Specialized plant metabolites from indolic and polyphenolic biosynthetic pathways in Wrightia religiosa (Teijsm. & Binn.) Benth. and Wrightia pubescens R. Br. (Apocynaceae)

Phytochemical investigation of different organs and of the latex of Wrightia religiosa (Teijsm. & Binn.) Benth. as well as of the stem bark of Wrightia pubescens R. Br. (Apocynaceae), both collected in Thailand, yielded a total of seven known compounds. All are specialized metabolites from indolic and polyphenolic biosynthetic pathways. From leaves of W. religiosa , 3-indole d -apio-β- d -furanosyl-(1→6)-β- d -glucopyranoside ( 1 ) and benzouracil ( 2 ) were isolated. Compound 1 and blepharin ( 3 ) were purified from the root bark, and the lignan 4-pinoresinol d -apio-β- d -furanosyl-(1→2)-β- d -glucopyranoside ( 5 ) was isolated from the stem bark of this species. Chromatographic separation of the hitherto unstudied latex yielded blepharigenin ( 4 ). The methanolic stem bark extract of W. pubescens yielded tryptanthrin ( 6 ) and kelampayoside A ( 7 ). Radical scavenging activities of the isolated compounds and of the crude methanolic extracts indicate that the isolated specialized metabolites do not contribute appreciable to the antioxidative properties of the plant extracts. The crude methanolic extracts do not show noteworthy anti-feedant response of the insect pest Spodoptera littoralis Boisduval. Ecological aspects are shortly addressed, and results are discussed in the phylogenetic framework of the studied species. • Seven compounds were reported from Wrightia religiosa and W. pubescens. • Latex of Wrightia religiosa was examined for the first time. • Benzoxacinoids are characteristic for Wrightia religiosa. • Indigo related compounds are present in both plant species.