Department of Biochemistry, Quaid i Azam University, Islamabad, Pakistan.
Ann Clin Microbiol Antimicrob. 2012 May 3;11:11. doi: 10.1186/1476-0711-11-11.
Four medicinal plants (Chrozophora hierosolymitana Spreng, Chrysanthemum leucanthemum L., Ephedra gerardiana Wall. ex Stapf, and Quercus dilatata L.) used by indigenous healers to treat various infectious diseases were selected for the present study. The major objective of the present study was isolation and characterization of antimicrobial components from the crude plant extracts using bioassay guided fractionation.
Seven methanolic extracts of the four plants were screened to identify any antimicrobial agents present in them. The active crude plant extract was fractionated first by solvent partitioning and then by HPLC. Characterization of the active fractions was done by using spectrophotometer.
All the seven methanolic extracts showed low antifungal activity, however, when these extracts were tested for antibacterial activity, significant activity was exhibited by two extracts. The extract of aerial parts of Q. dilatata was most active and therefore, was selected for further analysis. Initially fractionation was done by solvent-solvent partitioning and out of six partitioned fractions, ethanol fraction was selected on the basis of results of antibacterial activity and phytochemical analysis. Further, fractionation was carried out by RP-HPLC and purified active subfractions were characterized by comparing their absorption spectra with that of the known natural products isolated from the plants of Quercus genus.
The results suggest that this is the first report of the isolated antibacterial compounds from this genus.
四种药用植物（Chrozophora hierosolymitana Spreng、Chrysanthemum leucanthemum L.、麻黄属植物（Ephedra gerardiana Wall. ex Stapf）和栓皮栎（Quercus dilatata L.））被当地的治疗师用于治疗各种传染病，因此被选为本研究的对象。本研究的主要目的是使用生物测定指导的分级分离法从粗提物中分离和鉴定具有抗菌作用的成分。
对四种植物的七种甲醇提取物进行筛选，以确定其中是否存在任何抗菌剂。首先通过溶剂分配法对活性粗提物进行分级，然后再通过 HPLC 进行分级。使用分光光度计对活性部分进行了鉴定。
七种甲醇提取物均显示出低的抗真菌活性，然而，当对这些提取物进行抗细菌活性测试时，两种提取物表现出显著的活性。栓皮栎地上部分的提取物活性最强，因此被选择用于进一步分析。最初通过溶剂-溶剂分配法进行分级，在六种分配的馏分中，根据抗菌活性和植物化学分析的结果选择了乙醇馏分。进一步通过反相高效液相色谱（RP-HPLC）进行分级，并通过比较其吸收光谱与从栎属植物中分离出的已知天然产物的吸收光谱来对纯化的活性亚馏分进行鉴定。
结果表明，这是首次从该属植物中分离出具有抗菌作用的化合物。
