Studies On Antioxidant Capacity, Antimicrobial Activity And Inclusion Complex Of Ocimum Gratissimum L. Essential Oil And Eugenol

In recent years,with the in-depth study of spices,the antioxidant and antimicrobial capacity of spices has been paid more attention to.Ocimum gratissimum L.essential oil(OGEO) and its main component eugenol(EG) such as a spice extract posess the obivious effect,while they have the easily volatile,hard to slow-release and degenerative properties,which limit the applications of OGEO in the market.Cyclodextrin and its derivatives as food and drug effective ingredients play an important role in the determinations of various compositions.The main content and results were as follows:The activity of reducing power,reducing lipid peroxidation,hydrogen peroxide scavenging, the formation of phosphomolybdenum complex method,hydroxyl radical(·OH) were studied.It was found that OGEO and EG were much better radical scavenger than common food antioxidants.Effects of pH value,concentrations of CDs,and temperature on the inclusion interactions were studied to obtain further knowledge on the mechanism of inclusion process.The diameters of antimicrobial circles of OGEO were 13.0 mm and 12.5 mm against such Escherichia coli and Staphylococcus aureus,respectively.The diameters of antimicrobial circles of EG were 14.5 mm and 13.5 mm against such two bacteria,respectively.The minimal inhibitory concentration(MIC) of OGEO and EG was 0.16 mg/ml against Escherichia coli and 0.31 mg/ml against Staphylococcus aureus.The interaction capacities of CDs with EG were as the following order:HP-β-CD＞DM-β-CD＞HE-β-CD＞β-CD.The formation constants were derived by the modified Hildebrand-Benesi equation.The results show that EG with CDs formed 1:1 host-guest complexes.The content of OGEO of inclusion complex was 75.2%.The stability of inclusion complex was good,which was beneficial to storage.The inclusion interactions of eugenol(EG) withβ-cyclodextrin(β-CD) and its derivatives have been investigated by fluorescence method.The results show that EG with CDs formed 1:1 host-guest complexes.The thermodynamic parameters of inclusion process,△G,△H and△S were determined.△G was negative,which showed that the complexation is a spontaneous process.△H and△S was negative,which indicated that the inclusion process was deduced to be an exothermic and enthalphy-driven process.Furthermore,the IR spectra study has been made to confirm the inclusion and to provide information on the geometry of EG inside the cavity ofβ-CD.