Antimicrobial activity and preliminary phytochemical screening of oil extracted from food waste generated from Persea americana

Abstract

Persea americana (Mill) commonly known as avocado is a fruit consumed globally with great potentials for the pharmaceutical, food and cosmetics industries. However, the seeds and peels of this plant are commonly discarded as waste. This study was conducted to determine the antimicrobial activity and preliminary phytochemical screening of the oil from the seeds and peels of avocado against selected bacterial and fungal isolates previously characterized in the laboratory. The oil was extracted using soxhlet apparatus with n-hexane as extraction solvent. Efficacy was assessed using agar well diffusion method at various concentrations on Mueller Hinton agar. The result revealed that the extract from the seeds and peels were effective on Penicillium notatum (42.40 mm), Pseudomonas aeruginosa (35.30 mm), Escherichia coli (27.25 mm), Enterococcus faecium (23.21 mm),
Enterococcus faecalis (21.20 mm) and Aspergillus niger (20 mm) respectively. The peel extract had no inhibitory effect against Aspergillus niger even at the highest concentration tested. Phytochemical screening of the peels showed the presence of tannins (2.43%), Saponins (7.75%), flavonoids (22.05%), alkaloids (1.21%) and cyanogenic glycosides (15.26%).The high level of flavonoids favors its antioxidant properties. The seeds contains saponins (4.14), flavonoid (4.22), alkaloid (2.25), glycoside (19.08), steroid (12.87), reducing sugar (4.20) and phenolic compound (8.12). DPPH radical scavenging value was found to be 10.753 ± 4.301 µg/ml for peels and 26.344 ± 3.495 µg/ml for seeds against standard ascorbic acid 95.11±89.784. Hence, eluting and purification of the active ingredients in the extracts can make them promising alternative to orthodox drugs; value added products for the cosmetics and food industries as well as reduction in environmental pollution