Pregnane and pregnane tetraglycoside from Marsdenia roylei.

Pregnane oligoglycoside, namely roylinine, and a pregnane derivative, namely marsgenin, have been isolated from chloroform-soluble extract of dried stem of Marsdenia roylei, and their structures were determined using ¹H-NMR, ¹³C-NMR, ¹H-¹H COSY, HSQC, TOCSY and FABMS spectral techniques as well as chemical degradation and derivatisation.

Inhibitory activity of four demethoxy fluorinated anthracycline analogs against five human-tumor cell lines.

Four anthracycline analogs synthesized in our laboratory were evaluated in comparison with adriamycin (doxorubicin) for their growth-inhibitory effect against five human-tumor cell lines, including lung carcinoma, colon adenocarcinoma, breast adenocarcinoma, melanoma, and glioblastoma. The compounds included 4-demethoxy-7-O-(2,6-dideoxy-2-fluoro--l-talopyranosyl)daunomycinone (2), its 3',4'-diacetate (1), its 14-bromo derivative 3, and its 14-hydroxy analog, namely 4-demethoxy-7-O-(2,6-dideoxy-2-fluoro-α-l-talopyranosyl)adriamycinone (4). Compounds 1, 2, and 3 showed moderate cytotoxic effect in most of the cell lines, while compound 4 had a strong effect, comparable to or better than that of adriamycin in most of the cell lines.

Two pregnane oligoglycosides from Marsdenia roylei.

The structure of pregnane oligoglycosides, namely rocinine (1) and marsdinine (11), which have been isolated from the chloroform soluble extract of the dried stem of Marsdenia roylei, were elucidated using MS, (1)H NMR, (13)C NMR, (1)H-(1)H COSY, HSQC and TOCSY experiments as well as chemical degradation and derivatisation.

Synthesis of the trisaccharide repeating unit related to Klebsiella 012 serotype.

Synthesis of the trisaccharide, allyl α-l-rhamnopyranosyl-(1→3)-2-acetamido-2-deoxy-ß-d-glucopyranosyl-(1→4)-α-l-rhamnopyranoside related to O-chain glycans isolated from the deaminated LPSs of Klebsiella pneumoniae serotype 012, was achieved through condensation of suitably synthesized disaccharide, allyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-ß-d-glucopyranosyl-(1→4)-2,3-di-O-benzoyl-α-l-rhamnopyranoside and donor, ethyl 2,3,4-tri-O-acetyl-1-thio α-l-rhamnopyranoside starting from l-rhamnose and d-glucosamine hydrochloride. The trisaccharide can be utilized for the synthesis of neoglycoconjugates for use as a synthetic vaccine by coupling it with a suitable protein after deprotection. Various regio- and stereoselective protecting group strategies have been carefully considered, as protecting groups can influence the reactivity of the electrophile and nucleophile in glycosylation reactions on the basis of steric and electronic requirements.

Optimization of a high-performance liquid chromatography method for the separation and identification of six different classes of phenolics.

Flavonoids are chemical moieties widely distributed in certain plants that are important biologically active constituents of a daily human diet, with significant pharmacological potential (anti-hepatotoxic, anti-allergic, anti-inflammatory, anti-osteoporotic, and anti-tumor activities). Thus keeping in view the importance of this class of compounds, a rapid method for the separation and identification of fifteen phenols belonging to six different types of phenolics in a sole analysis has been developed and validated using selectivity, precision, recovery, and robustness as parameters. The method developed, which is rapid, accurate, and robust for the analysis of different classes of phenols, can be used in the quality control and standardization of plant extracts as well as herbal drugs, including compound herbal formulations.

Anthracycline glycosides of 2,6-dideoxy-2-fluoro-alpha-L-talopyranose.

The methyl beta-glycoside of the title sugar, obtained from 2-deoxy-2-fluoro-beta-D-glucopyranose tetraacetate by a sequence with detailed characterization of all intermediates, was converted by acetolysis-bromination into 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl bromide, coupling of which with (7S,9S)-4-demethoxydaunomycinone afforded the 3,4-diacetate of 4-demethoxy-9-O-(2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl)daunomycinone (19). The antitumor-active 19 was converted by way of its 14-bromo derivative into the 14-hydroxy analogue, the antitumor-active 4-demethoxyadriamycinone glycoside 21.

Bi(OTf)3 and SiO2-Bi(OTf)3 as effective catalysts for the Ferrier rearrangement.

Bi(OTf)3 and SiO2-Bi(OTf)3 are found to effectively catalyze the Ferrier rearrangement of tri-O-acetyl glycals with different alcohols providing an effective route to 2,3-unsaturated O-glycosides with good anomeric selectivity and good to excellent yields after short reaction times.

Pregnanes and pregnane glycosides from Marsdenia roylei.

Two pregnanes namely desacylkondurangogenin C (1) and deniagenin (3, new) and two new pregnane glycosides designated as denin (5) and marsin (12) have been isolated from chloroform soluble extract of dried stem of Marsdenia roylei. Chemical and spectroscopic evidences are consistent with the structures of deniagenin, denin and marsin as 3beta, 11alpha, l2beta, 14beta, 17beta, 20-hexahydroxy pregn-5-ene; desacylkondurangogenin C-3-O-alpha-D-glucopyranosyl-(1-->4)-O-alpha-L-fucopyranoside and ketocalogenin-3-O-alpha-L-fucopyranoside, respectively.

Antifungal activity of the stem bark of Ailanthus excelsa.

The methanol extract of stem barks of Alianthus excelsa was partitioned with chloroform. The chloroform extract showed fungistatic and fungicidal activity against Aspergillus niger, A. fumigatus, Penicillium frequentence, P. notatum and Botrytis cinerea.

Quassinoids from Ailanthus excelsa.

Three quassinoids, 1, 2 and 3, 4-dihydro excelsin 3 were isolated from the stem bark of Ailanthus excelsa, along with five known quassinoids excelsin, glaucarubine, ailanthinone, glaucarubinone and glaucarubolone. The glaucarubolone has been isolated for the first time from this plant. The structural elucidation is based on the analysis of spectroscopic data.