COMPARATIVE ANTIOXIDANT AND TOTAL PHENOLIC ANALYSIS OF FOUR INDIGENOUS HERBAL TEA PLANTS OF BOTSWANA

As they say “several cups of tea a day keeps the doctor away!” but is this true or merely shear fiction? And is one type of tea any better than the other? There is strong evidence from the literature that herbal tea plants have health improving properties. One of the reasons for reputed properties of teas is related to the levels of antioxidants they contain. In this work, the antioxidant profiles of four herbal tea plants indigenous in Botswana (Artemisia afra, Lippia javanica, Lippia scabberima  and Combretum hereroense were compared with commercial teas (Chinese Green Tea, Rooibos, and Five Roses). Free radical scavenging Activity (FRSA) of the teas was evaluated spectrophotometrically as maximum fading power of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) at 525nm. The total phenolic content of methanolic extracts was determined using the Folin-Ciocalteau method. At all tested concentrations, the scavenging power of C. hereroense (90%)fruit extract was higher than of all the other indigenous herbal teas and comparable to both Chinese green tea (90%) and Control quercetin (91%). Between 100 and 200µg/ml, all tested extracts had scavenging potencies (≥90%) comparable to quercetin and Chinese Green tea. The total phenolic content of C.hereroense (10 680 mg/l GAE) was tenfold greater than that of commercial teas. The other three tested indigenous herbal teas showed total phenolic contents (1000 to 2000mg/l GAE) comparable to the commercial teas including Chinese Green tea. These results demonstrate that these indigenous tea plants have a positive role in human health. The results also support the long history of use of these traditional teas as health improving remedies and support their use in combating diseases associated with oxidative damage.

Keywords: total phenols; herbal teas; free radical scavenging.