6-Hydroxy-5,6-seco-stemocurtisine: a novel seco-stemocurtisine-type alkaloid

A novel seco-stemocurtisine-type alkaloid, 6-hydroxy-5,6-seco-stemocurtisine was isolated from the aerial parts of Stemona curtisii (Stemonaceae) collected from Trang Province in Thailand. The unprecedented 5,6-seco-pyrido[1,2-a] azepine structure was elucidated by 2D NMR analysis and a single crystal X-ray crystallographic analysis. (C) 2013 Phytochemical Society of Europe

Stemofoline ethyl acetate solvate

Crystals of the title compound, C22H29NO5·C4H8O2, {[systematic name: (2R,3R,5R,5aS,6R,8aR,9S)-(5Z)-5-[3-butyl­tetra­hydro-6-methyl-2,5-methano-4,3,8a-[1]propan­yl[3]yl­idene­furo[3,2-f][1,4]oxazepin-7(5H)-yl­idene]-4-meth­oxy-3-methyl­furan-2(5H)-one ethyl acetate solvate} were isolated from the root extracts of Stemona aphylla (Stemonaceae). The structure closely resembles those of stemofoline derivatives which have previously been reported. Inter­molecular contacts are observed between some C-bonded H atoms and nearby O atoms, perhaps indicating weak inter­actions which could influence the packing of species within the unit cell

The pyrido[1,2-a]azepine Stemona alkaloids

This paper reviews the isolation, structure elucidation, proposed biosynthesis and biological activities of the small, but increasing, number of pyrido[1,2-a]azepine Stemona alkaloids

THE EFFECTS OF BUD SIZES AND BENZYLADENINE ON IN VITRO PROPAGATION OF CURCUMA AERUGINOSA ROXB.H.

Curcuma aeruginosa Roxb.H is one of the most valuable oriental herbs. Its rhizome extract has been used as antifungal agent and reported to have anticarcinogenic activity in animals. Natural propagation by rhizome is very poor and can not be done in winter because of its dormancy. The objective of this study was to investigate the effects of bud sizes and benzyladenine (BA) on in vitro propagation of C. aeruginosa. Buds in various sizes were cultured on Murashige and Skoog (MS) media under 1,500 lux of light intensity at 25OC for 4 weeks. It was found that 3.0 – 4.0 cm buds provided 66.67% survival, produced 100% shoots and gave the highest numbers of 2 shoots per explant. To determine the effect of BA, 3.0 – 4.0 cm buds, was also cultured on MS media supplemented with 0, 1, 2 and 3 mg/l of BA under the same condition for 4 weeks. The MS medium with 1 mg/l BA was found to induce 100% shoot formation with an average of 2.27 shoots per explant and induced the highest root formation of 72.73 %. Acknowledgements: This research was supported by Faculty of Science, Chiang Mai University, Thailand

Phytochemical and larvicidal studies on Stemona curtisii: Structure of a new pyriodo[1,2-a]azepine Stemona alkaloid

A new pentacyclic Stemona alkaloid, stemocurtisinol (3), with a pyrido[1,2-a]azepine A,B-ring system, and the known pyrrolo[1,2-a]azepine alkaloid oxyprotostemonine (4) have been isolated from a root extract of S. curtisii. The structure and relative stereochemistry of stemocurtisinol was determined by spectral data interpretation and X-ray crystallography. This compound is a diastereoisomer of oxystemokerrin and has the opposite configuration at C-4 and C-19. The individual alkaloid components showed significant larvicidal activity (IC50 4−39 ppm) on mosquito larvae (Anopheles minimus HO)

Phytochemical Studies on Stemona aphylla: Isolation of a New Stemofoline Alkaloid and Six New Stemofurans

A new stemofoline alkaloid, (2′S)-hydroxy-(11S,12R)-dihydrostemofoline (3), new stemofurans M-R (8-13), and known compounds stemofoline (1), (2′S)-hydroxystemofoline (2), stemofuran E (4), stemofuran F (5), stemofuran J (6), and stilbostemin F (7) have been isolated from the root extracts of Stemona aphylla. The structures and relative configurations of these new compounds have been determined by spectroscopic data interpretation and from semisynthetic studies. These natural and semisynthetic alkaloids were tested for acetylcholinesterase inhibitory activities and were found to be 10-20 times less active than 1′,2′-didehydrostemofoline itself. Stemofurans 4, 6, 8, 11, and 13 were tested for their antibacterial and antifungal activities. Three of these showed antibacterial activities against MRSA with MIC values of 15.6 μg/mL

Semisynthesis and acetylcholinesterase inhibitory activity of stemofoline alkaloids and analogues

Semisynthesis of the known Stemona alkaloids oxystemofoline (7) and methoxystemofoline (8) has been achieved starting from (11Z)-1′,2′-didehydrostemofoline (6), which confirmed their structures and absolute configurations. The synthesis of (1′R)-hydroxystemofoline (9) helped establish this compound as a natural product from Stemona aphylla. (1′S)- Hydroxystemofoline (10) and a number of related analogues were also prepared. In a TLC bioautographic assay, 9 was found to be the most active acetylcholinesterase inhibitor, but it was not as active as galanthamine

Response of Stemona alkaloid production in Stemona sp. to chitosan and yeast extract elicitors

The experiments were purposed to investigate the effect of chitosan and yeast extract on Stemona alkaloid production in Stemona sp. culture. Both elicitors enhanced Stemona alkaloid production over the control. Treatment with chitosan at a concentration of 25 mg/L for 1 week resulted in the highest production of Stemona alkaloids. It was found that 1\u27, 2\u27-didehydrostemofoline and stemofoline production was 2.65 fold and 2.95 fold higher than the control, respectively

Species-distinctiveness in the vocal behaviour of six sympatric bulbuls (genus Pycnonotus) in South-East Asia

Bulbuls (Passeriformes:Pycnonotidae) are a biodiverse group of birds that produce a variety of vocalisations, yet the vocal behaviour of most bulbuls has not been formally described or the subject of bioacoustical study. We present the first detailed descriptions of the song and singing behaviours of six species of bulbul in the genus Pycnonotus, based on recordings of birds in mixed-species flocks in the tropical forests of northern Thailand. All six species are frugivores that often forage together in the same fruiting tree. We compared nine fine structural features of the songs of these species to understand the vocal behaviour of each and the potential importance of vocalisations in species recognition in these mixed-species flocks. Our analyses reveal substantial differences in the structure of songs as well as marked differences in singing behaviour between species. Discriminant function analysis readily distinguishes the songs of the six species based on structural differences. Discriminant function analysis of species with the most similar plumage features (as assessed by human observers) readily distinguishes between phenotypically similar pairs of congeners. Our results provide evidence that vocalisations may be important in species recognition and as species-isolating mechanisms between closely related and sympatric Pycnonotus bulbuls. The species-typical features described here may be helpful to biologists and conservationists, particularly as several species of bulbul are of conservation concern. © 2012 BirdLife Australia