A new iridoid skeleton from Galium asparagifolium and biological activity studies

Abstract

This study identifies the detailed phytochemical content and biological effects of Galium asparagifolium, for the first time and gained one new iridoid aglycone (1), seven known iridoid glycosides (2–8), two flavonoids (9–10), and one carbohydrate derivative (11) to the literature. The 1D-, 2D- NMR analyses and ESI-Mass allowed us to resolve the structure of new compound as (1S,4aS,​​8aS)-pyrano[4,​3-​c]​pyran-1,​4a,​5,​7,​8,​8a-​hexahydro-​1-​hydroxy-​3-(​2-​hydroxyethyl)-​8-​methyl-8-​carboxylic acid namely galiumic acid. The compounds 1–11 and extracts from G. asparagifolium were investigated in terms of cytotoxic activity by MTT assay, antioxidant activity by DPPH method and antimicrobial activity by DDT and BMM methods. While all compounds and extracts did not show remarkable cytotoxicity, they had variable antimicrobial activities for a variety of gram-positive/gram-negative bacteria and yeast strains. Besides that, most of the compounds showed antioxidant effect with a wide range of DPPH% inhibition values. The structure of the new compound was also elucidated by some computational studies.