Stereochemistry of a Second Riolozane and Other Diterpenoids from Jatropha dioica
Elda M Melchor-Martínez1,2, David A Silva-Mares1, Ernesto Torres-López1
1Facultad de Medicina, Universidad Autónoma de Nuevo León , Avenida Madero y Aguirre Pequeño, Col. Mitras Centro s/n, Monterrey, N.L., C.P. 64460, México.
Abstract:
The dichloromethane extract of the roots of Jatropha dioica afforded riolozatrione (1) and a C-6 epimer of riolozatrione, 6-epi-riolozatrione (2), as a new structure and only the second reported riolozane diterpenoid. The two known diterpenoids jatrophatrione (3) and citlalitrione (4) were also isolated and characterized. Both epimers 1 and 2 are genuine plant constituents, with 2 likely being the biosynthesis precursor of 1 due to the tendency for the quantitative transformation of 2 into 1 under base catalysis. The structural characterization and distinction of the stereoisomers utilized 1H iterative full-spin analysis, yielding complete J-correlation maps that were represented as quantum interaction and linkage tables. The absolute configuration of compounds 1-4 was established by means of vibrational circular dichroism and via X-ray diffraction analysis for 1, 2, and 4. Additionally, the cytotoxic and antiherpetic in vitro activities of the isolates were evaluated.
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