| Bombyx batryticatus and mylabris are both Chinese herbals from insects. Bombyx batryticatus is dried silk worm body that was infected with Beauveria bassiana. Bombyx batryticatus contains 6.34% ash, 67.44% protein, 11.31% water and 4.38% fattiness. It is reported that Bombyx batryticatus is effective to treat convulsions, sore throat, skin itching, submandibular lymphadenitis and facial paralysis. Mylabris belongs to coleoptera meloidae insects. Mylabris is widely used for treatment of lump, ulcer and malignant, and the recent studies indicate its anticancer activity. Cantharidin that was isolated from mylabris is sesquterpenoids, which has exhibited better anticancer activity. Its derivatives, norcantharidin and dehydronorcantharidin have similar biological activities.Although the Bombyx batryticatus, cantharidin and its derivatives had been widely used in Chinese traditional medicine, there are no studies reported about their antimicrobial activities. This paper reports the studies on their antimicrobial activities, using Bombyx batryticatus extracts, cantharidin and its derivatives. The main results are as follows: 1. Studies on the extraction technology of antimicrobial components from Bombyx batryticatusThe efficiency of four different extraction methods (supersonic, microwave, decoction and cold dip extraction) and seven different extraction sovents (petroleum ether, dichloromethane, ethyl acetate, 95% ethanol,water and so on) on the yield of Bombyx batryticatus were analyzed. The optimum extraction was gained by supersonic extraction with 95% ethanol as extaction sovent.2. Study on antimicrobial activities of the extraction from Bombyx batryticatus The results of bioassay indicated that 95% ethanol extraction from Bombyx batryticatus had antibacterial activity against Bacillus subtilis, Klebsiella pneumoniae, Streptococcus pneumoniae and Salmonella enteritidis, and their MIC were 0.10g/ml, 0.20 g/ml, 0.40g/ml, 0.40g/ml respectively. The EC50of 95% ethanol extration from Bombyx batryticatus against Colletotrichum gloeosporioides, Valsa mali and Marssonina zanthoxyli were 0.048g/ml, 0.099g/ml and 0.078g/ml, respectively.The 95% ethanol extract from Bombyx batryticatus was extracted by petroleum ether, chloroform, ethyl acetate and n-butanol according to the different polarity of solvent, and the extracts of petroleum-ether phase(ASP) chloroform phase(ASC) ethyl-acetate phase(ASE) n-butanol phase(ASB) were obtained respectively. Their antimicrobial activity test showed that the antibacterial function of 0.50g/ml n-butanol fraction against different bacterium was the best. Diameter of inhibition zone of n-butanol fraction against Salmonella enteritidis was 10.75±0.50mm, but no antimicrobial activities for petroleum ether fraction.ASC and ASB were further separated with silica gel column chromatography, by which the ASC was isolated to different fractions. The bioactivity test showed the 1mg/ml fraction eluted by 50% alcohol was the best one against bacterium,and the diameter of inhibition zone against Salmonella paratyphib and Klebsiella pneumoniae were 10.50±0.03mm. ASB was isolated to many fractions by the same method, and the 1mg/ml fraction eluted by acetone/petroleum ether(2:1) was the best one against bacterium, and the diameters of the inhibition zone against Bacillus subtilis, Streptococcus pneumoniae, Escherichia coli and Salmonella paratyphib were 6.10±0.02mm, 4.90±0.10mm, 4.60±0.03mm and 4.40±0.05mm, respectively.3. Study on antifungi activity of cantharidin and its derivative against plant pathogens The antifungal activities of cantharidin and its derivative against plant pathogens were studied by measuring growth rate of mycelia. There was strong inhibition of canthaidin against Rhizoctonia solani,Valsa leucostoma with the EC50 of 2.489mg/l and 3.716mg/l, respectively. The bulged mycelia and malformed cellmembrane in Valsa leucostoma dealed with by cantharidin and demehylcantharidin were observed with the scanning electronic microscope. KEY WORDS: Bombyx batryticatus, canthaidin, demehylcantharidin, antimicrobial activities... |
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