in vitro antisalmonellal and antioxidant properties of leaves extracts of Zehneria scabra (L.F.) sond (Cucurbitaceae)
Herman MF Biekop, Marc K Kouam, Bridget Katte, Alexis Teguia
Conventional antibiotic are usually used in poultry farming to treat salmonellosis. Unfortunately, these antibiotics have negative side effects both on animal and human health, and also lead to anti bio-resistance; hence the need for an alternative means of treatment. Therefore, the aim of this study was to investigate the in-vitro antisalmonellal and antioxidant activities of aqueous, ethanolic, and hydro-ethanolic leaves extracts of Zehneria scabra against four Salmonella isolates. Antisalmonellal activity was evaluated using the broth microdilution method. To evaluate the antioxidants properties, the quantitative determination of total phenols, flavonoids and the phytochemical screening were performed using standard methods; four extract concentrations were evaluated (12.5, 25, 50, 100 and 200µg/mL). The ethanolic extract had the greatest antisalmonellal activities, with minimum inhibitory concentrations (MICs) value of 128µg/ml against Salmonella Typhimurium, Salmonella Enteritidis and Salmonella Typhi, and 256µg/ml against Salmonella Typhi ATCC6539. The ethanolic extract exhibited similar 1, 1-diphenyl-2picrylhydrazyl (DPPH) scavenging activity with control vitamin C, but had the strongest DPPH scavenging activity compared with aqueous and hydroethanolic extracts at 200 µg/mL. For the extract concentration of 200µg/ml and 100µg/ml, ethanolic and aqueous extracts showed comparable Nitric oxide scavenging activity with vitamin C. At 12.5, 100 and 200µg/ml, ethanolic extract showed a significantly (p<0.05) lower ferric reducing power as compared with all other extracts, as well as vitamin C. Phytochemical screening of extracts revealed the presence of flavonoids, phenol, tannins, and triterpenes in all the extracts while alkaloids, steroids and anthraquinone were absent. The results showed that Zehneria scabra leaves extracts are promising for a successful treatment of salmonellosis in poultry as well as in Salmonella-susceptible mammals but, in vivo studies are needed to confirm the efficacy and safety of this plant extract against Salmonella.