Windienoic acid, a new compound from themedicinal plant Wikstroemia indica

A phytochemical investigation of the roots of the medicinal plant Wikstroemia indica (Linn.) C. A. Mey led to the isolation of five compounds (1–5), comprising one previously undescribed metabolite (1), named windienoic acid, and four reported compounds (2–5). The structural elucidation of these compounds was accomplished through comprehensive analysis of spectroscopic data, including 1D (¹H and ¹³C NMR) and 2D NMR techniques (HSQC, COSY, and HMBC). Compounds 2–5 were identified as the monoterpene 6,7-dihydroxy-3,7-dimethyl-2-octenoic acid (2), the dibenzylbutyrolactone-type lignans (-)-nortrachelogenin (3) and (-)-trachelogenin (4), and the furofuran-type lignan pinoresinol (5) by comparing with literature data. Notably, the structure of compound 1 incorporated an extended conjugated system comprising a dienone moiety linked to a carboxylic acid group, which is rarely in acyclic compound, its structure was confirmed by 13C NMR calculation. The NMR assignment of dihydroxy-3,7-dimethyl-2-octenoic acid (2) is reported herein for the first time in methanol-d4. The cytotoxic screening assay against the A549 human lung cancer cell line of all compounds revealed that compound 3 exhibited weak activity with an IC₅₀ value of 42.3 μM.