Exploring Nature’s Antibiotics; In-vitro antibacterial evaluation of <i>Psidium guajava</i> and <i>Gymnema sylvestre</i>

The present study was designed to evaluate the antibacterial activity of water, methanol, chloroform and petroleum ether extracts of Psidium guajava and Gymnema sylvestre on Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhi by using agar well diffusion method. Both plant extracts showed considerable activity against gram positive and gram negative bacteria. Water extract of Psidium guajava showed good activity against gram positive bacteria and the methanolic extract against gram negative bacteria while chloroform and petroleum ether extracts have only activity against gram positive bacteria but less than water and methanolic extracts which indicated that its polar component have stronger activity against both gram positive and gram negative bacteria than non polar. Gymnema sylvestre extracts also showed activity against both gram positive and gram negative bacteria except water extract which showed no activity against the studied bacteria. The methanolic extract had stronger activity against gram-negative bacteria than chloroform and petroleum ether extracts and had no activity against Salmonella typhi at this concentration but had activity against Escherichia coli but weaker than chloroform and petroleum ether extracts. This indicated that its polar component (methanolic extract) had good activity against gram positive than gram negative bacteria. While chloroform and petroleum ether extracts have stronger activity against gram negative than gram positive bacteria. This indicated that its non-polar components have stronger activity against gram negative bacteria. Keywords: Antibiotic Resistance, Psidium guajava, Gymnema sylvestre, Inhibitory Zone, Plant Extracts, Solvents