Antibiotic activity against marine bacteria

Yoshikawa, K., Takedera, T., Adachi, K., Nishijima, M., and Sano, H., Korormicin, a novel antibiotic specifically active against marine Gram-negative bacteria, produced by a marine bacterium, J. Antibiot., 50, 949, 1997. 

The above described rationale of SAR can be exemplified by the bioactivities of the bromotyrosine derivatives, aeroplysinin-1 and dienone, as well as their complicated molecular substrates aerophobin-1 and isofistularin-3, isolated from the Mediterranean sponge, Aplysina aerophoba. Aeroplysinin-1 and dienone exhibit pronounced biological activity whereas aerophobin-1 and isofistularin-3 were always inactive when tested in equimolar concentrations [23]. Aeroplysinin-1 and dienone are antibiotically active against a broad spectrum of marine bacteria such as Vibrio, Micrococcus, and Alteromonas species [24] and are also cytotoxic to Ehrlich ascites tumour cells and HeLa tumour cells in the microculture tetrazolium (MTT) and clonogenic assays [25]. In these assays, it has been demonstrated that the free radical transformation of aeroplysinin-1 and dienone to its semiquinone structures are responsible for the cytotoxicity [25], Aeroplysinin-1 and dienone are the pharmacophores of aerophobin-1 and isofistularin-3. 

Antibiotic Activity against Several Marine Bacteria. 

Isomarinone (1679), an isomer of the previously known marinone (7), was isolated from the same tropical sediment bacterium (1638). Another marine-derived bacterium related to the genus Streptomyces has yielded the novel azamerone (1680) (1639). The British Columbian medicinal plant Moneses uniflora contains the antibiotic 8-chlorochimaphilin (1681), which is more active than chimaphilin (1640). Sesame roots (Sesamum indicum) have yielded the red chlorinated naphthoquinone chlorosesamone (1682) (1641). Cultures of Streptomyces strain LL-A9227 produce chloroquinocin (1683), which has some antibacterial activity against Gram-positive bacteria (1642). The two xestoquinones 1684 and 1685 were characterized from the Philippino sponge Xestospongia sp., and display topoisomerase II activity (1643). 

New vancomycin-type glycopeptide antibiotics are in clinical trials to combat methicillin-resistant bacteria (2612, 2613) such as the deadly Staphylococcus aureus (2614). For the first time, extracts of marine algae indigenous to Japan have shown activity against methicillin-resistant Staphylococcus aureus bacteria (2615, 2661). The therapeutic use of iodine has been rejuvenated (2616). For example, in the treatment of cyclic mastalgia (2617). 

A similar strategy has been followed for the preparation of the naphthoquinone nucleus (118) [202], a precursor of awamycin (119), another ansamycin antibiotic isolated from several Streptomyces species and active against Gram-positive bacteria, protozoa and marine tumors in vivo. The compound is also cytotoxic to Hela cells in vitro [203]. The structure of awamycin (119) has been determined by X-ray analysis [204] and it is structurally similar to damavaricin D (120), a degradation product and biosynthetic precursor of streptovaricin D (108). 

CstH N O.s M 1020.144 Bicyclic depsipeptide antibiotic. Prod, by a marine Streptoniycete. Mod. active against gram-positive bacteria. Pale yellow solid. 

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