Research On The Biological Active Ingredients And Polarity Companions Of The Tea Seed Oil

Tea seed oil,a new resource derived from the seeds of Camellia sinensis O.Ktze.,contains abundant active substances and has high nutritional value.Studies have shown that crude tea seed oil,which is rich in unsaturated fatty acids,can be stored for 1 to 2 years at room temperature.Compared with traditional edible vegetable oils,little basic research has been conducted on tea seed oil.In this study,tea seed oil was produced using tea seeds from nine major tea-producing areas of China.The content of physiologically active substances was analysed and compared to identify the differences and key characteristics of tea seed oils with different origins.Active polarity companions in tea seed oil were isolated and identified to clarify the compositions of substances present in the oil.The in vitro and in vivo antioxidant activity of polarity companions from tea seed oil was analysed in chemical experiments,cell experiments and animal experiments,respectively.Accelerated oxidation experiments and frying experiments were carried out to investigate the effect of polarity companions on the oxidative stability of the oil.The aim of this study was to reveal the mechanism behind the strong oxidative stability of tea seed oil,and to provide a theoretical basis for the moderate refining of tea seed oil.First,the physiologically active substances in the tea seed oil samples from different areas were analysed.It was found that the content of linoleic acid(20.23% to 28.23%)in tea seed oil was higher than in traditional edible vegetable oils.The content of total phenols was between 202.12 and 530.08 mg/kg,the VE content was between 382.34 and 685.52 mg/kg,and the total sterol content was between 2290.7 and 5710.4 mg/kg.There were 194 volatile flavour compounds in the tea seed oils from different origins.The content of physiologically active components of the oils from different regions was analysed by variance analysis,principal component analysis,cluster analysis and discriminant analysis.The results revealed clear differences in the content of physiologically active components in the tea seed oils from different areas.This suggests it is feasible to use these differences as the basis of an identification index to distinguish the source of tea seed oil and determine its quality.The overall results of the analysis suggested that tea seed oils from Sichuan,Guizhou and Yunnan were of superior quality,with relatively higher contents of active substances.Next,the polarity companions in tea seed oil were isolated using macroporous resin AB-8 in combination with Prep-HPLC.The constituents were identified using HPLC,high-resolution MS and NMR.Four compounds were identified as caffeine,pomelo peel element-7-O-[?-D-pyran xylose base(1?6)][?-D-glucose base(1?3)-alpha-L-rhamnose base(1?2)]-?-D-glycosidase,pomelo peel element-7-O-?-D-pyran xylose base(1?6)-?-D-glycosidase and pomelo peel element-7-O-?-D-glucose base(1?3)-alpha-L-rhamnose base(1?2)-?-D-glycosidase,respectively.The antioxidant capacity of polarity companions from tea seed oil from the nine regions and the four identified constituents was studied using DPPH assay,ABTS assay,?-carotene bleaching assay,ferric reducing/antioxidant power(FRAP)assay,assays of superoxide anions and hydroxyl-scavenging assay.It was found that the polarity companions of tea seed oil possessed good proton and electron transfer capability,explaining their strong antioxidant capacity in vitro.Due to differences in total phenol content,the antioxidant activities of tea seed oil from the nine regions were significantly different,and antioxidant activity was enhanced with increased concentrations of the polarity companions.The four identified constituents showed consistent antioxidant activity in all antioxidant tests,with antioxidant activity from strong to weak shown by pomelo peel element-7-O-?-D-pyran xylose base(1?6)-?-D-glycosidase,pomelo peel element-7-O-?-D-glucose base(1?3)-alpha-Lrhamnose base(1?2)-?-D-glycosidase,caffeine andpomelo peel element-7-O-[?-D-pyran xylose base(1?6)][?-D-glucose base(1?3)-alpha-L-rhamnosebase(1?2)]-?-Dglycosidase.CAA oxidation tests were carried out to study the in vitro antioxidant activity of the tea seed oil polarity companions and four identified constituents.The results showed that the tea seed oil polarity companions and the four identified constituents significantly reduced the fluorescence intensity in cells and reduced the level of reactive oxygen spec ies.The compounds showed an obvious antioxidant effect,which increased as the concentration of polarity companions increased.The antioxidant activity of the four identified substances was as follows: pomelo peel element-7-O-?-D-pyran xylose base(1?6)-?-D-glycosidase > pomelo peel element-7-O-?-D-glucose base(1?3)-alpha-L-rhamnose base(1?2)-?-Dglycosidase > caffeine > pomelo peel element-7-O-[?-D-pyran xylose base(1?6)][?-D-glucose base(1?3)-alpha-L-rhamnose base(1?2)]-?-D-glycosidase.The in vivo anti-oxidative properties of the polarity companions of tea seed oil were analysed with a D-galactose–induced aging test,which revealed that the polarity companions of tea seed oil had strong in vivo antioxidant activity.The results showed that the tea seed oil polarity companions had an obvious effect on oxidative damage in mice,improving T-AOC,SOD,and GSH-Px activity in the heart,liver and brain tissue of senescent mice,reducing MDA content and protecting mice tissues and organs.This protective effect could be strengthened by increasing the dose.The effect of the polarity companions on the oxidative stability of tea seed oil was investigated in an accelerated oxidation experiment.The effect of the polarity companions and VE on the oil samples' oxidative stability,and their interaction effects,were investigated.The rate of oxidation of the samples from fast to slow was as follows: lard oil > lard oil with added VE > lard oil with added polarity companions > lard oil with both polarity companions and VE added.The results showed that both polarity companions and VE could markedly delay the rancidity of lard oil,and the effect of polarity companions from tea seed oil was better than that of VE.The results of the interaction analysis showed that the polarity companions of tea seed oil were synergistic with VE in inhibiting lard oxidation.Finally,a frying experiment was carried out to investigate the effects of polarity companions on the oil's frying stability.The results showed that both polarity companions and VE decreased during frying,and their content was negatively related to all oxidant indexes,indicating that both polarity companions and VE could inhibit the high-temperature deterioration of oil.The order of the oxidative stability of oil samples was as follows: refined tea seed oil with addition of both polarity companions and VE > refined tea seed oil with addition of polarity companions > refined tea seed oil with addition of VE.The effect of the tea seed oil polarity companions on oil oxidation inhibition was superior to that of VE.The results of the interaction analysis showed that the polarity companions of tea seed oil were antagonistic with VE during frying.