Amphiporus alkaloid multiplicity implies functional diversity: initial studies on crustacean pyridyl receptors

Some hoplonemertines contain pyridyl alkaloids which are used for prey capture and chemical defense against predators. The first such alkaloid to be identified was anabaseine, a tetrahydro-bipyridyl isolated from the peregrine hoplonemertine Paranemertes peregrina Coe. Several Amphiporus species have also been shown to possess related pyridyl alkaloids. The chevron hoplonemertine Amphiporus angulatus (Fabricius) contains a particularly diverse group of bipyridyl and tetrapyridyl compounds. 2,3-bipyridyl, a fully aromatic analog of anabaseine, is the major paralytic toxin (Kem et al., 1976). It is even more potent in paralyzing crustaceans than anabaseine, but appears to be inactive on vertebrates. We have synthesized a number of 2,3-bipyridyl analogs and tested their ability to paralyze the freshwater crayfish Procambarus clarkii Girard. A structure-activity relationship (SAR) was found that resembles the SAR for activation of vertebrate nicotinic receptors by methylated nicotine and anabaseine compounds. This suggests that 2,3-bipyridyl, though lacking a positive charge at physiological pH, still acts as a nicotinic agonist in crustaceans. 2,3-bipyridyl and anabaseine stimulate crustacean dactyl neuron pyridyl chemoreceptors at M concentrations. Nemertelline, as well as these two compounds, was found to activate crayfish stomach muscle nicotinic receptors modulating chloride channels at sub-micomolar concentrations. We suggest that some amphiporid pyridyl alkaloids may deter predators not only by their central neurotoxic (paralytic) actions, but also by peripheral effects on pyridyl receptors affecting prey capture and digestion. A multiplicity of alkaloids probably provides the hoplonemertine with a variety of offensive and defensive chemical responses to the presence of other animals.     

Spatial and temporal distribution of the alkaloid sanguinarine in Sanguinaria canadensis L. (Bloodroot)

Acclimated and non-acclimated potted plants of Sanguinaria canadensis L. were harvested at early and late dormancy, anthesis, and immature and mature fruiting stages. Sanguinarine content and concentration were determined for rhizomes (distal, proximal, and middle sections), roots, leaves, flower, and fruit. Rhizomes had highest sanguinarine content and concentrations, and exhibited decreasing concentration gradients from the distal to proximal third. Concentrations in roots were a tenth of rhizome concentration. Concentrations in leaves, flowers, and fruit were one-thousandth of rhizome Sanguinarine content in whole acclimated plants was constant. Content in whole nonacclimated plants increased as the plant became physiologically active, but was constant during fruit maturation: content in roots, leaves, and fruit did not change. The substantial increase in whole-plant dry weight coupled with the unchanging sanguinarine content during fruit maturation suggests either a shift in photosynthate allocation from defense to growth, or a constant turnover of sanguinarine.     

A further quinazoline alkaloid from Adhatoda vasica

A new quinazoline alkaloid isolated from the leaves of Adhatoda vasica has been identified as 1,2,3,9-tetrahydro-5-methoxypyrrolo[2,1-b]quinazoline-3-ol.     

An alkaloid from Haplophyllum tuberculatum

A new alkaloid (+)-tuberine was isolated from Haplophyllum tuberculatum. Physicochemical and spectral evidence established its structure and stereochemistry as N- benzoyl-4′-[(2″S,3″S,6″S)-(+)-7″-acetoxy-2″-hydroxy-3″,7″-dimethyl-3″,6″-epoxyoctyloxy]phenethylamine.     

17-O-acetyl-19,20-dihydrovoachalotine,a new alkaloid from Voacanga chalotiana

The structure of 17-O-acetyl-19,20-dihydrovoachalotine, a new alkaloid from the root bark of Voacanga chalotiana, has been determined by spectroscopic analysis. The stereochemistry at C-20 has been deduced on the basis of ¹³C-NMR and comparison with other compounds containing the voachalotine skeleton.     

Structure of the carbazole alkaloid isomurrayazoline from Murraya koenigii

The structure of a new hexacyclic carbazole alkaloid from Murraya koenigii has been shown to be 9a,10,11,12,13,13a-hexahydro-5,9,9,12-tetramethyl-1     

金钗石斛生物碱的组织化学定位研究

利用组织化学定位方法对金钗石斛不同生长年限和不同营养器官的生物碱分布和积累进行比较分析。结果表明,金钗石斛茎生物碱主要分布于基本组织,三年生金钗石斛的生物碱含量高于一年生和二年生金钗石斛。金钗石斛根部生物碱含量同样较多,主要分布于皮层薄壁细胞中;金钗石斛叶片生物碱含量较低,存在于上下表皮细胞中,与铁皮石斛和铜皮石斛完全不同。说明三年生金钗石斛作为最适宜采收期,而且金钗石斛根部具有很好的开发利用价值。金钗石斛叶片表皮细胞中呈现生物碱的原因尚未清楚,需要进一步研究。     

Relative configuration of the alkaloid augustine

Structural confirmation and the relative configuration of the alkaloid augustine were achieved by NMR spectral analysis. The high resolution MS fragmentation pattern of the alkaloid is also discussed.     

Pyridine nucleotide metabolism in imaginal discs of Drosophila melanogaster

The pyridine nucleotide metabolism of imaginal discs of Drosophila melanogaster has been studied in vitro by incubating discs with labeled nicotinic acid in the presence and absence of ecdysterone. The major labeled compounds found within the discs are NAD, NADP, and nicotinic acid. There is preferential uptake of nicotinamide over nicotinic acid, although the Priess-Handler pathway is used exclusively. The presence of ecdysterone produces a small increase in the NADP/NAD ratio, and an increase in NAD synthesis, probably to compensate for increased NAD turnover.Supported by Grant GB 43569 from the National Science Foundation.     

Annonelliptine,an alkaloid from Annona elliptica

Annonelliptine has been isolated from Annona elliptica and its structure has been identified as (R)-7-hydroxy-1-(4′-hydroxybenzyl)-5,6-dimethoxy-N-methyl-1,2,3,4-tetrahydroisoquinoline.     

甘草生物碱成分的分析及含量测定

研究对主要药用甘草即乌拉尔（G.uralensis）、光果甘草（G.inflata）、胀果甘草（G.palliadiflora）、刺果甘草（G.pallidiflora）的根中生物碱成分进行了分析研究。结果表明：生物碱成分为喹啉衍生物类及异喹啉衍生物类,总含量平均为0.29%,此结果为生物碱类药物的生物及甘草的进一步开发利用提供科学依据。     

Scholaricine,an alkaloid from alstonia scholaris

A new alkaloid, scholaricine, has been isolated to which structure 2 (demethylscholarine) has been assigned.     

Sativanine-C: A cyclopeptide alkaloid from the bark of Zizyphus sativa

From the bark of Zizyphus sativa a previously undescribed 13 membered cyclopeptide alkaloid, sativanine-C has been isolated. The structure of this new compound was elucidated by spectroscopic methods, its transformation product and by chemical degradation.     

Sativanine-g,a cyclopeptide alkaloid from Zizyphus sativa

In addition to the already described peptide alkaloids from the bark of Zizyphus sativa, a new compound of this class, sativanine-G, has been isolated and its structure elucidated. This alkaloid contains a 13-membered ring system and belongs to the nummularine-C class.