Myricitrin as the main constituent of two species of Myrcia.

Myricitrin was isolated as the major constituent from Myrcia splendens (2 g %) and Myrcia palustris (0.5g %) of their fractions soluble in ethyl acetate. The presence of this compound was confirmed by chromatographic analyses using HPLC-DAD. The antioxidant activity was measured using reducing power in relation to the reduction of iron (III) to iron (II) ions and DPPH radical scavenging assay. The ethyl acetate and butanol fractions showed the highest antioxidant activity for both species. In relation to the ability of the sample to scavenge DPPH radicals the EC50 values were 8.44 and 9.35 μg/ mL for M. splendens and 17.83 and 15.34 μg/ mL for M. palustris for the ethyl acetate and butanol fractions, respectively. The antioxidant activity may be related to the myricitrin in these extracts that showed an EC50 = 13.93 μg/mL.

Chemical constituents and evaluation of the toxic and antioxidant activities of Averrhoa carambola leaves

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 apigenin6-C-(2"-O-α-L-rhamnopyranosyl)-β-L-fucopyranoside (2) were obtained. Apigenin6-C-(2"-O-α-L-rhamnopyranosyl)-β-D-glucopyranoside (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 (r² = 0.997), but a poor relationship with the flavonoids content (r² = 0.424). The n-hexane fraction was the only fraction to present good toxicity using A. salina with LC50 800.2 µg/mL.