Antimicrobial and food preservative activities of selected medicinal plants in seka chokorsa district, jimma zone, southwest Ethiopia

Abstract

Antimicrobial activity is the activity of either crude of the plant or medicine that can stop or eliminate the growth of microbes. Natural food preservation method is application of plant preservatives to prevent food spoilage and growth of food borne pathogens in food and foods products. The main purpose of the study was to assess antimicrobial and food preservative activity of selected medicinal plant in Seka Chekorsa, one of the districts in Jimma Zone, Oromia Region of Ethiopia. Commonly used medicinal plants by most of the practitioners were selected based on frequency from the medicinal plant practitioners. Based on this, Croton macrostachyus, Calpurnia aurea and Vernonia myriantha were collected, well dried, grinded by using coffee grind machine and then soaked in chloroform, acetone and methanol. After filtering using filter paper the solvents were removed using rotary evaporator. By re-dissolving the crude in DMSO antimicrobial activity of all crudes were conducted. Testing strains for antimicrobial activity (Staphylococcus aureus, Bacillus cereus, Eschercheria coli and Salmonella thyphurium) were isolated, while available strain of Candida albicans was used. After evaluating the antimicrobial activities of the plant crude extracts chloroform extracted Croton macrostachyus showed antimicrobial activity on S. aureus which is 23.33 ± 3.30 mm, while methanol extracted Croton macrostachyus showed good antimicrobial activity on C. albicans which is 22.33 ± 1.70 mm. long. Actone extracted croton macrostachyus also showed antimicrobial activity on S. aureus by 17.67 ± 2.05 mm, on C. albicans by 19.67 ± 0.94 mm, methanol extracted croton macrostachyus showed by 12.67 ± 2.05 mm, on C. albicans 22.00 ± 0.82 mm. Phytochemical screening of the crude showed that, alkaloids, flavonoids, saponin, phenols, tannins, terpenes and steroids were detected in the crude both crude of Croton macrostachyus and Calpurea aurea. MIC of those crude were determined by serially diluting at different folds. The MIC of C. macrostachyyus on B. cereus was 0.267 g/ml, 0.235 g/ml on S. aureus, 0.182 g/ml on C. albicans. In food preservative activity the mean log of 10 of the cfu in Zingiber officinale 6.08 and 2.49, in Moringa oliefera 3.54 and 2.62, in Allium sativum 3.60 and 2.72 control and experimental respectively. Generally, phytochemicals in Croton macrostachyus, Calpurnia aurea and Vernonia myriantha have good antimicrobial and while those in Zingiber officinale, Moringa oliefera and Allium sativum good food preservative activities. Therefore, scholars should work on the development study on the issue.