Discovery of structurally distinctive terpenoid derivatives from anti-inflammatory fractions of Syzygium tripinnatum leaves

The Syzygium genus (Myrtaceae family) demonstrates diverse bioactivities with significant development potential [ 1 ]. Among its members, Syzygium tripinnatum , native to Taiwan, remains largely unexplored with only nine compounds previously isolated and minimal characterization of its bioactive properties. Preliminary research revealed that different fractions of S. tripinnatum exhibit distinct anti-inflammatory mechanisms: the n -hexane fraction promoted Nrf2 activation, the ethyl acetate fraction inhibited elastase release, and the water fraction suppressed IL-6 production. Phytochemical investigation of the n -hexane fraction yielded six new compounds: two terpenoid-conjugated phloroglucinols (syzygidiones A-B, 1-2), two novel triterpenoids (tripisyzygin A, 3 and (20 R )-taraxastane-3β,20β-diol-28-al, 4), and two new sesquiterpenoids (syzygiterpenes A-B, 5-6), together with one triterpenoid first isolated from natural source ((3β)-3,28-dihydroxyoleanan-12-one, 7). Additionally, 28 known compounds were identified, including a terpenoid-conjugated phloroglucinol (8), triterpenoids (9-26), α-tocopherol derivatives (27-29), chlorophylls (30-31), steroids (32-33), a benzenoid (34), and a sesquiterpenoid (35). Compounds available in sufficient quantities were evaluated for anti-inflammatory activity. Notably, syzygidiones A (1) and B (2) represent phloroglucinols conjugated with sesquiterpenes, featuring a structural scaffold previously reported only within the Myrtaceae family. This study marks the first report of terpenoid-conjugated phloroglucinols from the Syzygium genus, significantly expanding its known phytochemical profile. Furthermore, tripisyzygin A (3) presents an unusual triterpenoid structure with a distinctive double bond at C-1/C-10 and an ether bridge connecting rings A and B. This comprehensive investigation of bioactive compounds from S. tripinnatum provides new opportunities for the discovery and development of anti-inflammatory therapeutics. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany