Bioactivity-guided isolation of mosquitocidal constituents from the rhizomes of Plumbago capensis Thunb

A bioassay-guided fractionation and chemical examination of chloroform extract of Plumbago capensis roots resulted in isolation and characterization of two new napthaquinone derivatives (4, 8) along with six known compounds (1–3, 5–7). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. All the compounds were tested for their mosquito larvicidal activity against fourth instar larvae of Aedes aegypti, and compared with that of rotenone. Among the tested compounds, isoshinanolone (3) and plumbagin (1) showed excellent toxicity with LC50 values of 1.26 and 5.43 μg/mL. New compound (8) displayed moderate toxicity against the tested mosquito species.

Graphical abstractBioassay guided isolation of mosquitocidal extract of P. capensis rhizomes yielded two new napthaquinones, isoplumbagolone (4) and chitranane (8) along with six known compounds (1–3, 5–7) as a mosquitocidal constituents, possessing varying degree of mosquitocidal potentials.Figure optionsDownload full-size imageDownload as PowerPoint slide