1H and 13C NMR assignments of abietane diterpenes from Aegiphila lhotzkyana

An NMR study of one new and several known abietane diterpenes isolated from the roots of Aegiphila lhotzkyana is described. In addition to 1D NMR, several 2D shift‐correlated NMR pulse sequences (¹H–¹H‐COSY, NOESY, HMQC and HMBC) were used to establish all the structures, and unambiguously perform the ¹H and ¹³C chemical shift assignments of the new natural diterpene and three derivatives, the NMR data for which have not been reported previously. Revision of current data assignment for teuvincenone H is also suggested. Copyright © 2003 John Wiley & Sons, Ltd.     

NMR spectroscopy as a tool to investigate the degradation of aromatic compounds by a Pseudomonas putida strain

Pseudomonas putida strain KT2442, harbouring the pWW0 TOL plasmid, was grown with a number of different homologous aromatic acids as carbon sources. Small samples of liquid culture supernatant were collected and directly analysed by 2D NMR spectroscopy. In all cases similar compounds with olefinic signals were observed to accumulate. To elucidate the structures of these compounds, 2D NMR experiments with 500 and 600 MHz spectrometers equipped with a CryoProbe (Bruker BioSpin) were performed on samples obtained from a culture growing on 4‐methylbenzoate and, for ¹³C spectroscopy, on ¹³C‐labelled 4‐methylbenzoate. In all cases a 1,2‐dihydroxycyclohexa‐3,5‐diene‐carboxylate derivative was identified. The use of this technique helped us to identify easily some metabolites that were released into the solution by bacteria and to follow their secretion as a function of time. The high sensitivity of the present approach allowed a clear and rapid acquisition of spectra, notwithstanding the low concentration of the compounds. The benefits of introducing the use of NMR cryoprobes to perform metabolic pathway studies is demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.     

NMR analysis of mono‐ and difructosyllactosucrose synthesized by 1F‐fructosyltransferase purified from roots of asparagus (Asparagus officinalis L.)

Two novel oligosaccharides, mono‐ and difructosyllactosucrose {[O‐β‐D ‐fructofuranosyl‐(2 → 1)]_n‐β‐D ‐fructofuranosyl‐O‐[β‐D ‐galactopyranosyl‐(1 → 4)]‐α‐D ‐glucopyranoside, n = 1 and 2} were synthesized using 1^F‐fructosyltransferase purified form roots of asparagus (Asparagus officinalis L.). Their ¹H and ¹³C NMR spectra were assigned using several NMR techniques. The spectral analysis was started from two anomeric methines of aldose units, galactose and glucose, since they showed separate characteristic signals in their ¹H and ¹³C NMR spectra. After assignments of all the ¹H and ¹³C signals of two units of aldose, they were discriminated as galactose and glucose using proton–proton coupling constants. The HMBC spectrum revealed the galactose residue attached to C‐4 of glucose, fructose residue attached to the C‐1 of glucose, and further fructosyl fructose linkage extended from the glucosyl fructose residues. Copyright © 2002 John Wiley & Sons, Ltd.     

Spectral assignments of new diterpenes from Hyptis martiusii Benth

The structural characterization of two new abietanes and a new spiro-fused tricyclic diterpene isolated from the roots of Hyptis martiusii is described. The first member of a new class of rearranged abietane diterpenoids designated martiusane was characterized by the use of 1D NMR and several 2D shift correlated NMR pulse sequences (1H,1H-COSY, HMQC, HMBC and NOESY). Unambiguous 1H and 13C chemical shift assignments for all compounds are reported.     

Brauhenefloroside E and F; acylated flavonol glycosides from Stocksia brauhica Linn

Two new acylated flavonol glycosides, 3‐O‐{[2‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside and 3‐O‐{2‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside, trivially named as brauhenefloroside E (1) and F (2), respectively, were isolated from the fruits of Stocksia brauhica and their structures were elucidated using spectroscopic methods, including 2D NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Micromelosides A–D,four new coumarins from the stem bark of Micromelum falcatum

Four new coumarins, micromelosides A–D, together with four known coumarins were isolated from the stem bark of Micromelum falcatum. The complete assignments of the ¹H and ¹³C NMR chemical shifts for these new compounds were achieved by means of 1D and 2D NMR techniques, including ¹H‐¹H COSY, HSQC, HMBC and NOE difference. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure elucidation of casbane diterpenes from Croton argyrophyllus

Two novel casbane diterpenes 1-hydroxy-(2E,6Z,12E)-casba-2,6,12-triene-4,5-dione (1) and 6E,12E-casba-1,3,6,12-tetraen-1,4-epoxy-5-one (2) were isolated from the ethanol extract of the stems of Croton argyrophyllus. Structural characterization including the relative stereochemistry of all compounds was established on the basis of spectroscopic methods, mainly 1D and 2D NMR, and HRESIMS.     

Two new acylated flavonoid glycosides from Morina nepalensis var. alba Hand.‐Mazz.

From the whole plant of Morina nepalensis var. alba Hand.‐Mazz., two new acylated flavonoid glycosides ( 1 and 2 ), together with four known flavonoid glycosides ( 3–6 ), were isolated. Their structures were determined to be quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (monepalin A, 1 ), quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranoside (monepalin B, 2 ), quercetin 3‐O‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (rumarin, 3 ), quercetin 3‐O‐β‐D ‐galactopyranoside ( 4 ), quercetin 3‐O‐β‐D ‐glucopyranoside ( 5 ) and apigenin 4^′‐O‐β‐D ‐glucopyranoside ( 6 ). Their structures were determined on the basis of chemical and spectroscopic evidence. Complete assignments of the ¹H and ¹³C NMR spectra of all compounds were achieved from the 2D NMR spectra, including H–H COSY, HMQC, HMBC and 2D HMQC‐TOCSY spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations

NMR spectroscopic studies are undertaken with derivatives of 2‐pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts (¹H, ¹³C, ¹⁵N) and coupling constants (¹H,¹H; ¹³C,¹H; ¹⁵N,¹H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of ¹³C,¹H spin coupling constants is accomplished by 2D (δ,J) long‐range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3‐hydroxy‐2‐pyrazinecarboxylic acid are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Detailed assignments of 1H and 13C NMR spectral data of 14 cyclopentane derivatives

Detailed assignments of ¹H and ¹³C NMR spectral data for 14 cyclopentane derivatives are reported. The assignments are based on 1D ¹H and ¹³C NMR and on 2D shift‐correlated [¹H, ¹³C‐HMQC], J‐resolved and NOEDIF experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

Two new complex triterpenoid saponins from Gledistsia dolavayi Franch.

Two new triterpenoid saponins, gledistside A ( 1 ) and gledistside B ( 2 ), isolated from the fruits of Gledistsia dolavayi Franch., were characterized as the 3,28‐O‐bisdesmoside of echinocystic acid acylated with monoterpene carboxylic acids. On the basis of spectroscopic and chemical evidence, their structures were elucidated as 3‐O‐β‐D ‐xylopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl‐28‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→4)‐[β‐D ‐galactopyranosyl‐(1→2)]‐α‐L ‐rhamnopyranosyl‐(1→2)‐{6‐O‐[2,6‐dimethyl‐6(S)‐hydroxy‐2‐trans‐2,7‐octadienoyl]}‐β‐D ‐glucopyranosylechinocystic acid ( 1 ) and 3‐O‐β‐D ‐xylopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranosyl‐28‐O‐β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐xylopyranosyl‐(1→4)‐[β‐D ‐galactopyranosyl‐(1→2)]‐α‐L ‐rhamnopyranosyl‐(1→2)‐{6‐O‐[2‐hydroxymethyl‐6‐methyl‐6(S)‐hydroxy‐2‐trans‐2,7‐octadienoyl]}‐β‐D ‐glucopyranosylechinocystic acid ( 2 ). The complete ¹H and ¹³C assignments of saponins 1 and 2 were achieved on the basis of 2D NMR spectra including HMQC‐TOCSY, TOCSY, ¹H–¹H COSY, HMBC, ROESY and HMQC spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Quantitative determination of aliphatic hydrocarbon compounds by 2D NMR

Quantitative analysis of complex mixtures by NMR is often hampered by heavily overlapping signals in 1D ¹H or ¹³C spectra. To resolve the overlap problem, we have been looking at the possibilities of using heteronuclear correlated 2D NMR methods for quantification. In this work, we applied 2D INEPT to analyze mixtures of tetradecane and squalane, which represent typical substructures of lube oil fractions. The factors affecting correlation peak volumes, namely the polarization transfer delays within pulse sequence, multiplicity of CH_n group and the magnitude of ¹J_{(C, H)} couplings were taken into account by product operator formalism calculations. The results indicate that if absolute precision in quantification is not essential, the current approach can be used for the quantitative analysis of the molecular composition of complex mixtures when conventional 1D NMR methods fail. Copyright © 2002 John Wiley & Sons, Ltd.     

Structural determination of saponins from Hedysarum polybotrys

Four saponins (1-4) were isolated from the roots of Hedysarum polybotrys Hand.-Mazz. and obtained from Hedysarum (Tourn.) L for the first time. Their structures were identified on the basis of spectroscopic data. MS, 1D and 2D NMR including HMQC, HMBC, 1H-1H COSY and NOESY permitted correct assignments of all 1H and 13C signals of 1 and 2, and the 13C NMR data of 2 were reported for the first time.     

1H and 13C NMR assignments for two new steroids from the coral Chromonephthea sp.

Two new steroids isolated from EtOH extracts of the South China Sea soft coral Chromonephthea sp. were identified. One‐dimensional (1D) and two‐dimensional (2D) NMR experiments including COSY, HSQC, HMBC and NOESY were used for the determination of their structure. Copyright © 2008 John Wiley & Sons, Ltd.     

Structure elucidation and total assignment of 1H and 13C NMR data for a new bisdesmoside saponin from Cordia piauhiensis

Extensive 1D (¹H NMR, HBBD‐¹³C NMR, DEPT‐¹³C NMR) and 2D (COSY, TOCSY, NOESY, HMQC and HMBC) NMR analysis was used to characterize the structure of a new bisdesmoside saponin isolated from the methanol extract of stems of Cordia piauhiensis Fresen as 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl]ursolic acid 28‐O‐[β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl] ester. Copyright © 2003 John Wiley & Sons, Ltd.     

Four new prenylated flavonoids from the roots of Cudrania tricuspidata

Four new prenylated flavonoids, cudraflavanones E‐F (1–2) and cudraflavones F‐G (6–7), together with eight known compounds were isolated from the roots of Cudrania tricuspidata. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses, including 1D and 2D NMR, HRESIMS and CD. Copyright © 2013 John Wiley & Sons, Ltd.     

Four new ursane‐type saponins from Morina nepalensis var. alba

Four new ursane‐type saponins, monepalosides C–F, together with a known saponin, mazusaponin II, were isolated from Morina nepalensis var. alba Hand.‐Mazz. Their structures were determined to be 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐L ‐rhamnopyranosyl‐(1 → 2)]‐α‐L ‐arabinopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside C, 1 ), 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[alpha;‐L ‐rhamnopyranosyl‐(1 → 2)]‐β‐D ‐xylopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside D, 2 ), 3‐O‐α‐L ‐arabinopyranosyl‐(1 → 3)‐&[beta;‐D ‐glucopyranosy‐(1 → 2)]‐α‐L ‐arabinopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranoside (monepaloside E, 3 ) and 3‐O‐β‐D ‐xylopyranosylpomolic acid 28‐O‐β‐D ‐glucopyranoside (monepaloside F, 4 ) on the basis of chemical and spectroscopic evidence. 2D NMR techniques, including ¹H–¹H COSY, HMQC, 2D HMQC‐TOCSY, HMBC and ROESY, and selective excitation experiments, including SELTOCSY and SELNOESY, were utilized in the structure elucidation and complete assignments of ¹H and ¹³C NMR spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Complete assignments of 1H and 13C NMR data of three new dihydrophenanthrofurans from Pleione yunnanensis

Three new dihydrophenanthrofurans, pleionesins A–C (1–3), together with two known dihydrophenanthrenes (4–5) were isolated from the tubers of Pleione yunnanensis (Rolfe). The complete ¹H and ¹³C NMR spectra assignments of these compounds were carried out using 1D and 2D NMR experiments (¹H, ¹³C, selective 1D NOE, HSQC and HMBC). Copyright © 2010 John Wiley & Sons, Ltd.     

Complete assignment of 1H and 13C NMR data of pravastatin derivatives

The complete ¹H and ¹³C NMR data of 27 pravastatin derivatives are presented. Assignment was achieved by use of 1D and 2D NMR experiments (selective 1D NOE, COSY, NOESY, HSQC, HMBC). Copyright © 2008 John Wiley & Sons, Ltd.