Investigation of In Vitro Antimicrobial and Antioxidant Activities of Eco-Enzymes Derived from Papaya, Pineapple, and Orange Fruit Peels for Acne Treatment

Ng, Wing Yet (2026) Investigation of In Vitro Antimicrobial and Antioxidant Activities of Eco-Enzymes Derived from Papaya, Pineapple, and Orange Fruit Peels for Acne Treatment. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Acne vulgaris, which is driven by opportunistic pathogens, remains a prevalent skin condition. Conventional acne treatments often lead to side effects like skin irritation and antibiotic resistance. Eco-enzymes, produced from the fermentation of fruit peel waste, are rich in bioactive compounds and offer a potential natural, sustainable alternative. This study aims to evaluate the physicochemical properties, antimicrobial activity against Staphylococcus epidermidis isolated from human acne, and antioxidant potential of fruit peel-derived eco-enzymes. Four eco-enzyme formulations, which were papaya + pineapple + orange eco-enzyme (EE1), pineapple + orange eco-enzyme (EE2), papaya + orange eco-enzyme (EE3) and papaya + pineapple eco-enzyme (EE4) were produced via fermentation for 117 days. Physicochemical properties (pH, colour, aroma) were recorded. S. epidermidis was isolated and identified using selective media, Gram staining, and 16S rRNA sequencing. The identification of S. epidermidis was confirmed through 16S rRNA gene sequencing. The antibacterial activity was assessed using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays against S. epidermidis. Antioxidant activity was determined using the DPPH assay at concentrations of 25–125 ppm. All eco-enzyme samples were acidic (pH ~2.97–3.46), indicating successful fermentation and organic acid production. The MIC results showed bacterial growth inhibition at 25% for all four eco-enzyme formulations. However, MBC results revealed varying bactericidal activity, with EE1 and EE2 showing the highest effectiveness as bacterial killing occurred at 25%, while EE3 required 50% concentration and EE4 required 100% concentration to achieve bactericidal effects. The antioxidant assay indicated that all four eco-enzyme formulations exhibited weak antioxidant activity, as concentrations above 150 ppm were required to achieve 50% inhibition. The study concluded that eco-enzymes derived from fruit peels exhibited significant antibacterial activity against S. epidermidis, but demonstrated limited antioxidant potential. Further studies should assess antimicrobial activity against other major acne-causing bacteria, such as Cutibacterium acnes, along with evaluation of its anti-inflammatory properties.