Isolation And Identification Of Antibacterial Compounds From Arthropods Gryllotalpa Orientalis Burmeister And Allomyrina Dichotoma Linnaeus

Secondary metabolites of arthropod insects are the organic compounds of the non-essential small molecules to maintain their celluar activities or normal growing development. The resources of arthropod insects are abundant, which has a long history as traditional Chinese medicine in our country. However, the study of their chemical biological information is far less than those of the plant and marine organism both in China and abroad. To further mine the value of medicial insects, it is thus significance to investigate the arthropod insects including both of their chemistry of secondary metabolites and biological activity.Targeted on Gryllotalpa orientalis Burmeister and Allomyrina dichotoma Linnaeus, the characteristic extracts were obtained using the method of "two-stage extraction biocompatibility" previously developed in our group. Combined the bioactivity-duided fractionation and the chromatographic separation, the antibacterial secondary metabolites of arthropods were isolated and purfied. The actively lead compounds were then confirmed in in vitro antibactiral tests. The study also investigated into the structural modification and synthesis of natural active compounds, thus providing the basis of futher research on the structure-activity relationship and the structure modification aiming to reduce toxicity and improve bioavailability.Seven compounds were successfully obtained from the 70% methanol extract of Gryllotalpa orientalis Burmeister. Their structure was elucidated using the infrared spectroscopy(IR), spectral analysis(NMR and 2D NMR) and mass spectrometry(MS) analysis. There are four new Buxus alkaloids named as Gryllotalpa A, Gryllotalpa B, Gryllotalpa C and Gryllotalpa D, respectively. Another three known compounds were 4-amino-1-(1-methylethyl)-2-pyrrolidinone, 2-amino-pyrimidine and Glycerol. All of the compounds were isolated from Gryllotalpa orientalis Burmeister for the first time.Five compounds were successfully obtained from the 70% methanol extract of Allomyrina dichotoma Linnaeus. Their structure was elucidated using the infrared spectroscopy(IR), spectral analysis(NMR and 2D NMR) and mass spectrometry(MS) analysis. A new skeleton compound, origned from a familiar norbornane derivertives, was named as Allomyrinanoid A and two new compounds of purine alkaloid were named as adenine-9-methylaldehyde oxime and 6-N-methyleneimine-adenine-9-methyl aldehyde oxime, respectiely. The known 12-twenty-three eicosapentaenoic acid and uracil were separated as well. All of the compounds above were firstly isolated from Allomyrina dichotoma Linnaeus.The activities of the compounds isolated have been evaluated in the antibacterial test. The result showed that Gryllotalpa A had the antibacterial activity against grampositive bacteria Bacillus subtilis, Staphlococcus aureus and gram-negative bacteria Escherichia coli. Gryllotalpa B had the antibacterial activity against Bacillus subtilis. Allomyrinanoid A had the antibacterial activity against Bacillus subtilis. Adenine-9-methylaldehyde oxime and 6-N-methyleneimine-adenine-9-methylaldehyde oxime had the antibacterial activities against Escherichia coli.The study also discussed the synthesis of natural product Karanal intermediate. The intermediate 2-methyl-2-sec-butyl malonate was successfully synthesized and the process was optimized through the alkylation reaction of 2-methyl malonate. This work made a useful exploration for the structural modification of natural product chemistry.