Atricephenols A and B, two phenolic compounds from Indigofera atriceps Hook.f. (Fabaceae)

Abstract

The phytochemical investigation of a previously unstudied species of the genus Indigofera, I. atriceps Hook.f. was undertaken and two new phenolic compounds, atricephenols A (1) and B (2) were isolated, along with nine known secondary metabolites viz., (-)-melilotocarpan D (3), genistein (4), melilotocarpan A (5), maackiain (6), p-hydroxybenzaldehyde (7), bornesitol (8), β-sitosterol (9), sitosterol-3-O-β-D-glucopyranoside (10) and stigmasterol-3-O-β-D-glucopyranoside (11). Their structures were elucidated by extensive NMR spectroscopic analyses and HRESIMS, and by comparing their data with those reported in the literature. Compounds 1, 4, 7–11 were tested for their antibacterial efficacies and for their potential to inhibit the enzyme urease. Compounds 7 and 9 showed significant antibacterial activity against Salmonella typhi (ZOIs of 13 and 15 mm, respectively), while the best urease inhibition was measured for compound 9 with an IC₅₀ value of 18.6 µM, which is higher than that of the potent inhibitor, thiourea (IC₅₀ = 21.5 µM).

Graphical Abstract

Keywords:

• Indigofera atriceps
• Fabaceae
• Phenolic compounds
• Atricephenols
• Antibacterial
• Enzyme urease

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

ILM is grateful to The World Academy of Sciences (TWAS) for a six-month fellowship at the HEJ Research Institute of Chemistry, University of Karachi. This study was also supported by The World Academy of Sciences (TWAS) (grant N° FR3240303654) and the Alexander von Humboldt Foundation (AvH) for the equipment subsidies (Ref 3.4 - 8151/20 002) and the Humboldt Research Hub grant (Ref 3.4 CMR - Hub).