Phytochemical screening and antibacterial activities of Tectona grandis L. f. (Teak) leaves on microorganisms isolated from decayed food samples

Abstract

Bacteria were isolated from decayed food samples (tomatoes, cooked beans and rice) collected from Afe Babalola University, Ado Ekiti (ABUAD) cafeteria and characterized. Some of these isolated microorganisms could pose serious harm to humans including animals and they are normally treated with commercial antibiotics. However, the majority of bacteria are resistant to many antibiotics therefore, the use of plant extracts with therapeutic potential against resistant bacteria is necessary. In this investigation, eight bacteria were isolated from decayed food samples. The bacterial isolates were identified as Bacillus cereus and B. siamensis from rice sample; Klebsiella oxytoxa, Salimicrobium halophilium and Norcardia brasiliensis from beans sample; Bacillus subtilis, Enterobacter taylore, and Brevibacillus agri from tomatoes. The leaf samples of Tectona grandis were screened qualitatively and quantitatively for the phytochemicals while the crude methanol and chloroform extracts were used as antimicrobial agents against the isolated microorganisms. Alkaloids, carotenoids and tannins were present in large amount. The bacterial isolates were more susceptible to commercial antibiotics than that of methanol extracts of T. grandis. The methanol extracts of T. grandis have a higher antimicrobial activity than the chloroform extracts.