The structure of manumycin. I. Characterization, structure elucidation and biological activity.

Abstract

Manumycin(1), produced by Streptomyces parvulus (strain Tu 64), was isolated from the mycelium by extraction with acetone and could easily be purified chromatographically. Chemical degradation of 1 (C8iH38N2O7) gave 2-acetamino-3-hydroxycyclopent-2-enone (2) by acetolysis, 2,4,6-trimethyl-2,4-decadienoic acid (3) by alkaline hydrolysis, and 2-(2,4,6-trimethyl-2,4-decadienoylamino)-5,6-epoxy-l ,4-benzoquinone (5) by mild chromic acid oxidation. In connection with a detailed spectroscopic analysis, the structure of 1 could be elucidated and the (^-configuration of the double bonds in the triene and diene chain was established.Manumycin exhibits biological activity against Gram-positive bacteria and fungi and furthermore, an inhibition of the developmental processes of someinsects.Streptomyces parvulus (strain Tu 64) produces the pale yellow antibiotic manumycin0in association with more lipophilic red pigments, which were identified as C25-prodigiosms2), and the colorless hydrophilic amino acid antagonist L-2,5-dihydrophenylalanine3). Previous reports1»4) have already described the isolation and structure of manumycin, whose structural elements could not be classified with a known group of antibiotics. In the meantime similar compounds such as asukamycin5'6), U-621627) and U-56,4078) have been discovered, which could be added to the manumycin group. Structural features incline us to consider these antibiotics as broken chain ansamycins9). To verify this hypothesis, biosynthetic studies of manumycin and asukamycin are in progress10*n). In our preliminary report0, chemical degradation reactions have been described to prove the structure of manumycin.Getting more information from subsequent spectra, we are nowable to derive the structure of manumycinby a detailed spectroscopic analysis in connection with only a few chemical derivatization reactions. In this full paper we describe the fermentation of strain Tu 64 as well as a simpler isolation method, more biological data and a detailed chemical and spectroscopic characterization of manumycin. Fermentation and Isolation Streptomyces parvulus (strain Tii 64) is unstable as its phenotype, and a good logarithmic growth phase is not a reliable indication for producing an identical spectrum of secondary metabolites. The production of the red prodigiosins, starting 36~40 hours after inoculation, does however indicate the formation of manumycin,because these compoundsappear simultaneously. The strain Tii 64 was cultivated in 1-liter, 10-liter and 120-liter fermentors, using soybean meal 2% and mannitol 2% as a culture medium.Inoculum was prepared in Erlenmeyer flasks containing the same mediumand shaken for 60 hours at 28°C. Fig. 1 shows a typical time course of the fermentation in a 10-liter fermentor. The production of manumycinstarts after the log-phase, reaching its maximum76 hours

Identification of Ras farnesyltransferase inhibitors by microbial screening.

“…UCF1-A (57 mg), UCF1-B (82 mg), and UCF1-C (63 mg) were obtained as yellow powder. NMR and MS studies revealed that UCF1-A and UCF1-B are related to manumycin (21,22) (Fig. 1).…”

“…A culture of newly isolated Streptomyces was found to produce active compounds designated UCF1. Isolation and structural characterization of these active compounds assigned them to the manumycin family of antibiotics (21,22) and resulted in the identification of two new compounds. In this study, we report the effect of these compounds on Ras PFT and Ras-activated murine tumors.…”

“…Details ofthe structure determination ofthese compounds will be published elsewhere. Oxidation and reduction of UCF1 were performed by the method of Zeeck and colleagues (22,24). The adduct with thiol was prepared by mixing UCF1-C with three equivalents of 2-mercaptoethanol in 20mM Tris HCl (pH 7.5)/methanol, 1:1, for 120 min at 4°C and was purified by HPLC.…”

“…A strain of Streptomyces freshly isolated from soil collected in Sakai, Japan, was found to produce active compounds. Isolation and purification afforded three active components, UCF1-A, -B, and -C. NMR and MS studies revealed that UCF1-C is identical to the known antibiotic manumycin (21,22), whereas UCF1-A and UCF1-B are structurally related to manumycin but differ from manumycin in the structure of the acylamino side chain at C-2 of the cyclohexenone epoxide (Fig. 1).…”

Antitumor activity of asukamycin, a secondary metabolite from the actinomycete bacterium Streptomyces nodosus subspecies asukaensis

“…The antitumor activity of this group of metabolites has been studied, for example, by using manumycins A-D, which are primarily produced by Streptomyces parvulus. They have shown cytotoxic effects against a variety of tumor cells including murine and human leukemia cells (5,6) as well as human colon, thyroid, hepatic and ovarian cancer cells (3,4,(7)(8)(9)(10). Only a very limited number of biological activities have been reported for asukamycin thus far.…”