Antibiotic produced by Streptomyces antibioticus ETH 28829: Hütter et al., Helv. Chim. Acta 50, 1533 (1967). The first known natural product in which boron has been found. It is a complex of boric acid with a tetradentate organic complexing agent and yields d-valine, boric acid and a polyhydroxy macrolide-type compound upon hydrolysis. Structure: Dunitz et al., ibid. 54, 1709 (1971). Mechanism of action studies: Pache, Zhner, Arch. Mikrobiol. 67, 156 (1969). Activity as a coccidiostat: Miller, Burg, US 3864479 (1975 to Merck & Co.). Biosynthesis: T. S. S. Chen et al., J. Org. Chem. 46, 2661 (1981). Partial synthesis: M. A. Avery et al., Tetrahedron Lett. 22, 3123 (1981). Synthesis of C-3′ to C-17′: S. Hanessian et al., J. Am. Chem. Soc. 103, 6243 (1981); of C-3 to C-17: eidem, Can. J. Chem. 61, 634 (1983); of C-1 to C-17: J. D. White et al., J. Am. Chem. Soc. 105, 6517 (1983). Total synthesis: eidem, ibid. 111, 790 (1989). Review: Pache in Antibiotics vol. 3, J. W. Corcoran, F. E. Hahn, Eds. (Springer-Verlag, New York, 1975) pp 585-587.