| Lagerstroemia indica belongs to the Lagerstroemia of Family Lythraceae.There are about 55 species of Lagerstroemia in the world.Lagerstroemia indica,also known as itchy tree,hundred day red,etc.The flowering period is from June to September every year.It has a long flowering period and bright colors.Lagerstroemia indica is widely planted in China and mostly used for Alee-tree and garden ornamental seedlings.Besides economic value and ornamental value,Lagerstroemia indica also has potential medicinal value.According to the compendium of Materia Medica,the root,leaf,flower and leather of Lagerstroemia indica have the effects of promoting blood circulation,relieving pain,clearing heat and detoxifying.Lagerstroemia indica,widely used in Southeast Asia,is locally known as "banaba".Its roots can be used as astringent agents.Leaves can be used to treat malaria and foot fractures,and can also be made into tea to treat diabetes and obesity.At present,the research of domestic and foreign researchers on Lagerstroemia indica mostly focuses on the chemical components and pharmacological activities of Lagerstroemia indica leaves,especially the hypoglycemic activity.However,there are few studies on the chemical components and antibacterial activity of Lagerstroemia indica fruits.In this paper,the volatile constituents and non volatile components of the fruits of Lagerstroemia indica were studied.The main research contents and results are as follows:(1)Study on extraction technology,chemical components and antibacterial activity of Lagerstroemia indica fruits volatile oil(LIFVO).In this paper,ultrasonic assisted organic reagent extraction method was used to extract LIFVO for the first time.The effects of extraction temperature,extraction time,ultrasonic power and liquid-solid ratio on the extraction yield of volatile oil from Lagerstroemia indica fruits were investigated.On the basis of this single factor experiment,the extraction process of LIFVO was optimized by response surface method.The best extraction process of LIFVO were as follows: using n-hexane as extractant,extraction temperature 69.36 ℃,extrction time 46.86 min,ultrasonic power 562.39 W and liquid-solid ratio 23.64 m L/g,the experimental results show that the fitting degree of the model is good.Then the chemical components in the LIFVO were analyzed by gas chromatography-mass spectrometry(GC-MS).A total of 27 chemical components were identified from the LIFVO,mainly including hydrocarbons,phenols,esters,alcohols and terpenes.Among them,the components with high content were tetracosane(17.307%),pentacosane(12.731%)and hexacosane(10.897%).Finally,the study of antibacterial activity showed that the bacteriostatic activity of the LIFVO was the strongest against Staphylococcus aureus,weaker against Escherichia coli and Listeria,and the weakest against Penicillium cinerea.The minimum inhibitory concentration(MIC)for these four bacteria were 1.00 mg/m L,2.00 mg/m L,4.00 mg/m L and 8.00 mg/m L respectively.Combined with the results of GC-MS,It can be preliminarily inferred that the main antimicrobial active components in the LIFVO are a variety of straight chain alkanes,alcohols,terpenes and phenols.(2)Study on preparation,content of active substances,cytotoxicity and antibacterial activity of non-volatile extracts from Lagerstroemia indica.The nonvolatile components in Lagerstroemia indica fruit were extracted with methanol.The extracts were extracted by petroleum ether,dichloromethane,ethyl acetate and nbutanol to obtain extracts with different polarity.The contents of polyphenols,flavonoids and tannins in the extracts with different polarity were determined.The results showed that the polyphenol content of different polar extracts ranged from 22.60%± 2.34% to 40.35% ± 2.67%;The content of flavonoids ranged from 15.16% ± 1.22%to 24.91% ± 2.50%;The range of tannin content is 12.62% ± 0.16%～14.88% ± 4.42%.The cytotoxicity study showed that the extracts with different polarity had certain cytotoxicity to He La cells,among which dichloromethane extract was the most toxic,followed by n-butanol extract,ethyl acetate extract and petroleum ether extract.Finally,the antibacterial activity study showed that the extracts of different polarity had certain antibacterial and bactericidal activities,and the inhibitory activity against Bacillus thuringiensis was stronger than that against Escherichia coli.The petroleum ether extract,dichloromethane extract and ethyl acetate extract also had a certain inhibitory effect on Penicillium cinerea,while the n-butanol extract had no inhibitory activity against Penicillium cinerea.In addition,in order to further determine which components in Lagerstroemia indica fruits exert antibacterial effect,this paper also analyzed the correlation between the content of polyphenols,flavonoids and tannins in extracts such as dichloromethane,ethyl acetate and n-butanol and antibacterial activity.The content of polyphenols in extracts showed a high correlation with the tested strains,while the content of flavonoids and tannins had little or no correlation with antibacterial activity.This proves that polyphenols in different polar extracts of Lagerstroemia indica fruits are the main components to exert antibacterial effect.(3)Isolation,purification and antibacterial activity of monomeric components from Lagerstroemia indica fruits.The dichloromethane and ethyl acetate extracts of Lagerstroemia indica fruits were separated and purified by silica gel column chromatography,ODS reverse column chromatography,semi preparative liquid phase and recrystallization.A monomer compound 3,3’,4’-Tri-O-methylellagic acid(ZW-1)was isolated and identified from dichloromethane extract,and two compounds,Nudiposide(ZW-2)and Lyoniresionl(ZW-3),were isolated and identified from ethyl acetate extract.These three compounds were isolated from the plant for the first time,and compounds ZW-2 and ZW-3 were isolated from Lagerstroemia for the first time.Then,the antibacterial activities of the three monomers were studied by microdilution method.Compounds ZW-2 and ZW-3 had strong inhibitory activities against Staphylococcus aureus and Escherichia coli.The MIC against Staphylococcus aureus and Escherichia coli were 1.00 mg/m L、0.50 mg/m L respectively,and 0.50 mg/m L、0.50 mg/m L respectively.Compound ZW-1 has a weak inhibitory effect on Staphylococcus aureus and Escherichia coli at high concentration.In this paper,the volatile and non-volatile components in Lagerstroemia indica fruits were studied.The results showed that Lagerstroemia indica fruits had potential antibacterial and medicinal value.This paper provides a reference for the in-depth development of Lagerstroemia indica fruits,and provides a theoretical basis for the further efficient industrial production of antibacterial components in Lagerstroemia indica fruits. |
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