Comparative antioxidant activity of selected plants possessing characteristic colours

Abstract

A wide variety of plants with economic values are rich in natural colours. These coloured plants contain phytochemicals that are believed to have many pharmacological  activities including anti-oxidant properties. In this study, five plants with known characteristic colours in any of their parts were selected for comparison of their anti-oxidant potentials. Rhizomes of turmeric,  tubers of beetroot, leaves of star cucumber, barks of camwood, and flowers of hibiscus were collected and carefully dried, powdered, extracted and subjected to qualitative and quantitative phytochemical studies, as well as in vitro antioxidant assessments using FRAP and DPPH scavenging activities protocols. The best performing coloured extract (turmeric) was thereafter subjected to in vivo anti-oxidant studies employing catalase and lipid peroxidase (MDA) protocols and using jackfruit concentrate in various proportions as vehicle for oral delivery. The phytochemical analyses revealed the presence of various valuable secondary and primary metabolites, including alkaloids, tannins, flavonoids, terpenoids, cardiac glycosides, reducing sugars, carbohydrates, and proteins. The antioxidant activity/reactive oxygen scavenging abilities comparison of plant extracts showed that turmeric on the overall, exhibited the best scavenging activity. The admixture of the jackfruit concentrate and turmeric extract of 8:2 gave the best anti-oxidant performance which is comparable to the positive control (ascorbic acid). Significantly, the jackfruit concentrate used as vehicle, gave very promising in vivo anti-oxidant activity. Invariably, an 8 : 2 admixture of jackfruit concentrate and turmeric extract will serve as a promising extemporaneous nutraceutical for  reactive oxygen scavenging.