Nattaya Lourith, Mayuree Kanlayavattanakul, Puxvadee Chaikul, Chaisak Chansriniyom, Pichaporn Bunwatcharaphansakun

Peel extracts of litchi and rambutan, and that of tamarind seed coat were investigated in relation to their utility in skin-aging treatments. Standardized extracts of tamarind were significantly (p < 0.05) more efficient at O2 •- scavenging (IC50 = 27.44 ± 0.09) than those of litchi and rambutan (IC50 = 29.57 ± 0.30 and 39.49 ± 0.52 μg/ml, respectively) and the quercetin standard (IC50 = 31.88 ± 0.15 μg/ml). Litchi extract proved significantly (p < 0.05) more effective for elastase and collagenase inhibition (88.29 ± 0.25% and 79.46 ± 0.92%, respectively) than tamarind (35.43 ± 0.68% and 57.69 ± 5.97%) or rambutan (31.08 ± 0.38% and 53.99 ± 6.18%). All extracts were safe to human skin fibroblasts and inhibit MMP-2, with litchi extract showing significantly (p < 0.01) enhanced inhibition over the standard, vitamin C (23.75 ± 2.74% and 10.42 ± 5.91% at 0.05 mg/ml, respectively). Extracts suppress melanin production in B16F10 melanoma cells through inhibition of tyrosinase and TRP-2, with litchi extract being the most potent, even more so than kojic acid (standard). These results highlight the potential for adding value to agro-industrial waste, as the basis for the sustainable production of innovative, safe, anti-aging cosmetic products.