Antimicrobial activity and stability of Fraxinus rhynchophylla Hance extract

Clostridium perfringens is a gram-positive, spore-forming and anaerobic bacterium which is widely found in the food and intestinal tract of human and animal. C. perfringens can cause diarrhea and abdominal pain in human and necrotic enteritis, enterotoxemia and hamorrhagic gastroenteritis in animal due to several exotoxins of C. perfringens. e.g. A type α-toxin, B type α, β, ε and C type α, β. In this study, antimicrobial activity of Fraxinus rhynchophylla Hance extract against C. perfringens isolated from intestinal tract of broiler chickens and stability agaist heat and pH were investigated. Ethanol extract of F. rhynchophylla suppressed growth of C. perfringens at a concentration of 0.1 mg/mL (Fig. 1), whereas the growth of lactic acid bacteria, Bifidobacterim bifidum, was not affected by the extract. Moreover, growth of B. bifidum was stimulated about 5˜16% compared with control after treated with the extract for 24˜72 hours (Fig. 2). Antimicrobial activity of F. rhynchophylla extract was not altered after heated at 100 °C for 60 minutes and sustained in wide range of pH (3˜11). These results suggested that F. rhynchophylla extract could be used as natural source for the development of antibiotics alternative.

Fig. 1: Inhibitory effect of F. rhynchophylla extract on the growth of C. perfringens. C. perfringens was incubated at 37 °C for 0˜72 hours under anaerobic condition, and the absorbance of broth was measured at 650nm. cont: cultured without F. rhynchophylla extract, 0.01: treated with F. rhynchophylla extract at a concentration of 0.01 mg/mL, 0.1: treated with F. rhynchophylla extract at a concentration of 0.1 mg/mL

Fig. 2: Stimulatory effect of F. rhynchophylla extract on the growth of B. bifidum. B. bifidum was incubated at 37 °C for 24˜72 hours under anaerobic condition, and the stimulatory activity of F. rhynchophylla extract was analyzed comparing with absorbance of non-treated broth medium (control). 0.01: treated with F. rhynchophylla extract at a concentration of 0.01 mg/mL, 0.1: treated with F. rhynchophylla extract at a concentration of 0.1 mg/mL. Means and standard errors are based on data from three replicates.