Potential therapeutic effects of Hermannia depressa N.E.Br. root extracts

Background: Hermannia depressa is a medicinal plant species from the Malvaceae family, and it is traditionally used in the treatment of ailments in which microbial and inflammatory processes are involved. Aim: This study aimed to validate the traditional medicinal claims of H. depressa through in vitro antimicrobial, anti-inflammatory, antioxidant, cytotoxicity, and phytochemical studies. Setting: The roots of H. depressa were collected in Thaba ‘Nchu, Free State province, South Africa. Methods: The broth microdilution method, nitric oxide assay, the DPPH assay and Hoechst 33 342 nuclear dye and propidium iodide exclusion method were used to evaluate antimicrobial, anti-inflammatory, antioxidant activity and cytotoxicity, respectively. Qualitative and quantitative phytochemical screening methods were used to evaluate the bioactive compounds of the extracts. Results: Methanol and acetone extracts from both plants showed antimicrobial activity against 13 microorganisms, with minimum inhibitory concentrations (MICs) ranging from 0.1 to 1.25 mg/mL, with Candida albicans and Bacillus cereus being the most inhibited isolates. Methanol and acetone extract further showed strong anti-inflammatory activity by inhibiting nitric oxide by more than 50%. Methanol (IC = 5.197 ± 0.10 µg/mL) and acetone (IC = 3.576 ± 0.44 µg/mL) extracts showed higher antioxidant capacity than ascorbic acid and Trolox. Acetone and methanol extracts demonstrated significant toxicity towards RAW 264.7 macrophages. Compounds with various pharmacological properties were detected from the H. depressa extracts Conclusion: These findings support traditional use of H. depressa to treat ailments and has potential to be a source of therapeutic agents. Contribution: This study contributes to the already existing knowledge on the pharmacological value of H. depressa.