Antifungal activity and Nystatin Interaction with crude aqueous and Methanolic extracts of Azadirachta indica (Neem) on some fungal isolates

Abstract

Antifungal activities of crude aqueous and methanolic extracts of Azadirachta indica on some fungal isolates were determined. Standard microbiological methods and methods in phamacognosy were used to determine phytochemistry, for antibiotic susceptibility testing (AST), and antibiotic-extract interaction. The results obtained from this research showed higher quantity of saponins in methanolic extracts while terpenes were more in aqueous extracts. The antifungal effect showed by the extracts increased with increasing concentrations (12.5 mg/mL, 25.0 mg/mL, 50 mg/mL, 100 mg/mL, 200 mg/mL) on Aspergillus niger (inhibition zone range: 10.2 ± 0.2 mm-19.5 ± 0.1 mm) Penicillium sp. (inhibition zone range: 6.0 ± 0.2 mm-16.3 ± 0.5 mm) and Candida albicans (inhibition zone range: 8.3 ±2.0 mm- 18.0 ± 1.2 mm) for both methanolic and aqueous extracts. Aqueous extracts showed higher potency than methanolic extracts (p < 0.01). Activity index as high as 1.8 was observed. MIC as low as 125 µg/mL and 250 µg/mL were also observed. Combined extract and nystatin at MIC and ½ MIC showed synergy against Aspergillus niger and Candida albicans, but showed indeterminate effect on Penicillium sp. The traditional use of Neem plant for treating diverse infectious diseases is hereby justified, while its combination with synthetic antifungal drugs when necessary would be effective.