Assessment of the Polyphenolic Content, Free Radical Scavenging, Anti-inflammatory, and Antimicrobial Activities of Acetone and Aqueous Extracts of Lippia javanica (Burm.F.) Spreng

BACKGROUND: Lippia javanica (Burm.F.) Spreng is one of the spice plants commonly found in almost every part of South Africa. Apart from its culinary uses, it is also traditionally used as an insect repellant and infusion for fever, flu, kidney stone treatment, cough, common cold, and chest pain. MATERIALS AND METHODS: The antioxidant activities of the aqueous and acetone extracts were determined by measuring their effects against 1,1-Diphenyl-2-picryl-hydrazyl, 2,2’azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), nitric oxide, phosphomolybdate, lipid peroxidation, hydrogen peroxide, and reducing power. The antimicrobial activities were evaluated against four bacterial (two Gram-positive, two Gram-negative) strains and 9 fungal pathogens using the agar well diffusion and microdilution methods. Anti-inflammatory activity was assessed by determining the inhibition against protein denaturation and membrane stabilizing effects. OBJECTIVE: The polyphenolic content, free radical scavenging, anti-inflammatory, and antimicrobial activities of the aqueous and acetone extracts of the plant were evaluated. RESULTS: A significantly high total phenolic content and free radical scavenging activities were observed in the acetone extracts of the plants. The study also revealed a concentration-dependent inhibition of protein denaturation and membrane stabilization effects by both the aqueous and acetone extracts at the concentrations studied. The ability of L. javanica extracts to inhibit protein denaturation and maintain membrane stability could be responsible for its folkloric use. The overall antimicrobial activity indicates that both extracts were active against the bacterial strains but the acetone extract exhibited the most potent antifungal activity higher than even the reference drugs. CONCLUSION: Overall, the acetone extract of L. javanica exhibited a more pronounced antioxidant, anti-inflammatory, and antimicrobial effects than the aqueous extract. SUMMARY: The polyphenolic content and biological activities of the spice plant, Lippia javanica from South Africa was evaluated. Significantly high polyphenolic content and free radical scavenging activities were observed for both extracts. Moderate antimicrobial action, concentration-dependent inhibition of protein denaturation and membrane haemolysis were also observed. Abbreviations used: AA: ascorbic acid, ABTS: 2,2’azino-bis (3-ethylbenthiazoline-6-sulfonic acid), BHT: Butylated hydroxytoluene, DPPH: 1,1-Diphenyl-2-picryl-hydrazyl, NBT: 2,2’-di-pnitrophenyl-5,5’-diphenyl-(3,3’-dimethoxy-4,4’-diphenylene)- ditetrazolium chloride, PMS: Potassium metabisulfite, ROS: Reactive oxygen species, TBA: Thiobarbituric acid, TCA: Trichloroacetic acid.