Carbon-13 NMR signals of some natural coumarins and their derivatives

The ¹³C NMR spectra of the natural coumarins ostruthin, osthol, aegelinol (enantiomer of decursinol), luvangetin, seselin, anomalin, oxypeucedanin (and its enantiomer prangolarin) and oxypeucedanin hydrate and some of their derivatives have been studied. Self-consistent resonance assignments have been made following chemical shift theory and using simple models. Carbon-hydrogen coupling constants of some compounds are also reported. The alkoxy group/s at C-5 and/or C-8 in linear furocoumarins, as well as in linear pyranocoumarins, have unusually small shielding effects on the ortho- and para-carbons. This study also indicates that the C-4a and C-8 resonance assignments of osthol, made earlier, should be reversed.     

蛇床子香豆素的薄层分离-直接进样-质谱鉴定

用丙酮提取,石油醚冷冻结晶,从蛇床子中得到混合香豆素。经薄层分离 ,直接进样和质谱分析 ,鉴定出8种香豆素化合物:Ⅰ.蛇床子素(osthol) ,Ⅱ.佛手内酯(bergapten) ,Ⅲ.欧芹属素乙(imperatorin) ,Ⅳ.花椒毒素(xanthotoxin) ,Ⅴ.异回芹内酯(isopimpinellin) ,Ⅵ.别异英波托林(alloisoimperatorin) ,Ⅶ.6 -甲氧基 -8 -甲基香豆精(6_methoxy_8_methylcoumarin) ,Ⅷ.花椒毒酚(xanthotoxol)。其中Ⅵ、Ⅶ首次于蛇床子中发现。     

短波近红外光谱法对蛇床子SFE萃取产物的定量分析

利用中药蛇床子CO2超临界萃取(SFE)的萃取物的短波近红外漫反射光谱(800～1100 nm),以HPLC分析值作参比值,采用化学计量学中的偏最小二乘法(PLS)建立短波近红外漫反射光谱与蛇床子SFE萃取物中主要成分蛇床子素和欧前胡素间定量分析数学模型.实现了快速、无损的测定双组分中药的有效成分.讨论了光谱的预处理方法和主成分数对PLS定量预测蛇床子萃取物中蛇床子素和欧前胡素含量能力的影响,并对预测集样品进行预测.     

用单分子胶束荧光法测定蛇床子中的蛇床子素

根据胶束增溶增敏作用 ,以β-环糊精为胶束试剂 ,测定了蛇床子中蛇床子素的含量。蛇床子素的线性范围为 2× 1 0 -8～ 8× 1 0 -7g/m L,检出限为 1 .89× 1 0 -10 g/m L,平均回收率为 98%。     

Preparative isolation of osthol and xanthotoxol from Common Cnidium Fruit (Chinese traditional herb) using stepwise elution by high-speed counter-current chromatography

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of osthol and xanthotoxol from Cnidium monnieri (L.) Cusson (Common Cnidium Fruit) using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1:1:1:1, v/v), and (5:5:6:4, v/v), which had been selected by analytical high-speed counter-current chromatography. Using a preparative unit of the HSCCC centrifuge, about a 308 mg amount of the crude extract was separated, yielding 88.3 mg of osthol and 19.4 mg of xanthotoxol at a high purity of over 98%.     

Long-chain alkanoic acid esters of lupeol from Dorstenia harmsiana Engl. (Moraceae)

In addition to lupeol (1a), three long-chain alkanoic acid esters of lupeol, in which two were new, were isolated from the hexane and ethyl acetate twigs extract of Dorstenia harmsiana Engl. (Moraceae). The structures of the new compounds were elucidated on the basis of 1D and 2D NMR experiments. Some isolated compounds were evaluated for their antimicrobial activities. The lupeol and its three long-chain alkanoic acid esters showed antifungal and antibacterial activities.     

Novel neuronal nitric oxide synthase (nNOS) selective inhibitor, aplysinopsin-type indole alkaloid, from marine sponge Hyrtios erecta

Two novel aplysinopsin-type indole alkaloids, 1 and 2, and three known indole alkaloids were isolated from the marine sponge Hyrtios erecta. These compounds exhibited selective inhibitory activity against the neuronal isozyme of nitric oxide synthase (nNOS). Furthermore, new quinolone 7 was also isolated from the same marine sponge. The chemical structures of these new compounds were elucidated on the basis of spectroscopic analysis.     

8‐(2‐Bromo‐3‐methoxy‐3‐methylbutyl)‐7‐methoxycoumarin

The title compound, C₁₆H₁₉BrO₄, is a derivative of osthol, isolated from the seeds of Imperatoria Osthruthium. The structure was solved in space group P, with two mol­ecules in the asymmetric unit, and was refined to a final R factor of 0.064. The two mol­ecules in the asymmetric unit differ in the orientation of their brominated substituent group. The benzo­pyran ring displays aromatic character. The packing of the mol­ecules in the lattice is mainly due to C—H⋯O hydrogen bonds.     

Chemical Constituents from Strychnos Cathayensis

Secostrychnosin ( 1 ), a new secoiridoid, as well as seven compounds never before isolated from nature: 4‐tert‐butyl‐2‐oxazolidinone ( 2 ), 3‐acetoxyindole ( 3 ), indole‐2‐carboxylic acid ( 4 ), benzocaine ( 5 ), 3‐acetylindole ( 6 ), butylparaben ( 7 ) and 2‐hydroxy‐3‐methoxybenzaldehyde ( 8 ), together with fifty other known compounds, have been isolated from the stem of Strychnos cathayensis. These compounds include twenty‐three alkaloids, twelve benzenoids, four steroids, three flavonoids, three iridoids, two triterpenoids, two secoiridoids, two fatty acids, one lignan, one acetophenone, one coumarin, one chromane, one tetraterpenoid, one tannin, and one organic acid. The structures of these compounds were determined by means of spectralanalyses.     

The constituents of the root and stem of Aristolochia cucurbitifolia Hayata and their biological activity

Four new compounds, three phenanthrene derivatives, aristolochic acid-III methyl ester (1), cepharanone C (2), and sodium 7-hydroxyl-8-methoxyaristolate (3), and the benzoate derivative, sodium 3,4-dimethoxybenzoate (4), together with 53 known compounds were isolated and characterized from the fresh root and stem of Aristolochia cucurbitifolia. Their structures were elucidated by spectral analyses and chemical transformations. The cytotoxicity and antiplatelet activity of the isolated compounds are also discussed.     

Antiangiogenic Activity and Bioassay‐guided Isolation of Aqueous Extract of Orthosiphon stamineus

Orthosiphon stamineus Benth. (Family: Lamiaceae), a famous traditional medicinal plant in tropical and sub‐tropical region, is being used for treating various ailments including inflammatory conditions. Since anti‐inflammation and antiangiogenesis involve cyclooxygenase‐II pathway, the present study is aimed to carry out antiangiogenic studies and bioassay‐guided isolation on aqueous extract of the plant. After antiangiogenic activity studies on the extract, fractions were prepared by partitioning the extract with hexane, chloroform and ethyl acetate, which were then evaluated for antiangiogenic activity. The most active, hexane fraction (HF) upon activity‐guided isolation gave three compounds, 1 (betulinic acid), 2 (oleanolic acid) and 3 (ursolic acid). The total contents of these three compounds were determined in the extract and its fractions using HPLC. The extract and HF exhibited 20% and 80% antiangiogenic activity, respectively, whereas, chloroform and ethyl acetate fractions were inactive. The three isolated compounds exhibited 100% antiangiogenic activity. Median effective concentrations (EC_50s) of HF, 1, 2 and 3 were found to be 84, 32, 34 and 38 μg/mL, respectively. The results of this study indicate that hexane fraction and the isolated compounds have promising antiangiogenic activity. Additionally, the isolated compounds may be sued as analytical markers to standardize extracts and formulations prepared from O. stamineus.     

Chemical constituents of Prangos tschiniganica; structure elucidation and absolute configuration of coumarin and furanocoumarin derivatives with anti-HIV activity.

The methanol extract of the dried aerial parts of Prangos tschimganica gave three new coumarin derivatives and 30 known coumarin derivatives. Their structures were established on the basis of chemical and spectroscopic evidence. Absolute configuration of the isolated compounds were determined by using a modified Mosher's method. Some of the isolated compounds showed anti-HIV activity.     

Sesquilignans and dilignans from Campylotropis hirtella (Franch.) Schindl

A new sesquilignan, erythro-Guaiacylglycerol-beta-O-4'-(5')-methoxylariciresinol, together with six known compounds including three sesquilignans and three dilignans, have been isolated from Campylotropis hirtella (Franch.) Schindl. that was used as traditional Chinese medicine for treatment of benign prostate hyperplasia. All these known compounds were found for the first time from the family leguminosae. The structure of the new compound and its relative configurations were elucidated on the basis of detailed spectroscopic analysis (NMR and MS). These compounds showed no obvious inhibition effect on prostate specific antigen secretion in LNCaP cells by ELISA method.     

Antioxidative flavanone glycosides from the branches and leaves of Viscum coloratum

Two new flavanone glucosides, (2S)-homoeriodictyol 7,4'-di-O-beta-D-glucopyranoside (4) and (2R)-eriodictyol 7,4'-di-O-beta-D-glucopyranoside (5) were isolated from the branches and leaves of Viscum coloratum (KOMAR) NAKAI (Loranthaceae), along with three known flavanone glucosides: (2S)-homoeriodictyol 7-O-beta-D-glucopyranoside (1), (2S)-eriodictyol 7-O-beta-D-glucopyranoside (2), and (2S)-naringenin 7-O-beta-D-glucopyranoside (3). The structures of these compounds were elucidated using spectroscopic methods. The antioxidant activities of these isolated compounds were evaluated by colorimetric methods based on their scavenging effects on hydroxyl radicals and superoxide anion radicals, respectively. All the compounds showed potent albeit varied degrees of antioxidative activities and the structure-activity relationship is discussed.     

Studies on the constituents of the leaves of Baccharis dracunculifolia (Asteraceae) and their cytotoxic activity

A new sesquiterpene, named baccharisketone (1), and a new monoterpene, p-methoxythymol acetate (2), were isolated from the leaves of Baccharis dracunculifolia along with seventeen known compounds (3-19). The structures of the new compounds were determined by spectroscopic means. The growth inhibitory activity of the isolated compounds against leukemia cells (L 1210) was tested and three terpene phenols (4, 6, 17) and five sesquiterpene alcohols (8, 10, 11, 13, 16) were found to exhibit strong cytotoxic activity.     

Spectrometric analysis,phenolics isolation and cytotoxic activity of <Emphasis Type="Italic">Stipagrostis plumosa</Emphasis> (Family Poaceae)

Grasses (family Poaceae) are economically important plants; they are used as crops and animal foods. Stipagrostis plumosa (L.) Munro ex T. Anderson is a member of this family and subjected to chemical and biological studies. The chromatographic techniques,  LC–ESI–MS and GC/MS were used for identification of polar and non-polar compounds in its extract. Ten compounds, including one new flavone glycoside; tricin 7-O-galactoside, three known flavones, three C-glycosyl flavones and three phenolic acids, were isolated from S. plumosa for the first time except tricin. Their structures were elucidated on the basis of extensive spectroscopic interpretation. In addition to the isolated compounds, eleven compounds were tentatively identified using LC–ESI–MS, five of them were detected for the first time from this species. 29 non polar compounds were identified using GC–MS analysis, representing 83.13% of S. plumosa diethyl ether extract. In addition to the DPPH activity evaluation, the crude extract and the isolated compounds were investigated against five human carcinoma cell lines; A549, HCT-116, HepG2, MCF-7 and PC3 at a concentration of 100 μg/ml. From the isolated compounds tricin and luteolin 6,8-di-C-glucoside could be considered as natural-free radical scavenging agents.     

A new xanthone from Hedychium gardnerianum

A new xanthone (2), 3-(2-hydroxyethoxy)xanthone, and three known compounds, 1-hydroxyxanthone, salicylic acid and the sesquiterpene oplopanone, were isolated for the first time from the rhizomes of Hedychium gardnerianum Rosc. The structures of these compounds were elucidated on the basis of detailed spectral analysis, including 2D NMR experiments.     

Three hydroxylated lupeol-based triterpenoid esters isolated from the Eastern Nigeria mistletoe parasitic on Kola acuminata

Column fractionation and purification of an n-hexane fraction led to the isolation of three lupeol-based triterpenoid esters from the leaves of the Eastern Nigeria mistletoe, Loranthus micranthus Linn parasitic on a local kola nut tree, Kola acuminata. These three compounds were adequately characterised using a combination of UV/visible, IR, NMR (13C-NMR and 1H-NMR), DEPT, MS and two-dimensional correlation (H-H COSY, Hetero-nuclear Single Quantum Correlation (HSQC), HMBC, NOE and NOESY) studies as 7β,15α-dihydroxyl-lup-20(29)-ene-3β-esters of palmitic (I), stearic (II) and eicosanoic acids (III). The characterisation of other isolated compounds is ongoing. Remarkably, this is the first report of the existence of fatty acid esters of an unusual 7β,15α-dihydroxylated lupeol in the Eastern Nigeria mistletoe. These isolated compounds might contribute in part to the numerous established bio-activities of the Eastern Nigeria mistletoes.     

Three New ent‐Labdane Diterpenoids from the Wood of Excoecaria agallocha Linn.

An extensive study of metabolites present in Excoecaria agallocha Linn . led to the isolation of three new ent‐labdane‐type diterpenoids, named agallochaexcoerins A–C ( 1 – 3 ), besides three known compounds. The skeleton present in compound 1 is rather unusual, containing of a seven‐membered lactone. The structures were elucidated on the basis of spectroscopic studies and comparison with known related compounds. The isolated compounds 1 – 6 were not active against Raw 264.7 (macrophage‐like), K 562 (leukemia), and COLO 205 (colon) human carcinoma cell lines.     

Tri-nordammarane triterpenoids and neoclerodane diterpenoids from Salvia aspera (Labiatae)

From the aerial parts of Salvia aspera one new tri-nordammarane named amblyol (1) was isolated besides amblyone (2). An X-ray analysis was performed on compound 1. In addition, three known neoclerodane diterpenoids were also isolated. The structures of these compounds were established by spectral and chemical methods. The presence of dammarane triterpenoids in a Mexican Salvia is described for the first time.