Quantitative phytochemical, antioxidant and antimicrobial properties of the seeds of Lawsonia inermis L.

Abstract

Lawsonia inermis, commonly known as Henna, is a plant that has been extensively utilized throughout the ages for its medicinal and cosmetic properties. This plant contains a variety of bioactive compounds and has attracted significant interest due to its potential antioxidant and antimicrobial activities. The aim of our study is to evaluate the antioxidant capacity and antibacterial activity of Lawsonia inermis seeds. L. inermis seed powder was extracted using hexane, dichloromethane, ethanol and water. The 4 fractions were quantified for polyphenols, flavonoids and tannins contents. The antioxidant capacity was assessed using 4 methods: 2,2?-Diphenyl- picrylhydrazyl hydrate (DPPH) , 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic) (ABTS), Ferric Reducing Antioxidant Power (FRAP), and Phosphomolybdate assay (PMA). Antimicrobial activity was determined by agar diffusion against Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The liquid dilution method was used to determine the minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration. The highest content of polyphenols and tannins was obtained in the ethanolic fraction, with values of 594.01±6.07 mg GAE/g dw and 242.4±1.6 mg CE/g dw respectively. The ethanolic fraction exhibited significant scavenging of free radicals (DPPH) with an IC50 of 3.06±0.01 µg/mL, lower than the IC50 of the standard quercetin (5.30±0.02 µg/mL). Moreover, the ethanolic fraction showed antimicrobial activity against S. aureus, B. cereus and E. faecalis strains, with zone of inhibition values of 15.5±0.7, 14.0±0.0 and 14.5±0.7 mm respectively. The minimum inhibitory concentration of the ethanolic fraction was found to be 1.563 mg/mL against both S. aureus and B. cereus strains, while the minimum bactericidal concentration was 3.125 mg/mL against B. cereus and 6.25 mg/mL against E. faecalis strains. L. inermis seeds exhibit significant antioxidant capacity and demonstrate antimicrobial activity. These findings indicate the potential of L. inermis seeds as a valuable source of bioactive compounds with antioxidant and antimicrobial properties.