4-Deoxybostrycin

Deoxybostrycin (1) is an anthraquinone compound derived from the marine mangrove fungus Nigrospora sp. No. 1403 and has potential to be a lead for new drugs because of its various biological properties. A series of new derivatives (2-22) of deoxybostrycin were synthesized. The in vitro cytotoxicity of all the new compounds was tested against MDA-MB-435, HepG2 and HCT-116 cancer cell lines. Most of the compounds exhibit strong cytotoxicity with IC₅₀ values ranging from 0.62 to 10 μM. Compounds 19, 21 display comparable cytotoxicity against MDA-MB-435 to epirubicin, the positive control. The primary screening results indicate that the deoxybostrycin derivatives might be a valuable source of new potent anticancer drug candidates.

Two crystalline red pigments with phytotoxic activity were isolated from culture filtrates of Alternaria eichhorniae, a pathogen of the water hyacinth Eichhornia crassipes. The pigments were present in the ratio of 4:1 and were identified as bostrycin and 4-deoxybostrycin, respectively. This is the first isolation of 4-deoxybostrycin from a natural source. Bostrycin, 4-deoxybostrycin, and their isopropylidene derivatives induced necrosis on tested plant leaves comparable to the A. eichhorniae-induced necrosis on water hyacinth. The lowest phytotoxic concentrations of crystalline bostrycin and 4-deoxybostrycin on water hyacinth leaves were about 7 and 30 microgram/ml, respectively. Both substances were inhibitory to Bacillus subtilis but were inactive against the fungus Geotrichum candidum.

4-Deoxybostrycin is a natural anthraquinone compound isolated from the Mangrove endophytic fungus Nigrospora sp. collected from the South China Sea. Nigrosporin is the deoxy-derivative of 4-deoxybostrycin. They were tested against mycobacteria, especially Mycobacterium tuberculosis. In the Kirby-Bauer disk diffusion susceptibility test, they both had inhibition zone sizes of over 25 mm. The results of the absolute concentration susceptibility test suggested that they had inhibitory effects against mycobacteria. Moreover, 4-deoxybostrycin exhibited good inhibition which was even better than that of first line anti-tuberculosis (TB) drugs against some clinical multidrug-resistant (MDR) M. tuberculosis strains. The gene expression profile of M. tuberculosis H37Rv after treatment with 4-deoxybostrycin was compared with untreated bacteria. One hundred and nineteen out of 3,875 genes were significantly different in M. tuberculosis exposed to 4-deoxybostrycin from control. There were 46 functionally known genes which are involved in metabolism, information storage and processing and cellular processes. The differential expressions of six genes were further confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). The present study provides a useful experiment basis for exploitation of correlative new drugs against TB and for finding out new targets of anti-mycobacterial therapy.