Chemical constituents of Eugenia catharinae and their antioxidant activity

Nine compounds were isolated from the leaves of Eugenia catharinae, namely monomethyl olivetol (1), β-sitosterol (2), stigmasterol (3), uvaol (4), erythrodiol (5), rotundic acid (6), quercetin (7), catechin (8) and myricitrin (9). The structures of 1–9 were established through analysis of their spectroscopic (¹H and ¹³C NMR) and spectrometric (MS) data. Compounds 1 and 6 are reported the first time in the Eugenia genus. In addition, these data were compared with those reported in the literature. The antioxidant activity of plant samples and compounds was measured using the DPPH radical scavenging assay. Flavonoids 7, 8, 9 and the ethanolic extract showed the best results, with IC₅₀ values of 20.94 μM, 44.20 μM, 30.01 μM and 58.82 μg/mL, respectively.