New biflavonoids isolated from Xylia kerrii leaves extract with selective cytotoxicity against MH7A human rheumatoid arthritis synovial fibroblast cells.

Three new biflavonoids (1-3) and two known flavonoids (4, 5) were isolated from Xylia kerrii collected in Thailand. Compounds 1-5 showed selective cytotoxicity against the rheumatoid fibroblast-like synovial MH7A cell line, and these compounds showed weak cytotoxicity against the human lung synovial fibroblast WI-38 VA13 sub 2 RA cell line. Notably, compound 1 was highly selective toward MH7A cells with an IC50 value of 6.9 µM, whereas the IC50 value for WI-38 VA13 sub 2 RA cells was > 100 µM. The western blotting analysis of MH7A cells treated with compound 1 showed increased CDKN2A /p16INK4A and caspase-8 levels.