Precursors in the biosynthesis of FR-900482, a novel antitumor antibiotic produced by Streptomyces sandaensis.

Abstract

A new antitumor antibiotic (1), isolated from the culture broth of Streptomyces sandaensis No. 6897, was found to have unique structure1*^. FR-900482 differs from the mitomycin family of antibiotics due to the lack of a quinoid structure, although FR-900482 resembles the mitomycins with respect to the aziridine function and a carbamoyloxymethyl group. Examination of the structure suggests that the biosynthesis of FR-900482 may be presumed to be derived from a number of compoundswhich structurally resemble parts of the molecule.Recently, it has been reported that 3-amino-5-hydroxybenzoic acid (AHBA) is involved in the biosynthesis of antibiotics, actamycin3), rifamycin B4), geldanamycin5) and mitomycins6). Theansamycinsand the mitomycinscontain a seven carbon amino unit, derived from AHBA. S. sandaensis No. 6897 was inoculated into a seed medium (40 ml) in a 250-ml Erlenmeyer flask and cultured at 30°C for 72 hours at 250 rpm using a rotary shaker. The seed medium(pH 7.0) was composed of soluble starch 2%, glucose 0.5%, dried yeast 1 %, Pharmamedia 1 %, corn steep liquor 0.5% and CaCO3 0.2%. The seed culture (1 ml) was transferred to 50ml of a production mediumand cultured for 144 hours under the same conditions. The production medium (pH 6.0) was composed of soluble starch 2%, maltose 2%, dried yeast 1%, wheat germ 3% and CoSO4à"7H2O 1 x10"3%. Radioactive compounds were added to fermentation broths at 72 hours to give the final concentration indicated in Table 1. After 72 hours of additional incubation, the fermentation was terminated and the mycelia were removed by centrifugation (2,000rpm for 15 minutes). The supernatant fluid was passed through a column of Diaion HP-20 and washed with deionized water. The column was eluted with 50% aq MeOH.The eluate was subjected to TLCon silica gel plates is approximately 0.1 %.As shown in Table 1

The biosynthesis of 3-amino-5-hydroxybenzoic acid (AHBA), the precursor of mC7N units in ansamycin and mitomycin antibiotics: a review

“…Later work has repeatedly confirmed the specific role of AHBA as precursor of the mC 7 N unit of various other compounds. [34][35][36][37][38][39] The biosynthetic question then raised was how AHBA was formed by a route that is related to the shikimate pathway. An important issue was whether the nitrogen of AHBA was attached to the carbon corresponding to C-3 or C-5 of shikimate.…”

“…However, it is also involved in the biosynthesis of other compound classes, as exemplified by the mitomycins and FR900482, in which it is combined with an aminosugar as the second component. 13,35,68 Other examples are the tetrapetalones, 38 which were shown to incorporate an AHBA moiety, and diazepinomicin, which was also proposed to incorporate an AHBA-derived moiety, although final proof is still outstanding. 69 A particularly intriguing example are the saliniketals from Salinispora arenicola, which share a biosynthetic pathway with the rifamycins.…”

Aziridine Natural Products – Discovery, Biological Activity and Biosynthesis

“…There has been one report on the biosynthesis of FR900482 [114]. Radiolabeled D-glucosamine 33 and AHBA 38 were efficiently incorporated into 6, and D-[1-13 C]-glucosamine was incorporated in the expected orientation (Figure 11.10).…”

The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

“…Like the mitomycins it is constructed from 3-amino-5-hydroxybenzoic acid (147) (incorporation of 7-14C-labelled material) and D-glucosamine (notable incorporation of 1 -13C-labelled material resulting in labelling of C-13, as expected). 75 Results of further work have been reported76 on B-factor [3'-(1 -butylphosphoryl)adenosine] which induces rifamycin production in a non-producing Nocardia mutant (cf. ref.…”