Polyhydroxy alkaloids: chromatographic analysis

An overview of therapeutic potential of N-alkylated 1-deoxynojirimycin congeners

Polyhydroxylated alkaloids display a wide range of biological activities, suggesting their use in the treatment of various diseases. Their most famous representative, 1-deoxynojirimycin (DNJ), is a natural product that shows α- and β-glucosidase inhibition. This molecule has been since converted into two clinically approved drugs i.e., Zavesca® and Glyset®, targeting type I Gaucher's disease and type II diabetes mellitus, respectively. This review examines the therapeutic potential of important DNJ congeners reported in last decade and presents concise mechanism of glycosidase inhibition. A brief overview of substituents conjugation's impact on DNJ scaffold (including N-alkylated DNJ derivatives, mono-valent, di-valent and multivalent DNJ congeners, N-[5-(adamantan-1-yl-methoxy)-pentyl]-1-deoxynojirimycin (AMP-DNM) look alike DNJ based lipophilic derivatives, AMP-DNM based neoglycoconjugates, DNJ click derivatives with varying carboxylic acids and aromatic moieties, conjugates of DNJ and glucose, and N-bridged DNJ analogues) towards various enzymes such as α/β glucosidase, porcine trehalase, as F508del-CFTR correctors, α-mannosidase, human placental β-glucocerebrosidase, N370S β-GCase, α-amylase and insect trehalase as potent and selective inhibitors have been discussed with potential bioactivities, which can provide inspiration for future studies.

Approaches for the isolation and identification of hydrophilic, light-sensitive, volatile and minor natural products

Water-soluble, volatile, minor and photosensitive natural products are yet poorly known, and this review discusses the literature reporting the isolation strategies for some of these metabolites.

Simple Indolizidine and Quinolizidine Alkaloids

This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis(quinolizidine) alkaloids.

Derivatization of carbohydrates for GC and GC-MS analyses

GC and GC-MS are excellent techniques for the analysis of carbohydrates; nevertheless the preparation of adequate derivatives is necessary. The different functional groups that can be found and the diversity of samples require specific methods. This review aims to collect the most important methodologies currently used, either published as new procedures or as new applications, for the analysis of carbohydrates. A high diversity of compounds with diverse functionalities has been selected: neutral carbohydrates (saccharides and polyalcohols), sugar acids, amino and iminosugars, polysaccharides, glycosides, glycoconjugates, anhydrosugars, difructose anhydrides and products resulting of Maillard reaction (osuloses, Amadori compounds). Chiral analysis has also been considered, describing the use of diastereomers and derivatives to be eluted on chiral stationary phases.

Astonishing diversity of natural surfactants: 6. Biologically active marine and terrestrial alkaloid glycosides

This review article presents 209 alkaloid glycosides isolated and identified from plants, microorganisms, and marine invertebrates that demonstrate different biological activities. They are of great interest, especially for the medicinal and/or pharmaceutical industries. These biologically active glycosides have good potential for future chemical preparation of compounds useful as antioxidants, anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been subdivided into several groups, including: acridone; aporphine; benzoxazinoid; ergot; indole; enediyne alkaloidal antibiotics; glycosidic lupine alkaloids; piperidine, pyridine, pyrrolidine, and pyrrolizidine alkaloid glycosides; glycosidic quinoline and isoquinoline alkaloids; steroidal glycoalkaloids; and miscellaneous alkaloid glycosides.

Alkaloidal components in the poisonous plant, Ipomoea carnea (Convolvulaceae)

Natural intoxication of livestock by the ingestion of Ipomoea carnea (Convolvulaceae) sometimes occurs in tropical regions of the world. Polyhydroxylated alkaloids were isolated from the leaves, flowers, and seeds of the poisonous plant and characterized. Chromatographic separation of the leaf extract resulted in the isolation of swainsonine (1), 2-epi-lentiginosine (2), calystegines B(1) (3), B(2) (4), B(3) (5), and C(1) (6), and N-methyl-trans-4-hydroxy-l-proline (7). The contents of 1 in the fresh leaves and flowers were 0.0029 and 0.0028%, respectively, whereas the contents of 1, 3, and 4 in the seeds were approximately 10 times higher than those in the leaves and flowers. Alkaloids 3, 4, and 6 showed a potent inhibitory activity toward rat lysosomal beta-glucosidase, with IC(50) values of 2.1, 0.75, and 0.84 microM, respectively, and alkaloid 5 was a moderate inhibitor of alpha- and beta-mannosidases. Although alkaloid 1 is known as a powerful inhibitor of lysosomal alpha-mannosidase (IC(50) = 0.02 microM), alkaloid 2, which has been thought to be an intermediate in the biosynthesis of 1, was also a potent inhibitor of alpha-mannosidase with an IC(50) value of 4.6 microM.

Preparative isolation of swainsonine from locoweed: extraction and purification procedures

The trihydroxy indolizidine alkaloid swainsonine, a plant toxin with potent alpha-mannosidase-inhibitory activity and chemotherapeutic potential, was isolated in gram quantities from locoweed (Astragalus lentiginosus). The key isolation and purification step was a continuous liquid/liquid extraction procedure using dichloromethane to extract a basified aqueous methanol solution obtained after isolation of the polar base fraction by ion-exchange. The concentration of swainsonine was increased from ca. 7% in the polar base material to 68% using the liquid/liquid extraction procedure. Pure swainsonine was then obtained by recrystallisation from ammonia-saturated chloroform or by sublimation. Small samples of swainsonine were also purified by formation of the chloroform-soluble methylboronate derivative, from which the alkaloid could be regenerated easily by hydrolysis.