Phytochemical screening and antifungal potency of Vernonia amygdalina (bitter leaf) extract against post harvest mycodeterioration of tomato (Lycopersicum esculentum)

Abstract

The study investigated fungi associated with post harvest tomato fruits sold in the open market in Port Harcourt Metropolis. The antifungal activity (bitter leaf) extracts against spoilage was studied using well-in-agar diffusion method. Results showed that mean percentage incidence of fungi isolated from tomato fruits were Rhizopus stolonifer (56%), Aspergillus niger (62%) and Altermaria altermata (35%). Aqueous and ethanolic extracts of Vernonia amygdalina at different concentrations (20%, 40%, and 60%) (w/v) were used against fungi isolates, while water and ketoconzole (0.5 mg/mL) served as negative and positive control, respectively. Aqueous and ethanolic extracts of V. amygdalina inhibited the growth of all three test fungi. There were significant differences (p > 0.05) in the mean inhibitory effects of plant extracts and control. Antifungal activity measured as diameter of zone of inhibition revealed that V. amygdalina acqueous extract at 60% was very active against Aspergillus niger (16.50 mm) and Alternaria altermata (16.00 mm), while being moderately active against Rhizopus stolonifer (13.00 mm). However, 60% ethanolic extract of V. amygdalina was very active against A. niger (19.00 mm), A. altermata (17.00 mm) and Rhizopus stolonifer (15.80 mm). Phytochemical screening of V. amygdalina revealed the presence of tannins, oxalate, saponnins, flavanoid, cynogenic glucoside, phytate and Alkaloids V. amygdalina could serve as a potentially viable alternative to chemical fungicides in the preservation of post harvest tomato fruits (Lycopersicum esculentum).