Cycloviracin B2

Kibdelosporangium albatum No. R761-7 (ATCC 55061) produced new antiviral antibiotics, cycloviracins B1 and B2. They show weak activity against Gram-positive bacteria and potent antiviral activity against herpes simplex virus type 1. Unique acylsaccharide structures were established for cycloviracins B1 and B2 by degradation and spectroscopic analysis.

A new species of the genus Kibdelosporangium is described. This soil organism forms long straight spore chains and numerous sporangium-like structures on the aerial mycelium. The new species has type IV cell walls and pattern A whole-cell sugars (meso-diaminopimelic acid, arabinose, and galactose are present), type PII phospholipids, MK-9(H4) as the major menaquinone, and no mycolic acids. On the basis of morphology and chemotaxonomy, the single isolate is assigned to the genus Kibdelosporangium. The isolate differs from two previously described species of the genus in fatty acid composition, the absence of melanin formation, and many physiological and biochemical characteristics and is identified as a new species. Accordingly, the name Kibdelosporangium albatum sp. nov. is proposed for this isolate. The type strain is R761-7 (= ATCC 55061).

The structures of novel antiviral antibiotics, cycloviracins B1 and B2 have been determined by means of chemical and spectroscopic methods including 2D NMR correlation spectroscopy. The antibiotics are unique macrocyclic diesters consisting of two D-glucoses, three 2-O-methyl-D-glucoses and two (C24 and C26) hydroxy fatty acids.