ABSTRACT:

Introduction: Green tea contains epigallocatechin gallate (EGCG) that widely use as antibacterial. Formulation development with buffer and emulsifier addition is needed to increase its stability and effectiveness. Buffer addition will increase EGCG stability while emulsifier will increase the cream stability. Objective: This study aimed to determine the optimal formulation from buffer combination between citric acid, ascorbat acid, and triethanolamine that produce pH 5 and also emulsifier combination from propylene glycol, tween 80 and span 80 using simplex lattice design method. Moreover, the effectiveness of optimum cream formula was tested against Propionibacterium acnes (P.acnes) and Staphylococcus epidermidis (S.epidermidis) while its sensitivity was tested on rabbit’s skin. Methods: Buffer optimization was obtained using 13 compositions with the combination of citric acid, ascorbat acid, and triethanolamine namely: 100-0-0,0-100-0,0-0-100,50-0-50,50-50-0,0-50-50,33-33- 33,1,67-1,67-6,67, 6,67-1,67-1,67, 1,67-6,67-1,67, 100-0-0,0-100-0,0-0-100. Data was analyzed using design expert. The optimum buffer combination from ethyl acetate fraction of green tea leaves extract then formulated in the cream which contained various emulsifier composition. The comparison from 13 emulsifier composition of propylene glycol, tween 80, and span 80 is 100-0-0,0-100-0,0-0-100,50-0-50,50-50-0,0-50-50,33 - 33-33,1,67-1,67-6,67,6,67-1,67-1,67, 1,67-6,67-1,67, 100-0-0,0-100 -0,0-0-100. Cream evaluation data included dispersive ability, adhesion and chemical stability was optimized using design expert. Furthermore, the optimal cream (contained 6% ethyl acetate fraction of green tea leaves extract, buffer composition, and optimal emulsifier) was evaluated its antibacterial activity through in vitro and sensitivity using patch test method. Result: The result showed that combination of 23,5 citric acid : 54 ascorbic acid : 22,5 triethanolamine as the optimum buffer composition and combination of 21 propylene glycol : 57 tween 80 : 22 span 80 as the optimum emulsifier composition. The amount of optimum cream hindrance on S.epidermis was 25mm, while on P.acnes was 18 mm. The optimum cream did not cause irritation on rabbit’s skin after 3 days evaluation. Conclusion: Optimal cream has the desired physical characteristics, chemical stability, and effectiveness.