Transformation of grayanotoxin III to 10-epi-grayanotoxin III. Its X-ray crystallographic analysis and acute toxicity in mice.
Grayanotoxin (GTX) III, a tetracyclic diterpenoid, is the main toxic component obtained from the leaves of Leucothoe grayana MAX. In this paper, we report the correlation between toxicity and C10 stereostructure of GTX-III. 10-epi-GTX-III was derived from GTX-III in four steps. Oxidation of the GTX-II-3,6,14,16-tetraacetate with formic acid/hydrogen peroxide in chloroform gave 10,20-epoxy derivation in high yield. Reduction of the 10,20-epoxyacetate with LiAlH4 in tetrahydrofuran gave the two products, 10-epi-GTX-III and 10,20-epoxy-GTX-II. The absolute structure of the 10-epi-GTX-III was deduced from the results of X-ray crystallographic analysis. Dosage level of acute toxicity of 10-epi-GTX-III in mice was estimated at about half of natural GTX-III.
Terai
T
T
Department of Applied Chemistry, Osaka Institute of Technology, Osaka, Japan.
Sato
M
M
Narama
I
I
Matuura
T
T
Katakawa
J
J
Tetsumi
M
M
D000818:Animals; D018360:Crystallography, X-Ray; D004224:Diterpenes / Q000737:chemistry* / Q000633:toxicity; D051379:Mice; D008813:Mice, Inbred ICR; D008968:Molecular Conformation; D010947:Plants, Toxic / Q000737:chemistry*; D014118:Toxins, Biological / Q000737:chemistry* / Q000633:toxicity
D004224:Diterpenes; D014118:Toxins, Biological; C020751:grayanotoxin III