In-vitro evaluation of the antioxidant activity of aqueous and ethanolic leaf extracts of Callistemon citrinus plant

Abstract

Above 85% of the countries are estimated to use traditional medicine including herbal medicines. The use of herbal medicines has increased greatly over the past three decades. In Uganda, over 60% of the population seek traditional/herbal medicines for various ailments. Despite the widespread use of these herbal medicines in Uganda, there is no published evidence of their safety and efficacy. This study was done to evaluate the in vitro antioxidant activity of Callistemon citrinus in order to provide laboratory evidence for the possible use of this plant as a source of antioxidation. In the methodology, C. citrinus plant leaves were collected and an aqueous and ethanolic extracts were prepared from them using cold maceration method. DPPH scavenging assay technique was used to determine the antioxidant activity of the two extracts. Ascorbic acid was used as positive control for these scavenging activity experiments. In addition, the phytochemical compositions of the extracts was also determined. The results showed that both the aqueous and ethanolic extracts had significant levels of antioxidant activity with IC90 values of 3.13 mg/ml and 2.50mg/ml respectively. Several phytochemicals were present including Saponins, Tannins, Flavonoids, Terpenoids, Alkaloids and Phenols. The phytochemicals were also more abundant in the ethanolic extract than the aqueous extract. The two extracts showed significant antioxidant activity. Further studies are recommended to explore the antioxidant potential of C. citrinus plant.