Study On Secondary Metabolites From Two Endophytic Fungi And Angiotensin Converting Enzyme Inhibitory Peptides From Soybean

Microorganisms exist widely in nature.Endophytic fungi are microorganisms that exist in the internal tissues of plants and form mutualistic symbiosis with host plants.Because microorganisms can produce metabolites with the same or similar structure and biological activity with host plants,many researchers have paid attention to them.Among them,endophytic fungi of plants and animals can metabolize secondary metabolites with novel structures and diverse activities due to their special living environment.In this paper,the research on secondary metabolites of microorganisms mainly focuses on endophytic fungi of lichens and earthworms.At the same time,hypertension,as a chronic disease associated with elevated arterial blood,can cause multiple organ function impairment.Angiotensin converting enzyme(ACE)is an important regulatory enzyme in renin-angiotensin system(RAS),which plays an important role in maintaining stable blood pressure and water and salt balance.ACE can catalyse the conversion of angiotensin Ⅰ(Ang Ⅰ)into angiotensin Ⅰ(Ang Ⅱ).Ang Ⅱ is a vasoconstrictor,and angiotensin converting enzyme inhibitors can inhibit the conversion of Ang Ⅰ to Ang Ⅰ,thus achieving the effect of vasodilation and lowering blood pressure.Angiotensin-converting enzyme inhibitor peptide(ACEIP)is a kind of antihypertensive peptide by inhibiting ACE,which has attracted wide attention due to its advantages of almost no side effects.In the first part,the secondary metabolites of two endophytic fungi derived from lichen and earthworm were studied,and the related biological activities of the new compounds were screened.The first endophytic fungus was isolated from lichen collected from Wuyi Mountain,Fujian Province and identified as Talaromyces variabilis(No.23-1).The second endophytic fungus was isolated from earthworms in the moss greenhouse and identified as Hypocrea lixii(BQ3).The Hypocrea sp.(BQ3)was extracted and isolated.Lichen endophytic fungus Talaromyces sp.(No.23-1)was amplified by rice culture medium and extracted by ethyl acetate to obtain crude extract.A variety of separation methods,such as gel column chromatography,silica gel column chromatography and HPLC,were used for systematic separation.A total of 21 compounds were isolated from the two endophytic fungi,of which 10 were new compounds.The planar and three-dimensional structures of the compounds were determined by NMR,high resolution mass spectrometry and circular dichroism.A total of 12 compounds(1-12)were isolated from Talaromyces sp.(No.23-1),including two ketones:Entonaemin A(9)and Torosachrysone(12);two Azaphilone spiro compounds:Azapspiro A(4a)and Azapspiro B(4b);two lactones:Rtmannilactone E(10)and Rtmannilactone F(11);three dimers:Skyrin(6),Rugulosin(7)and Flavomannin(8);three other compounds were Talarvaria A(1),Talarvaria B(2),Talarvaria C(3),of which 5 were new compounds(1-4b).A total of 9 compounds(13-21)were isolated from Hypocrea.sp.(No.BQ3),which were three ketones:Hypoclixii A(13),Hypoclixii B(14),and Hypoclixii C(15);three sterol compounds:Demethylincisterol A3(19),Volemolide(20),Citreoanthrasteroid B(21);one Azaphilone spiro compound:Azapspiro C(17);one Hazane diterpene:Haziaditer A(16);one other compound:Pestalotiopin A(18),of which 5 were new compounds(1317).The new compounds were screened for antibacterial and cytotoxic activities,but no related biological activities were found.In the second part,this paper studies the angiotensin-converting enzyme inhibitory peptide derived from soybean,and separates and purifies soybean peptide powder by anion exchange resin,gel column chromatography,silica gel column chromatography and high performance liquid chromatography(HPLC),and characterizes it by content analysis and hydrophobic value calculation,and selects polypeptides to be synthesized by the company.A total of 22 polypeptides(DTI-22)were isolated and synthesized from soybean peptide powder,of which 3 polypeptides(DT18,DT20,DT22)had angiotensin-converting enzyme inhibitory activity at high concentrations(1800-2000μM),and the inhibitory rate was about 75%,and the molecular docking simulation between these three peptides and angiotensin-converting enzyme sites showed that these three peptides could be well docked with angiotensin-converting enzyme sites.Based on the above studies,it can be concluded that there are many bioactive substances to be excavated in nature,and it is necessary to explore the potential bioactive ingredients by rational use of separation technology and biotechnology means.