The antibacterial and phytochemical evaluation of extracts of grape (Vitis vinifera) seeds

Abstract

The skins and seeds of grapes are known to be rich sources of phenolic compounds, both flavonoids and non-flavonoids. These compounds, when present in plants have been confirmed to have antibacterial property.  The antibacterial and phytochemical evaluation of grape seeds was done in vitro on selected bacteria (Bacillus cereus, Escherichia coli, Proteus vulgaris, Staphylococcus aureus, Shigella dysenteriae and Salmonella typhi). The seeds were collected from a local farmer in Ijare, Ondo State, dried and extracted using 98% ethanol and methanol respectively after blending the seeds to powder. The qualitative phytochemical analysis of the seeds was done using standard methods. The results showed that the methanol extract was more effective than the ethanol extract and had the highest diameter of zone of inhibition of 16.90mm on Staphylococcus aureus. The methanol extract had an average minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 25mg/ml on the microorganisms. It however had both MIC and MBC of 12.5 mg/ml on S. aureus. The extracts of the seeds contained various phytochemicals such as alkaloids, phenolic compounds, flavonoids, saponins, glycosides, phytosterols, and tannin. However, both of the extracts showed significant levels of antibacterial activity. Methanol extract was the most active one with remarkable antibacterial activity on the various species tested. The findings of the present study indicated that the seeds of Vitis vinifera possess various secondary metabolites having the potential for developing pharmaceutical drugs, especially antimicrobial ones.