Abstract
The leaves of loquat (Eriobotrya japonica) possess high medicinal value and have been used as traditional medicines. However, there are no evidence-based studies on the skin-care effects of E. japonica leaves. To explore new biological activities of E. japonica leaves against skin disorder and to gain a better understanding of the chemical components associated with bioactivities, we evaluated 18 triterpenoids from E. japonica leaves on anti-melanogenesis, anti-acne, anti-allergy and anti-aging activities. Our results revealed that eight compounds showed anti-melanogenesis activity, of which ursolic acid (1) and maslinic acid (7) were the most potent with the similar selective index to that of arbutin. Structure-activity relationship and possible mechanism of active compounds were proposed. Twelve compounds exhibited anti-acne effect; ursolic acid (1), maslinic acid (7), corosolic acid (8) and euscaphic acid (12) showed highest activities against P. acnes. Four compounds displayed anti-allergy and anti-inflammatory activity; 3-epicorosolic acid (9) and euscaphic acid (12) showed marked activity against β-hexosaminidase release. Finally, ursolic acid (1), pomolic acid (10), colosolic acid (8) and its methylated derivative (6) exhibited the highest anti-aging activity by stimulating collagen and hyaluronic acid (HA) production. Our findings provide valuable evidence that E. japonica leaves have potential applications as ingredients of function foods or cosmetics for health benefits and a number of triterpenoids may play an important role in these bioactivities.