Phytochemical Screening and Antibacterial Activity of the Ethanol Extract of Rubber Seed Shells (Hevea brasiliensis) against Escherichia coli and Staphylococcus aureus

Abstract

Background: The growing problem of antibiotic resistance has intensified the need to explore natural-based antibacterial alternatives. Objective: This study aimed to qualitatively identify the phytochemical profile and assess the antibacterial potential of an ethanol extract from rubber seed shells (Hevea brasiliensis) against Escherichia coli and Staphylococcus aureus using the Kirby-Bauer disc diffusion method. Methods: Rubber seed shells were processed through drying, grinding, and maceration using 96% ethanol. Extract yield was determined, followed by qualitative screening for secondary metabolites including alkaloids, flavonoids, saponins, tannins, terpenoids, and steroids. Antibacterial potential was evaluated via the disc diffusion (Kirby-Bauer) method at four concentrations (5%, 10%, 30%, and 50% w/v) using chloramphenicol as the positive control and sterile distilled water as the negative control (n=3), analyzed using the Kruskal-Wallis and Dunn tests. Results: The extract yield was 9.38%. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, and steroids, while saponins and terpenoids were not detected. No inhibition zone was observed against E. coli at any tested concentration (equivalent to the negative control). Against S. aureus, inhibition zones ranged from 8.00–9.50 mm (moderate category), with no significant difference among concentrations. Conclusion: The ethanol extract of rubber seed shell exhibited moderate antibacterial activity against S. aureus without a significant dose-response relationship, but showed no activity against E. coli, presumably related to differences in bacterial cell wall structure. Further research is recommended to explore higher concentrations, solvent fractionation, and alternative extraction solvents.