Investigation On Metabolites Produced By Two Endophytic Actinomycetes

Since Waksman found a landmark natural product, streptomycin, in1940, actinomycetes have been one class of star microorganisms developed for half a century with a high speed. The quality of human lives has been largely improved due to many antibiotics from actinomycetes. The actinomycetes has great contribution to human. After the entry of twenty-first century, indigenous marine actinomycetes and terrestrial actinomycetes in special environment along with their bioactive metabolites have been research highlight and more bioactive metabolites with new structures are being discovered, which brings much vitality to the study on the nature product of actinomycetes.In this research, two strains of symbiotic actinomycetes, which were screened by bioactive and spectral analysis, were isolated from the marine fish and termite bodies (mainly from the guts) and the two strains of actinomycetes were respectively named fang-1and BY-4. The two strains of actinomycetes were fermented and the broth was extracted with XAD-7resin.34compounds were separated and purified from the extraction on the basis of spectral experiments such as IR, MS,’H-NMR,13C-NMR, HMQC, COSY, HMBC, NOESY, CD, and single-crystal X-ray diffraction analysis. The structure of31compounds was characterized and the structure of3compounds was not identified. Some of the compounds were studied on antimicrobial and antitumor activity. The results were described in details below.A crude extract (4.2g) were obtained from the fermentation broth (50L) of fang-1.The EtOAc extraction (2.2g) of the crude extract was performed through Silica gel column chromatography, Gel(Sephadex LH-20) column chromatography, HPLC and other chromatographic methods, and then16compounds were separated and purified. By a combination of spectroscopic methods such as MS,1D NMR and related data, these compounds were unambiguously characterized. All the compounds were known.14of them were cyclic peptides and the rest were small molecules’ compounds.A crude extract (5.8g) were obtained from the fermentation broth (50L) of BY-4. The EtOAc extraction (2.2g) of the crude extract was performed through Silica gel column chromatography, Gel (Sephadex LH-20) column chromatography, HPLC and other chromatographic methods, and then18compounds were separated and purified. Using different spectral approaches such as IR, MS,1D NMR,2D NMR, UV, CD, and single-crystal X-ray diffraction analysis, the structures of15compounds were elucidated, the single crystal of compound17,21had been obtained. Compound22,23,24,25,26,27,28,29,30were novel compounds, which were never reported. The antimicrobial tests were shown that compound17,18,22,25,28,30had some activities, and compound28had some activities against six strains of bacteria or fungi. Compound26had activities against H. pylori. The antitumor tests showed that compound19had some activities against human gastric cancer cell SGC7901with IC5015.51μg/mL-1and against human liver cancer cell SMMC7721with IC50=23.47μg/mL.Furthermore, studies on nature products from actinomycetes were reviewed briefly.