Vibrational Circular Dichroism of Africanane and Lippifoliane Sesquiterpenes from Lippia integrifolia

• Published in: Journal of natural products (Washington, D.C.) Vol. 71; no. 6; pp. 967 - 971
• Main Authors: Cerda-García-Rojas, Carlos M, Catalán, César A. N, Muro, Ana C, Joseph-Nathan, Pedro
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society and American Society of Pharmacognosy 01.06.2008; Glendale, AZ American Society of Pharmacognosy; American Chemical Society
• Subjects: africanane sesquiterpenes; Biological and medical sciences; Circular Dichroism; circular dichroism spectroscopy; General pharmacology; Lippia; Lippia - chemistry; Lippia integrifolia; lippifoliane sesquiterpenes; Medical sciences; medicinal plants; Models, Molecular; Molecular Conformation; Molecular Structure; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; phytochemicals; Plants, Medicinal - chemistry; Sesquiterpenes - chemistry; Sesquiterpenes - isolation & purification; sesquiterpenoids; Stereoisomerism; Terpenoid; Pharmacognosy; Theoretical study; Tricyclic compound; Modeling; Vibrational circular dichroism; Medicinal plant; Folk medicine; Verbenaceae; Dicotyledones; Sesquiterpenes; Circular dichroism spectrometry; Angiospermae; Absolute configuration; Molecular model; Plant origin; Density functional method; Spermatophyta; Enone; Structural analysis
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/np8000927

The agreement between theoretical and experimental vibrational circular dichroism curves of (4R,9R,10R)-(+)-african-1(5)-ene-2,6-dione (1) and (4R,9S,10R)-lippifoli-1(6)-en-5-one (2), isolated from the widely used plant Lippia integrifolia, allowed the determination of the conformation and absolute configuration of 1 and confirmed both structural features for 2. Molecular modeling of 1 and 2 was carried out by means of a systematic and a Monte Carlo search protocol followed by geometry optimization employing density functional theory calculations with the B3LYP/6-31G(d), B3LYP/DGDZVP, and/or B3PW91/DGDZVP2 functionals/basis sets. Validation of the minimum energy conformations for both tricyclic substances was achieved by comparison of the experimental and theoretical vicinal 1H−1H NMR coupling constants obtained by DFT-GIAO calculations.