Complete assignments of 1H and 13C NMR data for seven arylnaphthalide lignans from Justicia procumbens

Three new arylnaphthalide lignans named 6'-hydroxy justicidin A (1), 6'-hydroxy justicidin B (2) and 6'-hydroxy justicidin C (3) have been isolated from the whole plant of Justicia procumbens, together with four known ones, neojusticin A (4), chinensinaphthol methyl ester (5), isodiphyllin (6) and taiwanin C (7). The complete assignments of 1H and 13C NMR chemical shifts for the new lignans and the 13C NMR chemical shifts for the known lignans were obtained for the first time by means of 2D NMR techniques, including HSQC and HMBC.     

1H and 13C NMR assignments for two lignans from the heartwood of Streblus asper

In our ongoing investigation of the bioactive constituents from plants, two new lignans, magnolignan A-2-O-beta-D-glucopyranoside and strebluslignanol were isolated from heartwood of Streblus asper, along with three known lignans, magnolignan A, magnolol, and magnaldehyde D. 1D and 2D NMR experiments, including COSY, HMQC, and HMBC, and other spectroscopic methods, including UV, IR, and MS were used for the determination of the structures and NMR assignments. Primary bioassays showed that magnolignan A-2-O-beta-D-glucopyranoside and strebluslignanol have medium cytotoxic activity against HEp-2 and HepG2 cells, with IC(50) of 13.3 microM, 46.4 microM and 10.1 microM, 21.7 microM, respectively.     

Complete assignments of 1H and 13C NMR spectral data for benzylidenebenzyl butyrolactone lignans

The structures of three benzylidenebenzyl butyrolactone lignans (gossypifan, carthamogenin, and savinin) have been established on basis of 1H NMR and 13C NMR spectroscopic data. The 1H NMR and 13C NMR spectra of these lignans have been fully assigned by the use of techniques such as gCOSY, non-edited gHSQC, and gHMBC. Complete assignment and most homonuclear hydrogen coupling constant measurements were performed, also providing enough data for the determination of the relative stereochemistry.     

Complete assignments of 1H and 13C NMR data for new dibenzocyclooctadiene lignans from Kadsura oblongifolia

Two new dibenzocyclooctadiene lignans, named kadoblongifolins A (1) and B (2), and one new natural product dibenzocyclooctadiene lignan, named kadoblongifolin C (3), were isolated from the stems of Kadsura oblongifolia (K. oblongifolia), together with five known ones, schizanrin F (4), propinquanin C (5), schisantherin G (6), heteroclitin Q (7), kadsurarin (8). The structures of these new lignans were elucidated by a combination of high‐resolution electron ionization mass spectrometry (HR‐EI‐MS), ¹H NMR, ¹³C NMR, HMQC, HMBC, and NOESY spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

The anti-HBsAg (human type B hepatitis, surface antigen) and anti-HBeAg (human type B hepatitis, e antigen) C18 dibenzocyclooctadiene lignans from Kadsura matsudai and Schizandra arisanensis

The C(18) dibenzocyclooctadiene lignans including three novel schizanrin F (1), G (2), H (3), along with the known kadsurarin (4), were isolated from Kadsura matsudai. A new C(19) homolignan named schiarisanrin E (5), together with the known C(18) lignans, gomisin B (6), G (7) and (+)-gomisin K(3) (8) were obtained from Schizandra arisanensis. Gomisin B, G and (+)-gomisin K(3) showed moderate to strong activity for antihepatitis in anti-HBsAg (human type B hepatitis, surface antigen) and/or anti-HBeAg (human type B hepatitis, e antigen) tests. The structural elucidations of new compounds 1-3 and 5 were based on two-dimensional (2D) NMR techniques including COSY, HMQC, HMBC, NOESY and CD spectra. Preliminary structure-activity relationship studies for these isolated lignans are also discussed.     

Chemical constituents from the leaves of Manglietia phuthoensis and their effects on osteoblastic MC3T3-E1 cells

Two new phenyl glycosides, mangliesides A and B (1, 2), a new ionol glycoside, manglieside C (3), two new lignan glycosides, mangliesides D and E (4, 5), were isolated from the leaves of Manglietia phuthoensis, along with two known lignans, 3-methoxymagnolol (6) and obovatol (7). Their structures were established by means of 1D and 2D NMR, electrospray ionization (ESI)-MS and HR-ESI-MS experiments. Among them, compounds 2 and 5 significantly (p<0.05) increased the growth and differentiation of osteoblastic MC3T3-E1 cells in vitro.     

Structure elucidation and NMR spectral assignment of five new xanthones from the bark of Garcinia xanthochymus

Five new xanthones, namely Garcinexanthones A-E (1-5), were isolated from the barks of Garcinia xanthochymus. Their structures were elucidated by spectral analysis, primarily NMR, MS, and UV. The complete assignments of the (1)H NMR and (13)C NMR chemical shifts for the compounds were achieved by using 1D and 2D NMR techniques, including DEPT, HSQC, and HMBC NMR experiments.     

Kadsutherins A–C: Three New Dibenzocyclooctane Lignans from the Stems of Kadsura Species

Three new dibenzocyclooctane‐type lignans, kadsutherins A–C ( 1 – 3 ), were isolated from the stems of two Kadsura species. Their structures and configurations were elucidated by spectroscopic methods including 2D‐NMR and HR‐MS techniques. Kadsutherin C ( 3 ) is the first dibenzocyclooctane lignan without an oxygen‐containing substituent at C(2).     

Complete assignments of 1H and 13C NMR spectral data for three new triterpenoid saponins from Ilex hainanensis Merr

Three new oleanane-type triterpenoid saponins, ilexhainanoside C, D and E, all with 24, 28-dioic acid groups, were isolated from the leaves of Ilex hainanensis. They were 3beta-hydroxyolean-12-ene-24, 28-dioic acid-28-O-beta-D-glucopyranoside(1), 3beta, 19alpha-dihydroxyolean-12-ene-24, 28-dioic acid-28-O-beta-D-glucopyranoside(2) and 3beta, 29-dihydroxyolean-12-ene-24, 28-dioic acid-28-O-beta-D-glucopyranoside(3). The structures of these three new compounds were elucidated and complete assignments of the (1)H and (13)C NMR spectroscopic data were achieved by 1D and 2D NMR experiments [heteronuclear single quantum coherence (HSQC), HMBC and rotational nuclear Overhauser effect spectroscopy (ROESY)].     

A new triterpene and dibenzocyclooctadiene lignans from Schisandra propinqua (WALL.) BAILL

A new triterpene and two new natural dibenzocyclooctadiene lignans were isolated from the stems of Schisandra propinqua. In addition, three known lignans, octadecanoic acid, 2,3-dihydroxypropyl ester and beta-sitosterol were isolated. The structures of the new triterpene and new natural products were elucidated base on spectral analysis, including 1D and 2D NMR experiments. The isolates were tested for their cytotoxic effects against several tumor cell lines by MTT assay.     

Complete assignments of 1H and 13C NMR spectral data for three sesquiterpenoids from Inula helenium

The complete assignments of all the (1)H and (13)C NMR signals of three sesquiterpene lactones, 4-oxo-5(6),11-eudesmadiene-8,12-olide (1), 4-oxo-11-eudesmaene-8,12-olide (2) and (1(10)E)-5beta-Hydroxygermacra-1(10),4(15),11-trien-8, 12-olide (3), were carried out by various 2D NMR experiments. Compounds 1-3 were isolated from the roots of Inula helenium for the first time. Among them, 1 was identified as a new nor-sesquiterpene lactone, and 2 was isolated from a natural source for the first time. The (13)C-NMR data of compound 3 was also reported for the first time.     

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.     

Assignment of the 1H and 13C NMR signals of some benzofurocoumarins

The complete 1H and 13C NMR assignment of four 6,7-benzo-fused furocoumarins (1-4) and three 3,4-benzo-fused furocoumarins (5-7) has been performed using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments.     

Heteroclitins N – Q,New Compounds from Stems of Kadsura heteroclita (Roxb.) Craib

From the stems of Kadsura heteroclita (Roxb .) Craib , a new novel C₁₉ homolignan, heteroclitin N ( 1 ), as well as three new lignans, heteroclitins O? Q ( 2 – 4 ), were isolated. Their structures were elucidated based on spectral analysis, including 1D and 2D NMR experiments. There is an additional spirocyclic oxirane system in heteroclitin O ( 2 ), which is the first example of a lignan with an oxirane ring in a spirobenzofuranoid dibenzocyclooctene structure in the genus Kadsura.     

Stereochemistry and conformations of natural 1,2-epoxy-guaianolides based on 1D and 2D NMR data and semiempirical calculations

From detailed study of 1D and 2D NMR spectra of ten natural 1,2-epoxyguaianolides (bis-1,2:3,4-epoxyguaianolides and guaianolide-1,2-epoxychlorohydrins), we identified general spectral traits helpful for stereochemical assignment of such sesquiterpene lactones. We found that the chemical shifts of certain (1)H and (13)C nuclei are consistently dependent on the configuration of 1,2-epoxy-ring which could be used as a simple rule for establishing this configuration. Then, from 1D and 2D (COSY, NOESY, HMQC, HMBC) NMR data, applying the observed rule, the structure and stereochemistry of two new, diastereomeric guaianolide-1,2-epoxychlorohydrins, isolated from Achillea serbica, are determined. The NMR data, namely, nuclear overhauser enhancement (NOE) correlations, pointed out two conformations of guaianolide's cycloheptane ring. The semiempirical calculations (AM1 and PM3 methods), performed in order to gain additional information regarding conformations, resulted in three geometries of investigated lactones. Even so, the conformations derived from the NMR data agreed well with those calculated by semiempirical methods.     

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.     

Complete NMR data assignments for novel pterocarpans from Harpalyce brasiliana

A NMR study of two new pterocarpans isolated from the roots of Harpalyce brasiliana is described. In addition to 1D NMR, 2D shift-correlated NMR pulse sequences ((1)H-(1)H-COSY, HSQC and HMBC) were used to establish the structures, and unambiguously perform the (1)H and (13)C chemical shift assignments.     

Complete assignments of 1H and 13C NMR spectroscopic data for three new stigmastane glycosides from Vernonia cumingiana

Three new steroidal saponins, Vernoniosides S1 ( 1 ), Vernoniosides S2 ( 2 ) and Vernoniosides S3 ( 3 ) were isolated from the stem of Vernonia cumingian. Their chemical structures were elucidated on the basis of MS, NMR spectroscopic and chemical analysis. Complete assignment of ¹H and ¹³C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HMQC, HMBC, ROESY). Copyright © 2008 John Wiley & Sons, Ltd.     

Structural and spectral assignment of a new diterpenoid isolated from Ballota undulata and a complete (1)H and (13)C NMR data assignment for three other structurally related compounds

The structure of 3beta-hydroxyballotinone, a new labdane diterpenoid isolated from Ballota undulata, has been established by NMR spectroscopic studies. In addition, complete and unambiguous assignments of the (1)H and (13)C NMR spectra of three other already known labdanes (ballotinone, ballonigrin and ballonigrinone) isolated from the same source have been achieved. The assignments are based on 2D shift-correlated (1)H--(1)H COSY, (1)H--(13)C gHSQC [(1)J(C,H)] and (1)H--(13)C gHMBC [(n)J(C,H) (n = 2 and 3)], and NOE experiments.     

Complete assignments of 1H and 13C NMR data for trypanocidal eremantholide C oxide derivatives

The chemical transformations of eremantholide C (1), a trypanocidal sesquiterpene lactone isolated from Lychnophora trichocarpha Spreng., gave five new oxide derivatives: 3'-hydroxyeremantholide C (2), 1'-formyleremantholide C (3), 1'-carboxyeremantholide C (4), 1'-carbomethoxyeremantholide C (5) and sodium 1'-carboxylate of eremantholide C (6). The (1)H and (13)C NMR data of all these derivatives were assigned based on 1D and 2D techniques. The derivatives were evaluated against Y and CL strains of Trypanosoma cruzi. All of them were inactive against the Y strain. Compounds 2 and 5 displayed 100% activity on the CL strain while compounds 4 and 6 were partially active on the CL strain.