Characterization and antibacterial activity of alkaloids and polyphenols extracts from Haplophyllum tuberculatum (forssk.)

Abstract

Haplophyllum tuberculatum is a medicinal plant belonging to the Rutaceae family, is renowned for its various therapeutic properties. This study aims to characterize the alkaloids and polyphenol extracts from this plant and assess their antibacterial activity. Herein, the extraction of polyphenols and alkaloids from this plant was performed by the maceration method. Folin Ciacalteu’s method was used to estimate the total phenolic content, and the qualitative characterization of the two extracts was performed by thin-layer chromatography. Whilst, the antibacterial activity of the two extracts was tested with the disk diffusion method on a solid medium and the minimal inhibitory concentration (MIC) of susceptible bacteria was determined using the agar dilution method. Our results indicate respective yields of 8.39% in polyphenols and 0.37% in alkaloid extracts, while the total phenolic content was estimated to be 74.45 mg GAE/g of dry matter in polyphenolic extract. Thin-layer chromatography analysis allowed choosing the system toluene-acetate-ethanol-concentrated ammonia (40:4:8:3, v/v) to separate H. tuberculatum alkaloids, and ethyl acetate-methanol-water (100:13.5:10, v/v/) for the separation of its polyphenols. The same analysis detected traces of quercitin, catechin, and rutin in the polyphenolic extract. Our findings demonstrated good antibacterial activity on Gram-positive strains such as Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633, and moderate activity on Pseudomonas aeruginosa ATCC 27953, with MICs ranging from 0.625 to 10 mg/mL for alkaloids and from 5 to 20 mg/mL for polyphenols.