Phytochemical Analysis and Antimicrobial and Antioxidant Activity Evaluation of Aloe debrana Leaf Latex Extracts against Selected Human Pathogenic Bacteria and Fungi

Abstract

Aloe debrana (Family: Liliaceae) is a stem-less evergreen endemic medicinal plant of Ethiopia, which is traditionally used to treat eye infection, wounds, and malaria. This study aimed to analyze phytochemicals and evaluate the bioactivity of A. debrana leaf latex crude extracts against human pathogens. To obtain crude extracts, various solvents were employed through the maceration process. Qualitative phytochemical analysis was conducted using standard techniques, and the essential oil extracted from A. debrana was obtained through hydro distillation using a Clevenger apparatus. The antimicrobial evaluation was carried out using the disk diffusion method. And, the minimum inhibitory concentration (MIC) of both crude extracts and isolated compounds was determined through the broth dilution method. Among the solvents used for extraction, the methanol extract displayed the highest crude yield 34.6%. Phytochemical analysis revealed the presence of saponins, flavonoids, tannins, terpenoids, phenols, and steroids. The essential oil extracted from A. debrana revealed the presence of 20 chemical components. The ethyl acetate was subjected to column chromatography to isolate pure compounds. Silica gel column chromatography separation of the ethyl acetate extract affords two compounds (Coded as compound 1 and compound 2). Compound 1 was identified to be flavonol skeleton and Compound 2 to be 2-4-dimethoxy chrysophanol based on spectral data (NMR). Regarding antimicrobial activity, the crude extracts, compounds, exhibited good inhibitory effects against selected human pathogenic bacteria and fungi. The methanol crude extract displayed a maximum zone of inhibition of 18±1.63 against Escherichia coli (ATCC 25922) at 200 mg/ml. At the same time, compound 1 and compound 2 showed good inhibition zones of 15.66±1.24 and 14.66±0.47 at 10 mg/ml against Escherichia coli (ATCC 25922), respectively. Crude extract and isolated compounds also showed inhibitory effects against C. albicans (ATCC 10231). MIC values ranged from 25 to 100 mg/ml for crude extracts and 2.5 to 10 mg/ml for isolated compounds, with positive results for minimum bacterial concentration and minimum fungal concentration. The study assessed antioxidant activity, revealing high Radical scavenging activity for ethyl acetate extract and compound 1 (IC50 values 42.01 and 5.03), respectively. The diverse phytochemical profile and promising biological activities suggest that A. debrana could be a valuable plant for future drug development.