Effect of acid hydrolysis in the microwave-assisted extraction of phenolic compounds from Geranium sibiricum Linne with the guidance of antibacterial activity
Geranium sibiricum Linne is widely employed for the therapy of dysentery and enteritis in traditional Chinese medicine (TCM) and it is always consumed as restorative food.Recent researches indicated that it has anti-inflammation,antiproliferative and antioxidant activities.However,the plant is always treated as weeds in farmland and turf.Therefore,lots of efforts have been devoted on the researches of full exploitation and usage.It reveals that polyphenols are the main compounds in the family,which should be responsible for the beneficial efficacies of G.sibiricum.Among the polyphenolic compounds,corilagin (CG) and geraniin (GE) are considered as the main pharmacological substances.Currently,cases of bacterial resistance after the treatment of antibiotics and hormones have ever been reported,and received more attention.It caused the escalating development of new antibacterial agents in a high number of sources,such as the secondary metabolites obtained from plants.Polyphenols from tea,Zanthoxylum,Origanum,Combretum,Jerusalem artichoke and others plants have been screened for their potential uses as alternative remedies for the treatment of many bacterial (Staphylococcus areus,Enterococcus faecalis,Pseudomonas aeroginosa,Bacillus cereus and Escherichia coli,etc) infections.The main mechanisms are associated with the inhibition of nucleic acid synthesis,cytoplasmic membrane function and energy metabolism.Nevertheless,the antibacterial activity of G.sbiricum has not been evaluated yet.To the best of our knowledge,the releasing polyphenols from the higher plant cell interfered with the presence of cell-wall (CW),which is influenced by the CW characteristics,such as structural parameters,physical traits and chemical composition and phenols chemical structure,anyway,cross-linking CW polysaccharides is the main barrier for the release of intracellular substances.Therefore,it thus becomes very urgent to develop the adequate hydrolysis methods to degrade CW,with the levels of environmental friendship,low-cost and high efficiency.Polyphenols are commonly extracted by alkaline hydrolysis.Phenols in coffee and apple,wheat,onion and spinach have been reported to be extracted using alkaline hydrolysis.They found that a dramatic increase in caffeic acid,ferulic acid,pcoumaric acid,syringic acid,vanillic acid,protocathecuic acid and gallic acid content was obtained in Trichilia emetica via alkaline hydrolysis.Very limited information,however,is available regarding the effects of acidic hydrolysis.The potential reasons are that acidic hydrolysis can elevate temperature and cause the loss of some phenols acid extraction yields.Microwave-assisted extraction (MAE) has been accepted as a potential and powerful alternative over conventional extraction methods in the extraction of organic compounds from solid matrices.The main advantages are shorter time,less solvent,higher extraction yield,less decomposition of the target species and better products for lower costs.However,little information is available on acid or alkali hydrolysis in MAE to obtain the phenolic compounds.Anyway,plant phenolics possess antibacterial activity,and alkali or acid hydrolysis can release phenolics from CW.However,two issues were raised since the MAE of phenolic compounds from G.sibiricum: (a) Whether alkali/acid hydrolysis in MAE could be feasible to break the cross-like of phenols and CW? (b) Will different hydrolysis methods affect the antibacterial activity of extracts ? Therefore,the aim of the present study was to evaluate the effect of acid and alkali hydrolysis on total phenolic content as well as CG and GE from G.sibiricum in MAE.Furthermore,the antibacterial activities of crude extracts obtained from different treatment methods were compared to screen the appropriate extracts preparation methods.In addition,a critical study of the most essential parameters involved in extraction using central composite design (CCD) followed by response surface methodology (RSM) was evaluated,then mass transfer characteristics of acid hydrolysis in MAE were described and the optimal irradiation time was calculated through a pseudo first order equation.Moreover,scanning electron microscopy (SEM) was used to detect the cell destructive degree under different treatment methods for verification of the efficiency of the extraction.We anticipate that this work will be useful in the comprehensive utilization of G.sibiricum and insight into the understanding of hydrolysis in MAE will be of value in the natural products extraction.The results demonstrated that acid hydrolysis was suitable for the extraction of phenols from G.sibiricum and hydrochloric acid (HCl) hydrolysis do not only performed the highest effectiveness,but also enhanced its antibacterial capacity.After the process was optimized,the total phenols content,yields of corilagin and geraniin were increased by 28.60,53.80 and 35.65%,respectively,as compared to only 20% in microwave-assisted extraction (MAE).Scanning electron microscopy (SEM) was employed to verify the destructive effects of the methods,the results represented that HCl hydrolysis in MAE method had dramatic destructiveness on cell wall.Thus,HCl hydrolysis in MAE provides an efficient and rapid approach for the natural products extraction and the research also provides a valuable nature resource for healthy food industry.
Yu-Chun Yang Zhi-Wei Yang Zhong-Hui Zhang Ji Li Yuan-Gang Zu Yu-Jie Fu
Forestry Academy of Jilin province,Changchun 130033,China School of Basic Medical Sciences,Jiamusi University,Jiamusi 154007,China Key Laboratory of Forest Plant Ecology,Ministry of Education,Northeast Forestry University,Harbin 15
国内会议
南京
英文
1-2
2012-09-01（万方平台首次上网日期，不代表论文的发表时间）