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At least 271 records · Page 15Linked to original sources
PubMed2002

Synthesis of (-)-calicoferol B.

The first total synthesis of (-)-calicoferol B (III) is described. The cyclozirconation product I, prepared in enantiomerically pure form, was converted into the CD ring chiron II. This was coupled with the aromatic A-ring, and then the side chain was constructed with control of relative and absolute configuration to complete the total synthesis of III. The first total synthesis of (-)-calicoferol B (1) is described. The cyclozirconation product 8, prepared in enantiomerically pure form, was converted into the CD ring chiron 6. This was coupled with the aromatic A-ring, and then the side chain was constructed with control of relative and absolute configuration to complete the total synthesis of 1.

Aldehydes↗
PubMed2001

Furodysin lactone and pyrodysinoic acid, new sesquiterpenes from a Philippines Dysidea species.

Chemical investigation of a Dysidea sponge, collected at Siquijor, Philippines, has afforded two new sesquiterpenoid metabolites, which we have termed furodysin lactone (1) and pyrodysinoic acid (2). The known 3,6,11-trihydroxy-9,11-secoergostane-7,24(28)-dien-9-one (3) was also encountered. Structure elucidation of the isolated metabolites involved high-field 2-D NMR spectroscopy including (1)H-(1)H COSY, HSQC, and HMBC.

Animals↗
PubMed2004

Cytotoxic withaphysalins from the leaves of Acnistus arborescens.

Three withaphysalins, rel-(17S,20R,22R)-5 beta,6 beta:18,20-diepoxy-4 beta-hydroxy-1,18-dioxowitha-2,24-dienolide(withaphysalin M) (1), rel-(17S,20R,22R)-5 beta,6 beta:18,20-diepoxy-4 beta-hydroxy-18-ethoxy-1-oxowitha-2,24-dienolide (withaphysalin F ethyl ether, withaphysalin O) (2), and rel-(17S,20R,22R)-5 beta,6 beta:18,20-diepoxy-4 beta-hydroxy-1,18-dioxowitha-24-enolide (withaphysalin N) (3), were isolated from the leaves of Acnistus arborescens. The structures were deduced from 1D ((1)H NMR, (13)C NMR, DEPT-(13)C NMR) and 2D (COSY, HMQC, HMBC) NMR analysis and the relative stereochemical assignments based on 1D NOESY correlations and analysis of coupling constants. Compounds 1 and 2 displayed potent cytotoxic activity against a panel of human cancer cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Physalins from Witheringia solanacea as modulators of the NF-kappaB cascade.

Crude extracts of Witheringia solanacea leaves showed inhibition of NF-kappaB activation at 100 microg/mL induced by phorbol 12-myristate-13-acetate (PMA) in HeLa cells stably transfected with a luciferase reporter gene controlled by the IL-6 promoter. Three physalins were isolated from an active fraction, namely, physalins B (1), F (2), and D (3). Of these compounds, 1 and 2 demonstrated inhibitory activities on PMA-induced NF-kappaB activation at 16 and 8 microM and induced apoptosis after 24 h in a cell-cycle analysis using a human T cell leukemia Jurkat cell line. Compound 2 also inhibited TNF-alpha-induced NF-kappaB activation at 5 microM through the canonical pathway, but was inactive in the Tet-On-Luc assay, indicating specificity of action, although it interfered with Tet-On-Luc at higher concentrations. It is suggested that the presence of a double bond and an epoxy ring between carbons 5 and 6 in compounds 1 and 2, respectively (which are not present in compound 3), are related to their anti-inflammatory activity.

Anti-Inflammatory Agents↗
PubMedDate not supplied

Potential antitumor agents. XVII. physalin B and 25,26-epidihydrophysalin C from Witheringia coccoloboides.

An investigation of Witheringia coccoloboides (Dammer) A. T. Hunziker [Capsicum fuscoviolaceum (Cufodontis) Mort. And Standl.] roots has resulted in the isolation of two cytotoxic compounds: physalin B (1) and a novel physalin, which was characterized by spectral analysis as 25,26-epidihydrophysalin C (2). Both compounds have demonstrated cytotoxic activity in 9KB and 9PS tumor cells (in vitro). Physalin B (1) has demonstrated moderate activity against the 3PS mouse leukemia (in vivo).

Animals↗
PubMedDate not supplied

Spectroscopic and biological investigation of nimbolide and 28-deoxonimbolide from Azadirachta indica.

The reisolation of nimbolide [1] from Azadirachta indica of Tanzanian origin and the isolation and structure elucidation of a new limonoid, 28-deoxonimbolide [2], from the same plant source are reported. For the first time, unambiguous 1H- and 13C-nmr assignments of compounds 1 and 2 are presented, as well as their in vitro cytotoxic activity against human tumor cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Antimalarial activity of tropical Meliaceae extracts and gedunin derivatives.

Extracts of 22 species of Meliaceae were examined for antimalarial activity using in vitro tests with two clones of Plasmodium falciparum, one sensitive to chloroquine (W2) and one chloroquine-resistant (D6). Twelve extracts were found to have activity, including extracts of Cedrela odorata wood and Azadirachta indica leaves, which contained the limonoid gedunin. These extracts were more effective against the W2 clone than the D6 clone, suggesting there is no cross-resistance to chloroquine. Gedunin was extracted in quantity, and nine derivatives prepared for a structure-activity study, which revealed essential functionalities for activity. The study also included four other limonoids derived from related Meliaceae. Only gedunin had better activity than chloroquine against the W2 clone. This active principle could be used to standardize a popular crude drug based on traditional use of A. indica in West Africa.

Animals↗
PubMed1997

Luffasterols A-C, 9,11-secosterols from the Palauan sponge Luffariella sp.

The Palauan sponge Luffariella sp. contained manoalide (6) and secomanoalide (7) as the major metabolites. The minor metabolites, luffasterols A-C (3-5) are 9,11-secosterols that contain a 3 beta-acetoxy-5 alpha,6 alpha-epoxy-9-oxo-9,11-secocholest-7-en-11-al ring system joined to three different side chains. The structures of the luffasterols were elucidated by interpretation of spectroscopic data.

Animals↗
PubMed1998

A bioactive secosterol with an unusual A- and B-ring oxygenation pattern isolated from an Indonesian soft coral Lobophytum sp.

A secosterol with a gorgosterol side chain and an unusual oxygenation pattern on the A and B rings was isolated from an Indonesian soft coral Lobophytum sp. The A and B rings of the reported compound 1 have hydroxyl groups at C-3 and C-7 and an epoxide ring at C-5-C-6. The structures of 1 was solved by 2D NMR methods and by chemical shift analogy to the known secogorgosterol 2. Compound 1 was found to have activity against human ovarian tumor and human leukemia cell lines.

Animals↗
PubMed2000

Two novel secoergosterols from the fungus Tylopilus plumbeoviolaceus.

Two novel secoergosterols, 3beta-hydroxy-8alpha,9alpha-oxido-8, 9-secoergosta-7,9(11),22-triene (tylopiol A) (1) and 3beta-hydroxy-8alpha,9alpha-oxido-8,9-secoergosta-7,22 -dien-12-one (tylopiol B) (2), were isolated from the fresh fruit bodies of Tylopilus plumbeoviolaceus, along with three known compounds, ergosta-7,22-dien-3beta-ol, uridine, and allitol. Their structures were elucidated by NMR techniques, including (1)H NMR, (13)C NMR, HMQC, HMBC, and MS. The structure and stereochemistry of compound 1 were demonstrated by X-ray crystallography.

Agaricales↗
PubMed1977

The substrate specificity and stereochemistry, reversibility and inhibition of the 3-oxo steroid delta 4-delta 5-isomerase component of cholesterol oxidase.

1. 5-Cholesten-3-one was shown to be an intermediate in the conversion of cholesterol into 4-cholesten-3-one by Nocardia cholesterol oxidase. 2. The absence of a C-17 side chain from 5-androstene-3,17-dione slightly increased the Vmax. of the isomerase activity relative to 5-cholesten-3-one (1.7-fold), but greatly increased the Km. 3. Incubations of [4alpha-2H]-and [4beta-2H]-cholesterol with cholesterol oxidase showed that the 4beta-hydrogen atom can be transferred to the 6beta-position. However, incubations of cholesterol, 5-cholesten-3-one and 4-cholesten-3-one with the enzyme in 2H2O led to some incorporation of 2H into the 4-cholesten-3-one products, mostly at position 6beta. 4. Both the isomerase and the oxidase activities of cholesterol oxidase were inhibited by 5,10-seco-19-nor-5-cholestyne-3,10-dione.

3-Hydroxysteroid Dehydrogenases↗
PubMed1987

Pseudomonas mutant strains that accumulate androstane and seco-androstane intermediates from bile acids.

Transposon mutant strains which were affected in bile acid catabolism were isolated from four Pseudomonas spp. Two of the mutant groups isolated were found to accumulate 12 alpha-hydroxyandrosta-1,4-diene-3,17-dione as the major product from deoxycholic acid. Strains in one of these two groups were able to grow on steroids such as chenodeoxycholic acid, which lacks a 12 alpha-hydroxy function, whereas the one member of the second group could not. With chenodeoxycholic acid, this latter strain accumulated a yellow muconic-like derivative, tentatively identified as 3,7-dihydroxy-5,9,17-trioxo-4(5),9(10)-disecoandrosta-1(10)2 -dien-4-oic acid. Members of two further mutant groups accumulated either 12 beta-hydroxyandrosta-1,4-diene-3,17-dione or 3,12 beta-dihydroxy-9(10)-secoandrosta-1,3,5(10)-triene-9,17-dione as the major product from deoxycholic acid. The relationship between the catabolism of m- and p-cresol, 3-ethylphenol and the bile acids was also examined.

Androstadienes↗