Chandrananimycin C

The addition of anthranilic acid to the culture medium of the marine derived Halomonas sp. strain GWS-BW-H8hM completely altered the secondary metabolite pattern relative to the standard conditions. The red-orange color of the culture filtrate extract was the result of the production of 2-aminophenoxazin-3-one (1), chandrananimycin C (5) and three new derivatives of 1 with a previously unknown substitution pattern: 2-amino-, 2-amino-8-benzoyl-, and 2-amino-8-(4-hydroxybenzoyl)-6-hydroxyphenoxazin-3-one (2-4). The compounds were determined to have antibacterial and cytotoxic activities; a mode of action other than DNA intercalation is discussed.

An efficient conjugation method has been developed for the marine Actinomyces sp. isolate M048 to facilitate the genetic manipulation of the chandrananimycin biosynthesis gene cluster. A phiC31-derived integration vector pIJ8600 containing oriT and attP fragments was introduced into strain M048 by bi-parental conjugation from Escherichia coli ET12567 to strain M048. Transformation efficiency was (6.38+/-0.41)x10(-5) exconjugants per recipient spore. Analysis of eight exconjugants showed that the plasmid pIJ8600 was stably integrated at a single chromosomal site (attB) of the Actinomyces genome. The DNA sequence of the attB was cloned and shown to be conserved. The results of antimicrobial activity analysis indicated that the insertion of plasmid pIJ8600 seemed to affect the biosynthesis of antibiotics that could strongly inhibit the growth of E. coli and Mucor miehei (Tü284). HPLC-MS analysis of the extracts indicated that disruption of the attB site resulted in the complete abolition of chandrananimycin A-C production, proving the identity of the gene cluster. Instead of chandrananimycins, two bafilomycins were produced through disruption of the attB site from the chromosomal DNA of marine Actinomyces sp. M048.

The criteria currently followed for selecting antitumor compounds include agents that can target apoptosis inhibitor proteins and cancer cell markers. In silico studies are often used to identify suitable antitumor compounds for the cancer targets. The aim of the present study is to evaluate the interactions of some antitumor compounds reported from marine Streptomyces with cancer target proteins. Nine compounds were selected from marine Streptomyces based on previous reports and evaluated for their interactions with cancer target proteins by in silico molecular docking approach. Interactions of the selected ligand with target proteins were studied by PatchDock bioinformatics docking tool. Among the compounds tested marmycin A was interacted very effectively with human epidermal growth factor receptor 2 (HER2) and showed a least binding energy of -472.92 kcal/mol. The compound altemicidin showed a least binding energy of -415.66 kcal/mol with cyclin dependent kinase 4 (CDK4). The ligands resistoflavine and resistomycin also interacted with HER2 and showed the binding energy of -402.10 kcal/mol and -377.78 kcal/mol respectively. Other ligands proximycin A, chandrananimycin C, echinosporin, streptochlorin and streptokordin also showed the binding energy of -341.11 kcal/mol, -313.31 kcal/mol, -305.64 kcal/mol, -291.91 kcal/mol and 222.34 kcal/mol respectively with CDK4 protein. These results of our study suggest that HER2 and CDK4 are better cancer drug targets for therapy.