Paper Details

PJB-2021-561

Study on the anatomical structure of Gelsemium elegans Benth and the antibacterial action of alkaloids

Meng Zhao
Abstract

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【Objective】 In the present study, the microstructure of Gelsemium elegans vegetative organs was observed, and the alkaloids in plants were localized. Also, the antibacterial activity of the alkaloids was explored, and the antibacterial mechanism of the alkaloids was analyzed. 【Methods】 The anatomical study of structural characteristics of G. elegans vegetative organs were carried out with anatomical methods, and through histochemical staining, the alkaloids in the plant were localized. The antibacterial activity and minimal inhibitory concentration (MIC) of the alkaloid were determined by filter paper method and double microdilution method. The morphology and internal structure of Staphylococcus aureus ATCC25923 and Escherichia coli O157 were observed by transmission electron microscope (TEM) after treatment with its inhibitory and lethal concentrations. 【Results】 Microscopic observation results showed that the leaf of G. elegans was dorsiventral, and there were starch granules deposited in stem pith. Alkaloids were mainly distributed in the mesophyll tissue of leaves. In the stem, alkaloids were mainly distributed in stem epidermis, cortex cells and phloem parenchyma cells. Also, alkaloids were distributed in parenchyma cells of pith and ray cells. Yellow-brown sedimentation also could be observed in the cork cambium, the inner layer, the cortex, phloem parenchyma and ray cells of the rhizome. The antibacterial activity results showed that the G. elegans alkaloid had antibacterial activity against Listeria monocytogenes ATCC19115, Staphylococcus aureus ATCC25923, Staphylococcus aureus CMCC26003, Escherichia coli ATCC25922, Escherichia coli O157, Pseudomonas aeruginosa ATCC27853, and Pseudomonas aeruginosa CMCC10104. And with the increase of alkaloid concentration, the antibacterial effect was also enhanced, among which the inhibitory effect on Listeria monocytogenes was the most obvious. After treatment with its inhibitory and lethal concentrations, the morphology and internal structure of Staphylococcus aureus ATCC25923 and Escherichia coli O157 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. 【Conclusion】The structure of G. elegans performed the typical characteristics of the dicotyledonous plants; The histochemical results showed that the vegetative organs of G. elegans contained alkaloids. The G. elegans alkaloid had a broad-spectrum antibacterial activity, the morphology of S. aureus changed at inhibitory concentration and the cell wall of E. coli was stratified, which indicated that G. elegans alkaloid destroyed the permeability of the cell membrane, impeded the formation of the cell wall, and lysed the bacteria.

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