Comparative Study of the Composition of Aqueous Extracts of Green Tea (Camellia Sinensis) in Total Alkaloids, Total Flavonoids, Total Polyphenols and Antioxidant Activity With the Leaves of Combretum Glutinosum, Combretum Micranthum and the Red Pulps of Hibiscus Sabdariffa

Abstract

Green tea ( Camellia sinensis ) is by far the most consumed beverage in the world after water. This consumption is mainly due to its antioxidant properties and its secondary metabolites richness. In Senegal, tea is consumed, but also herbal teas, including Combretum glutinosum , Combretum micranthum , for breakfast or Hibiscus sabdariffa , as a drinking juice. The purpose of this study is to compare green tea with these herbal teas in term of secondary metabolites content and antioxidant activity. The plant material used consists of leaves Camellia sinensis , Combretum glutinosum , Combretum micranthum , and red pulp of Hibiscus sabdariffa . These different parts of plants were dried and then ground into fine powder before being extracted by infusion and then concentrated the infuser in a dry rotary evaporator. The dry extracts are used for the quantitative determination of alkaloids, flavonoids, polyphenols and the antioxidant activity by the ABTS method. On the different plant extracts tested, the leaves of Combretum glutinosum are richer than all the other plants studied here in terms of alkaloids, flavonoids and polyphenols with concentrations of 6.96 μg/mg, 134.94 μg/mg and 374.50 μg/mg of dry extracts. In flavonoids, leaves of C. Glutinosum are followed by the red pulp of Hibiscus sabdariffa with 1.626 μgQE/mg. The latter is also the poorest in flavonoids and polyphenols compared to Camellia sinensis and leaves of C. Micranthum with respective concentrations of 107.90μgQE/mg and 97.70 μgQE/mg in flavonoids and 258.50 μgGAE/mg 223.50 μgGAE/mg of polyphenols. With regard to the antioxidant activity, C. Glutinosum are most active with an IC 50 of 6.101 μg/ml followed by tea with 6.713 μg/ml at the moment when C. Micranthum and Hibiscus sabdariffa had respectively IC 50 s of 6.727 and 11.76 μg/ml.