Squamocin-O(1) and squamocin-O(2), new adjacent bis-tetrahydrofuran acetogenins from the seeds of Annona squamosa

Two bis-tetrahydrofuran acetogenins, squamocin-O(1) (1) and squamocin-O(2) (2), were isolated from a MeOH extract of seeds of Annona squamosa L. Their structures were determined by spectral means including precursor-ion scanning mass spectral analysis for their aminal derivatives. The configurations at the oxymethine chiral centers were assigned as 12R,15R,16R,19R,20R,23R,24S,28S,36S for 1 and 12S,15R,16R,19R,20R,23R,24S, 28S,36S for 2, based on 1H NMR analysis of their Mosher's ester derivatives and CD data.     

Aporphine and bisaporphine alkaloids from Aristolochialagesiana var. intermedia

Corydines, isocorydines, and analogous aporphine alkaloids were isolated from the leaves of Aristolochia lagesiana var. intermedia, together with three bisaporphine salts (lagesianines B-D). Their structures were determined by chemical derivatizations and spectroscopic analyses. Lagesianines B and C are the first examples of N-CH₂-N′ and C-2-O-C-1′ linked dimeric aporphine alkaloids, respectively, while the monomeric units of lagesianine D, which has a carbon skeleton, are linked through C-7-C-5′ via an ethane-1,2-diol group (C-7-CHOHCHOH-C-5′).     

Aporphine alkaloids and lignans formed in response to injury of sapwood in Liriodendron tulipifera

Two new phenolic aporphine alkaloids, (+)-lirioferine and (+)liriotulipiferine, were isolated from discolored sapwood of L. tulipifera. Injury to the tree stem greatly stimulated biosynthesis of glaucine and phenolic alkaloids related to glaucine including thaliporphine, predicentrine, N-methylaurotetanine and corunine as well as the above two compounds. Injury also stimulated synthesis of oxoaporphine related and other polymeric pigments. Corunine was responsible for at least part of the color of discolored sapwood. None of the above compounds except glaucine was detected in normal sapwood or heartwood of L. tulipifera. Thus, formation of alkaloids and lignans in discolored sapwood differs both quantitatively and qualitatively from that observed during the normal transition of sapwood to heartwood in this tree. The compounds formed in response to injury differed substantially from one zone of injury to another within the same tree.     

Pregnane alkaloids from Pachysandra axillaris

Nine new pregnane alkaloids, pachysamines J-R (1-9), together with seven known ones, were isolated from Pachysandra axillaris. The chemical structures of the new alkaloids were elucidated by spectroscopic methods. All the compounds were evaluated for their inhibitory activities against HL-60, SMMC-7721, A-549, SK-BR-3, and PANC-1 cell lines. Compound 15 possessed moderate activities against A-549, SK-BR-3, and PANC-1 cells, with the IC₅₀ values of 11.17, 4.17, and 10.76 μM, respectively. Besides, compound 11 showed cytotoxicities against A-549 cell, with the IC₅₀ values as 24.94 μM.     

Secondary and tertiary isoquinoline alkaloids from Xylopia parviflora

From the secondary and tertiary alkaloidal fractions of the root and the bark of Xylopia parviflora (Annonaceae), the isoquinoline alkaloids, 10,11-dihydroxy-1,2-dimethoxynoraporphine and parvinine were isolated, along with 39 known alkaloids. Their structures were determined on the basis of analysis of spectroscopic data.     

Quaternary alkaloids of Thalictrum foliolosum

The isolation and identification of eleven alkaloids from the quaternary alkaloid fraction of a root extract of Thalictrum foliolosum are described     

Minor indole alkaloids of Alstonia macrophylla

Three indole alkaloids have been isolated from Alstonia macrophylla Wall. Two of these have been identified as affinisine (I) and picrinine (II). The third, a new base designated picralstonine, has been shown to possess structure (III).     

Pyrrolizidine alkaloids in the antipodean genus Brachyglottis (Asteraceae)

The phylogeny of the genus Brachyglottis suggests that its constituent species should contain pyrrolizidine alkaloids. Consistent with this hypothesis, and the established occurrence of such alkaloids in Brachyglottis repanda, Brachyglottis kirkii, and Brachyglottis hectori, an investigation of Brachyglottis adamsii revealed the presence of senecionine and retrorsine; Brachyglottis huntii was found to contain senkirkine and retrorsine; 7-O-angelylheliotridine was the predominant alkaloid in Brachyglottis perdicioides, and the same alkaloid together with senecionine, senkirkine and intergerrimine was present in the Brachyglottis hectori × B. perdicioides “Alfred Atkinson” horticultural hybrid; Brachyglottis sciadophila contained clivorine and neopetasitenine (acetylfukinotoxin); the latter alkaloid was also present in B. kirkii together with the previously reported senkirkine and senkirkine 12-acetate.     

Predator-induced changes in fluted giant clam (Tridacna squamosa) shell morphology

Predator-induced defences have been demonstrated in numerous marine molluscs, but never in giant clams (Bivalvia: Tridacnidae). Water-borne cues from the predatory crab Myomenippe hardwickii were tested for their ability to induce changes in the shell morphology, strength and growth of juvenile fluted giant clams, Tridacna squamosa. Specimens were maintained in effluent from tanks holding ‘fed crabs’, ‘starved crabs’ and ‘no crabs’. To ensure changes were due to predator cues only, food for the crabs was provided ex situ and measures were taken to minimise the prey signal. After 182 days, MANOVA identified differences in various shell parameters relating to shape and strength. CDA showed a clear change in overall morphology, with strong separation among the three treatments. Effluent from ‘fed crabs’ had a greater influence than effluent from ‘starved crabs’, possibly because the starved crabs were perceived as weaker, and thus less risk. Significantly more clams died in ‘fed crabs’ treatments (25%) and ‘starved crabs’ treatments (30%) compared to the ‘no crabs’ control (0%). This degree of mortality has not been observed in similar experiments elsewhere and represents a new challenge to interpret. We suggest that the cause is unlikely to be related to the plastic responses, but rather a result of some form of crab-associated contaminant.     

Steroidal alkaloids of Marsdenia rostrata

Some of the main constituents of Marsdenia rostrata, originating from two localities, were isolated and identified. The sample from the Toonumbar State Forest in northern New South Wales contains the known alkaloid anabasine and two new steroidal ester alkaloids, rostratine and dihydrorostratine. They were identified as O-acetyl-O-nicotinoylsarcostin and O-acetyl-O-nicotinoyldihydrosarcostin. The sample from the South Coast of N.S.W. yielded the two new ester alkaloids and a number of neutral polyhydroxy pregnane aglycones, one of which has been identified as metaplexigenin, but there was no anabasine.     

Dopamine-iridoid alkaloids in Carapichea affinis (= Psychotria borucana) confirm close relationship to the vomiting root Ipecac

Broad-based HPLC-UV comparison of 57 methanolic crude extracts of the Psychotria complex (Rubiaceae), representing about 20 different species collected in Costa Rica, exhibited a clear chemical segregation of Psychotria borucana. In contrast to the more widespread tryptamine-iridoid alkaloids it deviated by an accumulation of dopamine-iridoid alkaloids. Similar to the South American vomiting root Ipecac, Psychotria ipecacuanha (= Cephaelis ipecacuanha), cephaeline and emetine were found together with four related glycosides characterized by various N-acylations. Two glycosides were identified as the known N-acetates ipecoside and 6-O-methylipecoside, whereas the two others represent corresponding N-O-methylcaffeate derivatives from which borucoside was described as a new compound. Structure elucidation of all compounds was carried out by NMR- and MS-analyses supported by CSEARCH-NMR-database system. In addition to morphological characters and analyses of nucleotide sequence variation the chemical profile of P. borucana supported a recent taxonomic rearrangement where it has been grouped together with P. ipecacuanha in a separate genus Carapichea.     

Biosynthesis of pyridine alkaloids from Tripterygium wilfordii

Nicotinic acid-6-¹⁴C and nicotinamide adenine dinucleotide-carbonyl-¹⁴C were rapidly metabolized in T. wilfordii Hook. with formation of all compounds in the pyridine nucleotide cycle. Nicotinic acid-6-¹⁴C and the nicotinamide moiety of NAD were efficiently incorporated into wilfordic acid and hydroxywilfordic acid, the pyridinium moieties of the ester alkaloids. The structures of wilfordic acid and hydroxywilfordic acid were confirmed using GLC-MS. The molecular formulae of the four isolated alkaloids were determined by high resolution MS and agreed with earlier results based on elemental analysis.     

Aporphine alkaloids and lignans in heartwood of Liriodendron tulipifera

The following compounds were isolated from heartwood of Liriodendron tulipifera: glaucine, dehydroglaucine, asimilobine, N-acetylnornuciferine, norushinsunine, liriodenine, O-methylatheroline, (+)-syringaresinol, (+)-syringaresinol dimethyl ether and syringaldehyde. The occurrence of 1-benzyltetrahydroisoquinoline alkaloids also has been indicated by mass spectroscopy. Some characteristic spectral properties of these aporphine alkaloids and their probable biosynthetic pathways are discussed.