The Preliminary Study On Bioactive Natural Products For Treatment Of MRSA

MRSA (methicillin-resistant Staphylococcus aureus), is a common pathogens to cause pyogenic infection and nosocomial infection. Because of the bacterium evolution and drug abuse, the resistance of bacteria has increased gradually, especially MRSA. It has become a global focus. MRSA has the characteristic of antimicrobial drug resistance, even began to resist to vancomycin which is considered the present most effective medicine. Once the MRSA resists vancomycin universally, a dangerous situation is appearing:patients who have infected MRSA will not be cured by any drugs. So it has a great significance to research and develop new drug for treatment of MRSA.There are a variety of effective components in Chinese traditional medicine. For the structural complexity and diversity, natural compounds are great treasures to develop new drugs, which are also the advantages of our country.Many herbs have antimicrobial activities, such as Radix Isatidis, Andrographis paniculata(Burm.f.) Nees, Herba corydalis Bungeanae, Phellodendron amurense and Houttuynia cordata Thunb. Their components such as berberine, emodin, andrographolide and peiminine are the effective constituent. Chinese medicines remain to be sensitive to multiple drug resistance bacteria, which suggest the obvious advantages in treatment of resistant strains.Traditional Chinese medicine monomer, which has strong activities against MRSA, has been made deep researches. The aim of our research is to find a new anti-MRSA active ingredients and provide a theoretical basis and experimental base for the development of new drug for treatment of MRSA.There are three parts in the study:(I)23kinds of Chinese herbs extracts against MRSA were screenedAnti-MRSA activities among23kinds of Chinese herbal medicine water and ethanol extracts were determinated by96well plates initially. Eight species which have strong anti-MRSA activities are obteined, they are:Grimonia pilosa Ledeb, Taraxacummongolicum Hand. Mazz,Prunella vulgaris L, Scutellaria barbata D. Don, Platycladu orientalis, Chaenomeles sinensis, Sargentodoxa cuneata, Morus alba L, and the inhibitory effect was positively correlated with concentration. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of8kinds of Chinese herbs extracts against11strains MRSA are determined. The water extract and alcohol extract of G rimonia pilosa Ledeb has the strongest activity in anti-MRSA, and the MIC and MBC of the drug concentration was6.24mg.ml-1.(Ⅱ) The anti-MRSA activities of33kinds of traditional Chinese medicine monomer were studied33kinds of Chinese herbal monomer were detected anti-MRSA activities, and10kinds of traditional Chinese medicine monomers which have inhibitory activity on MRSA were found. They are:Taxifolin, Noroxylin, Dihydromyricetin, proanthocyanidins, gallic acid, Curcumin, Vrsolic Acid, Patchouialcohol, Silymarin, Gramine, and Myricetrin. The MIC of these monomers is:50μg.mL-1,50μg.mL-1,100μg.mL-1,100μg.mL-1,200μg.mL-1,400μg.mL-1,400μg.mL-1,400μg.mL-1,400μg.mL-1,400μg.mL-1,400μg.mL-1,800μg.mL-1respectively. At the same time, the Taxifolin, Dihydromyricetin, proanthocyanidins, bacteriostasis, which had relatively strong ant-MRSA activities, were investigated. The results showed that with these3kinds of traditional Chinese medicine monomers, the anti-MRSA activities of ofloxacin, cefoxitin sodium, chloramphenicol and cefazolin sodium were not getting stronger.(Ⅲ) Effective components of Grimonia pilosa Ledeb extracts on MRSA were researchedSolvent separation and column chromatography combination were used to separete acohol extracts from Grimonia pilosa Ledeb, and the activities of associative detachments were tested with96well plates.5strong anti-MRSA activity components from petroleum ether portion by silica gel column chromatography was obtained (ethyl acetate:petroleum ether=7:3elution).It was confirmed that anti-MRSA activities in water extracts was Tanni. And tannin extraction and purification process were studied preliminary.Screening anti-MRSA substance from Chinese herbal medicine and traditional Chinese medicine monomer was the first step and some valuable results were obtained, which made further research foundation. The results also showed that, many Chinese herbal medicines contain antioxidant MRSA, but how to get good antibacterial substance, how to separate and purify, is emphasis and difficulty for the next step research.