O-36 Phytochemical screening and Antibacterial potential of Psidium guajava (Guava) leaf extract.

Methods:  Dried pulverised guava leaves were macerated using four solvents: hexane, ethyl acetate, methanol and 95% ethanol; and concentrated using a rotary evaporator. The crude extracts were screened for phytochemicals namely; saponins, alkaloids, tannins, flavonoids, phenols, steroids and terpenoids, according to standard testing procedures. Sterile filter paper discs were soaked in different concentrations of the various extracts. The Kirby Bauer disc diffusion method was done on Mueller Hinton agar seeded with bacteria. Discs were placed in triplicate on each plate. Discs soaked in pure solvent were used as the negative control. The positive controls used were ciprofloxacin, ceftazidime and tetracycline. After incubation, zones of inhibition around the discs were measured in millimeters and the results expressed as mean ± SD.

Results:  All the phytochemical that we screened for were present the guava leaf extracts. Large zones of inhibition were seen with the ethyl acetate extracts especially at 100mg/ml for S. aureus (22.0±6.1mm), E.coli (16.3±0.9mm) and P. aeruginosa (15.0±0.0mm). Zones of inhibition were seen for the ethanolic abstracts especially at 100mg/ml for K pneumoniae (22.0±4.3mm) and P aeruginosa (14.0±1.0mm). Zones for the 100mg/ml extracts against S. aureus were larger than those for ceftazidime (19mm), while those of P. aeruginosa were larger than those for tetracycline (9mm).

Conclusion:  P. guajava leaves contains many phytochemicals which in turn posses great antibacterial activity and therefore have great potential as a novel alternative to antibiotic treatment.