Synergistic antioxidant interactions between green tea and Ocimum gratissimum

Objective: To evaluate the antioxidant interactions between aqueous infusions of green tea and Ocimum gratissimum at different ratios. Methods: Antioxidant activities of aqueous infusion of green tea and Ocimum gratissimum (leaves) alone or in combination at various proportions (3:1, 2:1, 1:1, 1:2, 1:3) were determined by DPPH, ABTS, NO and ex-vivo assays including lipid peroxidation and haemolysis. Total phenolic content and flavonoid content was calculated by Folin-Ciocalteu reagent and aluminum chloride colorimetry method, respectively. A correlation study was also conducted between the antioxidant activity and total phenolic/flavonoid content of various infusions. The interactions were analyzed by combination index applying CompuSyn software. Results: Green tea exhibited high radical scavenging ability as compared to Ocimum gratissimum infusion. Combination of green tea and Ocimum gratissimum exhibited moderate antagonism to strong synergistic interaction at various ratios. A strong correlation was found between total phenolic content/total flavonoid content and antioxidant activities of individual infusions (green tea and Ocimum gratissimum). For binary mixture at different ratios, a weak to strong correlation was observed between total phenolic content and antioxidant activity and almost no correlation between total flavonoid content and antioxidant potential. Conclusions: Overall, green tea and Ocimum gratissimum combination (1:1) displayed the highest antioxidant potential and maximum synergism.