Parviflorals A-F, trinorcadalenes and bis-trinorcadalenes from the roots of Decaschistia parviflora

Trinorcadalenes, parviflorals A and B (1 and 2), and four bis-trinorcadalenes, parviflorals C–F (3–6), together with the known trinorcadalenes, syriacusins A (7) and C (8), scopoletin (9) and stigmasterol were isolated from roots of Decaschistia parviflora. Their structures were established by spectroscopic techniques. The CD spectra of the bis-trinorcadalenes (3–6) established their absolute configurations at the binaphthyl axis. Further, structure 6 was confirmed by a single-crystal X-ray crystallographic analysis. Compounds 2 and 6 showed antimalarial activity against Plasmodium falciparum with IC50 values of 11.45 and 6.85 μM, respectively. Compounds 1, 5, 7 and 8 also exhibited weak antifungal activity against Candida albicans, with IC50 values in the range of 37.03–197.68 μM. Compounds 1–3 and 5–8 showed weak antimycobacterial activity against Mycobacterium tuberculosis with MIC values in the range of 54.30–192.13 μM. In addition, several of these compounds possessed cytotoxicity towards the cancer cell lines, KB, MCF7 and NCI-H187 with IC50 values in the range of 2.20–90.09 μM.