The Antioxidant Activities And Model Study Of The Inhibitory Effect Of Clinacanthus Nutans On Cronobacter Sakazakii Growth

Cronobacter sakazakii(C.sakazakii)is an emerging foodborne pathogen which is parasitic on gut of human and animals.It can cause neonatal meningitis,septicemia and necrotizing enterocolitis.Clinacanthus nutans(CN),a well-known medical plant in Southeast Asia,is traditionally used to treat infection,cancer as well as edible wild herbs.From a kinetic of view,the present study aimed to estimate the quantitative inhibitory effect of CN leaf extracts from different region of China on Cronobacter sakazakii growth at different incubation temperature(25,30,33,37 and 43℃).Predictive models were employed to evaluate the inhibitory action of these plants on Cronobacter sakazakii.The main results were shown as follows:(1)The antioxidant potentials of the methanol extracts from CN w ere measured as 1,1-diphenyl-2-picrylhydrazyl(DPPH)and 2,2’-azino bis-(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS)radical scaven ging abilities as well as the reducing power assay.IC50 of CN extr act from Hainan province were respectively 0.895mg/mL(DPPH),0.494mg/mL(ABTS)and 0.932mg/mL(OH-),while these values of C N extract from Jieyang were 0.685 mg/mL(DPPH)and 0.262 mg/mL(ABTS),0.801mg/mL(OH-).The result illustrated that the antio xidant activities of CN extract from Jieyang was stronger than that of Hainan.It suggested that CN extract could be considered as na tural antioxidant sources and dietary nutritional supplements to pre vent oxidation-related diseases.(2)The growth data were matched by three different primary models(Baranyi model,Huang model,Gompertz model)to describe the growth of C.sakazakii in the BHI tube(37℃)at the concentration of 0 mg/mL,25mg/mL,50mg/mL,75mg/mL and 100 mg/mL CN extracts.Results showed that Huang model was particularly more suitable for describing the growth of C.sakazakii than Baranyi model,Gompertz model.The growth curve of C.sakazakii in BHI came through lag phase,logarithmic phase and stationary phase.The lag phase increased with the concentration increased.In contrast,the growth rate was decreased when concentration increased.The result showed that CN extracts had the inhibitory effects on C.sakazakii since the extracts could prolong the lag time as well as decrease the growth rate.(3)Three different primary models(Huang model,Baranyi model,Gompertz model)were used to describe the inhibitory effect of CN extracts at different temperature(25,30,33,37 and 43℃)on the growth rate of C.sakazakiit.Results showed that the best primary model of C.sakazakii in BHI with 100mg/mL CN extracts was Huang model.The growth rate of C.sakazakii in BHI contained CN extracts was very slow.The lag phase of Jieyang was longer than Hainan,at the same time,the CN extract from Jieyang showed higher inhibition of decreasing the growth rate.This study demonstrated that CN extracts possessed inhibitory properties toward Cronobacter sakazakii.Hence this plant could be subjected to further pharmacological evaluation and isolation of the therapeutic antimicrobial.