Chemical constituents and nitric oxide inhibitory activity of capparis micracantha and maerua siamensis

Abstract

The chemical investigation of two plants in Capparaceae family, which are Capparis micracantha and Maerua siamensis, leads to the isolation of 13 compounds. The structures of the isolates were elucidated using spectroscopy techniques and comparison of the previous reports. Of five known compounds from the stems of C. micracantha were an indole alkaloid (methyl 6-methoxy-3-indolecarbonate), a benzoic acid derivative (vanillic acid), a lignan [(−)-syringaresinol], and two stilbene dimers [(+)-ampelopsin A and (−)-pauciflorol E]. In addition, eight new indole alkaloids named (+)-maeruanitrile A, maeruanitrile B, maeroximes A-C and maeruabisindoles A-C were isolated from the roots of M. siamensis,. All isolates were tested for inhibition of nitric oxide production in lipopolysaccharide-induced RAW 264.7 macrophage cells compared with a positive control (indomethacin). (−)-Pauciflorol E and methyl 6-methoxy-3-indolecarbonate from C. micracantha stems exhibited half maximum inhibitory concentration (IC50) values of 123.40 ± 4.51 and 198.00 ± 5.57 µM, respectively. Moreover, maeruabisindoles B - C, maeroxime C, (+)-maeruanitrile A and maeruanitrile B from M. siamensis roots showed IC50 values of 31.1±1.04, 56.7 ± 2.2, 92.2 ± 5.1, 186.4 ± 13.0 and 186.8 ± 13.3 µM, respectively, while the IC50 of indomethacin was in the range of 150.0 - 166.3 µM. This study supports the use of C. micracantha stems and M. siamensis roots for anti-inflammation according to Thai traditional medicine knowledge.