Benastatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Abstract

Benastatins have been isolated as part of a program designed to find microorganism-produced inhibitors of glutathione S-transferase from Streptomyces sp. MI384-DF12. They were purified by chromatography of reversed-phase silica gel, silica gel and Capcell Pak C18 (HPLC) followed by solvent extraction and then isolated as yellow powders. Benastatins A and B have the molecular formulae, C30H28O7 and C30H30O7, respectively. They were competitive with 3,4-dichloronitrobenzene as the substrate, and the inhibition constants (Ki) of benastatins A and B were 5.0 x 10~6 and 3.7 x 10~"6, respectively. 1385 Glutathione 5-transferase (EC 2.5.1.18) (GST) catalyses the transfer of the glutathionyl group to an electrophilic acceptor and is distributed in a wide variety of mammaliancells as a multi-functional enzyme1*.

Purification and Biochemical Properties of Glutathione S-Transferase from Lactuca sativa

“…The I 50 value of S-hexylGSH and SmethylGSH, a derivative of GSH, for the enzyme was approximately 15 µM. The I 50 of benastatin A, an electrophilic substrate-like compound (Aoyagi et al, 1992) and S-(2,4-dinitrophenyl)glutathione, a conjugation product of GSH with CDNB, for the enzyme were 0.41 µM and 3.4 µM, respectively.…”

“…chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), ethacrynic acid (ETA), 1,2-epoxy-3-(p-nitrophenoxy) propane (EPNP), DEAE-Sephacel and glutathione-Sepharose were obtained from Sigma (St. Louis, USA). S- (2,4-dinitrophenyl) glutathione was synthesized by the method of Schramm et al Benastatin A was gifted by Prof. T. Aoyagi (Aoyagi et al, 1992). All other reagents used were of the highest grade commercially available.…”

Naphthacemycins, novel circumventors of β-lactam resistance in MRSA, produced by Streptomyces sp. KB-3346-5. I. The taxonomy of the producing strain, and the fermentation, isolation and antibacterial activities

“…The ethyl acetate extract was purified by silica gel column chromatography twice and HPLC to yield naphthacemycins A 1 -A 11 (1-11), B 1 -B 4 (12)(13)(14)(15) and C 1 -C 2 (16)(17). Their structures were elucidated by NMR experiments and X-ray analysis, as reported elsewhere.…”

“…Its desulfonated analog, benastatin A (25), is active against Gram-positive bacteria. 17 Bischloroanthrabenzoxocinone (26), produced by Streptomyces sp., also has the same unit. 18,19 It also inhibits bacterial type II fatty acid biosynthesis and shows antibacterial activity against Gram-positive bacteria.…”

“…2 We have also reported that cyslabdan enhances imipenem activity against MRSA. 3,4 Our continuous study to find microbial metabolites, like cyslabdan, that circumvent β-lactam resistance of MRSA, led us to discover further novel compounds, the naphthacemycins A 1 -A 11 (1-11), B 1 -B 4 (12)(13)(14)(15) and C 1 -C 2 (16)(17) (Figure 1), reported as KB-3346-5 substances in the patent by our group 5 , isolated from a culture broth of Streptomyces sp. KB-3346-5.…”