Bioactive fractions in the stem charcoal of Ozoroa insignis used by the pastoral communities in West Pokot to preserve milk

Abstract

Objective: To determine the potential of Ozoroa insignis Del to preserve milk as practiced by the pastoralists of West Pokot, Kenya. Methodology and results:The aqueous and organic solvents extracts of the peeled stem charcoal of Ozoroa insignis were screened for qualitative phytochemical composition by the Trease and Evans (1989) method. Antimicrobial activity was determined using the cork and bore diffusion method against test organisms Staphylococcus aureus (ATCC 22923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922)and Candida albicans (ATCC 90028). Antioxidant activities measured as hydrogen donating radical scavenging ability was determined using the stable radical 2, 2 diphenyl picrylhydrazyl (DPPH) (Brand et al. 1995). Toxicity test was carried out using brine shrimp larvae (Artemia salina, Aqua farm, USA) as the test organism (Meyer et al., 1982). Flavonoids, saponins, sterols and steroids were detected in the three extracts. Alkaloids were detected in the chloroform and methanol extracts, while hydrolysable tannins were detected in the methanol extract. The chloroform and methanol extract fractions were significantly (p<0.05) active against P. aeruginosa, E. coli and S. aureus compared to the aqueous extract that had no activity against any of the test organisms. This implies that alkaloids were directly responsible for the inhibition and growth of micro-organisms and also that the effective phytochemicals were not able to dissolve in water. The antioxidant activity in all the extracts was very high and reduced 2, 2 diphenyl picrylhydrazyl (DPPH) in the first minute by about 84.5%. Conclusions and application of findings: These results show that there is scientific justification for the use of Ozoroa insignis Del in the preservation of milk by the pastoralists of West Pokot. This herb can therefore be considered as viable substitute for the chemical preservatives in the markets where more consumers show greater preference for products preserved with non-artificial compounds. Key words: Ozoroa insignis, antibacterial activity, in vitro screening