Syzygium formosum (Wall.) Masam leaf is known as a Vietnamese traditional herbal medicine used to treat atopic dermatitis and stomach ulcers. Recently, its potent anti-allergic effects were reported with possible active compounds analysis. Here, we collected S. formosum leaves from 12 wild trees and compared compositions of triterpenic acids (TA) with Centella asiatica. Anti-inflammatory activities of S. formosum leaf extract (SFLE) was compared with C. asiatica extract (CAE) using human keratinocyte, HaCaT. In this study, up to seven TAs were identified in SFLE, while only madecassic and asiatic acids were detected in the CAE. Total TA content varied among SFLE, but asiatic, corosolic, and betulinic acids were the major components. Surprisingly, wild tree sample 12 (S12) contained total TA of 27.2 mg/g dry-leaves that was 5-fold greater than that in the C. asiatica sample, and S4 had the highest content of asiatic acid (12.6 mg/g dry-leaves) that accounted for 50% of the total TA. S4 and S12 showed more than 3-fold higher anti-oxidative power than the CAE. In the UVB irradiation model, S4 and S12 (5 μg/mL) strongly repressed mRNA levels of pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) and COX-2, while the CAE at the same condition showed moderate or weak repression. The difference in anti-inflammation effects between the SFLE and the CAE was also confirmed by protein quantifications. Taken together, SFLE has great potentials as a new cosmeceutical ingredient with a higher amount of skin-active phytochemicals.

Syzygium formosum (SF) leaves have long been used in traditional medicine for the treatment of skin-related diseases such as atopic dermatitis and psoriasis. To understand the underpinning pharmacological mechanism of skin relief functionality, the quantitative profile of phytochemicals in the leaf extract has been performed. Twenty phytochemical components including eight flavonoids, three phenolic acids, and nine triterpenoids were identified and quantitatively analyzed from the SF leaves. The dominant flavonoids of the SF leaves were found to be catechin and myricetin-3-O-rhamnoside. Gallic acid was the most abundant phenolic acid. Among triterpenoids, asiatic acid, corosolic acid, and betulinic acid exhibited a high concentration ranging 2.78–8.59, 3.19–3.91, and 3.58–6.14 mg/g dry leaf, respectively. The total triterpenoid contents were 14.18–19.00 mg/g dry leaf which were 3-fold higher than those in the Indonesian Centella asiatica leaves. In human keratinocytes assay, industrial scale extract of SF significantly reduced expressions of proinflammatory cytokines and cyclooxygenase-2. Furthermore, that SF extract exhibited very strong antibacterial activity on Staphylococcus aureus and Cutibacterium acnes that possibly induce serious skin problems. Our results proved that S. formosum leaf extract with high content of biologically active compounds could be a superior bioactive ingredient in cosmetic and pharmaceutical products.