Strobilanthes heyneanus root extract as a potential source for antioxidant and antimicrobial activity

Abstract

Background: Strobilanthes heyneanus (Nilgirianthus heyneanus) belongs to the family Acanthaceae that contains many species with potential for diverse medicinal uses. It is also called 'Karun kurinji' and is commonly found in the SouthWest regions of India. The species are commonly used in rheumatic complaints, sprain of the ankle, and hernia. The objectives of the study were to evaluate the antioxidant activity, phytochemical analysis, and antibacterial activities of the root extract of S. heyneanus. Results: The radical scavenging and reduction assays such as DPPH • radical and OH • radical scavenging assays, as well as phosphomolybdenum reduction and Fe 3+ reducing power assays, were determined for the root extract. The highest DPPH • radical scavenging activity was 88.23 ± 1.32 at 120 μg/mL concentration, and the calculated IC 50 was 38.52 μg/mL concentration. The highest OH • radical scavenging activity was 51.28 ± 1.06 at 120 μg/mL concentration, and the calculated IC 50 was 51.28 μg/mL concentration. The highest ABTS •+ radical scavenging activity was 91.28 ± 1.12 at 30 μg/mL concentration, and the calculated IC 50 was 33.92 μg/mL concentration. The highest phosphomolybdenum reduction was 87.43 ± 0.90 at 120 μg/mL concentration, and the calculated RC 50 was 24.74 μg/mL concentration. The highest Fe 3+ reduction was 89.38 ± 0.98 at 120 μg/mL concentration, and the calculated RC 50 was 31.06 μg/mL concentration. The antibacterial activity of S. heyneanus showed the highest zone of inhibition of 24 mm for Salmonella typhi with 500 μg/mL concentration. The cytotoxicity limits of the root extracts were tested by MTT assay using human dermal fibroblast cell lines, reflecting > 90% cell viability at a concentration of 500 μg/mL. Conclusions: The current study showed that the root extract of S. heyneanus has better antioxidant properties and potential anti-bacterial compounds. The phytochemical analysis of the root extract showed the presence of alkaloids, steroids, terpenoids, phenols, flavonoids, tannins, saponins, glycosides, and carbohydrates, which are responsible for the antibacterial root extract of S. heyneanus synergistically.