Total flavonoid content and antioxidant activity of launaea Cornuta leaf methanol and aqueous extracts

Abstract

Plants contain chemical constituents identified as phytochemicals which are vital in their therapeutic properties. These bioactive compounds have seen a wide application of medicinal plants in managing various conditions both chronic and acute. Phenolic compounds such as flavonoids constitutes the huge percentage of phytochemicals present in plants. These compounds are characterized by presence of hydroxyl groups. This characteristic feature has seen them possess the antioxidant activity elicited through free radical scavenging mechanism. The use of plants as alternatives to the conventional medication has seen growth in the percentage of research basing on pharmacological properties of plant. This study aimed at evaluating the total flavonoid content and the antioxidant activity of methanol and aqueous leaf extract of Launaea cornuta. The total flavonoid content was evaluated using the aluminum chloride calorimetric method while DPPH free radical scavenging method was used to evaluate the antioxidant activity. Catechin was used as the standard flavonoid while L-ascorbic acid was used as the standard antioxidant. From the catechin standard calibration curve the total flavonoid content in methanol and aqueous extract was 8.004±0.005 mg CE/g dw 7.986±0.028 mg CE/g dw respectively. The total flavonoid content of both extracts was not significantly different (p>0.05). The DPPH free radical scavenging activity results showed that L-ascorbic acid significantly scavenged the free radicals more as compared to both methanol and aqueous leaf extract from 1 µg/ml to 1000 µg/ml (p<0.05). Aqueous leaf extracted showed higher antioxidant activity as compared to methanol leaf extract between concentration levels 0.01 µg/ml to 10 µg/ml. However, methanol leaf extract recorded significantly higher antioxidant as compared to aqueous extract between concentration levels 100 µg/ml and 100 µg/ml. L ascorbic acid, methanol and aqueous leaf extract recorded IC 50 values of 4.0800 µg/ml, 4.620 µg/ml and 5.140 µg/ml respectively. In conclusion, this study revealed that Launaea cornuta has free radical scavenging activity.