Absolute configuration of (13R)- and (13S)-labdane diterpenes coexisting in Ageratina jocotepecana.
Chemical investigation of the hexanes extracts of Ageratina jocotepecana afforded (-)-(5S,9S,10S,13S)-labd-7-en-15-oic acid (1), methyl (-)-(5S,9S,10S,13S)-labd-7-en-15-oate (2), (+)-(5S,8R,9R,10S,13R)-8-hydroxylabdan-15-oic acid (3), and (-)-(5S,9S,10S,13Z)-labda-7,13-dien-15-oic acid (5). The coexistence of (13R)- and (13S)-labdanes in this member of the Asteraceae family was demonstrated by vibration circular dichroism measurements of ester 2 and methyl (+)-(5S,8R,9R,10S,13R)-8-hydroxylabdan-15-oate (4) in comparison to the DFT B3LYP/DGDZVP-calculated spectra. In addition, transformation of 1 and 3 with HClO4 in MeOH yielded epimeric methyl (+)-(5S,10S,13S)-labd-8-en-15-oate (6) and methyl (+)-(5S,10S,13R)-labd-8-en-15-oate (7), respectively, confirming the presence of C-13 epimers in this plant. Diterpene 1 showed remarkable antibacterial activity against Bacillus subtilis (MIC 0.15 mg/mL) and Staphylococcus aureus (MIC 0.78 mg/mL), while diterpene 3 exhibited moderate activities against the same organisms.
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo , Ciudad Universitaria, Morelia, Michoacán 58030, Mexico.
Edgar
E
García-Sánchez
César B
CB
Ramírez-López
Armando
A
Talavera-Alemán
Alejandra
A
León-Hernández
Rosa E
RE
Martínez-Muñoz
Mauro M
MM
Martínez-Pacheco
Mario A
MA
Gómez-Hurtado
Carlos M
CM
Cerda-García-Rojas
Pedro
P
Joseph-Nathan
Rosa E
RE
del Río
D036603:Ageratina / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects; D002942:Circular Dichroism; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D008800:Mexico; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D015394:Molecular Structure; D013211:Staphylococcus aureus / Q000187:drug effects; D013237:Stereoisomerism
D000900:Anti-Bacterial Agents; D004224:Diterpenes