| Aging is a natural process characterized by molecular and cellular damage that leads to a progressive decline in organ function and ultimately death.It is considered as a major risk factor for various age-related diseases including cancer,diabetes,cardiovascular diseases,Alzheimer’s disease,and Parkinson’s disease.With the improvement of material life and medical conditions,the lifespan of the human becomes longer and longer.According to the World Health Organization(WHO),it is estimated that the population of aged people with 60 years and over will be doubled by 2050.The prevalence increase of age-related diseases is becoming a severe threat to human health in an aging society.How to keep health lifespan is the most important research projects now.In the context of global aging and age-related disorders,the research and development of anti-aging drugs to delay aging and prevent elderly disorder,are of great importance.For a long period,the structural studies of natural products(NPs)served as the principal driving force for drug discovery and still constitute a unique source for novel leads and pharmacophores for medicinal chemistry.Natural products have a wide range of diversity of unique chemical structures;in the meantime,their bioactive constituents have also won considerable attention.Therefore,this study focuses on the purification of anti-aging substances from natural products under the bioassay guide,their structure elucidation and brief anti-aging mechanism of action.These results will lay a foundation for the research and development of antiaging drugs.In the present study,a large number of extracts from natural products were screened for anti-aging activity.As a result,the extract of randomly selected Onosma bracteatum wall and selectively chosen Glycyrrhiza uralensis Fisch(甘草)and Gastrodia elata Blume(天麻)exhibited anti-aging activity by extending the replicative lifespan of K6001 yeast significantly."Shennong’s Classic of Materia Medica"described that G.uralensis and G.elata have anti-aging effect and in our study for search of anti-aging molecules,these two traditional Chinese medicines were considered as most important samples.Under the guidance of bioassay system,the three active extracts of these natural products were separated by a series of open column chromatography,then purified by high-performance liquid chromatography(HPLC).Three new compounds with significant anti-aging activity were identified by various spectral analyses and two compounds with possible new skeleton whose partial chemical structure were proposed also exhibited significant anti-aging activity.The chemical structures of 38 known compounds were determined by comparison with the spectral data reported in the literature,of which 32 had significant anti-aging activity.Moreover,three fractions with significant anti-aging activity,low content and complex nature were analyzed by high-resolution LCMS to insight chemical information for SAR study and eighteen compounds were identified and proposed their structures after comparison with the compounds reported in the literature of G.uralensis.Onosma bracteatum Wall is a traditional medicinal plant in ayurvedic and Unani systems of medicine.The powdered plant material of O.bracteatum was extracted with methanol and then partitioned between ethyl acetate and water to give active ethyl acetate layer which was subjected to series of silica gel and ODS open column and finally purified by reverse phase HPLC to yield twenty-four compounds.Among these,twenty compounds exhibited significant anti-aging activity while four compounds were inactive.The chemical structures of three new active compounds were identified by combination analysis of 1D,2D NMR and HR-ESI-TOF-MS.The structure analysis results indicated the presence of two active compounds with a possible unique skeleton and their partial chemical structure were proposed.The chemical structures of 19 known compounds were determined by comparison with the spectral data reported in the literature.The purified compounds possess four types of structure features,including seven benzoquinones,five ursane type triterpenoids,eleven phenolic derivatives,and one unsaturated fatty acid.Based on the structure-activity relationship(SAR)analysis of isolated benzoquinones,we can clearly understand that benzoquinone skeleton is essential for biological activity and it was shared by all isolated benzoquinone derivatives.Based on the SAR of similar triterpenoids,we can infer that ursane-type skeleton is essential for the biological activity of isolated terpenoids.SAR analysis of isolated ursane type triterpenoids indicated that the triterpenoids without sugar moiety exhibited significant anti-aging effects while triterpenoid with sugar moiety did not show anti-aging activity.Bioassay results of eleven phenolic compounds indicated that eight phenolic compounds showed significant anti-aging activity while other’s not.Bioassay results indicated that it is not easy to conclude the SAR results of these phenolic compounds.To get exact SAR results,we need to find more phenolic compounds.G.uralensis is one of the popular and oldest traditional Chinese medicine.This study focuses on isolation,structure elucidation,anti-aging activity evaluation and SAR analysis of compounds from the extract of G.uralensis.The dried roots and rhizomes of G.uralensis were extracted with 20%aqueous ethanol and then partitioned between ethyl acetate and water.The active ethyl layer was separated by silica gel and ODS open column and finally purified by HPLC to yield eighteen compounds.The structures of these compounds were identified by spectroscopic analysis,HR-ESI-TOF-MS as well as comparison of spectroscopic data with the literature.The structure types of the isolated compounds were related to phenolic derivatives.Bioassay results indicated that sixteen compounds purified from G.uralensis showed significant anti-aging activity and two compounds had no anti-aging activity.To better understand the anti-aging potential of G.uralensis,three anti-aging active fractions with low content and complex composition were analyzed through HR LC-MS.Eighteen compounds were identified from these fractions and proposed their structures after comparison with the compounds reported in the literature of G.uralensis.SAR analysis of these proposed compounds and purified compounds,we can infer that phenolic features of compounds play an important role in the anti-aging activity and any substitution may increase or decrease the anti-aging activity.Gastrodia elata Blume is a popular traditional Chinese medicine.One compound with significant anti-aging activity was isolated from the rhizome of G.elata.To understand the anti-aging mechanism of action,oxidative stress assessment and replicative lifespan assay of sod1,sod2,uth1,skn7 yeast mutant strains were performed.Mechanism studies revealed that anti-oxidative ability and regulating the genes of Sod1,Sod2,skn 7,and Uth1 are involved in the anti-aging ability of compound from G.elata.In summary,forty-three compounds were purified from O.bracteatum,G.uralensis and G.elata under the guidance of the bioassay system including three novel anti-aging compounds.In addition,two active compounds with possible unique skeleton were obtained and their partial chemical structure were proposed.Their structure types of isolated compounds included benzoquinones,ursane-type triterpenoids,phenolic derivatives and unsaturated fatty acid.In addition,active fractions of G.uralensis were analyzed through HR LC-MS and eighteen compounds were identified after comparison with the references,which led to further understanding of the anti-aging potential of G.uralensis.An anti-aging compound from G.elata extended the lifespan of yeast and mechanism studies indicated that anti-oxidative ability and regulating the genes of Sod1,Sod2,skn7,and Uth1 are responsible for the anti-aging potential of compound from G.elata.The discovery of the above compounds and the study of the structure-activity relationship will lay the foundation for the determination of anti-aging active lead compounds,in-depth study of the mechanism of action and anti-aging drug development,and provide important structural information for the synthesis of highly active anti-aging active lead compounds.In addition,the study supports the deep development and utilization of these three natural drugs. |
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