Twenty-five aromatic nitro, dinitro and trinitro compounds were isolated in low yields of less than 1 mg l À1 from a Salegentibacter sp. strain T436 derived from Arctic pack ice. Their structures were elucidated by MS and NMR techniques. Seven of these compounds, namely, 2-hydroxy-3-(4¢-hydroxy-3¢-nitrophenyl)-propionic acid methyl ester (6), 2-chloro-3-(4¢-hydroxy-3¢-nitrophenyl)propionic acid methyl ester (7), 3-(4¢-hydroxy-3¢,5¢-dinitrophenyl)-propionic acid methyl ester (14), 4¢-hydroxy-3¢,5¢-dinitrophenylethylchloride (16), (4¢-hydroxy-3¢,5¢-dinitrophenyl)-2-chloropropionic acid methyl ester (17), N-acetyl-3¢,5¢-dinitrotyramine (18) and 2,6-dinitro-4-(2¢-nitroethenyl)phenol (19) are new, and five are reported in this study from a natural source for the first time.
In addition to luisol A (1a), luisol B (2), and aloesaponarin II, the marine streptomycete B7617 produced a new derivative of 1a, 2-hydroxy-luisol A (1b). In an attempt to increase the biological activity, luisol A (1a) was oxidized and delivered with Jones reagent or by Swern oxidation the derivatives 3a/3b and 4a/4b, respectively, but none of these compounds showed antimicrobial or cytotoxic activities. All structure elucidations are based on 2D NMR analyses or were derived by comparison with published data.
IntroductionIn the course of our screening program for new antibiotics, aloesaponarin II [1], luisol A (1a) [2], luisol B (2) [2] and the new tetraol, 2-hydroxyluisol A (1b), were isolated from the marine actinomycete isolate B7617. Compounds 1a and 1b are tetraline derivatives related to granaticin [2] and particularly to MM44785 [3], nanaomycin E [4] and kalafungin [5], which are based on the same hydroxy-tetrahydropyrane system. Luisol B (2) [2] and the fungal metabolite arthrinone [6] are the only natural products possessing an epoxynaphtho[2,3c]furan skeleton.
Results and DiscussionThe marine actinomycete B7617 isolated from the sediment of a littoral site near Punta Arenas, Tierra del Fuego (Chile), was found to be closely related with Streptomyces rectiviolaceus. The strain was cultivated in M 2 medium with 50 % seawater and worked up by ethyl acetate and solid phase extraction (Fig.
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