Phytochemical Investigation, in vitro Antioxidant and Anti-inflammatory Evaluation of Leaf Extracts of Solanum erianthum

Aims: Solanum erianthum has been used in the treatment of various diseases by traditional medical practitioners in south-western Nigeria. The leaf extracts of the plant have been shown to possess antimicrobial activities. However, very little exists in literature on the antioxidant and anti-inflammatory properties of the plant. This study examines leaf extracts of Solanum erianthum for antioxidant and anti-inflammatory activities.

Place and Duration of Study: Department of Chemistry, Federal University of Technology Akure, Nigeria between September 2015 and January 2017.

Methodology: Leaf extracts were subjected to successive extraction using hexane, ethylacetate and methanol. The extracts were screened for the presence of phytochemicals using standard procedures. The DPPH and Ferric Reducing Antioxidant Assays were used to evaluate the antioxidant properties of the extracts. The DPPH scavenging properties of the extracts were assessed by comparing their IC50 values with that of the standard (Ascorbic acid). The ferric reducing properties of the extracts were determined as the concentration that gave a ferric reducing ability equivalent to that of ascorbic acid. The total phenolic content of the extracts was measured as milligram Gallic acid equivalent per gram of extract (mg GAE/g). The membrane stabilizing properties of the extracts were determined and used as a measure of their in vitro anti-inflammatory activities. The anti-inflammatory properties of the extracts were compared with that of the standard drug (Indomethacin).

Results: Phytochemical screening showed that the extracts contain flavonoids, alkaloids, tannins, glycosides, saponins, terpenoids, phlobatannins, sterols and carbohydrates. In the DPPH assay, the extracts had IC50 values ranging between 0.379 and 2.025 compared to the ascorbic acid with IC50 value of 0.017. The ferric reducing properties of the extracts ranged between 1.187 and 6.743 mg ascorbic acid equivalent/g of sample. The methanol extract showed the highest DPPH and ferric reducing antioxidant properties. The phenolic contents of the extracts ranged between 3.039 and 4.196 mg GAE/g sample. In the in vitro anti-inflammatory assay, the ethylacetate extract, showed a membrane stabilizing property higher than that of Indomethacin at 0.2 mg/ml and 0.5 mg/ml. The anti-inflammatory activities of the hexane and methanol extracts are lesser than that of Indomethacin at all the test concentrations.

Conclusion: The results showed that the leaf extracts of Solanum erianthum possess a broad range of medicinal properties. This could justify the use of the plant in the treatment of various diseases by traditional medical practitioners in Southwestern Nigeria.