Study On The Anatomical Structure Of Gelsemium Elegans Benth And The Antibacterial Action Of Alkaloids

Gelsemium elegans,the evergreen woody vine of the genus Gelsemium of the Loganiaceae family in China.There are three species in the world,and there are two species in North America.In China,there are only one species.Its active component indoles alkaloids not only can reduce swelling and detoxification,insect repellent,sedative,but also in anti-tumor,immune regulation,analgesia,treatment of anxiety disorders and other aspects have a particular effect.At present,scholars at home and abroad mainly focus on chemical constituents,toxicology,pathology,pharmacology and so on,but few studies on plant anatomy,distribution and bacteriostasis of the alkaloids.In this paper,the anatomy of the vegetative and reproductive organs was studied,and the alkaloids in plants were localized.Also,the antibacterial activity of the alkaloids was also explored,and the antibacterial mechanism of the alkaloids was analyzed.The main findings are as follows:(1)Microscopic observation of the vegetative and reproductive organs of the crochet was carried out using plant anatomy.showed that the structure of G.elegans conformed to the typical characteristics of the general dicotyledonous plants.The G.elegans leaf is a dorsiventral leaf,the epidermis has a stratum corneum,no hair,and the palisade tissue is narrow.And only the lower epidermis has stomata,which is irregular,the orifice is elliptical,external toughness of vascular bundle;round stem,the epidermis has stomata,and there is starch granule deposition in the pith;The cork layer of the rhizome is thick,the xylem is broad,with pith;ovary is 2-loculed,axile placenta,multiple ovules;the anthers are 4-loculed,Pollen grains with 3-pore grooves with " protruding oncus" structure.These structural features are not only the adaptation of the plant to the environment,but also can be used as the basis for the anatomical identification of the G.elegans.(2)Through histochemical staining,using a variety of reagents such as modified bismuth potassium iodide,iodine-potassium iodide,concentrated nitric acid,etc.,the alkaloids in the plant were localized.The results showed that the whole plant contained alkaloids.Alkaloids were mainly distributed in the mesophyll tissue of leaves,especially the palisade tissue content is more,the sponge tissue is less,and the vascular bundle is less or absent;In the stem,alkaloids are mainly distributed in stem epidermis,cortex cells and phloem parenchyma cells.Also,alkaloids are also distributed in parenchyma cells and myeloid ray cells around stem pith.Yellow-brown sedimentation was observed in the cork cambium,the inner layer,the cortex,phloem parenchyma and ray cells of the rhizome.In addition to the vegetative organs,Yellow-brown sedimentation was found in ovules and basic tissues of the ovary,and alkaloids were also found in anther connective and pollen grains.(3)Extraction of G.elegans alkaloids,and the antibacterial activity and minimal inhibitory concentration(MIC)of the alkaloid were determined by filter paper method and double microdilution method.The results showed that the G.elegans alkaloid had a broad-spectrum antibacterial activity against Listeria ATCC19115,Staphylococcus aureus ATCC25923,Staphylococcus aureus CMCC26003,Escherichia coli ATCC25922,Escherichia coli O157,Pseudomonas aeruginosa ATCC27853,and Pseudomonas aeruginosa CCC10104.and with the increase of alkaloid concentration,the antibacterial effect is also enhanced,among which the inhibitory effect on Listeria is the most obvious,its MIC is 125mg/ml,and the antibacterial effect against Pseudomonas aeruginosa ATCC27853 is the worst.The MIC is 500mg/ml,and the MIC of the other five strains is 250mg/ml.This part of the experiment explores the antibacterial activity of the G.elegans alkaloid and provides a theoretical basis for the application of antibacterial.(4)Gram-positive bacteria Staphylococcus aureus ATCC25923 and negative bacteria E.coli O157 were selected,and their minimum lethal concentrations(MBC)were determined to be 500 mg/ml and 750 mg/ml,respectively.The morphology and internal structure of Staphylococcus aureus ATCC25923 and Escherichia coli O157 were observed by transmission electron microscope(TEM)before and after treatment with its inhibitory and lethal concentrations.The results showed that both of the two kinds of bacteria changed in different degrees,such as rough surface,depression,rupture of the cell membrane and cell wall,overflow of internal substance and even cell lysis.We found that the morphology of Staphylococcus aureus changed at inhibitory concentration and the cell wall of Escherichia coli was stratified,which indicated that alkaloids destroyed the formation of cell wall because the shape of bacteria was affected by peptidoglycan vesicles.Cell death at lethal concentration may be due to loss of mechanical strength and permeability of the wall and fragmentation.In this experiment,the anatomical identification of G.elegans,the distribution of the G.elegans alkaloid and its antibacterial activity were studied.The results showed that the microscopical identification of the plant was supplemented and perfected,and reasonable suggestions were given to the planting and harvesting position of the plant,and a reasonably basis was provided for its development in the field of bacteriostatic activity.It provides a certain theoretical basis for the further development and utilization of G.elegans.