In-vitro and in-vivo Activities of the Ethanol Pulp Extract of Annona muricata (Linn) Fruit in Albino Rats Infected with Salmonella typhi

Aims: To investigate the in-vitro and in-vivo activities of the crude ethanolic extract of unripe Anonna muricata fruits in albino rats infected with Salmonella typhi.

Methodology: Matured unripe fruits of A. muricata were collected, dried, powdered and extracted using 70% ethanol. The extract was constituted with 30% dimethylsulphoxide (DMSO) to make varying concentrations. For the in vitro examination, clinical and typed isolates of S. typhi were obtained from Don Bosco Catholic Hospital, Akure and Department of Pharmacognosy, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria. After which the ethanolic crude extract was assayed against the isolates using agar well diffusion method while the comparative study with standard antibiotics was done by disc diffusion method. Meanwhile, eighteen healthy albino rats of same age between 170-220g in weight were selected and divided into six groups containing three each. The infectivity dose (ID) was determined with the clinical S. typhi. After which the rats were infected and orally administered a standard dose of the A. muricata fruit extract (400 mg/kg) accordingly for 7 days. During the treatment period, the fecal samples were collected to monitor the ability of the extract to reduce the fecal shedding of S. typhi. Also, the rats were weighed daily to establish the effect of treatment on their metabolism.

Results: Ethanol extract of pulp of A. muricata, at concentrations of 50 mg/ml – 200 mg/ml, could not produce zone of inhibition (ZI) on cultures of clinical and typed S. typhi isolates but at concentrations of 250 mg/ml and 500 mg/ml it produced ZI of 4.93 – 11.37 mm(P< 0.05) on the clinical isolate. Minimum inhibitory concentration of the extract on typed S. typhi and on the clinical isolate was 150 mg/ml and 250 mg/ml, respectively. The MBC for the two S. typhi isolates were 350 mg/ml and 400 mg/ml respectively. S. typhi colony forming units per ml (cfu/ml) of suspensions of faeces of infected rats, treated with the ethanol extract of A. muricata pulp decreased significantly (P<0.05) as days of the treatment increased while the cfu/ml of the control group increased(P<0.05). There was no significant (P> 0.05) difference between weights of S. typhi-infected rats treated with any of the regimes but weight of the untreated group (control) significantly (P<0.05) decreased.

Conclusion: Ethanol extract of pulp of unripe A. muricata appears to have inhibitory effects against Salmonella typhi.