Newbouldiaquinone A: A naphthoquinone–anthraquinone ether coupled pigment, as a potential antimicrobial and antimalarial agent from Newbouldia laevis

Abstract

The study of the chemical constituents of the roots of Newbouldia laevis (Bignoniaceae) has resulted in the isolation and characterization of a naphthoquinone–anthraquinone coupled pigment named newbouldiaquinone A ( 1) together with 14 known compounds: apigenin, chrysoeriol, newbouldiaquinone, lapachol, 2-methylanthraquinone, 2-acetylfuro-1,4-naphthoquinone, 2,3-dimethoxy-1,4-benzoquinone, oleanolic acid, canthic acid, 2-(4-hydroxyphenyl)ethyl triacontanoate, newbouldiamide, 5,7-dihydroxydehydroiso-α-lapachone, β-sitosterol, and β-sitosterol glucopyranoside. The structure elucidation of the isolated compounds was established based on spectroscopic studies, notably of the 2D NMR spectra. The antimalarial activity of compound ( 1) against Plasmodium falciparum in vitro shows moderate chemo suppression of parasitic growth. Its antimicrobial activity against a wide range of microorganisms was 13- and 24-fold more active against Candida gabrata and Enterobacter aerogens than the reference antibiotics nystatin and gentamycin.