INTRODUCTION:
Jatropha tanjorensis has been consumed as leafy vegetable and as a medicinal plant in Nigeria has shown hematological, antimalarial, antimicrobial, hypoglyceamic, hypolipidemic and antihypertensive activities. Piper guineense, a West African spice used in many folklore medicines has a number of verified pharmacological activities.

METHODS:
This study evaluated the antibacterial activities of Jatropha tanjorensis and Piper guineense leaf extracts against Staphylococcus aureus and Escherichia coli using biochemical, phytochemical, and microbiological analyses. Standard microbiological techniques were employed for the isolation and identification of test organisms. Gram staining and biochemical tests confirmed the isolates as S. aureus (Gram-positivecocci, catalase- and coagulase-positive) and E. coli (Gram-negative rods, indole- and catalase-positive). Methanolic and ethanolic extracts of both plants were prepared via cold maceration and screened for phytochemicals, revealing high concentrations of alkaloids, flavonoids, tannins, and saponins. Antibacterial activity was evaluated using the agar well diffusion method on Mueller-Hinton agar at concentrations ranging from 12.5 mg/ml to 200 mg/ml, with Ciprofloxacin as a positive control and DMSO as a negative control.

RESULTS:
The methanolic extract of J. tanjorensis exhibited significant, concentration-dependent inhibition against S. aureus, with a maximum zone of inhibition of 22 mm at 200 mg/ml, while E. coli showed moderate susceptibility. The ethanolic extract showed moderate activity with inconsistent inhibition patterns. Similarly, P. guineense methanolic extract showed moderate antibacterial activity, whereas its ethanolic extract was largely ineffective, against S. aureus. Minimum Inhibitory Concentration and Minimum Bactericidal Concentration tests revealed the ethanolic extract of J. tanjorensis had bactericidal effects at 25 mg/ml, while P. guineense extract failed to achieve complete bacterial kill. The combined extract of both plants displayed potential synergistic effects against S. aureus but no activity against E. coli.

CONCLUSIONS:
These findings support the potential use of J. tanjorensis as a promising natural antimicrobial agent against Gram-positive bacteria.