Anticholinesterase and Anti-inflammatory Constituents from Caralluma awdeliana, a Medicinal Plant from Yemen.

From the dichloromethane (DCM) fraction of the crude ethanolic extract of Caralluma awdeliana, four pregnane glycosides and a flavone glycoside were isolated using a bio-guided isolation approach. The different extracts of C. awdeliana were subjected to in vitro enzyme inhibitory assays of anticholinesterase (AChE and BChE) and anti-inflammatory (COXs and 5-LOX). The highest inhibitory activity was exhibited by DCM fraction against COX-1, COX-2, and 5-LOX with IC50 of 4.8±0.5 μg/mL, 0.68±0.2 μg/mL, and 39.5±3.0 μg/mL, respectively. The DCM showed also a moderate activity against AChE (IC50 384.72±3.6 μg/mL), and BChE (384.72±3.6 μg/mL). The repeated chromatography of DCM fraction resulted in the isolation of two new pregnane glycosides, namely awdeliosides A (1) and B (4), two known ones, namely caratuberoside B and D, along with the known flavone glycoside identified as luteolin 4'-O-neohesperidoside. All the isolated compounds were tested for their in vitro enzyme inhibitory assays. Among the isolated compounds, awdelioside B (4) showed the most potent effect against COX-1 with IC50 value of 10.99±0.35 μM, compared to standard celecoxib (230.74±2.62 μM). All the isolated compounds showed weak anticholinesterase, except a moderate activity observed for awdelioside B (4) against BChE with IC50 value of 15.63±3.5 μM, compared to standard donepezil (IC50 0.77 ± 0.0088 μM).