The Protective Effects And Mechanisms Of Turnip(Brassica Rapa L.)on Focal Cerebral Ischemia Injury

Turnip（Brassica rapa L.,Turnip）,a Brassica plant of Cruciferae,is a kind of multipurpose plant for food,medicine and feed,which grows on Qinghai-Tibet Plateau.According to the classic book“The Four Medical Tantras”recognized in the field of Tibetan medicine,highlighted that turnip was a heat-clearing,detoxifying and anti-hypoxic agent.For thousands of years,turnip has been used as a good anti-hypoxia product to relieve altitude sickness for Tibetans and livestock living on the Qinghai-Tibet Plateau.The progress of modern science and technology and the improvement of living standards have prolonged the average life span of human beings,but they have not improved the mortality and disability rate caused by stroke.Population growth and aging have become the main reasons for the increase of stroke patients in the world.Due to the lack of effective treatment measures for stroke,prevention is considered to be the best protection method at present.Since then,various dietary guidelines or functional foods have emerged to reduce the incidence of stroke.In this paper,the middle cerebral artery occlusion/reperfusion（MCAO/R）model in vivo and oxygen and glucose deprivation/reperfusion（OGD/R）model in vitro were established on the basis of the anti-hypoxia study of turnip.The protective effect of turnip on ischemia and hypoxia injury was studied.A functional monomer was obtained for the first time through step-by-step separation,and its protective ability and mechanism of glucose and oxygen deprivation injury were systematically studied.The specific contents of the study are as follows:1.Using the MCAO/R model of mice,it was preliminarily confirmed that turnip is helpful to restore the behavioral ability of mice with brain injury and effectively reduce the brain atrophy volume.Furthermore,in vitro experiments showed that turnip significantly increased the cell viability after OGD/R injury,effectively inhibited the expression of lactate dehydrogenase（LDH）and reactive oxygen species（ROS）,and increased the contents of endogenous antioxidant enzymes superoxide dismutase（SOD）,glutathione peroxidase（GPx）and catalase（CAT）.2.In order to effectively identify the range of anti-ischemia and hypoxia functional components in the turnip,four organic reagents with different polarities were used to extract the turnip step by step to obtain petroleum ether extraction of turnip（PET）,chloroform extraction of turnip（CET）,ethyl acetate extraction of turnip（EAET）,n-butanol extraction of turnip（SBET）and aqueous extraction of turnip（AET）.Through OGD/R model,taking cell vitality,LDH,ROS and endogenous antioxidant enzymes as evaluation indexes,the protective ability of five extracts on neurons was verified respectively,and it was found that the AET group had the best antioxidant effect on OGD/R injury.3.The MCAO/R model and OGD/R model were used to further verify the protective ability and mechanism of AET against ischemia and hypoxia injury.The results showed that AET can effectively improve the recovery ability of mouse behavior and reduce the brain atrophy volume.At the same time,the expression of cytochrome c oxidase IV subtype（COXIV）was significantly restored,and the functional state of respiratory chain and energy generation of cells were improved.In addition,AET can regulate the expression of PI3K signal transduction factor during OGD/R injury,and then further cause the activation of Akt and mTOR,and inhibit the death of neurons.4.After clarifying the protective effect and possible mechanism of AET against ischemia and hypoxia injury,the research scope was further narrowed.AET was separated step by step by using MCI separation column,HW-40 separation column,ODS-A and ODS-AQ separation column,with the help of thin layer chromatography and cell ROS detection,and a new functional monomer（AET-1）was found,which structure was analyzed by¹H-NMR,¹³C-NMR and¹³⁵DEPT-NMR。5.In the OGD/R model in vitro,AET-1 can enhance the anti-oxidative stress ability of neurons after OGD/R injury,improve the expression activity of COXIV,reduce the further injury by activating PI3K/Akt/mTOR signaling pathway,and promote（inhibit）the expression of anti（pro）-apoptosis factors.In summary,turnip can play protective effect against ischemia and hypoxia.This study provides scientific basis and theoretical support for the comprehensive development and utilization of turnip.The economic value and medicinal value of this plant can be improved,whether it is developed as a functional product by relying on the AET or using AET-1 as one of the additive components of the combined therapy.Future research must continue to clarify the roles of AET-1,PI3K,Akt and mTOR in the nervous system and apoptosis,so as to successfully transform functional monomers and kinase targets into effective and safe prevention/treatment strategies in neurodegenerative diseases.