Analysis Of Antioxidant Activity Of The Leaves Of Pepper(Piper Nigrum L.) And The Active Constituents Separation And Identification

Piper nigrum L. is one of the important spices in the world, it has a variety of health care value.The China’s cultivated area and the yield of pepper, of which Hainan province occupied60%, ranked it sixth and fifth out of the word.But, that most of the pepper product are agricultural primary products which is low value-added products restricts piper industry’s development.However, the piper leaves have the potential development value.The pepper and the piper leaves are both have significant antioxidant activity and the latter also have Anti-atherosclerosis function.And people eat the leaves in Tailand to cure disease.In addition, picking off leaves can increases the productivity of the pepper and the essential oil of piper leaves may replace that of pepper which is expensive.But we don’t know the leaves’active factor behind its functional roles. It is for this reason, we can’t take full advantage of this Ancient and important plant. In order to solve the problem to provide basis for exploiting the functional foods of Piper nigrum L., in this work, the piper leaves’s antioxidant activity were analyzed systematically, the essential oil chemical components of the piper leave’s were studied, and the antioxidant factors of the alcohol extract were separated and identified. Specific information is as follows.The DPPH free radical scavenging activity, total polyphenolic content and the ORAC value of the pepper fruit(fresh、black and white) and pepper leaf extracts prepared from water and acetone were determined. and Chemical difference of them was analyzed by HPLC.The results showed that the radical scavenging capacity and polyphenol content of pepper leaf were higher than those of pepper fruit(fresh、black and white) and the difference of chemical substances in them is bigger. As far as the antioxidant activity of pepper leaf and pepper fruit were concerned, they were all suitable for exploiting antioxidant functional foods of pepper series, meanwhile, the pepper leaf can be applied to process pepper power and other products. In general, the test shows the leaves may contain high active antioxidants.The volatile constituent of the piper leaves were analyzed firstly.The essential oil of the pepper fruits (fresh、black and white) and leaves were prepared by the steam distillation and analyzed by GC-MS, the yields of the essential oil were1.46%,1.77%,2.30%and1.25%, respectively.And38、31、36and63chemical components were identified in the essential oil for the above four types of samples, respectively.The contents of δ-elemene,3-carene, D-limonene, α-copaene, caryophyllene and humulene were higher in fruits and leaves than the other components.The contents of pinene, β-myrcene, a-phellandrene and M-cymene were much higher in the fruits than those from the leaves, and the contents of1-ethenyl-1-methyl-2-(1-methylethenyl)-4-(1-methy letheny lidene)-cyclohexane, a-cubebene, β-elemene, a-burjunene, P-copaene, a-selinene, β-chamigrene,4-isopropylidene-7-methyl-6-methylene-2-octenoic acid methyl ester and spathulenol were much higher in the leaves than those in the fruits. Besides, electronic nose technique in combination with discriminate function analysis (DFA) can effectively discriminate the powdered samples prepared from the pepper fruits and leaves. And it is prepossessing that the content of δ-elemene which have Significant antitumor activity in leaves was38.54%.It was ascertained that the ethanol and water extraction solutions with a stronger DPPH free radical scavenging activity and polyphenol content by means of the system solvent extraction method, and as well as the ORAC method. Conclusions were obtained that the older leaves with a stronger antioxidant activity when compared with that of the tender leaves, the complete stability lobe and the old leaves. Meanwhile, the sample solution obtained from the50%ethanol has a stronger activity of free radical scavenging capacity and higher levels of polyphenol content and flavonoids content while different concentrations of ethanol solutions were tested. In addition, the DPPH free radical scavenging capacity of the leaves dried by lyophilization was stronger than that from hot-air drying and the distinction of chemical profile obtained from ethanol extraction was unclear through antioxidant activity and HPLC analysis.Now, the ORAC value has been an important criterion of these countries, such as America, Europe and Japan, to evaluate the antioxidant activity of the food especially the functional food.So, in this section, Using ORAC value as an activity monitoring parameter, the strongest antioxidative subtances of pepper leaves were obtained through chromatographic processing such as Silica gel chromatography, Gel chromatography (Sephadex LH-20resin), Reversed-phase chromatography, Thin-layer chromatography and HPLC.And the structures of compounds were identified by ultraviolet-vis, infrared, ESI-MS,1H-NMR and13C-NMR spectrums.Ultimately, two monosemers, hinokinin and rhoifolin were obtained, and their ORAC values were16070μmol TE/g and10823μmol TE/g, respectively.