Antibacterial, partially acetylated oligorhamnosides from Cleistopholis patens

Three new (1-3) and five known (4-8) partially acetylated oligorhamnoside derivatives were obtained from Cleistopholis patens via high-throughput natural products chemistry procedures. The rapid structure elucidation and dereplication were performed primarily utilizing a capillary-scale NMR probe and LR-/HRESIMS spectroscopic methods. Compounds 1, 2, and 6 were found to possess significant in vitro antibacterial activity against the Gram-positive bacteria methicillin-resistant Staphylococcus aureus ATCC 33591 and S. aureus 78-13607A with MICs of < or =16 microg/mL. Furthermore, 2 and 6 were found to show significant in vitro antibacterial activity against an expanded panel of Gram-positive pathogens including either ATCC strains or well-characterized clinical isolates from the global SENTRY Antimicrobial Surveillance Program.     

Novel biflavonoids from the stem bark of Ochna integerrima

Two new biflavonoids, namely, 6'"-hydroxylophirone B (1) and 6'"-hydroxylophirone B 4"'-O-beta-glucoside (2), were isolated from the stem bark of Ochna integerrima, together with five known compounds. The structures of 1 and 2 were determined by spectral data interpretation.     

Glycosides from the stem bark of Fraxinus sieboldiana

A norditerpene glucopyranoside with a novel carbon skeleton (1), eight new aromatic glycosides (2-9), and 25 known glycosides have been isolated from a H2O-soluble portion of an ethanolic extract of the stem bark of Fraxinus sieboldiana. Their structures were determined by spectroscopic and chemical methods. Based on analysis of the NMR data of threo- and erythro-arylglycerols in different solvents, an application of Delta delta C8-C7 values to distinguish threo-arylglycerol and erythro-arylglycerol isomers was proposed. In the in vitro assays, compound 5 displayed TNF-alpha secretion inhibitory activity with an IC50 value of 1.6 microM, compound 6 showed antioxidative activity inhibiting Fe+2-cystine-induced rat liver microsomal lipid peroxidation with an IC50 value of 0.9 microM, and plantasioside (10) showed selective activity against the human colon cancer cell line (HCT-8) with an IC50 value of 3.4 microM.     

Furanocembranoids from the stem bark of Croton oblongifolius

Four novel furanocembranoids (1-4) were isolated from the stem bark of Croton oblongifolius. Their structures were elucidated on the basis of spectroscopic analysis, mainly NMR and MS. Compounds 1, 3, and 4 exhibited good cytotoxicity against several human tumor cell lines.     

Cytotoxic lignans from the stem bark of Magnolia officinalis

Three new lignans, 4'-methoxymagndialdehyde ( 1), 4'-methoxymagnaldehyde B ( 2), and 4'-methoxymagnaldehyde E ( 3), were isolated from hexane- and EtOAc-soluble fractions of the stem bark of Magnolia officinalis, together with eight known compounds ( 4- 11). The structures of compounds 1- 3 were determined on the basis of spectroscopic and physicochemical data analysis. Compounds 1- 11 were tested in vitro for their cytotoxic activity against the K562, HeLa, and A549 cancer cell lines. Among the compounds tested, compound 1 showed the most potent cytotoxic activity against these cancer cell lines, with IC50 values of 3.9, 1.5, and 3.7 microg/mL, respectively.     

Tigliane diterpenoids from the stem bark of Neoboutonia macrocalyx

Neoboutonia macrocalyx is a plant used by traditional healers among the Meru community in Kenya. Chromatographic fractionation of the petroleum ether and dichloromethane extracts of this plant yielded one known (1) and three new tigliane-type diterpenoids (2-4). The chemical structures of the isolated compounds were established through spectroscopic data interpretation.     

Isoprenylated flavonoids from the stem bark of Erythrina abyssinica

Three new prenylated flavanones, abyssinoflavanones V, VI, and VII (1-3), together with eight known flavanones (4-11) and two chalcones (12-13), were isolated from the stem bark of Erythrina abyssinica. Their structures were elucidated on the basis of spectroscopic and physicochemical analyses. All the isolates, with the exception of 1 and 8, strongly inhibited PTP1B activity in an in vitro assay with IC50 values ranging from 14.2 +/- 1.7 to 26.7 +/- 1.2 microM.     

Bioactive oligostilbenoids from the stem bark of Hopea exalata

Hopeanolin (1), an unusual resveratral trimer with an ortho-quinone nucleus, was isolated and characterized from the stem bark of Hopea exalata. Also obtained were six known stibenoids, shoreaphenol (2), vaticanol G (3), alpha-viniferin (4), pauciflorol A (5), vaticanol A (6), and trans-3,5,4'-trihydroxystilbene 2-C-glucoside (7). The structure of 1 was determined by spectroscopic data interpretation. Compounds 1-7 were tested for antifungal activity and inhibitory effects against jack bean urease. Hopeanolin (1) demonstrated antifungal activity in the MIC value range 0.1-22.5 microg/mL.     

Taxane diterpenoids from the stem bark of Taxus mairei

Three new 11(15-->1)-abeo-taxanes, taxumairols U-W (1-3), have been isolated from extracts of the stem bark of Formosan Taxus mairei. The structures of 1-3 were identified as 5alpha,7beta,9alpha,13alpha,20-pentaacetoxy-2alpha,10beta,15-trihydroxy-11(15-->1)-abeo-taxene, 5alpha,7beta,9alpha,20-tetraacetoxy-2alpha,10beta,13alpha,15-tetrahydroxy-11(15-->1)-abeo-taxene, and 2alpha,4alpha,7beta,10beta-tetraacetoxy-5beta,20-epoxy-9alpha,13alpha,15-trihydroxy-11(15-->1)-abeo-taxene, respectively, on the basis of 2D NMR techniques including COSY, HSQC, HMBC, and NOESY experiments as well as chemical reactions of compounds 1-3 to give 4 (5alpha,7beta,9alpha,10beta,13alpha,20-hexaacetoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene) and 5 (4alpha,7beta,10beta-triacetoxy-9alpha,13alpha-dibenzoxy-5beta,20-epoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene), which are also novel taxane derivatives. Taxumairols U (1) and V (2) exhibited significant cytotoxicities against human hepatoma tumor cells, while taxumairol W (3) was inactive.     

刺桐化学成分的研究

目的研究刺桐E ry thrina varieg a ta茎皮的化学成分。方法采用硅胶、Sephadex LH-20柱色谱分离化合物,运用波谱技术分析确定化学结构。结果从刺桐茎皮65%乙醇提取物的醋酸乙酯萃取层中分离得到9个化合物,利用理化性质及波谱分析确定其结构分别为:5,4′-二羟基-8-(3,3-二甲基烯丙基)-2,″2″-二甲基吡喃[5,6∶6,7]异黄酮(Ⅰ)、豆甾醇(Ⅱ)、erythrinas inate B(Ⅲ)、3-羟基-2,′2′-二甲基吡喃[5,6∶9,10]紫檀烷(Ⅳ)、5,7-二羟基-8-(3,3-二甲基烯丙基)-二氢黄酮(Ⅴ)、5,4′-二羟基-2,″2″-二甲基吡喃[5,6∶6,7]异黄酮(Ⅵ)、5,7,4′-三羟基-6,8-二(3,3-二甲基烯丙基)异黄酮(Ⅶ)、5,2,′4′-三羟基-8-(3,3-二甲基烯丙基)-2,″2″-二甲基吡喃[5,6∶6,7]异黄酮(Ⅷ)、5,4′-二羟基-6-(3,3-二甲基烯丙基)-2,″2″-二甲基吡喃[5,6∶7,8]异黄酮(Ⅸ)。结论化合物Ⅰ、Ⅲ、Ⅳ、Ⅶ、Ⅸ为首次从该植物中分离得到,化合物Ⅴ为首次从该属植物中分离得到。     

黄瑞香茎皮的化学成分研究

目的研究黄瑞香Daphne giraldii茎皮的化学成分。方法采用液-液萃取和硅胶柱色谱对黄瑞香茎皮乙醇提取物中的成分进行分离纯化,利用核磁共振和质谱等方法确定化合物的结构。结果从乙醇提取物中分离得到7个化合物,核磁和质谱等光谱数据分析确定其分别为E-咖啡酸十八碳醇酯(Ⅰ)、( )-nortrachelogenin(Ⅱ)、西瑞香素(Ⅲ)、daphneticin(Ⅳ)、7,8-二羟基香豆素(Ⅴ)、7-羟基香豆素(Ⅵ)和木犀草素(Ⅶ)。结论化合物为新化合物,化合物Ⅱ、Ⅳ和Ⅻ为首次从该植物中分离鉴定。     

Antibacterial steroid alkaloids from the stem bark of Holarrhena pubescens

Holarrhena pubescens (syn. H. antidysenterica) (L.) WALL. stem bark was tested for antibacterial efficacy against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa using the microdilution broth method as well as the disc diffusion method. The crude methanolic extract was active against all tested bacteria. Further chemical fractionation indicated that the antibacterial activity was mainly associated with the alkaloids. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for the crude extract, the total alkaloids and the neutral fraction using microdilution broth method. The results were compared with reference antibiotics. The total alkaloids showed remarkable activity against S. aureus (MIC = 95 microg/ml).     

An antifungal constituent from the stem bark of Butea monosperma

The petroleum and ethyl acetate extracts of the stem bark from Butea monosperma displayed antifungal activity against Cladosporium cladosporioides. The active constituent of low polarity was isolated by bioassay-monitored chromatographic fractionation, and identified as (-)-medicarpin by comparison of physical data. The antifungal activity of (-)-medicarpin was found to be greater than that of Benlate, a standard fungicide, while (-)-medicarpin acetate also exhibited significant activity against C. cladosporiodes.     

Antimalarial 4-phenylcoumarins from the stem bark of Hintonia latiflora

The EtOAc extract of the stem bark of Hintonia latiflora showed the suppression of total parasitemia and the chemosuppression of schizont numbers, when tested in vivo against Plasmodium berghei infection in mice. Bioassay-directed fractionation of the EtOAc extract, using the in vitro 16 h and the in vivo 4-day suppression tests on P. berghei schizont numbers, led to the isolation of the new compound 5-O-beta-D-glucopyranosyl-7,4'-dimethoxy-3'-hydroxy-4-phenylcoumarin (1), along with the known 5-O-beta-D-glucopyranosyl-7-methoxy-3',4'-dihydroxy-4-phenylcoumarin (2). The structure of compound 1 was established on the basis of spectroscopic data interpretation. Compounds 1 and 2 suppressed the development of P. berghei schizonts in vitro with IC50 values of 24.7 and 25.9 microM, respectively. Compound 2 suppressed the development of schizonts at the dose of 40 mg/kg by 70.8% in the in vivo assay.     

Acylated triterpenoid saponins from the stem bark of Foetidia africana

Nine new acylated triterpenoid saponins (4-12) were isolated from the stem bark of Foetidia africana. They all possess barringtogenol C as the aglycone, esterified by acetic and/or isovaleric acids. The sugar chain consists of up to three units: D-glucuronic acid (GlcUA) linked to C-3 of the aglycone and substituted by D-galactose (Gal) (at GlcUA C-2) and/or L-rhamnose (Rha) (at GlcUA C-4). The structures were established by acid and alkaline hydrolysis, by NMR experiments including (1)H-(1)H (COSY, HOHAHA, ROESY) and (1)H-(13)C (HSQC, HMBC) spectroscopy, and by mass spectrometry (ESIMS, ESIMS(n)).     

Potential antitumor-promoting diterpenoids from the stem bark of Picea glehni

A novel rearranged labdane-type diterpenoid, 19(4-->3)abeo-8alpha, 13(S)-epoxylabda-4(18),14-diene (1), and two new abietane-type diterpenoids, 19-nor-abieta-4(18),8,11,13-tetraen-7-one (2) and 12-hydroxydehydroabietic acid (3) were isolated from the stem bark of Picea glehni, together with seven known diterpenoids-13-epimanoyl oxide (4), dehydroabietic acid (5), (11E)-14, 15-bisnor-8alpha-hydroxy-11-labden-13-one (6), abieta-8,11, 13-trien-7-one (7), 9alpha,13alpha-epidioxyabiet-8(14)-en-18-oic acid (8), 9,10alpha-epoxy-9,10-seco-abieta-8,11,13-trien-18-oic acid (9), and methyl 15-hydroxy-7-oxo-dehydroabietate (10). Compounds 5-8 and 10 showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate.     

Antiplasmodial compounds from Cassia siamea stem bark extract

Cassia siamea L. (Fabaceae) was identified from the southwest Nigerian ethnobotany as a remedy for febrile illness. This led to the bioassay-guided fractionation of stem bark of the plant extract, using the parasite lactate dehydrogenase assay and multi-resistant strain of Plasmodium falciparum (K1) for assessing the in vitro antimalarial activity. Emodin and lupeol were isolated from the ethyl acetate fraction by a combination of chromatographic techniques. The structures of the compounds were determined by spectroscopy, co-spotting with authentic samples and comparison with literature data. Both compounds were found to be the active principles responsible for the antiplasmodial property with IC(50) values of 5 microg/mL, respectively.     

金刚纂二萜类成分研究

目的研究有毒药用植物金刚纂Euphorbia neriifolia茎皮的二萜类化学成分及其抗HIV-1活性。方法利用硅胶、ODS、MCI CHP-20P、Sephadex LH-20等柱色谱和高效液相色谱技术进行系统分离,通过理化性质和NMR、MS波谱数据鉴定化合物结构;采用HIV-1病毒株NL4-3感染的人淋巴MT-4细胞作为细胞检测模型对所得化合物进行抗HIV-1活性测试。结果从金刚纂茎皮的丙酮水提取物的醋酸乙酯萃取部分分离得到9个二萜类化合物,分别被鉴定为12α-乙酰氧基-3β,7α-二羟基-8α-甲氧基续随子烷(1)、3β,8α,12α-三乙酰氧基-7α-苯甲酰氧基续随子烷(2)、3β,8α,12α-三乙酰氧基-7α-巴豆酰氧基续随子烷(3)、对映-3-氧代阿替生烷-16α,17-缩丙酮(4)、13β-羟基-3,15-二氧代阿替生烷-16-烯(5)、对映-3β,(13S)-二羟基阿替生烷-16-烯-14-酮(6)、3β,13(S)-二羟基阿替生烷-16-烯-14-酮(7)、对映-(13S),18-二羟基阿替生烷-16-烯-3,14-二酮(8)、4,13β-二羟基-14-氧代-3,4-开环阿替生烷-16-烯-3-酸甲酯(9)。结论化合物1为新天然产物,化合物2~4、6~8为首次从该植物中分离得到,药理实验结果表明化合物4具有一定的抗HIV-1活性,EC50为8.7μg/m L(SI=1.92)。     

了哥王中的1个新双香豆素

目的:研究了哥王茎皮的化学成分。方法:通过硅胶、ODS柱色谱分离化合物,利用质谱、核磁共振等现代波谱技术鉴定化合物结构。结果:分离鉴定了7个化合物,分别鉴定为西瑞香素(Ⅰ)、5,7,4′-三羟基-3′,5′-二甲氧基黄酮(Ⅱ)、胡萝卜苷(Ⅲ)、β-谷甾醇(Ⅳ)、伞形花内酯(Ⅴ)、芫花素(Ⅵ)、6-′OH,7-O-7′-双香豆素(Ⅶ)。结论:化合物Ⅶ为新化合物,化合物Ⅲ,Ⅴ为首次从该植物中分离得到。