Isolation of Bioactive Compounds from Calicotome villosa Stems.

A phenylethanoid, two steroids, a flavone glucoside and a chalcone have been isolated for the first time from the stems of Calicotome villosa together with a previously isolated flavone glucoside. Their structures were determined by spectroscopic analyses (NMR, HRMS) as basalethanoïd B ( 1 ), β-sitosterol and stigmasterol ( 2 ), chrysine-7- O -β-d-glucopyranoside ( 3 ), chrysine 7-((6''- O -acetyl)- O -β-d-glucopyranoside) ( 4 ) and calythropsin ( 5 ). The crude extracts and the isolated compounds (except 4), were evaluated for their antioxidant, antimicrobial (against two Gram-positive bacterial strains: Staphylococcus aureus , Bacillus cereus , four Gram-negative bacterial strains: Staphylococcus epidermidis , Klebsiella pneumonia , Acinetobacter baumanii , and three yeasts: Candida albicans , Candida tropicalis , and Candida glabrata ), hemolytic, antidiabetic, anti-inflammatory and cytotoxic activity. The crude extracts showed good ability to scavenge the free radical DPPH. Methanol stem extract followed by the dichloromethane stem extract showed moderate antimicrobial potency; furthermore, at 1 mg/mL the methanol extract showed an inhibition of C. albicans growth comparable to nystatin. Dichloromethane, methanol, and aqueous extracts inhibited 98%, 90%, and 80% of HeLa cell proliferation at 2 mg/mL respectively. Weak hypoglycemic and hemolytic effects were exhibited by the crude extracts. Among all the tested compounds, compound 3 showed remarkable hypoglycemic potential (93% at 0.1 mg/mL) followed by compound 5 (90% at 0.3 mg/mL). Compound 5 was the most effective in the DPPH . scavenging assay (100% at 0.1 mg/mL) and cytotoxic assay on HeLa cells (99% and 90% after 24 and 48 h of treatment at 0.1 mg/mL, respectively). No anti-inflammatory effects were displayed by any of the crude extracts or the isolated compounds at any of the tested concentrations.