2-alkyl-3,4-dihydroxy-5-hydroxymethylpyridine derivatives: New natural vitamin B-6 analogues from a terrestrial Streptomyces sp.

The ethyl acetate extract of the strain Streptomyces sp. GW23/1540 has yielded four new 2-alkyl-5-(hydroxymethyl)pyridine-3,4-diols, 5-hydroxymethyl-2-isopropyl-pyridine-3,4-diol (1a), 5-hydroxymethyl-2-propyl-pyridine-3,4-diol (1b), 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c), and 5-hydroxymethyl-2-isobutyl-pyridine-3,4-diol (1d). Similarly, the strain Streptomyces sp. GW63/1571 afforded 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c) and another new natural product, (3aS, 7aR)-3a-hydroxy-3a,4,7,7a-tetrahydro-1-benzofuran-2(3H)-on e (3), together with anthranilic acid, anthranilamide, and phenylacetamide. The new natural products were inactive against three micro algae, the fungus Mucor miehei, the yeast Candida albicans, and the bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Streptomyces viridochromogenes.