Study On Extraction And Antioxidant Activity Of Caffeine In The Seeds Of Abelmoschus Esculentus (Linn.) Moench

Abelmosk: formal name is Abelmoschus esculentus(Linn.) Moench, with another name okra. It is originally produced in the south of Ethiopia. it has been commonly seen in Southern China in recent years. In fact, its fruit can be eatable. It falls into two categories according to its colors: green and red. Besides, okra has a crispy, tender, and gravy taste, being smooth but not greasy. In addition, it is uniquely flavored and its fruit can be used as raw materials for oil manufacture. Furthermore, okra is highly nutritious. In recent years, it has become well-known healthy vegetable. Moreover, okra seeds are of high utilization value with about 28% content of protein, being rich in fatty acid. Particularly, content of unsaturated fatty acid takes up a relatively high proportion.Caffeine can function to resist oxidation and fatigue, improve memory and anticancer, etc. Okra seeds are mostly used for oil manufacture in China, development of caffeine in okra seeds can maximize their utilization rate.On the above basis, functional healthy food can be researched, which can be beneficial to improve human immune system and prevent diseases.The paper mainly focus on digestion of caffeine in okra seeds through ways of ultrasonic assistance and ethanol heating. Based on single-factor experiment, the paper designs 29 sets of optimized experiments by means of Box-Benhnken center combination experiment. Through variance analysis, the author has found out the best technological conditions for extraction: 4h of extraction time; 79% of ethanol volume fraction; extraction temperature at 86℃; solid to liquid ratio being 1:20. Under such conditions, actual extraction rate of caffeine is 1.04mg/g.Besides, it presents repeatability through experiment verification. On the above experimental basis, the author takes crude extracts from caffeine in okra seeds as raw materials to study on its antioxidant activity. In addition, the paper also examines its restoration capacity and competence to clear three kinds of free radicals, including DPPH, hydroxyl radical and superoxide anion. Experiment results show that with concentration of caffeine sample increasing, its restoration capacity and competence to clear three kinds of free radicals tend to gradually increase with a certain dose-effect relationship. When sample concentration is 4mg/mL, its clearance rate for hydroxyl radical and superoxide anion can reach to 60.12% and 71.62% respectively. When sample concentration is 10mg/mL, its restoration capacity(A700) and DPPH clearance competence is 0.752 and 51.75% respectively. The overall antioxidant capacity and restoration capacity present to be positive.Targeting at the crude extracts from caffeine in okra seeds, the author carries out separation and purification by means of D101-type macroporous absorbent resin and high efficiency liquid chromatography in succession. Under the circumstances when absorption condition is at 40 mL sample volume with 1mL/min absorption flow velocity, absorption rate can reach to 69.26% at most. Under the circumstances when elution condition is at 80% of ethanol volume fraction with 1mL/min elution flow velocity, resolution rate can reach to 68.32% at most. Through high efficiency liquid chromatography method, the author manually collects correspondent components of caffeine and gains caffeine samples.In the end, the author examines purified samples through high efficiency liquid chromatography method and electrospray ionization mass spectrometry. Results indicate that retention time of its high efficiency liquid chromatography is in line with caffeine samples. Molecular weight of mass spectrometry is 194.1, which corresponds to that of caffeine. It determines that the substance after extraction, separation and purification is caffeine.The purpose of this paper is to improve the use value and economy of okra seeds for okra seeds as raw material to develop functional health food to provide the reference.