFE and the MEFE (n = 3) MLFE concentration (mg/ml) Tyrosinase inhibition(%) t p-Value MLFE MEFE 0.4 7.89 ± 0.90 8.64 ± 0.89 −2.387 0.037 2 10.52 ± 1.80 18.42 ± 2.1 −4.943 0.003 10 11.40 ± 2.30 23.68 ± 1.8 −7.282 0.001 50 15.78 ± 1.5 29.82 ± 0.7 −14.68 0.000

ANTIOXIDANT PROPERTIES OF FERMENTED MANGO LEAF EXTRACTS 11 Both lactobacillus and EM fermentations showed increasing tyrosinase inhibitory activi- ties with increasing concentrations of the extract. Antioxidant activity increased with increasing concentrations of the extracts. EM fermen- tations showed a higher antioxidant effect over lactobacillus fermentations through in- creased inhibition of ROS production. Cytotoxic effect also augmented with increasing concentration of fermentation extracts as well. Both fermentations demonstrated stable cytotoxicity level demonstrated as cell viability percentage 85% at different concentra- tions tested (38). The results of this study show that mango leaf extracts fermented with lactobacillus and EM impart positive effects on RAW 264.7 cells by reducing ROS pro- duction as well as enhancing cytotoxicity-related stability and antioxidant activity. One of the limitations of this study is differential time duration required to ferment each culture the difference of 7 days for EM activation versus 2 days for Lactobacillus fermentation remains a signifi cant challenge to the equivalent effi cacy assumption despite equal seed culture concentration used to prepare the MLFE and the MEFE. Longer duration required for optimal fermentation should be balanced against addi- tional antioxidant effect obtained from the use of EM. Another limitation is in the Figure 6. Inhibitory effects of the MLFE and MEFE on tyrosinase activity (%). Tyrosinase was used for the in vitro melanin synthesis. Data presented are mean ± S.D. (n = 3). Table IV Nitrite Scavenging Abilities (%) of the MLFE and the MEFE at pH 2.5 (n = 3) MLFE concentration (mg/ml) Nitrite scavenging activity (%) t p-Value MLFE MEFE 0.4 0.08 ± 0.12 0.19 ± 0.08 −1.659 0.086 2 2.21 ± 0.07 26.03 ± 0.17 −182.5 0.000 10 46.51 ± 0.06 84.93 ± 0.01 −589.0 0.000 50 94.97 ± 0.06 95.89 ± 0.03 −12.54 0.000