Study On Chemical Composition And Bacteriostatic Activity Of Veratrum Lobelianum Bernh.

Veratrum nigrum L.,a perennial herb in Liliaceae,has significant medicinal value and good antifungal effect.It is widely used in the development and research of pesticides and traditional Chinese medicine.Veratrum lobelianum bernh.Is mainly distributed in the Altai mountains of Xinjiang,with rich plant resources.In this study,Veratrum lobelianum bernh.was used as the raw material to study the antibacterial activity and chemical composition of the crude extracts in the underground part of the plant.Through calculation and simulation to assist in structural analysis and derivatization of alkaloid precursor compounds.Four extracts of petroleum ether,chloroform,ethyl acetate and water were extracted from the roots and rhizomes of Veratrum lobelianum bernh.by ultrasonic assisted extraction,and four extracts of petroleum ether,chloroform,ethyl acetate and water were obtained.The antibacterial activities of Veratrum lobelianum bernh.extracts against Botrytis cinerea,Alternaria solani,Fusarium oxysporum and Alternaria alternata were determined by mycelial growth inhibition method.The results showed that the four extracts had a certain inhibition effect on the four pathogens tested,and the best inhibition effect was 72 hours.The extracts had the highest inhibition rate against Alternaria alternata,and the half effective concentration(EC50)of chloroform,ethyl acetate and water extracts were 929,766 and 358 μg·mL-1,respectively.The water extract had the best inhibitory effect on the four pathogenic bacteria.The EC50 of Botrytis cinerea,Alternaria solani and Alternaria alternata were 939,554 and 358 μg·mL-1 respectively.The chemical composition of each extract was analyzed by high-performance liquid chromatography(HPLC),and the chemical composition of the four extracts was different.It can be preliminarily explained that the activity of the extract is related to the chemical composition of Veratrum lobelianum bernh.In order to clarify the chemical substance basis,further search for monomer compounds.The Veratrum lobelianum bernh.extract was separated and purified by traditional separation methods,and 8 compounds were identified,including three typical steroid alkaloids:C25H39NO(2),C25H39NO2(5),C25H31NO(6);two plant sterols:C27H44O(1),β-sitosterol(8);three organic acids:C10H14O2(3),C23H38O2(4),C18H34O2(7).Because the three-dimensional structure of natural products is difficult to determine,the cis and trans structures,infrared and Raman spectra of resveratrol,the representative compound in Veratrum,were analyzed and identified through simulation calculations.The simulated trans-resveratrol spectrum is basically consistent with the experimental results.And after examining the structure of the combination of negative ions and Ag+,it can be concluded that the number of peaks can distinguish the cis and trans structures of the combination of resveratrol anion and Ag+;when Ag+is bound to the monophenolic hydroxyl position of resveratrol,the Raman activity is increased by more than 10 times.The cis and trans structures of resveratrol and its negative ions and Ag+ can be identified according to the different Raman activities.According to the calculation and simulation results,the resveratrol monophenolic hydroxyl group has greater activity.Taking alkaloids as the target compound,combining the greater activity of resveratrol monophenolic hydroxyl group and the medicinal value of coumarin,in this paper,4-amino-7-hydroxycoumarin was synthesized from resorcinol and cyanoacetic acid as the precursor compounds of alkaloids,and its hydroxyl sites were derived to obtain compounds 9a～9n.By comparing the inhibitory activities of the precursor compounds and their derivatives on Botrytis cinerea,Alternaria solani,Fusarium oxysporum and Alternaria alternata at 200 μg·mL-1,it was obtained that the phenolic hydroxyl group was modified by substitution,The conclusion that derivatives have increased bacteriostatic activity.It is preliminarily speculated that when the hydroxyl group of the precursor compound is modified,the more branches,the stronger the activity of the contained group,and the closer the active group is to the coumarin ring,the better the antibacterial effect.