NMR spectral assignments of isoprenylated flavanones from Sophora tonkinensis

The phytochemical investigation of extracts from the roots of Sophora tonkinensis yielded three new isoprenylated flavanones, the tonkinochromanes F (2), G (3), and H (5), along with four known compounds. Structural elucidation of the compounds were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences ((1)H-(1)H COSY, HSQC, HMBC, and ROESY).     

Two New Isoprenoid Flavonoids from Sophora flavescens with Antioxidant and Cytotoxic Activities

Sophora flavescens is a regularly used traditional Chinese medicine. In an attempt to discover adequate active agents, the isoprenoid flavonoids from S. flavescens were further investigated. In this work, two new compounds (1–2, kurarinol A-B) together with 26 known ones (3–28) were isolated and elucidated on the basis of extensive NMR, UV and MS analyses. Furthermore, the antioxidant activity of all constituents was assessed through ABTS, PTIO and DPPH methodologies and also were evaluated for cytotoxic activity by three tumor cell lines (HepG2, A549 and MCF7) and one human normal cell line (LO2 cells). As a result, a multitude of components revealed significant inhibitory activity. In particular, compound 1–2 (kurarinol A-B), two new flavanonols derivatives, exhibited the most potent ABTS inhibitory activity with IC₅₀ of 1.21 µg/mL and 1.81 µg/mL, respectively. Meanwhile, the new compound 1 demonstrated remarkable cytotoxicity against three cancer cells lines with IC₅₀ values ranging from 7.50–10.55 μM but showed little effect on the normal cell. The two new isoprenoid flavonoids could be promising antioxidant and anti-tumor nature agents.     

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.     

NMR assignments of unusual flavonoids from the kino of Eucalyptus citriodora

Two unusual flavonoids, 3,5,4',5'-tetrahydroxy-7-methoxy-6-[1-(p-hydroxy-phenyl)ethyl]flavanone (1) and 3,5,7,4',5'-pentahydroxy-6-[1-(p-hydroxy-phenyl)ethyl] flavanone (2), were isolated from the kino of Eucalyptus citriodora. Structural elucidation of the new compounds were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences ((1)H, (1)H-COSY, HMQC, HMBC).     

Two New Antibacterial Flavanones from Sophoraflavescens

The dry root of Sophora flavescens, which is a well-known Chinese herbal medicine, has been used for the treatment of diarrhea, gastrointestinal hemorrhage and eczema1. Here we report the structure elucidation of two new flavanones isolated from this plan…     

Structural determination of three new eudesmanolides from Inula helenium

Ten sesquiterpenens were isolated from Inula helenium. Among them, three eudesmanolides: 15-hydroxy-11betaH-eudesm-4-en-8beta,12-olide (1), 3alpha-hydroxy-11betaH-eudesm-5-en-8beta,12-olide (2) and 2beta, 11alpha-dihydroxy-eudesm-5-en-8beta,12-olide (3) are new compounds. Their chemical structures were determined by spectral methods including 2D NMR.     

Phenolic Metabolites from the Stems and Leaves of Sophora flavescens

Two new compounds, (?)‐(6aR,11aR)‐4‐methoxy‐8,9‐(methylenedioxy)pterocarpan 3‐O‐β‐D ‐glucopyranoside ( 1 ) and 5‐hydroxy‐7‐methoxyisoflavone 4′‐O‐β‐D ‐xylopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 2 ), were isolated, together with 30 known compounds from the stems and leaves of Sophora flavescens Aition . Their structures were elucidated by extensive spectroscopic analysis, including HR‐ESI‐MS data. A preliminary comparison of phenolic metabolite profiles, based on the qualitative HPLC analysis, indicated that the composition of the roots and the aerial parts were significantly different.     

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.     

Structural determination of two new steroidal saponins from Smilax china

Two new steroidal saponins (1 and 2) were isolated from the BuOH fraction of the 70% EtOH extract of the tubes of Smilax china, together with four known analogues, 3–6. The structures of the new compounds were elucidated by means of chemical evidence and spectroscopic analyses, including HR‐MS, IR, ¹H‐ and ¹³C‐NMR, and 2D experiments (¹H–¹H COSY, HSQC and HMBC). Copyright © 2009 John Wiley & Sons, Ltd.     

Complete NMR data of methoxylated cis- and trans-stilbenes as well as 1,2-diphenylethanes

Resveratrol is a polyphenol isolated from many natural sources including grapes, mulberries, eucalyptus, spruce, lilies, and peanuts. The hydroxyl groups in polyphenols can be substituted with various functional groups, allowing production of multiple derivatives. NMR spectroscopy is used to identify new derivatives. Since the complete NMR data of the known derivatives can be useful for identification of the newly isolated derivatives, here, we report the synthesis of 14 methoxylated stilbenes and four 1,2-diphenylethanes and their NMR data.     

Secondary metabolites from Paronychia argentea

Two new oleanane saponins (1 and 2) and one new flavonol glycoside (3) together with six known flavonoids, were isolated from the aerial parts of Paronychia argentea. Their structures were elucidated by 1D and 2D NMR experiments including 1D-TOCSY, DQF-COSY, NOESY, HSQC, and HMBC spectroscopy, as well as ESI-MS analysis.     

Unequivocal assignments of flavonoids from Tephrosia sp. (Fabaceae)

¹H and ¹³C NMR chemical shifts of praecansone B, pongaflavone and dehydrorotenone isolated from Tephrosia egregia Sandw and obovatin from T. toxicaria Pers. were unambiguously assigned by 1D and 2D NMR experiments including ¹H, ¹H COSY, gHMQC and gHMBC, allowing the correction of literature assignments.Copyright © 2009 John Wiley & Sons, Ltd.     

Structural and spectral assignment of three forskolin-like diterpenoids isolated from Plectranthus ornatus

Three labdane diterpenoids were isolated from an acetone extract of Plectranthus ornatus. Their structures, closely related to that of forskolin, were determined by NMR studies. Unambiguous and complete assignments of the 1H and 13C NMR chemical shifts for these substances are presented. The assignments are based on 2D shift-correlated [1H, 1H-COSY, 1H, 13C-gHSQC-1J (C,H), 1H, 13C-gHMBC-(n)J (C,H) (n = 2 and 3)] and NOE experiments.     

Structural determination of quercusides A and B,new flavonoid glucosides from Quercus incana,by 1D and 2D NMR spectroscopy

Quercusides A and B, new flavonoid glucosides have been isolated from the chloroform soluble fractions of Quercus incana. Their structures were assigned from ¹H and ¹³C nuclear magnetic resonance spectra, distortionless enhancement by polarization transfer (DEPT) and by correlation spectroscopy, heteronuclear multiple quantum correlation (HMQC) and heteronuclear multiple bond correlation (HMBC) experiments. Lupeol, β‐sitosterol and ursolic acid have also been reported from this species. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural determination of two new triterpenoids biotransformed from glycyrrhetinic acid by Mucor polymorphosporus

Five hydroxylated derivatives of glycyrrhetinic acid by Mucor polymorphosporus were isolated. Among them, 6β, 7β‐dihydroxyglycyrrhentic acid (2) and 27‐hydroxyglycyrrhentic acid (3) are new compounds. Their chemical structures were identified by spectral methods including 2D‐NMR. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural determination of prunusins A and B,new C‐alkylated flavonoids from Prunus domestica,by 1D and 2D NMR spectroscopy

Prunusins A (1) and B (2), the new C‐alkylated flavonoids, have been isolated from the seed kernels of Prunus domestica. Their structures were assigned from ¹H and ¹³C nuclear magnetic resonating spectra, DEPT and by correlation spectroscopy, HMQC and HMBC experiments. 3, 5, 7, 4′‐Tetrahydroxyflavone (3) and 3, 5, 7‐trihydroxy‐8, 4′‐dimethoxyflavone (4) have also been reported from this species. Both compounds (1) and (2) showed significant antifungal activity against pathogenic fungus Trichophyton simmi. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural determination of abutilins A and B,new flavonoids from Abutilon pakistanicum,by 1D and 2D NMR spectroscopy

Two new flavonoids, abutilin A and B, were isolated from the chloroform soluble fraction of Abutilon pakistanicum and their structures assigned from ¹H and ¹³C NMR spectra, DEPT and by 2D COSY, HMQC and HMBC experiments. Ferulic acid (3), (E)‐cinnamic acid (4), 5‐hydroxy‐4′,6,7,8‐tetramethoxyflavone (5), kaempferol (6), luteolin (7) and luteolin 7‐O‐β‐D ‐glucopyranoside (8) have also been reported from this species. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopy

Selaginellins G ( 1 ) and H ( 2 ), two new selaginellin derivatives, were isolated from the whole plant of Selaginella pulvinata. Their structures were elucidated, and complete assignments of the ¹H and ¹³C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, COSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with an IC₅₀ value of 5.3 µg/ml. Copyright © 2010 John Wiley & Sons, Ltd.     

NMR对苯并噁嗪类化合物结构的研究

利用'H、'13CNMR谱及HMBC、HMQC二维谱对10种苯并噁嗪类化合物的结构进行了研究,初步得出了它们的NMR谱特征,分析了化学位移的影响因素。     

Structural and spectral assignments of six anthraquinone derivatives from the mangrove fungus (ZSUH-36)

A new natural product named 6,8,1'-tri-O-methyl averantin (1) has been isolated together with five known anthraquinones 1'-O-methyl averantin (2), 6,8-di-O-methyl averufin (3) averufin (4), versicolorin C (5) and 6,8-di-O-methyl averufanin (6) from a mangrove endophytic fungus ZSUH-36 collected from the South China Sea. NMR techniques including COSY, HMQC, and HMBC were used to elucidate the structures of these compounds. We report the unambiguous assignments of the (1)H and (13)C NMR spectra of the new compound 6,8,1'-tri-O-methyl averantin(1).