Rekayasa proses ekstraksi kulit buah Langsat (Lansium domesticum var. langsat) sebagai bahan antibakteri dan antioksidan

Abstract

Langsat, a fruit plant in the family of Meliaceae, has long been used in traditional medicine to treat fever, diarrhea, malaria, and tumor. This study aims to obtain the optimum extraction condition and method of langsat fruit peel with the best antibacterial and antioxidant activities. The methods used to determine activities were agar diffusion method, dillution method for MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) for antibacterial and DPPH (1,1-diphenyl-1-picrilhydrazyl) for antioxidant activity. Solvents used in the maceration extraction were hexane (non polar), ethyl acetate (semi-polar) and ethanol (polar). Solvent that gave the best antibacterial and antioxidant activity was further used for the microwave extraction. Conventional extraction methods namely reflux and maceration were then compared to microwave extraction. The microwave power and extraction time was determined based on the highest total phenol extract of langsat fruit peel. The best extraction method was used to optimize the extraction process with response surface method to determine the optimal conditions for the extraction of langsat fruit peel. The results showed that ethanol extracts have the highest antibacterial and antioxidant activity compared to other extracts. The MIC and MBC values of ethanol extracts were 62.5 and 125 ppm for bacteria S. aureus, while the bacteria E. coli with value of 500 and 1000 ppm, respectively. The antioxidant activity of ethanol extract DPPH method has IC50 value of 77.60 ppm. Microwave with power of 400 watt for 3 minutes, produced the highest total phenol extract. Extraction with microwave produced phenol with a total of 13.92% and 22.64%, higher than extraction with reflux and maceration. The optimum extraction of langsat fruit peel was obtained at the microwave power of 336.56 watts and for extraction time of 3.24 minutes, which resulted in a total phenolic extract of the langsat fruit peel 44.07 mg TAE/g. The validation results experimentally showed the value of total phenols 0.66% smaller than predicted. Validation results showed an increase in antibacterial and antioxidant activity than before the optimization, the MIC and MBC values for S. aureus were 31.25 and 62.5 ppm, whereas E. coli with value of 125 and 250 ppm. The antioxidant activity of the validation result has IC50 value of 47.44 ppm.