Chemical composition, antioxidant and antinociceptive properties of Litchi chinensis leaves

Abstract

Objectives: Litchi chinensis has been traditionally used in folk medicine to treat several ailments. In this study, we investigated the chemical composition, antioxidant and antinociceptive activity of L. chinensis leaves.

Methods: The antioxidant capacity of the extract, fraction and compounds was evaluated using the 1,1-diphenyl-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, and the liposome model with peroxyl radicals generated by 2,2'-azobis (2-amidinopropane) dihydrochloride radical. The pharmacological models of acute nociception used in mice were: writhing test with acetic acid (AA), hotplate (HP), glutamate (GLU), capsaicin (CP) and formalin (FM) tests.

Key findings: The main compounds isolated were procyanidin A2 (PA2), procyanidin B2 (PB2) and (-)-epicatechin. The biochemical features of the crude extracts and their ethyl acetate fraction (EtOAcFR) presented high antioxidant activity, and the antioxidant activity of PA2 and PB2 was remarkably high, with DPPH and ABTS. The crude methanol extract (MeOHEXTR), EtOAcFR and PB2 were effective in reducing nociception in FM and HP models. MeOHEXTR and EtOAcFR treatments also reduced pain induced by GLU and AA. In the CP model, only EtOAcFR and PB2 were effective.

Conclusions: The results demonstrate the antinociceptive and antioxidant of MeOHEXTR, EtOAcFR and PB2.

Keywords: L. chinensis; antinociceptive; antioxidant activity; lipid peroxidation; phenolic compounds.