Absolute Stereochemistry Of Compounds Research Articles

Halogenated Cyclic Monoterpenoids with Anti-biofouling Activity from the Okinawan Red Marine AlgaePortieria hornemannii.

The red algal genus Portieria is a prolific producer of halogenated monoterpenoids. In this study, we isolated and characterised monoterpenoids from the Okinawan red algae Portieria hornemannii. A new polyhalogenated cyclic monoterpenoid, 2(R)-chloro-1,6(S)-dibromo-3(8)(Z)-ochtoden-4(R)-ol (1), along with three known monoterpenoids, (2R,3(8)E,4S,6R)-6-bromo-2-chloro-1,4-oxido-3(8)-ochtodene (2), 1-bromo-2-chloroochtoda-3(8),5-dien-4-one (3), and 2-chloro-1-hydroxyochtoda-3(8),5-dien-4-one (4) were isolated from the methanol extract of three populations of P. hornemannii. These compounds were characterised using a combination of spectroscopic methods and chemical synthesis, and the absolute stereochemistry of compounds 1 and 2 was determined. In addition, all isolated compounds were screened for their anti-biofouling activity against the mussel Mytilus galloprovincialis, and 1 exhibited strong activity. Therefore, halogenated monoterpenoids have the potential to be used as natural anti-biofouling drugs.

Chemical Constituents of Thesium chinense Turcz and Their In Vitro Antioxidant, Anti-Inflammatory and Cytotoxic Activities.

Three novel compounds (1-3) along with twenty-six known compounds, two known steroids (4-5) and twenty-four known phenylpropanoids (6-29) were isolated from the whole plant of Thesium chinense Turcz. The structures of the three new compounds were elucidated on the basis of ESI-MS, HR-ESIMS, 1D and 2D NMR, IR, UV spectroscopic data. The absolute stereochemistry of compound 1 was determined by the Gauge-Including Atomic Orbitals (GIAO) method. The in vitro antioxidant, anti-inflammatory and cytotoxic activities of the isolated compounds were evaluated by DPPH radical-scavenging assay, LPS-activated RAW 264.7 cells model and CCK-8 kit, respectively. Compound 11 showed high antioxidant activity with an SC50 value of 16.2 ± 1.6 μM. Compound 21 showed considerable anti-inflammatory activity with an IC50 value of 28.6 ± 3.0 μM. Compounds 4 and 5 displayed potent cytotoxic activity against human NCI-H292, SiHa, A549, and MKN45 cell lines, with the compound 4 having IC50 values of 17.4 ± 2.4, 22.2 ± 1.1, 9.7 ± 0.9, 9.5 ±0.7 μM, and the compound 5 having all IC50 values less than 0.1 μM in vitro.

Eremophilane sesquiterpenoids from the endophytic fungus Curvularia lunata BCC76963

A chemical investigation on broth and mycelia extracts of the endophytic fungus Curvularia lunata BCC76963 led to the isolation of five new eremophilane sesquiterpenoids, curvuleremophilanes A−D (1–4) and septeremophilane I (5), one new conjugated unsaturated fatty acid, (6S,2E,4E)-8-hydroxy-4,6-dimethylocta-2,4-dienoic acid (6), and one new phenylacetic acid derivative, 4′-chlorocurvulin (8), along with ten known compounds. The chemical structures were elucidated based on the analyses of HRESIMS and NMR spectroscopic data. The absolute configurations of eremophilanes were assigned by the evidence from NOESY correlations, chemical conversion, optical rotation values, and ECD spectroscopic data in conjunction with biogenetic considerations. In addition, the absolute stereochemistry of compound 5 was confirmed by X-ray crystallography. Curvuleremophilane A (1), dendryphiellin I (10), chaetopenoid B (11), and bipolaroxin (12) displayed antimalarial activity against Plasmodium falciparum K1 with IC50 values in a range of 3.64–7.77 μM and antibacterial activity against Bacillus cereus and Staphylococcus aureus with MIC values in a range of 3.13–12.50 and 1.56–25.00 μg/mL, respectively. These compounds, except for compound 11, also showed cytotoxicity against NCI-H187 and Vero cells with respective IC50 values in a range of 2.76–3.97 and 2.34–4.67 μM.

Artemzhongdianolides A1-A21, antihepatic fibrosis guaiane-type sesquiterpenoid dimers from Artemisia zhongdianensis

In the search for new antihepatic fibrosis candidates, it was observed that the EtOH extract of Artemisia zhongdianensis and EtOAc fraction had cytotoxicity against hepatic stellate cell line LX2 (HSC-LX2) with the inhibitory ratios of 85.7 % and 83.9 % at 400 μg/mL. 21 new guaianolide dimers, artemzhongdianolides A1 − A21 (1–21) were isolated from the active fractions under the guidance of bioassay, and elucidated by spectral analyses (HRESIMS, 1D and 2D NMR, IR, ECD). The absolute stereochemistry of compounds 1, 13, and 14 was determined by single-crystal X-ray diffraction analyses. Cytotoxicity evaluation suggested that nine compounds exhibited activity against HSC-LX2 with IC50 values ranging from 14.0 to 95.2 μM. Of them, compounds 2, 6, and 13 displayed significant cytotoxicity against HSC-LX2 with IC50 values of 22.1, 24.3 and 14.0 μM, which were 6 to 10 times more active than the positive drug silybin (IC50, 148.6 μM). Preliminary mechanism study revealed that compounds 2, 6, and 13 could markedly inhibited the deposition of human collagen type Ⅰ (Col Ⅰ), human hyaluronic acid (HA), and human laminin (HL) with IC50 values of 37.9, 54.8, and 28.0 μM (Col Ⅰ), 29.5, 25.3, and 42.9 μM (HL), 31.2, 94.6, and 12.4 μM (HA), which were 1.5 to 13-fold more potent than silybin.

A New Isoflavan From the Heartwood of Dalbergia cochinchinensis

A new isoflavan, named dalbergiacochan A (1), was isolated from the heartwood of Dalbergia cochinchinensis, along with two known isoflavans, namely mucronulatol (2) and 2′-O-methylsepiol (3). Their structures were elucidated based on extensive spectroscopic analyses, including one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), and mass spectroscopy (MS) data, and the absolute stereochemistry of compound 1 was determined as R-3′,6-dihydroxy-2′,4′,8-trimethoxyisoflavan from its circular dichroism spectrum. Compound 1 was inactive against Escherichia coli, Bacillus thuringiensis, and Shigella dysenteriae.

Estrogenic and anti-neutrophilic inflammatory phenanthrenes from Juncus effusus L.

Juncus effusus L. (J. effusus) is a Traditional Chinese Medicine (TCM) that has long been used for dealing with gynaecological disorders, such as relieving insomnia, preventing tinnitus, reducing edema with diuretic effect. In our course of evidence-based medical research focused on this herb, one new phenanthrene, Junfusol B (2), together with seventeen known compounds were isolated and identified. All the structures of these compounds were elucidated by spectroscopic methods. The absolute stereochemistry of compounds 1 and 2 was further determined by comparing their calculated and experimental Electronic Circular Dichroism (ECD) spectra and optical rotation (OR) values. The isolates were evaluated for their estrogenic and anti-inflammatory activities which were considered as relevant etiological factors of insomnia, tinnitus and edema in the ancient TCM theory. The results revealed that most of the obtained phenanthrenes in this work were found exerting agonistic effects on estrogen receptor. This is the first report to declare the exact estrogen-regulating potential among this type of compounds from J. effusus. Moreover, phenanthrenes 3 − 7 exhibited significant inhibitions on superoxide anion generation and elastase release in fMLP/CB-induced human neutrophilic inflammation model. J. effusus may be developed as a complementary agent utilized in menopausal multiple syndromes.

Artematrovirenins A–P, guaiane-type sesquiterpenoids with cytotoxicities against two hepatoma cell lines from Artemisia atrovirens

Random screening revealed that the EtOH extract of Artemisia atrovirens showed significant cytotoxicity against two human hepatoma cell lines (HepG2 and Huh7) with the inhibitory ratio of 98.9% and 99.7% at the concentration of 100 μg/mL. Further bioactivity-guided isolation of active fraction led to 16 new guaiane-type sesquiterpenoids, artematrovirenins A–P (1–16). Their structures were elucidated by extensive spectroscopic data. The absolute stereochemistry of compounds 1 and 14 was determined by single-crystal X-ray diffraction analyses. Pharmacological evaluation suggested that five compounds (3, 5, 8, 10, and 15) exhibited cytotoxicity, compounds 3 and 5 displayed cytotoxicity against HepG2 cell line with an IC50 values of 8.0 and 16.0 μM, as well as against Huh7 cell line with values of 18.2 and 32.2 μM.

Triterpenoids from stems of Kadsura heteroclita

In the present work, we reported the triterpenoids isolated from n-butanol fraction of Kadsura heteroclita which is a Tujia ethnomedicine with trivial name “Xuetong”. This effort resulted in the isolation of six unpresented triterpenoids xuetongsu A-F (1–6), along with five known triterpenoids (7–11). The structures of the reported compounds were established on the 1D, and 2D NMR and HRESIMS spectra, along with CD spectroscopic analysis. Moreover, the absolute stereochemistry of compound 7 was determined by X-ray diffraction analysis. Antioxidant and cytotoxic activities were evaluated for all isolated compounds, compound 7 shown weak cytotoxic activity against HL-60 with IC50 value of 50.0 μM.

One new sesquiterpene and one new iridoid derivative from Valeriana amurensis

One new sesquiterpene 1S, 3S, 4S, 7S 3,4-dihydroxy-bisabolol (1), one new iridoid amurensin A (2) and 10 known compounds were isolated from the whole plants of Valeriana amurensis. Their structures were established on the basis of extensive spectroscopic analysis and the absolute stereochemistry of compound 1 was assigned by X-ray diffraction analysis with Cu-Kα irradiation. All of compounds were evaluated for their inhibitory effects on NO production in LPS-induced RAW264.7 macrophages. Compound 12 displayed significant anti-inflammatory activity with IC50 value of 1.97 μM.

Natural Products from Diaporthe arecae with Anti‐Angiogenic Activity

AbstractA new indoleglycerol, designated as arecine (1), and twenty‐three known diketopiperazines 2–24 were isolated from the endophytic fungus Diaporthe arecae associated with mangrove Kandelia obovate. Structures of all secondary metabolites 1–24 were identified on the basis of their spectrometric data, especially the nuclear magnetic resonance, optical rotation, and mass data. The absolute stereochemistry of compound 1 was determined by comparing its experimental electronic circular dichroism spectrum to those of in silico generated. Moreover, the 1H and 13C NMR spectroscopic data of isolated diketopiperazines 3–24 were measured in dimethyl sulfoxide‐d6 and presented in Table 2 for a convenient comparison. Pharmacological study showed cordysinin A (2) possessed mild anti‐angiogenic activity, which suppressed tube formation with an IC50 value of 15.1±0.2 μg/mL.

Rhabdaprovidines D–G, Four New 6,6,5-Tricyclic Terpenoids from the Vietnamese Sponge Rhabdastrella providentiae

Four new 6,6,5-tricyclic terpenoids, named rhabdaprovidines D-G (1–4), were isolated from the Vietnamese sponge Rhabdastrella providentiae. The structures of 1–4 were elucidated by extensive analysis of HR-ESI-MS and NMR spectroscopy. The absolute stereochemistry of compounds 3 and 4 were determined by both experimental and theoretical calculated circular dichroism (CD) spectra. Compounds 1, 2, and 4 contained trans-syn-trans 6,6,5-tricyclic nucleus meanwhile compound 3 possessed trans-syn-cis ring junction. Compound 4 displayed novel structure by the presence of five rings and nine chiral carbon centers in the isomalabaricane triterpene backbone.

Two new cyclopropane monoterpene epimers from Varthemia iphionoides of Jordanian origin

Two new monoterpenes, varthemic acid I (1) and varthemic acid II (2), in addition to 12 known compounds were isolated from the aerial parts of Varthemia iphionoides (Asteraceae family) growing wild in Jordan. Structural elucidation of all isolated compounds was performed utilizing extensive spectroscopic data including UV, IR, MS, and NMR (1 & 2D) spectroscopy. The absolute stereochemistry of compound 1 was determined by X-ray.

ChemInform Abstract: Selacyclicbiflavone A, an Unusual Macrocyclic Biflavone from Selaginella uncinata (Desv.) Spring.

Abstract An unusual macrocyclic biflavone, selacyclicbiflavone A ( 1 ), have been isolated from Selaginella uncinata . The structure was elucidated on the basis of rigorous spectroscopic analysis including 1D and 2D NMR experiments as well as HRESIMS techniques. The absolute stereochemistry of compound 1 was further confirmed by comparing experimental data with calculated electronic circular dichroism (ECD) spectra. This is the first report of the macrocyclic biflavone with an unprecedented methylene bridge. A possible biosynthetic pathway was also postulated.

Selacyclicbiflavone A, an unusual macrocyclic biflavone from Selaginella uncinata (Desv.) Spring

An unusual macrocyclic biflavone, selacyclicbiflavone A (1), have been isolated from Selaginella uncinata. The structure was elucidated on the basis of rigorous spectroscopic analysis including 1D and 2D NMR experiments as well as HRESIMS techniques. The absolute stereochemistry of compound 1 was further confirmed by comparing experimental data with calculated electronic circular dichroism (ECD) spectra. This is the first report of the macrocyclic biflavone with an unprecedented methylene bridge. A possible biosynthetic pathway was also postulated.

Allahabadolactones A and B from the endophytic fungus, Aspergillus allahabadii BCC45335

Two new compounds, allahabadolactones A (1) and B (2), along with 10 known compounds including 16-amino-isopimar-7-en-19-oic acid (3), 16-α-d-glucopyranosyloxyisopimar-7-en-19-oic acid (4), 16-α-d-mannopyranosyloxyisopimar-7-en-19-oic acid (5), ergosterol, (22E)-5α,8α-epidioxyergosta-6,22-dien-3β-ol, cerevisterol, (R)-(−)-methoxycarbonylmellein, (−)-piliformic acid, 7-dechlorogriseofulvin, and cytochalasin D, were isolated from the endophytic fungus, Aspergillus allahabadii BCC45335. Their chemical structures were determined based on NMR spectroscopic and mass spectrometric analyses. The absolute stereochemistry of compound 1 was established by an X-ray crystallographic analysis and the reactions with Mosher's reagents. A plausible biosynthesis of allahabadolactones A (1) and B (2) was also proposed. Antibacterial activity against Bacillus cereus and cytotoxicity against MCF-7, KB, NCI-H187, and Vero cells of the isolated compounds were also evaluated.

ChemInform Abstract: An Unusual Indole Alkaloid with anti‐Adenovirus and anti‐HSV Activities from Alstonia scholaris.

A novel alkaloid, 17-nor-excelsinidine (1), possessing an unusual 1-azoniatricyclo [4.3.3.0] undecane moiety was isolated from the twigs and leaves of Alstonia scholaris alongside its biogenetically related strictamine (2). The structure and absolute stereochemistry of compound 1 were rigorously determined by a combination of NMR spectroscopy and X-ray crystallography. The 17-nor-excelsinidine (1) and strictamine (2) showed significant inhibitory activity against herpes simplex virus (HSV) and adenovirus (ADV). (C) 2014 Elsevier Ltd. All rights reserved.

Amarusine A, a new dioxaspiro[4.4]nonane derivative with a butyrolactone ring from Pleioblastus amarus

Amarusine A (1), a new polyketide derivative possessing an unusual dioxaspiro[4.4]nonane derivative with a butyrolactone ring, was isolated from the leaves of Pleioblastus amarus. The structure and absolute stereochemistry of compound 1 were rigorously determined using UV, IR, HRESIMS, and 1D and 2D NMR techniques and by comparing experimental and calculated electronic circular dichroism (ECD) spectra. Amarusine A (1) exhibits a good antioxidant activity for scavenging the DPPH radical. A possible biosynthetic pathway was postulated.

An unusual indole alkaloid with anti-adenovirus and anti-HSV activities from Alstonia scholaris

A novel alkaloid, 17-nor-excelsinidine (1), possessing an unusual 1-azoniatricyclo [4.3.3.0] undecane moiety was isolated from the twigs and leaves of Alstonia scholaris alongside its biogenetically related strictamine (2). The structure and absolute stereochemistry of compound 1 were rigorously determined by a combination of NMR spectroscopy and X-ray crystallography. The 17-nor-excelsinidine (1) and strictamine (2) showed significant inhibitory activity against herpes simplex virus (HSV) and adenovirus (ADV).

Isolation and Characterization of Limonoids from Kigelia africana

Two new limonoids, 1-O-deacetyl-2a-methoxykhayanolide (1) and kigelianolide (2), together with deacetylkhayanolide E (3), 1-O-deacetyl-2α-hydroxykhayanolide E (4) and khayanolide B (5) were isolated from the ethyl acetate-soluble fraction of the methanolic extract of Kigelia africana. The structures of these limonoids (1-5) were elucidated by the combination of 1D (1H and 13C NMR) and 2D (HMQC, HMBC and COSY) NMR spectroscopy and mass spectrometry (EIMS, HREIMS), and in comparison with literature data of related compounds. The structure of compound 1 was further confirmed by X-ray crystallography, and the absolute stereochemistry of compounds 1 and 2 was determined by electronic circular dichroism (ECD) spectroscopy. Limonoids 1-5 showed weak inhibitory activities against the enzymes acetylcholinesterase (AChE), butyrycholinesterase (BChE) and lipoxygenase (LOX) in a concentration-dependent manner with IC50 values in the ranges 137.5 - 225.2 μM for AChE, 185.4 - 241.5 μM for BChE and 281.2 - 189.6 μM for LOX

Two new nonacosanetriols from Ginkgo biloba sarcotesta

Two new fatty alcohols named as (7S,8R,11S)-nonacosanetriol (1) and (10R,12R,15S)-nonacosanetriol (2), along with eight known compounds including ginkgolic acid (3), hydroginkgolic acid (4), sciadopitysin (5), ginkgetin (6), isoginkgetin (7), ginkgolide A (8), ginkgolide B (9) and ginkgolide C (10) have been isolated from the petroleum ether extract of Ginkgo biloba sarcotesta. Their structures were elucidated by means of chemical and extensive spectroscopic analysis. The absolute stereochemistry of compounds 1 and 2 was elucidated on the spectroscopic analysis of the R- and S-MTPA esters. Compounds 1 and 2 exhibited slight activity of antithrombin and moderate activity of antiplatelet aggregation in vitro. This was the first report regarding the anticoagulative activities of biflavonoids in G. biloba, and isoginkgetin (7) showed significant antithrombin and antiplatelet aggregation activity.