Structure of the antibiotic griseoviridin

Abstract

The three-dimensional structure of griseoviridin methanolate, C22H2707N&CH3OH, was determined by x-ray crystallography. The substance crystallizes in the monoclinic space group 6' 21 and the unit cell dimensions are a = 10.559 ( I ) , b = 13.066 (3), and c = 9.433 (1) b;, @ = 99.00 (1)'. Intensity data were collected with a diffractometer and the structure was solved by a combination of Patterson superposition and tangent refinement techniques. Contrary to a previous proposal the structure contains an oxazole ring. The relative contributions of three canonical structures are assessed on the basis of bond lengths in that ring. It is estimated that the uncharged species contributes 80% to the structure while delocalizations of oxygen electrons to the ring nitrogen and to a conjugated amide oxygen account for an additional 10% each. The molecular structure is quite rigid and most atoms lie in one of four major planes. There are several short intramolecular contacts which give rise to some unusual bond angles and torsion angles

Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

“…Recently, Dat et al 40 isolated the dimeric lactones ardimerin (74) and ardimerin digallate (75) from the extracts of Ardisia japonica, a plant used in Oriental traditional medicine as antitussive and diuretic, as well as to stop uterine bleeding. The diolide 75…”

“…75,76 This alkaloid contains, among other functionalities, an unsaturated ninemembered thioether-lactone subunit.…”

Chemistry and Biology of the Streptogramin A Antibiotics

“…Eventually, the structure of griseoviridin was reassigned as 5 on the basis of X-ray diffraction analysis [13], although one of these references incorrectly assigned the relative stereochemistry for the C18-C20 diol as trans. The correct stereochemistry of this group is cis-as is indicated in structure 5 [13]. Since the configuration at C5 was known from degradation studies, this allowed for the complete stereochemical assignment.…”

“…Kingston's group has investigated the biosynthetic origin of virginiamycin M1 (1) based on incorporation of 13 C and 14 C labeled precursors into the antibiotic produced by Streptomyces virginiae strain PDT 30 ( Fig. 3) [15].…”

“…The antibiotic produced in the presence of [1-13 C] acetate exhibited enrichment at C5, C7, C12, C14, C16, and C18, while 1 produced in the presence of [2-13 C] acetate exhibited enrichment at C4, C6, C11, C13, C15, C17, as well as at C33. Notably, growth of the microorganism fed with [1,[2][3][4][5][6][7][8][9][10][11][12][13] C2] acetate afforded virginiamycin M1 which exhibited 13 C- 13 C couplings between C4 and C5, C6 and C7, C11 and C12, C13 and C14, C15 and C16, and C17 and C18. Notably, there was no coupling between C12 and C33.…”