| Perilla frutescens is an annual herb with wide applications and high economic value. It’s a medicinal and edible plant. The exploitations of Perilla frutescens as food and color additives in foods have been forming. Phenols and anthocyans in Perilla frutescens leaves have good antioxidant activities. But the differences of components and antioxidant activities in strains have not been reported. More carcinogenic and damaging health reports about synthetic antioxidants, more popular natural antioxidants are. In order to develop antioxidant activities of Perilla frutescens leaves, we studied extraction processes of oxidation resistant components from Perilla frutescens leaves. We determined the contents of total polyphenols, flavonoids, saponins and procyanidines of Perilla frutescens leaves extractions, also we determined the deoxidization abilities, O2-scavenging ratio,·OH scavenging ratio and inhibition ratio to lipid peroxidation of Perilla frutescens strains from different producing areas, what’s more, we analysed the components of Perilla frutescens leaves extractions. The results were as follows:1. An orthogonal array design was applied to optimize ultrasound-assisted extraction of antioxidant properties from Perrila frutescens. Three relevant factors that influence the antioxidant activity of the Perrila extract were investigated:ethanol concentration, extracting time and solid-liquid ratio. And the effect of each factor was estimated using deoxidization ability and elimination ratio of hydroxyl radicals as indicators. The results showed that optimal conditions for the extraction can be used40%ethanol as extraction solvent with a solid-liquid ratio1:45(g·mL-1) for75min. Under this condition, the deoxidization ability and elimination ratio of hydroxyl radicals of extractions were the best with value at1.21±0.021and22.49%±7.94%, respectively.2. Five P. frutescens strains (4red varities:P06-1, P06-4, P06-11, P07-1.1green one: P06-15.) were cultivated in Ya’an, Jiangyou, Meishan, Du jiangyan, Suining at the same time in2010, leaves were harvested in florescence, respectively. The main components were measured by spectrophotometry. The deoxidization ability, inhibition ratio to lipid peroxidation, OH-and O2-scavenging ratio were measured by FRAP, TBS, Fenton and pyrogallic acid methods, respectively. The contents of total polyphenols, total flavonoids, total saponins, proanthocyanidins about materials are11.73-83.93mg·g-1dw,16.29-133.30mg·g-1, dw29.17-93.83mg·g-1dw,1.13-19.78mg·g-1dw, the antioxidant activities of reducing capacity, inhibition ratio to lipid peroxidation,·OH and O2-scavenging ratio are22.17-1234.35μmol·L-1,2.05%-18.14%,8.46%-44.29%,2.60%-20.71%. In all strains, the contents of total polyphenols, total flavonoids, total saponins, proanthocyanidins of P06-1are the highest, P06-1and P06-4strains have better antioxidant activities. The two strains are fine matters to extract polyphenol and antioxidants. Contents of the four kinds of P. frutescens leaves from Du jiangyan were the highest.The antioxidant activities of reducing capacity of extracts are better than BHT and Trolox with the same mass concentration, while the· OH scavenging ratio are lower. Reducing capacity and4chemical components have positive correlated relationship. There were negative correlation between inhibition ratio to lipid peroxidation and proanthocyanidins. Different antioxidant activities are correlated with the kinds of chemical components. The contents of4chemical components and antioxidant activities of the leaf extracts of P. frutescens were affected by Perilla frutescens strains and environment.3. Germplasm resources, environment and interaction of the two all have statistical difference with antioxidant activities of Perilla frutescens extractions, except for O2-scavenging ratio.Coefficients of variation of contents and antioxidant activities of P. frutescens leavea from different producing areas are greater than10%, especially content of proanthocyanidins, inhibition ratio to lipid peroxidation and OH scavenging ratio, their coefficients of variation were27.25%,29.09%,27.02%respectively. In different strains, coefficient of variation of O2-scavenging ratio was6.16%, it’s less than10%and had no significant. The variation of content of proanthocyanidins was the most remarkable, coefficient of variation was55.93%, the second one was inhibition ratio to lipid peroxidation (29.10%). It shows that antioxidant activities of Perilla frutescens extractions are affected both by germplasm resources and environment. Specific antioxidant activities were discrepancy under different fertilizations, that means field management and fertilizations could affected antioxidant activities, too.4. Building a HPLC method to determinate9kinds of polyphenols. We inspected stability, precision, reproducibility and average recovery of this method, found that this HPLC method could quantitative analysis the contents and kinds of Perilla frutescens extractions as follow conditions:methanol and0.1%phosphoric acid as mobile phase, gradient elution, column temperature30℃, detection wavelength280,320,350nm. We detected9kinds of polyphenols, they are protocatechualdehyde, chlorogenic acid, caffeic acid, ferulic acid, rosmarinic acid, esculetin, quercetin, luteolin, apigenin. Detected the contents of polyphenols of different Perilla frutescens strains, we found that:the contents of different kinds of polyphenols are different, purple ones have more kinds than green ones. Polyphenols mainly contain phenolic acids and flavonoids, the percentage of phenolic acids was more than80%. Rosmarinic acid was main constituent of phenolic acids, its percentage was more than50%, the next was caffeic acid. There was a positive correlation between the deoxidization ability and the contents of rosmarinic acid and caffeic acid, while a negative correlation between·OH scavenging ratio and the contents of rosmarinic acid.5. Alcohol extracts is a chemically complex extraction, its antioxidant activities are wide range, but not obvious, so we extracted antioxidants, then concentrated extraction. After water dissolved concentrations, we extracted it with different polar solvents and measured their antioxidant activities. The results showed that:ethyl acetate extractive has the strongest deoxidization ability and DPPH scavenging ratio, and stronger than BHT and Vc, its yield was2.38%. Specific antioxidant activities were enhanced in different polar solvents. So we can choose different polar solvents to extract antioxidants based on different antioxidant needs, in order to improve specificity of antioxidant activities. |
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