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

Phytochemical and Larvicidal Studies on Stemona curtisii: Structure of a New Pyrido[1,2-a]azepine Stemona Alkaloid

A new pentacyclic Stemona alkaloid, stemocurtisinol (3), with a pyrido[1,2-α]azepine A,B-ring system, and the known pyrrolo[1,2-α ]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)

A RAPID IN VITRO METHOD FOR THE EVALUATION OF CANDIDATE REPELLENTS AGAINST LEPTOTROMBIDIUM CHIGGERS

Scrub typhus is an acute febrile zoonotic disease resulting from infection with the gram-negative intracellular bacteria Orientia (formerly Rickettsia) tsutsugamushi (Hyachi) (Seong et al. 2001). The disease is endemic in much of south and central Asia, with approximately one million cases each year and more than a billion people at risk worldwide (Rosenberg 1997). Scrub typhus is transmitted by several species of larval trombiculid mites which are commonly known as chiggers (Tanskul et al. 1998). Repellents provide an effective method of protecting individuals from arthropods (Gupta and Rutledge 1994). In this study 6 essential oils were tested to evaluate their repellent activity against the chigger, Leptotrombidium imphalum Vercammen-Grandjean and Langston. A rapid and economic in vitro procedure which requires only 5 min and a small number of chiggers was used to determine the median effective doses. The results showed that clove oil was significantly more effective than others with ED50 of 53.2 µg followed by vetiver oil

Alkaloids from the roots of Stemona aphylla

Three known compounds, stemofoline (1), (2′S)-hydroxystemofoline (2), and (11Z)-1′,2′-didehydrostemofoline (3), along with two new alkaloids, stemaphylline (4) and stemaphylline-N-oxide (5), have been isolated from a root extract of Stemona aphylla. The structures of these alkaloids were determined on the basis of their spectroscopic data. The analysis of the crude dichloromethane extract by GC-MS in the EIMS mode showed the presence of alkaloids 1-4, the alkaloid 11, and stilbostemin R (12). The crude dichloromethane extract and 4 were tested for their comparative biological activities. The results of their acetylcholinesterase (AChE) inhibitory activities showed that the crude extract had higher activity than that of 4. The insecticidal properties of the crude extract and 4, using a topical application, showed that 4 had an activity similar to the positive control, methomyl, whereas the crude extract had much lower activity. Their antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas auruginosa ATCC 27853, and Candida albicans ATCC 90028 was weak (MIC 62.5-125 μg/mL, MBC 125-250 μg/mL, MFC 125 μg/mL) but much higher than that of the crude extract. © 2009 American Chemical Society and American Society of Pharmacognosy

A RAPID IN VITRO METHOD FOR THE EVALUTION OF CANDIDATE REPELLENTS AGAINST LEPTOTROMBIDIUM CHIGGERS

Scrub typhus is an acute febrile zoonotic disease resulting from infection with the Gram-negative intracellular bacteria Orientia (formerly Rickettsia) tsutsugamushi (Hyachi) (Seong et al. 2001). The disease is endemic in much of south and central Asia, with approximately one million cases each year and more than a billion people at risk worldwide (Rosenberg 1997). Scrub typhus is transmitted by several species of larval trombiculid mites which are commonly known as chiggers (Tanskul et al. 1998). Repellents provide an effective method of protecting individuals from arthropods (Gupta and Rutledge 1994). In this study 6 essential oils were tested to evaluate their repellent activity against the chigger, Leptotrombidium imphalum Vercammen-Grandjean and Langston. A rapid and economic in vitro procedure which requires only 5 min and a small number of chiggers was used to determine the median effective doses. The results showed that clove oil was significantly more effective than others with ED50 of 53.2 µg followed by vetiver oil

Phytochemical studies on Stemona burkillii prain: Two new dihydrostemofoline alkaloids

Two new dihydrostemofoline alkaloids, 11(S),12(R)-dihydrostemofoline (3) and stemoburkilline (4), along with stemofoline (1) and 2′- hydroxystemofoline (2) have been isolated from a root extract of Stemona burkillii Prain. The structure and relative configuration of 3 have been determined via spectroscopic data and from comparison with synthetic 11(S),12(S)-dihydrostemofoline (5). The configuration of the exo-cyclic alkene group in 4 is tentively assigned as E on the basis of mechanistic considerations

A RAPID IN VITRO METHOD FOR THE EVALUTION OF CANDIDATE REPELLENTS AGAINST LEPTOTROMBIDIUM CHIGGERS

Scrub typhus is an acute febrile zoonotic disease resulting from infection with the Gram-negative intracellular bacteria Orientia (formerly Rickettsia) tsutsugamushi (Hyachi) (Seong et al. 2001). The disease is endemic in much of south and central Asia, with approximately one million cases each year and more than a billion people at risk worldwide (Rosenberg 1997). Scrub typhus is transmitted by several species of larval trombiculid mites which are commonly known as chiggers (Tanskul et al. 1998). Repellents provide an effective method of protecting individuals from arthropods (Gupta and Rutledge 1994). In this study 6 essential oils were tested to evaluate their repellent activity against the chigger, Leptotrombidium imphalum Vercammen-Grandjean and Langston. A rapid and economic in vitro procedure which requires only 5 min and a small number of chiggers was used to determine the median effective doses. The results showed that clove oil was significantly more effective than others with ED50 of 53.2 µg followed by vetiver oil

Semisynthesis and biological activity of stemofoline alkaloids

The semisynthesis of the Stemona alkaloids (3′R)-stemofolenol (1), (3′S)-stemofolenol (2), methylstemofoline (3), and (3′S)- hydroxystemofoline (5) and the unnatural analogues (11E)-methylstemofoline (15) and 3′R-hydroxystemofoline (11) has been achieved starting from (11Z)-1′,2′-didehydrostemofoline (4). This synthesis allowed, for the first time, access to diastereomerically enriched samples of 1 and 2 and the assignment of their absolute configurations at C-3′. These compounds were obtained in sufficient quantities to allow for their biological testing. In a quantitative assay as AChE inhibitors, (11Z)-1′,2′- didehydrostemofoline (4) and (3′S)-hydroxystemofoline (5) were found to be the most active. © 2009 American Chemical Society and American Society of Pharmacognosy

Phytochemical, Synthetic and Biological Studies on Stemona and Stichoneuron Plants and Alkaloids: A Personal Perspective

This report is an overview of our research on phytochemical, synthetic and biological studies of the Stemona and Stichoneuron species of plants