A new and independent method for the quantification of alpha-acids in hops and hop products has been developed. NMR was used as a qualitative method for the complete assignment of all 1H- and 13C-NMR signals of the three main alpha-acids, cohumulone (1), humulone (2) and adhumulone (3). In a 13C two-dimensional INADEQUATE experiment, the 13C-NMR spectrum of 1 was unambiguously assigned via the carbon-carbon connectivities. Use of NMR as a quantitative method allowed quantification of the pure and individual alpha-acids 1 and 2, and the determination of the absolute concentration of solutions of these compounds. Quantification of alpha-acids by NMR is less complicated and more reliable than the methods used until now.

Cyclohexanones↗

PubMedDate not supplied

beta-Glucosidase and peroxidase stability in crude enzyme extracts from green beans of Vanilla planifolia Andrews.

The extraction method for beta-glucosidase from green vanilla beans has been studied. The effect of storage of green beans and protein extracts on beta-glucosidase and peroxidase activity was investigated: the best method, resulting in the highest enzyme activities, particularly for glucosidase, was through extraction of very fresh green beans in the presence of BisTris propane buffer at pH 8. The best method for storage of the extracts was at -80 degrees C after addition of 15% glycerol, when over 90% of initial activity was still present. Peroxidase activity did not change in frozen beans or in frozen extracts.

Orchidaceae↗

PubMedDate not supplied

Phytochemical investigation of Tabernaemontana crassa.

From the stembark of Tabernaemontana crassa the alkaloid ibogaine was isolated as the major component. Ibogaine showed activity against the gram-positive Bacillus subtilis. Conopharyngine was identified as one of the minor compounds.

Alkaloids↗

PubMedDate not supplied

Some new decussine-type alkaloids from Strychnos decussata, Strychnos dale and Strychnos elaecocarpa.

From the stem bark of Strychnos decussata (Pappe) Gilg (Loganiaceae), four tertiary indole alkaloids have been isolated: bisnordihydrotoxiferine and three new alkaloids. The structures of two of the new alkaloids, 3,14-dihydrodecussine (III) and 10-hydroxy-3,14-dihydrodecussine (IV), have been ascribed on the basis of their spectral data. The muscle-relaxant activity of these new compounds is discussed. Further studies of the alkaloids present in the stem bark of Strychnos dale and Strychnos elaeocarpa revealed the presence of decussine (V) and dihydrodecussine in S. dale and decussine, dihydrodecussine, and bisnordihydrotoxiferine in S. elaeocarpa.

Alkaloids↗

PubMedDate not supplied

Revised structure of phaeantharine.

Revised structure 8 is proposed for the quaternary bisbenzylisoquinoline alkaloid phaeantharine, based on spectrometric data. Phaeantharine, which occurs in Phaeanthus ebracteolatus (fam. Anonaceae), has current interest as a potential insecticide. Phaeantharine also exhibits moderate activity against gram-positive bacteria.

Alkaloids↗

PubMedDate not supplied

11-Methoxy-macusine A. A new quaternary alkaloid from Strychnos angolensis.

The major quaternary alkaloid from Strychnos angolensis was isolated, and its structure was determined by its spectral data as 11-methoxy-macusine A. The alkaloid showed muscle-relaxant activity.

Africa↗

PubMedDate not supplied

Antimicrobially active alkaloids from Tabernaemontana chippii.

From Tabernaemontana chippii root bark, forty-five alkaloids were isolated; thirty-four were fully characterized by means of their spectral data and/or co-tlc; eight alkaloids were new, four of them being 3-hydroxy derivatives of known dimeric voacamine type alkaloids. Most of the twenty-six known alkaloids belonged to the corynanthean, ibogan, or bisindole classes. The structures of eleven other alkaloids--all minor--were only partially elucidated, most of them being new alkaloids. All the dimeric alkaloids were shown to possess strong antimicrobial activity against gram-positive bacteria and moderate to weak activity against gram-negative bacteria.

Alkaloids↗

PubMedDate not supplied

The alkaloids of Strychnos dolichothyrsa.

In the stem bark of Strychnos dolichothyrsa Gilg ex Onochie et Hepper (Loganiaceae) the following alkaloids were found: bisnor-dihydrotoxiferine, bisnor-C-curarine, bisnor-dihydrotoxiferine N-oxide and bisnor-dihydrotoxiferine di-N-oxide. Tentatively, two alkaloids were identified as bisnor-C-alkaloid D and 18-deoxy Wieland-Gumlich aldehyde. Bisnor-dihydrotoxiferine seems to give dichlorometho compounds and N-oxides easily, analogous with strychnine and brucine.

Alkaloids↗