Abstract:
This study was aimed to study antimicrobial activity of Terminalia catappa leaf extracts prepared from 3 different leaf stages including green-, yellow- and red-leaf stage. The different stages of leaves were extracted by conventional shaking method with 4 different solvents (acetone, methanol, ethanol and water) for 3 hours. The bioactive compounds were colorimetrically analyzed by Foiln Ciocalteu and aluminium chloride method. The result showed that the yellow leaf extracted by ethanol significantly provided the highest phenolic content (852.14±3.35 mg GAE/g extract), while acetone extract of the yellow leaf showed the highest flavonoid content (515.10±0.30 mg QE/g extract). Evaluation of antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans by disk diffusion method revealed that the all Terminalia catappa leaf extracts, except acetone extract of the green leaf, had inhibitory effect on Staphylococcus aureus only. The minimal inhibitory concentration (MIC) of the green leaf extracted with methanol, ethanol and DI water was 5, 10 and 20 mg/ml respectively, whereas the yellow and red leaf extracts, except water extract of the red leaf, showed similar MIC value of 10 mg/ml. For minimum bactericidal concentration (MBC), it can be observed that MBC value of the green leaf extracted with methanol, ethanol and DI water was 10, 20 and 20 mg/ml, respectively while the yellow and red leaf extracts provided MIC value of 10 mg/ml and the red leaf extracted with water showed the value of 20 mg/ml. Moreover, the correlation of total phenolic content of the yellow and red leaf extracts, and antimicrobial activity expressed in term of inhibition zone was proven that they strongly correlated with correlation coefficient (R) of 0.947 and 0.775 respectively. Therefore, it can be concluded that the all 3 colored leaf extracts of Terminalia catappa had a potential to inhibit the gram positive bacterium. They could be possibly developed as natural preservatives or preservative promotor for cosmetic applications.