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The new flavonol trioside, isorhamnetin 3-O-4Rham-galactosylrobinobioside and five known flavonol glycosides, isorhamnetin 3-robinobioside, isorhamnetin 3-rutinoside, isorhamnetin 3-galactoside, isorhamnetin 3-glucoside and free isorhamnetin were isolated from the leaves and young stems of Nitraria retusa and characterized by UV and NMR spectroscopy. Isorhamnetin 3-xylosylrobinobioside was also tentatively identified.
A new phenolic glycoside, asterbatanoside A [p-hydroxyacetophenone-4-O-beta-D-xylopyranosyl-(1-->6)-beta-D- glucopyranoside], and two new triterpenoid saponins, asterbatanoside B [2 alpha,3 beta,23-trihydroxyolean-12-en-28-oic acid-28-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] and asterbatanoside C [3-O-beta-D-glucopyranosyl-2 beta,3 beta,23-trihydroxyolean- 12-en-28-oic acid-28-O-beta-D-glucopyranoside] were isolated from the roots of Aster batangensis. Their structures were determined by spectroscopic methods and chemical evidence. The total synthesis of asterbatanoside A is also reported.
From the seeds of Trifolium alexandrinum, two new oleanene-type triterpene glycosides were isolated as their methyl esters, together with five known saponins. The structures of the isolated compounds were determined by NMR and mass spectral analyses.
A new acetophenone glycoside, affinoside, was isolated from the aerial parts of Exacum affine and its structure was determined as 2-O-primeverosylpaenol. The known glucosides, gentiopicroside, 2'-O-E/Z-p-coumaroylloganin and glucopaeonol, were also identified.
From the mesocarp of Balanites aegyptiaca fruits, two pregnane glycosides were isolated. One is new and identified as pregn-5-ene-3 beta,16 beta,20(R)-triol 3-O-(2,6-di-O-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside (balagyptin), while the other is known and assigned as pregn-5-ene-3 beta,16 beta,20(R)-triol 3-O-beta-D-glucopyranoside.
Two new triterpenes, alpha- and beta-kudinlactone, and six new triterpenoid glycosides, kudinosides D-G, I and J, were isolated from the leaves of Ilex kudincha. Their structures have been elucidated by spectroscopic and chemical means.
In addition to solamargine, isoanguivine and solasonine, two new steroid alkaloid glycosides, xylosylsolamargine and xylosyl-beta-solamarine, have been isolated from the aerial parts of Solanum coccineum, the structures of which have been elucidated as (25R)-3 beta-[O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-rhamnopyranosyl- (1-->4)-O-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranosyloxy+ ++]-22 alpha N-spirosol-5-ene and (25S)-3 beta-[O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-rhamnopyranosyl- (1-->4)-O-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranosyloxy+ ++]-22 beta N-spirosol-5-ene.
From the bark of Meliosma lanceolate, nine triterpenoid glycosides including the 28-O-beta-D-glucopyranosyl ester of bayogenin-3-O-beta-D-glucuronopyranoside, its 4'-O-beta-D-galactopyranoside and 4'-O-alpha-L-arabinopyranoside were isolated and the structures characterized along with that of 28-O-beta-D-glucopyranosyl-bayogenin-3-O-beta-D-4'-anhydro-4', 5'-didehydroglucuronopyranoside. Bisdesmosidic triosides of hederagenin were obtained as minor components.
Two pregnane ester glycosides were isolated and identified from the alcohol extract of the aerial parts of Caralluma retrospiciens. Their structures were established as 12 beta-benzoyloxy-20-isovaleroyloxy-8 beta,14 beta-dihydroxypregnane-3-O -[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl -(1-->4)-beta-D-(3-O-methyl-6-deoxy)-galactopyranoside] (caretroside A) and the bioside 12 beta-benzoyloxy-8 beta,14 beta-dihydroxypregn-20-one-3-O-[beta -D-oleandropyranosyl-(1-->4)-beta-D-cymaropyranoside]. They were characterized through physical and chemical methods in addition to standard spectroscopic techniques especially 2D NMR (COSY, HMQC and HMBC). This is the first report of the isolation of these compounds from a natural source.
The beta-D-glucoside, gentiobioside and 6-O-alpha-L-arabinosyl-beta-D-glucoside of benzyl alcohol, androsin and a new simple aliphatic glycoside, isopentylgentiobioside, have been found in the cell cultures of Lycopersicon esculentum. Their structures were elucidated from chemical and spectroscopic evidence.
The effect of palytoxin (PTX) on compound resting potential and compound action potential of frog sciatic nerve was studied using the sucrose-gap technique. PTX irreversibly depolarized the compound resting potential and reduced the amplitude of the compound action potential. PTX evoked a marked depolarization when extracellular Na+ was replaced by Li+, Cs+ and the organic cations methylammonium, hydroxylammonium, and methylhydroxylammonium but not by tetramethylammonium, tetraethylammonium, choline or the divalent cations, Ca2+ and Ba2+. The maintained depolarization was not sensitive to inhibition by saxitoxin (300 nM) or procaine (10 mM). The depolarization was inhibited by ouabain or cymarin but not by the aglycon, strophanthidin. However, strophanthidin did antagonize the inhibitory action of cymarin which suggests that PTX and cardiac glycosides do not share an identical binding site but there may be some overlap. We conclude that in frog sciatic nerve, PTX interacts with the (Na+-K+) pump to induce the opening or formation of a relatively non-selective cation pore within or near the pump protein.
Crude glycoside extracts from the plant, Sarcolobus globosus, were tested on the rat phrenic nerve-diaphragm, chick biventer cervicis and frog rectus abdominis preparations. Nerve-stimulated twitches were inhibited by the extract. The muscle paralysis was not similar to that by curare-like blockers as it was not reversed by neostigmine or by a tetanus. Although contractures to acetylcholine or carbachol were not affected by 0.6 mg/ml of the extract, higher concentration of the extracts (3 mg/ml) depressed the log dose-response curve of acetylcholine and carbachol. The results suggest that the neuromuscular blocking effect of the extracts is either dose-dependent or due to a mixture of toxins with presynaptic or postsynaptic actions.
Over 70 naturally occurring and synthetic flavonoids were screened for mutagenicity with 5 tester strains in the Salmonella/mammalian microsome assay: TA1535, TA100, TA1537, TA1538 and TA98. Frameshift mutagenicity was confined to the flavonols (flavon-3-ols) in strain TA98, TA1537 and TA100. The two most mutagenic falvonols, namely, quercetin (3,3',4',5,7-pentahydroxyflavone) and kaempferol (3,4',5,7-tetrahydroxyflavone), exhibiting 12 and 7 revertants/nmol in TA98 respectively, are also the most common flavonols occurring in plants. Other flavonols exhibited less activity (revertants/nmol): galangin (2.0), rhamnetin (0.45), kaempferide (0.24), fisetin (0.14), myricetin (0.12), robinetin (0.06) and morin (0.05). All of these flavonols apparently exhibited significant activation by Aroclor 1254 induced rat-liver microsome preparations (S9). However, subsequent study revealed that only those flavonols either lacking or possessing one B ring hydroxyl group had an absolute requirement for microsomal activation. Alternatively, quercetin with two B-ring OH groups is not activated by microsomal enzymes, but by soluble (S100) enzymes from liver which are apparently constitutive and not subject to the usual chemical induction. 3 flavonol glycosides, namely, quercetrin (quercetin-3-O-rhamnoside), rutin (quercetin-3-O-rutinoside) and robinin (kaempferol-3-O-galactosido-rhamnoside-7-O-rhamnoside), were found to be nonmutagenic. They could, however, be activated by a variety of mixed glycosidases incorporated in the usual pour plate procedure. The most effective enzyme mixtures were obtained from rat cecal bacteria and from the snail Helix pomatia.
Complexes of Con A with alpha-D-glycosides were studied using 1H-NMR, ESR and fluorescence methods. Correlation times, tau c, for the interaction of the aglycon protons with the manganese ion, present at the S1 site of the protein, were calculated from T1 measurements at two frequencies. The protons of aromatic aglycons have tau c values comparable to the rotational correlation time of the protein molecule, whereas those of non-aromatic aglycons have tau cs 10 to 100 times lower. The correlation times were combined with the experimentally acquired paramagnetic contributions to proton relaxation due to the presence of the manganese ion to yield manganese-proton distances. These distances show that aromatic aglycons have additional favorable contacts with the protein which stabilize the lectin-saccharide interaction. The results are compared to the crystal structure of the methyl alpha-D-glycopyranoside complex with Con A and to models earlier proposed for the binding of monosaccharides to Con A.
Cassava is a staple food for 450-500 million people in 26 tropical countries. Groups of pregnant hamsters were fed diets consisting of cassava meal:laboratory chow (80:20) during Days 3-14 of gestation. One low cyanide (sweet) cassava meal and one high cyanide (bitter) cassava meal were studied. One additional group was fed a diet which resembled cassava in nutritional value, but which lacked the cyanogenic glycosides. Thiocyanate concentrations increased significantly in the urine and blood of dams fed cassava diets. Increased tissue thiocyanate concentrations were observed in fetuses recovered from cassava-fed dams. Cassava-fed dams gained significantly less weight than did control animals and their offspring showed evidence of fetotoxicity. Reduced fetal body weight and reduced ossification of sacrocaudal vertebrae, metatarsals, and sternebrae were associated with cassava diets. High cyanide cassava diets were also associated with a significant increase in the numbers of runts compared to litters from dams fed either low protein or laboratory stock diets.
A cream formulation containing high concentrations (10%) of a standard mixture of solasodine glycosides (BEC) has been shown to be effective in the treatment of malignant and benign human skin tumours. We now report that a preparation (Curaderm) which contains very low concentrations of BEC (0.005%) is effective in the treatment of keratoses, basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) of the skin of humans. In an open study, clinical and histological observations indicated that all lesions (56 keratoses, 39 BCCs and 29 SCCs) treated with Curaderm had regressed. A placebo formulation had no effect on a smaller number of treated lesions. Curaderm had no adverse effect on the liver, kidneys or haematopoietic system.
A study has been made of the association and the temperature-dependent conformation of adenosine 3',5'-monophosphate (cyclic AMP) in a neutral aqueous (2H2O) solution by means of proton magnetic resonance chemical shift and relaxation. The concentration and temperature-dependent chemical shifts of H(1'), H(2), and H(8), have enabled us to estimate the self-association constant, Ka = 1.1 +/- 0.3 M-1 at 25 degrees C and thermodynamic parameters delta H = -5.8 +/- 1.5 kcal/mol and delta S (25 degrees C) = -19.0 +/- 3 cal/mol per degree. The NMR-DESERT (Deuterium Substitution Effect on Relaxation Times) method has been utilized for the determination of the syn-anti conformational equilibrium in the monomeric state and for the determination of the mutual orientation of the two adenine rings in the dimeric state of cyclic AMP. The molecules were found to coexist with nearly equimolarity or syn-anti conformers and thermal activation of the molecules perturbs the syn-anti conformational equilibrium to comprise the syn form in preference at higher temperature. The glycosidic isomerization (from anti to syn) was found to be characterized both by a positive enthalpy change and by a positive entropy change. The cyclic AMP molecules prefer to take a 'trans-stacking' conformation in the dimeric state where the two molecules are arranged in such a way that the H(2) of one molecule is close to the H(8) of the other.
A hemolytic fraction has been obtained from fresh tubers of Momordica cochinchinensis. The fraction was strongly adsorbed on DEAE-Sepharose CL6B. It did not stain with Coomassie brilliant blue in SDS-polyacrylamide gel electrophoresis and it gave no immunoprecipitin arcs in immunoelectrophoresis. The hemolytic activity of the fraction was resistant to heat and proteolytic enzymes. The behavior of the fraction in thin-layer chromatography and its positive reaction in Liebermann-Burchard test indicated that the hemolytic activity of the fraction can be attributed to a steryl glycoside(s).
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