Study On The Preparation Of Isothiocyanates From Papaya Seed And Its Features

Isothiocyanates (ITCs) are hydrolysis products of glucosinolates (GLS) under endogenous myrosinase which are mainly existed in cruciferae of brassica plants. ITCs are concerned for their anticancer and bacteriostatic activity. GLS were found in papaya seed in recent years. In this research papaya seed were used as raw material. Enzymolysis technology of GLS and preparation technology of ITCs were studied and the extracted ITCs were embed by β-cyclodextrin. This achievement can lay the foundation of the utilization of waste papaya seed.The enzymatic hydrolysate was analyzed by Gas Chromatograph Mass Spectrometer (GC-MS) and by which the structure of GLS was ensured. BBD experiment design and response surface analysis were used to study the influence of different factor on GLS enzymolysis based on single factor experiment and the optimum enzymolysis condition was obtained. Organic solvent extraction, steam distillation extraction, simultaneous distillation-extraction were compared to extract benzyl isothiocyanates. The extracted benzyl isothiocyanates was purified by column chromatography of silica gel and identified by infrared spectrometer. Benzyl isothiocyanates was embed by β-cyclodextrin using saturated solution method and different factor related to embedding rate were studied. Benzyl isothiocyanates, P-cyclodextrin and their inclusion complex were studied by phase solubility curve analysis, thermo gravimetric analysis, infrared spectroscopy analysis, X-ray scattering techniques, scanning electron microscope analysis, particle size analysis, nuclear magnetic resonance analysis to see the changes before and after inclusion.Result showed that only one kind of GLS existed in papaya seed which is benzyl glucosinolate glycosidase and the enzymatic hydrolysate were mainly benzyl isothiocyanates with a small quantity of benzyl isocyanate, benzyl cyanide, benzyl thiocyanate. The optimum enzymolysis condition for benzyl glucosinolate glycosidase were buffer solution pH 4.8, enzymatic hydrolysis time 40 min, enzyme solution temperature 27 ℃, material liquid rate 1:20 w/v, particle size>100 mesh and the enzymatic hydrolysis rate under optimum condition was 94.0% and benzyl isothiocyanates yield was 1.35% . Simultaneous distillation and extraction was eventually chosen as extraction method with methylene dichloride as extraction agent, extraction time was 2 h. Ethyl acetate:petroleum ether (1:20) was chosen as developing solvent for column chromatography. Infrared spectroscopy result showed that the extract was benzyl isothiocyanates combined with GC-MS result. The final embedding condition was core material rate 0.5, embedding temperature 40 ℃, embedding time 3 h. Phase solubility curve showed that the solubility of benzyl isothiocyanates increased after embedding. Thermo gravimetric analysis showed that the heat stability promoted after embedding. X-ray diffraction result showed that the crystal structure changed before and after embedding which also can be seen from scanning electron microscope that particle size increased after embedding. Infrared spectroscopy and nuclear magnetic resonance analysis can be used to predict the structure of inclusion complex. Based on the above date we can confirm that benzene ring of the benzyl isothiocyanates was embed into the cavity of P-cyclodextrin partially or fully and the-N=C=S group was partially embed.In this research the enzymolysis condition of benzyl glucosinolate was studied and benzyl isothiocyanates was extracted, purified and embed by β-cyclodextrin. The achievement of the research can increase the additional value and lay the foundation of functional study of benzyl isothiocyanates.