Search results for "compounds"
showing 10 items of 3372 documents
Morphogenesis in Root Tip Meristem Cultures of Digitalis obscura L.
1987
Summary The morphogenic capacity of Digitalis obscura L. root tip meristems cultured in vitro has been studied, noting hormonal factors inducing differentiation and development of shoots as well as those promoting somatic embryogenesis. Caulogenesis was obtained with different auxin/cytokinin combinations but a high rate of shoot regeneration was induced by 0.1 or 0.5 ppm IAA and 1.0 ppm BA. Different stages of somatic embryo development were observed in media supplemented with auxins or high auxin/cytokinin ratios, although no complete plant regeneration was achieved. This is the first report known of shoot regeneration from root tips of Digitalis obscura L.
Plant regeneration from cultured leaves of Lavandula latifolia Medicus: Influence of growth regulators and illumination conditions
1989
Leaves were obtained from 4-week-old seedlings of Lavandula latifolia Medicus grown in vitro. Leaf explants were then cultured on MS medium supplemented with different concentrations and combinations of the auxins IAA or NAA with the cytokinin BA and maintained under three illumination conditions, 16h photoperiod, darkness or darkness followed by a photoperiod, to assess morphogenic responses. Irrespective of illumination conditions, bud regeneration was achieved only in media containing BA or BA/auxin combinations, with the best results being obtained in the presence of BA and 0.06 or 0.6 μM IAA or NAA. A photoperiod of 16h appeared to yield the best response in terms of bud regeneration p…
Novel Porphyrin-Cholic Acid Conjugates as Receptors for Biologically Important Anions
2005
A series of novel receptors showing high binding affinity in aqueous media for biologically important anions are reported. These naturally chromophoric porphyrin-based receptors contain cholic acids connected via quaternary alkyl ammonium amido linkages.
An Uncommon Pathway in the Biosynthesis of Acetylenic Fatty Acids in Mosses
1995
Although more than 600 acetylenic compounds of various structures have been found in plants [1], hardly anything is known about the formation of the triple bonds. The acetylenes so far known from Bryophytes, have been identified as long chain fatty acids with a characteristic arrangement of one triple bond and one to three double bonds.
ChemInform Abstract: (S)-Proline Benzyl Ester as Chiral Auxiliary in Lewis Acid-Catalyzed Asymmetric Diels-Alder Reactions.
1989
Asymmetric Diels-Alder reaction of cyclopentadiene (I) with (S)-proline benzyl ester (II) yields a mixture of the diastereomeric cycloadducts (R)-(III) and (S)-(IV).
Dihydrodiol Dehydrogenase: An Important Enzyme in Dihydrodiol-Epoxide Pathway — Mediated Benzo(A)Pyrene Mutagenicity
1978
Benzo(a)pyrene is metabolized to two major groups of mutagenically reactive metabolites: Monofunctional epoxides and dihydrodiol-epoxides. Various monooxygenase forms catalyze the various pathways at very different rates. In metabolic situations where the contribution by dihydrodiol-epoxides is small, epoxide hydratase represents a very efficient protective system. However, in situations where the mutagenic effect is predominately due to dihydrodiol-epoxide, the effect of epoxide hydratase is complicated and weak. We have now obtained evidence that a dihydrodiol dehydrogenase represents an efficient protective system in the latter situation. The enyzme was purified to homogeneity and the pu…
Dihydrodiol Dehydrogenase: Substrate Specificity, Inducibility and Tissue Distribution
1982
The present study shows that: Dihydrodiol dehydrogenase activity is present in the 100,000 g supernatant fraction of extrahepatic tissues. Dihydrodiol dehydrogenase is able to oxidize the hydroxy group and to reduce the keto group of a number of xenobiotics including quinones derived from polycyclic aromatic hydrocarbons. Dihydrodiol dehydrogenase was not inducible by various substances including hormones, polycyclic aromatic hydrocarbons, substrates of the enzyme and potent inducers of monooxygenases, epoxide hydrolase and glutathione S-transferases. Only in the case of thyroxine was a weak induction with a high dose of the hormone observed.
Individual Differences in DNA Repair Capacities in Man
1987
After metabolic activation of benzo[a]pyrene to the 7,8-dihydrodiol- 9,10-epoxide, this ultimate carcinogen preferentially binds to the exocyclic amino group of guanine. In order to investigate possible interindividual differenes in the capacity of repair of the DNA adducts formed from benzo[a]- pyrene 7,8-dihydrodiol 9,10-epoxide, their persistence in freshly isolated lymphocytes of several donors was studied. The results show a surprisingly large interindividual variation in DNA adduct formation and their persistence in freshly isolated lymphocytes. This range included several individuals with an apparent complete lack of repair capability for these adducts. Compared with controls, smoker…
Structure and properties of pharmacologically active polymers
1975
Although the concept of using pharmacologically active macromolecular compounds as drugs is still regarded with much skepticism for both theoretical and practical reasons, interest in this field has grown in recent years because of the opportunity to take advantage of the specific properties of polymeric materials. For low molecular weight drugs, changes in structure often lead to a loss of specific activity. On the other hand, the properties of macromolecular drugs depend on the structure of the polymer used and this can be varied over a wide range by the incorporation of comonomer units, by the application of polymer-analogous reactions, or by related structural changes. A new model is pr…
ChemInform Abstract: Studies on Bicyclo[3.3.1]nonanes for Synthesis of Cyclooctenes.
2010
This paper describes a full conformational and stereochemical study of bicylo[3.3.1]nonanes, obtained from the reaction between cinnamaldehyde and 1-morpholine 1-cyclohexene. NMR data and stereochemistry were unequivocally established and assigned by two-dimensional experiments and single-crystal X-ray analysis. The crystal structure of a minor compound, 4, is reported. Cyclooctenes, which are present in natural products with biological activities, were synthesized from the bicyclononanes via the Wharton fragmentation.