Bioactive chemical constituents from the root of Clerodendrum phlomidis

Abstract

Hexane and ethyl acetate extracts of Clerodendrum phlomidis roots show antitubercular activity. Bioguided fractionation of active extracts led to the isolation of a new phenylethanoid glycoside, β-(4-hydroxyphenyl)-ethyl-O-α-l-rhamnopyranosyl(1 → 3)-β-D-(4-O-2′,6′-dihydroxycinnamoyl)-glucopyranoside (phlomidoside, 10) along with 12 known compounds. The structures of the isolated compounds were elucidated on the basis of detailed spectroscopic analysis (NMR, Mass and IR). All the compounds except 2, 4, and 8 have been isolated for the first time from C. phlomidis. Antitubercular activity of extracts and isolated compounds was determined by BACTEC radiometric susceptibility assay against Mycobacterium tuberculosis H37Rv (ATCC 27294). In addition, isolated compounds were also evaluated for their effect on lipopolysaccharide-stimulated macrophages for production of pro-inflammatory cytokines, tumor necrosis factor-α and interleukin-6. This is the first report on the antitubercular potential of C. phlomidis, indicating the underlying mechanism involved in the therapeutic application of a traditionally used plant.