Anti-inflammatory quinoline-4(1H)-one derivatives from the aerial parts of Waltheria indica linn

Abstract

Eight previously undescribed quinoline-4(1H)-one derivatives (1–8) and five known analogues (9–13) were isolated from the 95% aqueous extract of the aerial parts of Waltheria indica Linn. Their chemical structures were determined by analyzing 1D NMR, 2D NMR and HRESIMS data comprehensively. Compounds 1–8 possess diverse side chains at C-5 of quinoline-4(1H)-one or tetrahydroquinolin-4(1H)-one skeleton. The absolute configurations were assigned via comparison of the experimental and calculated ECD spectra, and analysis of the ECD data of the in situ formed [Rh2(OCOCF3)4] complex. Additionally, all 13 isolated compounds were evaluated for their anti-inflammatory activities by measuring the inhibitory effects of nitric oxide (NO) production in lipopolysaccharide-induced BV-2 cells. Compounds 2, 5 and 11 showed moderate inhibition toward NO production with IC50 values of 40.41 ± 1.01, 60.09 ± 1.23 and 55.38 ± 0.52 μM, respectively.