Abstract:The liquid-liquid partitioning of a crude hydroalcoholic extract of Averrhoa carambola L., Oxalidaceae, leaves led to the isolation of a sterol and three flavone C-glycosides. From the n-hexane fraction β-sitosterol was isolated and from the ethyl acetate fraction apigenin-6-C-β-L-fucopyranoside (1) and apigenin- (3) was isolated from the n-butanol fraction. Compound 3 is new, while 1 and 2 have been previously isolated from A. carambola. The antioxidant activity was measured using the DPPH radical scavenging assay and reducing power of iron (III) to iron (II) ions. The ethyl acetate and n-butanol fractions showed the most antioxidant activity. As evaluated by ability of the sample to scavenge DPPH the IC50 values were 90.92 and 124.48 µg/ mL, respectively. In the assay of reducing power these fractions presented 135.64 and 125.12 of ascorbic acid equivalents, respectively. The antioxidant activity exhibited a significant relationship with the phenolic content (r 2 = 0.997), but a poor relationship with the flavonoids content (r 2 = 0.424). The n-hexane fraction was the only fraction to present good toxicity using A. salina with LC50 800.2 μg/mL.

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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 (H and C 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 IC values of 20.94 μM, 44.20 μM, 30.01 μM and 58.82 μg/mL, respectively.

The presented results show that P. sabulosa has significant anti-inflammatory activity, as does its main compound, PC. Moreover, the results suggest that PC exerts its effects mainly by inhibited the NF-κB and p38 MAPK pathways.

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