{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:27:23Z","timestamp":1760243243675,"version":"build-2065373602"},"reference-count":18,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2014,4,15]],"date-time":"2014-04-15T00:00:00Z","timestamp":1397520000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>(\u2012)-Encecanescin (1) has been isolated from the leaves of Eupatorium aschembornianum. Two conformers are present in the crystal structure as a result of molecular disorder. The structure of 1 was established by 1H- and 13C-NMR spectroscopy in CDCl3 solution using 2D NMR techniques (gHSQC, gHMBC and NOESY). A Monte Carlo random search using molecular mechanics followed by the geometry optimization of each minimum energy structure using density functional theory (DFT) calculations at the B3LYP\/6\u201331G* level and a Boltzmann analysis of the total energies generated accurate molecular models describing the conformational behavior of 1. The three most stable conformers 2\u20134 of compound 1 were reoptimized at the B3LYP\/6-311++G(d,p) level of theory using CHCl3 as a solvent. Correlations between the experimental 1H- and 13C-NMR chemical shifts (\u03b4exp) have been found, and the GIAO\/B3LYP\/6-311++G(d,p) calculated magnetic isotropic shielding tensors (\u03c3calc) for conformers 2 and 3, \u03b4exp = a + b \u03c3calc, are reported. A good linear relationship between the experimental and calculated NMR data has been obtained for protons and carbon atoms.<\/jats:p>","DOI":"10.3390\/molecules19044695","type":"journal-article","created":{"date-parts":[[2014,4,15]],"date-time":"2014-04-15T13:23:16Z","timestamp":1397568196000},"page":"4695-4707","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Molecular Disorder in (\u2012)-Encecanescin"],"prefix":"10.3390","volume":"19","author":[{"given":"Benito","family":"Reyes-Trejo","sequence":"first","affiliation":[{"name":"Laboratorio de Productos Naturales, \u00c1rea de Qu\u00edmica, Departamento de Preparatoria Agr\u00edcola  AP 74 Oficina de Correos Chapingo, Universidad Aut\u00f3noma Chapingo, Km. 38.5 Carretera M\u00e9xico-Texcoco, Texcoco 56230, Estado de M\u00e9xico, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Diana","family":"Guerra-Ram\u00edrez","sequence":"additional","affiliation":[{"name":"Laboratorio de Productos Naturales, \u00c1rea de Qu\u00edmica, Departamento de Preparatoria Agr\u00edcola  AP 74 Oficina de Correos Chapingo, Universidad Aut\u00f3noma Chapingo, Km. 38.5 Carretera M\u00e9xico-Texcoco, Texcoco 56230, Estado de M\u00e9xico, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Holber","family":"Zuleta-Prada","sequence":"additional","affiliation":[{"name":"Laboratorio de Productos Naturales, \u00c1rea de Qu\u00edmica, Departamento de Preparatoria Agr\u00edcola  AP 74 Oficina de Correos Chapingo, Universidad Aut\u00f3noma Chapingo, Km. 38.5 Carretera M\u00e9xico-Texcoco, Texcoco 56230, Estado de M\u00e9xico, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rosa","family":"Santill\u00e1n","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica, CINVESTAV-IPN, Apdo. Postal 14-740, M\u00e9xico D.F. 07000, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mar\u00eda","family":"S\u00e1nchez-Mendoza","sequence":"additional","affiliation":[{"name":"Escuela Superior de Medicina, Instituto Polit\u00e9cnico Nacional, Plan de San Luis y D\u00edaz Mir\u00f3n, Colonia Santo Tom\u00e1s, Delegaci\u00f3n Miguel Hidalgo, M\u00e9xico D.F. 11340, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jes\u00fas","family":"Arrieta","sequence":"additional","affiliation":[{"name":"Escuela Superior de Medicina, Instituto Polit\u00e9cnico Nacional, Plan de San Luis y D\u00edaz Mir\u00f3n, Colonia Santo Tom\u00e1s, Delegaci\u00f3n Miguel Hidalgo, M\u00e9xico D.F. 11340, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lino","family":"Reyes","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Qu\u00edmica, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Ciudad Universitaria, Delegaci\u00f3n Coyoac\u00e1n D.F. 04510, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2014,4,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"542","DOI":"10.1126\/science.986685","article-title":"Discovery of insect anti-juvenile hormones in plants. Plants yield a potential fourth-generation insecticide","volume":"193","author":"Bowers","year":"1976","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1086","DOI":"10.1021\/jm010999g","article-title":"6-Sulfonylchromenes as highly potent KATP-channel openers","volume":"45","author":"Salamon","year":"2002","journal-title":"J. Med. Chem."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1902","DOI":"10.1016\/0031-9422(88)80478-3","article-title":"Chromenes from ageratina arsenii and revised structures of two epimeric chromene dimers","volume":"27","author":"Fang","year":"1988","journal-title":"Phytochemistry"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1016\/0031-9422(83)83045-3","article-title":"Dimeric chromenes and mixed dimers of a chromene with euparin from encelia canescens","volume":"22","author":"Bohlmann","year":"1983","journal-title":"Phytochemistry"},{"key":"ref_5","first-page":"1563","article-title":"Structure of (\u2212\/+)-encecanescin","volume":"C46","author":"Abboud","year":"1990","journal-title":"Acta Crystallogr."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.fitote.2009.07.009","article-title":"Bioassay-guided isolation of an anti-ulcer benzochromene from Eupatorium aschembornianum: Role of nitric oxide, prostaglandins and sulfhydryls","volume":"81","author":"Arrieta","year":"2010","journal-title":"Fitoterapia"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1107\/S0108767307043930","article-title":"A short history of SHELX","volume":"A64","author":"Sheldrick","year":"2008","journal-title":"Acta Crystallogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1002\/(SICI)1097-461X(2000)77:3<661::AID-QUA7>3.0.CO;2-J","article-title":"Scaling factors for the prediction of vibrational spectra. I. Benzene molecule","volume":"77","year":"2000","journal-title":"Int. J. Quantum Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1016\/S1386-1425(01)00509-1","article-title":"Quantum chemical predictions of the vibrational spectra of polyatomic molecules. The uracil molecule and two derivatives","volume":"58","author":"Rastogi","year":"2002","journal-title":"Spectrochim. Acta A"},{"key":"ref_10","unstructured":"Simpson, J.H. (2008). Organic Structure Determination Using 2-D NMR Spectroscopy, Elsevier Academic Press."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1002\/mrc.856","article-title":"GIAO\/DFT calculated chemical shifts of tautomeric species. 2-Phenacylpyridines and (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines","volume":"39","author":"Kolehmainen","year":"2001","journal-title":"Magn. Reson. Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4379","DOI":"10.1021\/ja00194a035","article-title":"An internal-coordinate Monte Carlo method for searching conformational space","volume":"111","author":"Chang","year":"1989","journal-title":"J. Am. Chem. Soc."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5648","DOI":"10.1063\/1.464913","article-title":"Density-functional thermochemistry. III. The role of exact exchange","volume":"98","author":"Becke","year":"1993","journal-title":"J. Chem. Phys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"8554","DOI":"10.1063\/1.475007","article-title":"Density-functional thermochemistry. V. Systematic optimization of exchange correlation functionals","volume":"107","author":"Becke","year":"1997","journal-title":"J. Chem. Phys."},{"key":"ref_15","unstructured":"Hehre, W.J., Random, L., Schleyer, P.V.R., and Pople, J.A. (1986). Ab Initio Molecular Orbital Theory, Wiley."},{"key":"ref_16","first-page":"16378","article-title":"Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions","volume":"13","author":"Marenich","year":"2009","journal-title":"J. Phys. Chem. B"},{"key":"ref_17","unstructured":"Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., and Petersson, G.A. (Gaussian 09, 2009). Gaussian 09, Revision A.1."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"8251","DOI":"10.1021\/ja00179a005","article-title":"Efficient implementation of the gauge-independent atomic orbital method for NMR chemical shift calculations","volume":"112","author":"Wolinski","year":"1990","journal-title":"J. Am. Chem. Soc."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/19\/4\/4695\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:10:19Z","timestamp":1760217019000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/19\/4\/4695"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,4,15]]},"references-count":18,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2014,4]]}},"alternative-id":["molecules19044695"],"URL":"https:\/\/doi.org\/10.3390\/molecules19044695","relation":{},"ISSN":["1420-3049"],"issn-type":[{"type":"electronic","value":"1420-3049"}],"subject":[],"published":{"date-parts":[[2014,4,15]]}}}