In the course of screening for new antibacterial agents, a new isolate collected from a soil sample of an arid area in south Algeria, produced a red pigment which was shown an antagonistic action against a Gram-positive bacterium Bacillus subtilis. The isolate was identified as Saccharothrix sp. and named SA 103. The red pigment, eluted by HPLC on reverse phase C18 column, contained two compounds of an anthracycline antibiotics group. The structure of the major product (2) was characterized as mutactimycin C, and PR (1) was a new member of this group, designated as mutactimycin PR. These compounds showed an antibiotic activity against certain Gram-positive bacteria in vitro. This is the first report of mutactimycins production by the genus Saccharothrix.
A new antibiotic termed mutactimycin PR (1) was isolated along with the known mutactimycin C (2) from the fermentation broth of Saccharothrix sp. SA 103. The two compounds belong to the anthracycline group. The structure of these antibiotics was elucidated with the aid of NMR and mass spectrometric investigations. The novel compound mutactimycin PR was characterized as 5, 12 Naphtacenedione, 7-[(6-deoxy-3-O-methyl-α-L-mannopyranosyl) oxy]-4-[(6-deoxy-α-L-mannopyranosyl)oxy]-7, 8, 9, 10-tetrahydro-6, 9, 11-trihydroxy-9 methyl.
Through our screening for novel antifungal compounds, YM-215343 was found in the culture extract of Phoma sp. QN04621. The structure of YM-215343 was determined by several spectroscopic experiments as a novel compound closely related to apiosporamide and fischerin. YM-215343 exhibited antifungal activity against the pathogenic fungi, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus with MIC values of 2-16μg/ml. It also showed cytotoxicity against HeLa S3 cells with an IC50 of 3.4μg/ml.
Landomycin E (LaE) overproducing strain Streptomyces globisporus SMY6222 has been developed using UV induced mutagenesis and selection for streptomycin resistance. SMY622 has been shown by HPLC to produce 200-fold higher amounts of LaE when comparing with parental strain. The levels of transcription of regulatory gene lndI and oxygenase gene lndE are two times higher in the mutant than in the wild type. Gene rpsL for ribosomal protein S12 from SMY622 was shown to contain point mutation K43R. Possible reasons for increased LaE synthesis in SMY622 are discussed.
FR901512, a new specific inhibitor of HMG-CoA reductase, was isolated from the culture of an agonomycetous fungus No. 14919. FR901512 inhibited cholesterol synthesis from [14C] acetate in Hep G2 cells with an IC50 of 1.0nM. An increase of cell surface LDL receptors observed on the FR901512 treated human hepatoma cell line Hep G2 cells. Single oral administration of FR901512 strongly inhibited sterol synthesis in rats. Daily oral administration of FR901512 to beagle dogs decreased plasma cholesterol levels.