Bis-iridoid and lignans from traditional Tibetan herb Pterocephalus hookeri

A new bis-iridoid, pterhookeroside (1) was isolated from the roots of Pterocephalus hookeri along with three known iridoids (2–4) and five lignans (5–9). The structure elucidation of the isolates was accomplished by extensive 1D and 2D-NMR experiments as well as HRESI-MS. The bis-iridoid and lignans were encountered for the first time in the genus Pterocephalus.     

Chemical constituents of Peperomia tetraphylla (Forst. F.) Hooker et Arnott

Sixteen compounds were isolated from the whole herbs of Peperomia tetraphylla (Forst. F.) Hooker et Arnott by phytochemical methods, including eight flavonoids (1–3, 6, 7, 14–16), three lignans (8–10), three beta sitosterols (4, 5, 11), and two phenolic acids (12, 13). Their structures were identified by the analysis of NMR and MS, as well as the comparisons to the reported data. Among them, 2″-O-xylosylisoswertisin (14) was firstly isolated from the Piperaceae family, as well as ten compounds (1–4, 7, 10–11, 13, 15–16) were isolated from P. tytraphylla for the first time. Moreover, the chemotaxonomic significance of constituents isolated from P. tytraphylla was also discussed.     

Chemical constituents isolated from Valeriana officinalis L

Phytochemical investigations on the leaves of Valeriana officinalis L. led to the isolation of 18 compounds, including eight lignans (1–8), three sesquiterpenoids (9–11), five iridoids (12–16), and two aldehydes (17–18) The structure elucidation of isolated compounds was achieved on the basis of NMR and mass spectral data. Among them, three compounds (9–16, 18) are reported from V. officinalis for the first time and one compound (5) was isolated from the genus Valeriana for the first time. In addition, six compounds (2, 4, 6–8, 17) are isolated for the first time from Valerianaceae family. The chemotaxonomic significance of these isolated compounds has also been discussed.     

Three new cytotoxic aryltetralin lignans from Sinopodophyllum emodi

Three new aryltetralin lignans, 4-acetyl-4-demethyl-podophyllotoxin (1) and sinolignans A, B (2-3), and two new natural products (4-5), were isolated from the roots and rhizomes of Sinopodophyllum emodi together with twelve known lignans (6-17). Their structures and stereochemistry were elucidated on the basis of spectroscopic evidence, and circular dichroism (CD) method. The cytotoxic activities of all isolated compounds were evaluated against HeLa and KB cell lines. Compared with etoposide, compounds 1, 6-9, and 13 showed more potent cytotoxicities against two tumor cell lines. On the basis of IC₅₀ values, deoxypodophyllotoxin (7) was about 579 and 1123 times more toxic than etoposide in HeLa and KB cell lines, respectively. The preliminary SAR study indicated that an oxygenated group at C-7′ might decrease cytotoxicity against two cell lines, which was different from most previous studies. However, this needs to be systematically verified by extensive pharmacological experiments.     

Iridoids and lignans from Valeriana officinalis L. and their cytotoxic activities

Two new iridoids (1 and 2), one new lignan (3) together with one known iridoid (4) and twelve known lignans (5－16) were obtained from the roots of Valeriana officinalis L. (V. officinalis). The structures were determined using IR, MS, ¹D and ²D NMR spectroscopy and the absolute configurations of the new structures were deduced by ECD experiments. All of the isolated compounds were assayed for their cytotoxic activities against three tumour cell lines (A549, HCT116 and SW620) and the results showed that compounds 9 and 10 showed cytotoxicities against A549 cells, compounds 9 and 11 showed cytotoxicities against SW620 cells and compound 10 showed cytotoxicities against HCT116 cells.     

Isolation,structure elucidation and in-vitro evaluation of new trisubstituted Tetrahydrofuran Lignans from Rabdosia lophanthoides var. gerardiana as anti-inflammatory agents

Four new trisubstituted tetrahydrofuran lignans, named (−)-sesaminone-rutinoside (1), (+)-episesaminone-rutinoside (2) and rabdosiacosides B (3) and C (4) were isolated from the air-dried whole herbs of Rabdosia lophanthoides var. gerardiana together with two known compounds, (+)− 1-hydroxypinoresinol-1-β-d-glucoside (5) and rosmarinic acid (6). The structures of these new lignans were elucidated by a combination of mass spectrometry, 1D and 2D NMR experiments including distortionless enhancement by polarization transfer, ¹H–¹H correlation, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, and nuclear Overhauser effect spectroscopies. Both the cell viability and their anti-inflammatory effects of the lignans were further studied. Among them, no significant cytotoxic activity was exhibited. Compound 4 dramatically suppressed LPS-induced nitric oxide release and reduced the release of the pro-inflammatory cytokines TNF-α and IL-6 in a dose-dependent manner. Overall, our findings indicate that compound 4 was noteworthy in reducing LPS-induced inflammatory responses in RAW264.7 macrophages.     

Anti-hepatitis B virus lignans from the root of Streblus asper

Four new lignans, strebluslignanol F (1), (7′R,8′S,7″R,8″S)-erythro-strebluslignanol G (2), isomagnaldehyde (3) and isostrebluslignanaldehyde (4), along with 12 known lignans (5–16) were isolated from the ethyl acetate-soluble part of MeOH extract of the root of Streblus asper. Their structures were elucidated through various spectroscopic methods, including 1D NMR (¹H NMR, ¹³C NMR), 2D NMR (HMQC, HMBC and NOESY) and HRMS. The stereochemistry at the chiral centers was determined using CD spectra, as well as analyses of coupling constants and optical rotation data. The isolated lignans were evaluated for their anti-HBV activities in vitro using the HBV transfected HepG2.2.15 cell line. The most active lignans, (7′R,8′S,7″R,8″S)-erythro-strebluslignanol G, magnolol, isomagnolol and isolariciresinol, exhibited significant anti-HBV activities with IC₅₀ values of 1.58, 2.03, 10.34 and 3.67 μM, respectively, for HBsAg with no cytotoxicity, and of 3.24, 3.76, 8.83 and 14.67 μM, respectively, for HBeAg with no cytotoxicity. (7′R,8′S,7″R,8″S)-erythro-Strebluslignanol G and magnolol showed significant anti-HBV activities to inhibit the replication of HBV DNA with the IC₅₀ values of 9.02 and 8.67 μM, respectively.     

Chemical constituents from the roots of Zizyphus jujuba Mill. var. spinosa

One new flavonoid, named (R)-2-hydroxynaringenin (1), along with fifteen known compounds, including six flavonoids (2–7), six lignans (8–13), two phenolic glycosides (14–15) and one alkaloid (16) were isolated from the roots of Zizyphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou. Their structures were established on the basis of spectroscopic evidence, including 1D and 2D NMR, circular dichroism (CD) curve analysis, and by comparison with literature data. Compounds 2, 3 and 8–16 were found in Z. jujuba Mill. var. spinosa for the first time, while compounds 8, 10 and 13–15 were new to the Rhamnaceae family. In addition, the chemotaxonomic significance of the isolates was discussed in this paper.     

Bioactive lignans from the stems of Mappianthus iodoides

Two new lignans, mappianthines A (1) and B (2), along with ten known analogues (3-12), were isolated from the stems of Mappianthus iodoides. The structures with the absolute configurations of 1 and 2 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons their data with those reported in the literatures. All new compounds were evaluated for their anti-inflammatory activities via examining the inhibitory activity on nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro. Compounds 1 and 2 exhibited inhibitory effects with IC₅₀ values comparable to that of hydrocortisone.     

Two dimeric lignans with an unusual α,β-unsaturated ketone motif from Zanthoxylum podocarpum and their inhibitory effects on nitric oxide production

Two new dimeric lignans, zanthpodocarpins A (1) and B (2), and five known lignans, eudesmin (3), (1R,2R,5R,6S)-2-(3,4-dimethoxyphenyl)-6-(3,4-dihydroxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (4), dimethoxysamin (5), rel-(1R,5R,6S)-6-(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octan-2-one (6), and magnone A (7), were isolated from the barks of Zanthoxylum podocarpum. Their structures were identified by using spectroscopic methods. Compounds 1 and 2 are rare dilignans bearing an unusual α,β-unsaturated ketone group from a natural source. Bioassay showed that compounds 1 and 2 could inhibit nitric oxide (NO) production in LPS stimulated RAW 264.7 cells with IC₅₀ values of 5.31 μM and 12.15 μM, respectively.     

Caged xanthones displaying protein tyrosine phosphatase 1B (PTP1B) inhibition from Cratoxylum cochinchinense

Four new caged xanthones (1–4) and two known compounds (5, 6) were isolated from the roots of Cratoxylum cochinchinense, a polyphenol rich plant, collected in China. The structures of the isolated compounds (1–6) were characterized by obtaining their detailed spectroscopic data. In particular, compounds 1 and 6 were fully identified by X-ray crystallographic data. The isolated compounds (1–6) were evaluated against protein tyrosine phosphatase 1B (PTP1B), which plays an important role in diabetes, obesity, and cancer. Among these compounds, 3, 4, and 6 displayed significant inhibition with IC₅₀ values of 76.3, 43.2, and 6.6 µM, respectively. A detailed kinetic study was conducted by determining K_m, V_max, and the ratio of K_ik and K_iv, which revealed that all the compounds behaved as competitive inhibitors.     

Lignans from the fruit of Schisandra sphenanthera,and their inhibition of HSV-2 and adenovirus

The systematic isolation of the EtOAc extract from Schisandra sphenanthera fruit was performed during a search for HSV-2 and adenovirus inhibitors. Sixteen lignans were obtained, with compound 1 representing a new and rare type of lignan in the genus Schisandra. Their structures were elucidated by spectroscopy and comparison with literature data. Among all the lignans tested for their antiviral activities, compound 14 was the most active against HSV-2 with a selectivity index value up to 29.83. Moreover, the new compound 1, and the known ones (4, 6, 7, 10 and 14) also exhibited moderate inhibition of HSV-2 and adenovirus. To the best of our knowledge, this is the first report that these lignans from Schisandra genus were shown to have modest activity against HSV-2 and adenovirus. Meanwhile, structure–activity relationships of some lignans for the inhibitory activity against HSV-2 and adenovirus were discussed in this study.     

A new acorane sesquiterpenes of Lysionotus pauciflorus maxim. Form Guizhou province,China

A new acorane sesquiterpene (1), together with fourteen known compounds were isolated from the whole plant of Lysionotus pauciflorus Maxim. The chemical structures of the compounds were identified by physio-chemical properties and 1D-NMR, 2D-NMR, ESI-MS, IR and ECD spectra. Among them, six compounds (1, 4, 6, 7, 13, 15) were first found in the genus Lysionotus. The chemotaxonomic significance of the isolated compounds in the genus Lysionotus and family Gesneriaceae were discussed.     

Chemotaxonomic significance of lignans from Serissa japonica (Thunb.) Thunb

Sixteen known lignans were isolated from the 95% alcohol extract of the whole plant of Serissa japonica (Thunb.) Thunb., including nine furofurans (1–9), three tetrahydrofurans (10–12) and four arylnaphthalenes (13–16). In the present report, compounds (+)-epipinoresinol (1), (+)-1-hydroxy-6-epipinoresinol 4,4″-di-O-methyl ether (3), (−)-pinoresinol (4), (+)-8-hydroxypinoresinol (6), pseuderesinol (7), (+)-1-hydroxysyringaresinol (8), (−)-(7′S,8S,8′R)-4,4′-dihydroxy-3,3′,5,5′-tetramethoxy-7′,9-epoxylignan-9′-ol-7-one (10), wikstrone (11), 7'-(+)-oxomatairesinol (12), (+)-cycloolivil (13), (+)-isolariciresinol (14), 5-methoxy-(+)-isolariciresinol (15) and cyclolignans (16) were reported from the Serissa genus for the first time, and compounds (+)-lirioresinol A (2) and (−)-lirioresinol B (5) were firstly isolated from the plant. Their structures were elucidated on the basis of extensive spectroscopic and chemical analyses. Moreover, the chemotaxonomic significance of the isolated compounds is discussed.     

New antibacterial sesquiterpene aminoquinones from a Vietnamese marine sponge of Spongia sp.

Two new sesquiterpene aminoquinones, langcoquinones A (1) and B (2), together with seven known meroterpenoids (3⿿9), were isolated from the marine sponge Spongia sp. collected in Vietnam. Their structures were determined on the basis of spectroscopic analyses and comparisons with published data. The antibacterial activities of the isolated compounds (1⿿9) were investigated against four bacterial strains. Among these, the new sesquiterpene aminoquinones (1 and 2) and the known related compounds (3, 5, 6, 8, and 9) exhibited significant antibacterial activities against Staphylococcus aureus and Bacillus subtilis, with MICs ranging from 6.25 to 12.5 μM.     

Two new aryl naphthalide lignans from Polygala chinensis

Chinensinaphthol and chinensinaphihol methyl ether, two new 1-ary]-2,3-naphthalide lignans, have been isolated from the title plant. Structures (2) and (3) have been established for them by chemical transformations and spectral evidence. Significant quantitative variations in the content of the cyclic and the acyclic lactonic lignans (1–3, 5–7) of P. chinensis have been observed in plant material, collected from the same locality and examined in 3 consecutive years.     

Two new quinic acid derivatives from the fruits of Chaenomeles speciosa

Two new quinic acid derivatives (1, 2), together containing eighteen (3–20) known compounds, were isolated from the fruits of Chaenomeles speciosa. Spectroscopic methods and previous data retrieved from the literature were used to determine the chemical structures of the compounds. Among the compounds, quinic acid derivatives (3, 4, 6, 7), phenolic acid compounds (8, 10, 11) and catechin derivatives (18, 19, 20) were isolated for the first time from the family Chaenomeles. The chemotaxonomic significance of the compounds was also discussed.     

Anti-hepatitis B virus constituents from the stem bark of Streblus asper

Seven compounds, (7′S,8′S)-trans-streblusol A, (7′R,8′S)-erythro-streblusol B, (7′S,8′S)-threo-streblusol B, 8′R-streblusol C, streblusquinone, (8R,8′R)-streblusol D, and streblusol E, along with 15 known compounds (8–22) were isolated from the n-butanol-soluble part of the MeOH extract of stem bark of Streblus asper. Their structures were elucidated through application of extensive spectroscopic methods, including ESI-MS and 2D NMR spectroscopy (HMQC and HMBC). The stereochemistry at the chiral centers was determined using CD spectra, as well as analyses of coupling constants and optical rotation data. The isolated lignans and allylbenzene derivatives were evaluated for their anti-HBV activities in vitro using the HBV transfected Hep G2.2.15 cell line. The most active compounds, magnolol and 9-β-xylopyranosyl-isolariciresinol, exhibited significant anti-HBV activities with IC₅₀ values of 2.03 and 6.58 μM for secretion of HBsAg, with no cytotoxicity, and of 3.76 and 24.86 μM for secretion of HBeAg, with no cytotoxicity.     

New pyranonaphthazarin and 2-naphthoic acid derivatives from the mangrove endophytic fungus Leptosphaerulina sp. SKS032

Two new compounds, named leptospyranonaphthazarin A (1) and leptosnaphthoic acid A (2), together with four known compounds (3–6) were isolated from an endophytic fungus Leptosphaerulina sp. SKS032. Their structures were assigned using spectroscopic methods, computational methods, and single-crystal X-ray diffraction analysis. In the antibiotic assay, compounds 1, 2, and 6 exhibited antibacterial activities against Staphylococcus aureus with minimal inhibitory concentration (MIC) values of 25.0, 50.0, and 50.0 μg/mL, respectively.     

Chemical constituents from Ailanthus altissima (Mill.) Swingle and chemotaxonomic significance

Sixteen compounds were isolated from the root barks of Ailanthus altissima (Mill.) Swingle, including thirteen lignans (1–13), two coumarins (14–15), and one chalcone (16). This is the first report on the occurrence of compounds 1–16 in the genus Ailanthus. Their structures were elucidated on the basis of NMR spectroscopic data. The plant distribution network of all isolated compounds was described to illustrate the significance of taxonomy. The presence of these congenetic lignans (1–13) and their biosynthetic relationships may be used for identification of Ailanthus genus.