Solvent effects in the structure dereplication of caffeoyl quinic acids

Abstract

The choice of solvent is an important but often neglected cofactor in the structure determination and compound dereplication of caffeoyl quinic acid derivatives (CQAD). Both unforeseeable shift effects and substantial influences on molecular conformation caused by the various solvents lead to marked changes in the shifts and the coupling pattern. Therefore, the assignment of the relative stereochemistry of the cyclohexane ring substituents is complicated and can be misleading, especially when relying on literature data. Both 1H and 13C shift values were determined for prominent CQAD. Furthermore, the proton spin systems were fully analyzed in order to establish changes in molecular geometry that are due to solvent effects. Copyright © 1999 John Wiley & Sons, Ltd.

Caffeic Acid Derivatives from Eupatorium perfoliatum L.

“…The two main constituents of the ethyl acetate fraction, C2 and C6 , were identified as 5-O-caffeoyl-quinic acid (chlorogenic acid) and 3,5-O-dicaffeoylquinic acid by 1 H-NMR spectroscopy (data not shown) and comparison with recorded data [25, 26]. Peak C1 proved to be a structural analogue of chlorogenic acid, which by comparison with known spectra was identified as 3-O-caffeoylquinic acid (neochlorogenic acid) [25].…”

Highly glycosylated and acylated flavonols isolated from kale (Brassica oleracea var. sabellica) — Structure–antioxidant activity relationship

“…Structure 1 has been already described by means of NMR (Pauli, Kuczkowiak, & Nahrstedt, 1999), as well as compounds 5 and 7 and compounds 4 and 6 have been identified from cabbage (Nielsen et al, 1993(Nielsen et al, , 1998. Compound 2 was previously identified by Harbaum et al (2007) from pak choi.…”

5-O-Caffeoylquinic acid: A spectroscopic study and biological screening for antimicrobial activity

“…Later, Pauli, Kuczkowiak, and Nahrstedt (1999) analyzed the 1 H and 13 C NMR spectra of 5-CQA and 3-CQA in different solvents (CD 3 OD, acetone, pyridine, D 2 O, DMSO) and provided information on the conformation of molecules in solutions on the basis of the analysis of the proton spin system. Full assignment of the 1 H NMR spectra was not done, though.…”

“…Although 1 H and 13 C NMR spectra of 5-CQA were rigorously analyzed (Pauli, 254 Poetsch, & Nahrstedt, 1998;Pauli, Kuczkowiak, & Nahrstedt, 1999), some mistakes 255 concerning the assignment of the 13 C signals have been made in the literature. The authors 256 precisely assigned resonances of the spectra recorded in CD 3 OD, but spectra registered in 257 other solvents were probably assigned by analogy.…”