Srunya Vajrodaya

Mahidol University, Bangkok, Bangkok, Thailand

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Publications (24)61.29 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: On the basis of a comparison of 42 Stemona samples, representing eight different species collected and cultivated in Thailand, species-specific accumulation trends of Stemona alkaloids were analyzed. An overview was achieved by comparative HPLC analyses of methanolic crude extracts of underground parts coupled with diode array or evaporative light scattering detectors. All major compounds were isolated and their structures elucidated by NMR and MS analyses. Protostemonine- and stichoneurine-type derivatives dominated, from which the latter characterize S. tuberosa and S. phyllantha accumulating species-specific isomers of tuberostemonine (3). The widespread S. curtisii and S. collinsiae clearly deviate by protostemonine-type derivatives dominated by stemofoline (10) and/or didehydrostemofoline (11). Further diversification within this structural type results from a mutual accumulation of derivatives with a pyrrolo- or pyridoazepine nucleus, leading to chemical variability in S. curtisii and S. aphylla.
    Journal of Natural Products 09/2011; 74(9):1931-8. · 3.29 Impact Factor
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    ABSTRACT: The isolation of (Z,Z)-pandanamine (1) and its corresponding isomers (Z,E)-pandanamine (2) and (E,E)-pandanamine (3) from Stichoneuron calcicola of the family Stemonaceae is of outstanding chemosystematic importance. This alkaloid was previously only known from the family Pandanaceae, where it was accompanied by a series of pyrrolidines, collectively called Pandanus alkaloids. The pyrrolidines pandamarilactonines A (4), B (5), C (6), and D (7) were also detected in the present study, most likely representing artificial cyclization products of pandanamine (1-3) formed by acidic conditions during chromatographic separation on silica gel. Similar structures were found in various Stemona alkaloids, suggesting a close relationship between the two plant families. Structurally, pandanamine (1-3) can be regarded as a direct precursor of croomine (8), originally isolated from Croomia, a genus closely related to Stichoneuron, but later also found in various Stemona species. The co-occurrence of pandanamine (1-3), croomine (8), and stichoneurin (9) in the family Stemonaceae represents a sound argument for a new interpretation of the biogenetic origin of Stemona alkaloids and at the same time substantiates the removal of the family from the order Dioscoreales and its inclusion into Pandanales, as already suggested by DNA sequencing.
    Journal of Natural Products 10/2009; 72(9):1708-11. · 3.29 Impact Factor
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    ABSTRACT: Fifteen prenylated or geranylated flavanones and flavanonols were isolated from the leaf extracts of different Glycosmis species collected in Thailand and Malaysia. All structures were elucidated by spectroscopic methods, especially 1D and 2D NMR. Six compounds were described for the first time and two were only known so far as synthetic products. The chemotaxonomic significance of flavanoid accumulation within the genus Glycosmis is highlighted.
    Phytochemistry 07/2009; 70(8):1030-7. · 3.05 Impact Factor
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    ABSTRACT: Lipophilic crude extracts of leaves, stem and root bark of six different provenances of Aglaia silvestris were compared to determine species-specific chemical trends as well as infraspecific variability. 3,4-Secodammarane triterpenes formed the basic chemical equipment accompanied by the 2,3-seco derivative aglasilvinic acid, probably representing the precursor of the silvaglin A and isosilvaglin A characterised by a five membered ring A. In addition, the pregnane steroid pregnacetal was isolated and identified together with the known sesquiterpenes alpha-muurolene and viridiflorol, and the bisamide pyramidatin. Depending on the collection site all major triterpenes showed two different stereochemical trends either towards 20R or 20S configuration, giving rise to isolation and identification of the two isomers methylisofoveolate B (20S,24R) and methylfoveolate B (20R,24S) as well as the known derivatives shoreic acid (20S,24R), isoeichlerianic acid (20R,24S), and methylisoeichleriate (20R,24S). The structures were elucidated by 2D-NMR experiments and silvaglin A additionally by X-ray diffraction. The structural diversity and distribution of triterpenoids within the genus Aglaia is highlighted with respect to chemotaxonomic implications.
    Phytochemistry 11/2008; 69(15):2696-703. · 3.05 Impact Factor
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    ABSTRACT: Six amide-esters and two sulphur-containing bisamides were isolated from the leaves, stem and root bark of Aglaia tenuicaulis together with two bisamides from the leaves of A. spectabilis. Their structures were elucidated by spectroscopic methods. The co-occurrence of amide-esters and bisamides suggests close biosynthetic connections replacing only one nitrogen atom of putrescine with oxygen. Putrescine appears to be the common building block linked to various acids from which the cinnamoyl moiety represents the prerequisite for an incorporation of bisamides into flavaglines. Corresponding amide-esters are apparently not incorporated, but closely related amide-alcohol derivatives were found as part of benzopyran and benzofuran flavaglines. The structure of a amide-alcohol is described, representing an artifact due to hydrolysis of an amide-ester during TLC purification. A hypothetical amide-amine building block is suggested to form the characteristic pyrimidinone structures only found in benzofuran flavaglines. Structural and biosynthetic connections between amide-esters, bisamides and flavaglines are discussed and the chemotaxonomic significance of accumulating specific derivatives within the genus Aglaia is highlighted.
    Phytochemistry 03/2008; 69(4):928-38. · 3.05 Impact Factor
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    ABSTRACT: Broad-based phytochemical investigations on 31 Stemona species and geographical provenances led to an overview concerning characteristic accumulation trends and the distribution of different Stemona alkaloids. Two major metabolic differences suggested a taxonomic segregation of the complex Stemona tuberosa group from the other species, and was supported by morphological characters. Whereas most of the Stemona species were characterised by protostemonine type alkaloids, the S. tuberosa group clearly deviated by accumulation trends towards tuberostemonine or croomine derived alkaloids belonging to two different skeletal types. Also of chemotaxonomic relevance was the structural divergence of protostemonine type alkaloids into pyrrolo- or pyridoazepine derivatives represented by stemofoline or oxystemokerrine, respectively, as major constituents. Their common occurrence in different provenances of S. curtisii, also deviating from the other species by various chromosome numbers, deserves special taxonomic attention. Species specific chemical markers were given by the unique accumulation of didehydrostemofoline (=asparagamine A) in S. collinsae and stemokerrine in S. kerrii. In contrast to previous reports, no bisdehydro derivatives with an aromatic pyrrole ring were detected supporting the hypothesis that these alkaloids are artifacts. A new stereoisomer of tuberostemonine was isolated and identified by spectroscopic methods.
    Phytochemistry 06/2007; 68(10):1417-27. · 3.05 Impact Factor
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    ABSTRACT: Five new methylsulfonylpropenamides were isolated from different Glycosmis species collected in Thailand. Four of these derivatives contain 4-geranyloxy-3-hydroxy-substituted phenethylamine moieties, Sakerine (1) has a simple geranyloxy side chain; sakerone (2), sakerol (3), and dihydroisosakerol (4) are characterized by different states of oxidation in the geranyloxy residue. Methylgerambullal (5) contains a 4-geranyloxy-substituted phenethylamine unit with a terminal formyl group. Two additional amides, doisuthine (6) and methoxydoisuthine (7), exhibit the structures of N-methylanthranilic acid amides with phenethylamine and p-methoxyphenethylamine as amine components. All structures were elucidated by IR, UV, 1H-, 13C-, 2D-NMR spectroscopy, mass spectrometry, and CD spectroscopy.
    Annalen der Chemie und Pharmacie 01/2006; 1995(10):1789 - 1794. · 3.10 Impact Factor
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    ABSTRACT: Three new pyrroloazepine type alkaloids, stichoneurines A and B and 6-hydroxycroomine were isolated from the lipophilic root extracts of Stichoneuron caudatum and Stemona tuberosa collected in Thailand together with the already known croomine, tuberostemonine, and tuberostemonine A. The structures were elucidated by spectroscopic methods including H/H-COSY, HMQC, and HMBC. Information on the relative stereochemistries and conformational behaviour was obtained by analysis of the NOESY spectra. The formation of pyrroloazepine alkaloids in the genus Stichoneuron is reported for the first time and supports its affiliation to the family Stemonaceae. The occurrence of two different types of alkaloids, of the tuberostemonine and croomine series, in different geographical provenances of Stemona tuberosa is of special chemosystematic interest and may contribute to a more natural species delimitation within that complex group.
    Monatshefte fuer Chemie/Chemical Monthly 01/2005; 136(9):1671-1680. · 1.63 Impact Factor
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    ABSTRACT: From the roots of various Stemona species four new dehydrotocopherols (chromenols) were isolated and their structures and stereochemistry elucidated by spectroscopic methods. The double bond between C-3 and C-4 proved to be a typical chemical character of the genus found in most of the species. Various C-methylations of the aromatic ring reflect differences in methyltransferase activities and agreed with the current species delimitations showing an exclusive accumulation of dehydro-delta-tocopherol for the Stemona tuberosa group, whereas different provenances of Stemona curtisii were characterized by dehydro-gamma-tocopherol accompanied by small amounts of dehydro-alpha-tocopherol. From Stemona collinsae all four tocopherols were isolated with a clear preponderance of dehydro-delta-tocopherol accompanied by smaller amounts of the rare dehydro-beta-tocopherol. Stemona burkillii and a group of unidentified species showed a weak accumulation trend towards dehydro-alpha-tocopherol, whereas Stemona cochinchinensis and especially Stemona kerrii clearly differed by a preponderance of chromanol derivatives. In Stemona cf. pierrei no tocopherols could be detected at all. Based on TLC tests and microplate assays with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*) the antioxidant capacities of all chromenol derivatives were comparable with that of alpha-tocopherol showing no significant differences among each other, except for a more rapid kinetic behaviour of the 5,7,8-methylated dehydro-alpha-tocopherol.
    Phytochemistry 11/2004; 65(19):2719-29. · 3.05 Impact Factor
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    ABSTRACT: Three new dihydrophenanthrenes, stemanthrenes A-C, along with the new dihydrostilbene stilbostemin G were isolated and identified from the underground parts of Stemona cf. pierrei together with the known pinosylvin, 4'-methylpinosylvin, dihydropinosylvin, stilbostemins B, D, and E as well as the pyrrolo[1,2-a]azepine alkaloids protostemonine and stemonine. The structures of all new stilbenoids, elucidated by NMR analyses, showed a common substitution pattern for aromatic ring A and characteristic C-methylations for ring B. The trivial name racemosol, previously reported for S. collinsae, was renamed to stemanthrene D due to its priority for another compound. Bioautographic tests on TLC plates with Cladosporium herbarum displayed high antifungal activity for compounds with an unsubstituted aromatic ring A, e.g. pinosylvin, but only weak effects for the higher substituted stilbostemin G and stemanthrenes A-C. Similar results were obtained by germ tube inhibition of five microfungi using 2-fold serial broth dilutions determined by a microplate reader. Because of weak inhibition and chemical instability of stemanthrenes, no EC(50) and EC(90) values could be calculated.
    Phytochemistry 02/2004; 65(1):99-106. · 3.05 Impact Factor
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    ABSTRACT: On the basis of chronic feeding bioassays with neonate larvae of Spodoptera littoralis reared on an artificial diet, the methanolic leaf and root extracts from Stemona collinsae displayed very high insect toxicity compared to those of two Aglaia species, a commercial Pyrethrum extract, and azadirachtin, whereas S. tuberosa extracts demonstrated low activity in roots and no activity in leaves. Beyond that, in leaf disk choice tests against fifth instar larvae, S. collinsae showed strong antifeedant activity, whereas S. tuberosa was characterized by remarkable repellency. The anti-insect properties of both species were based on pyrrolo[1,2-a]azepine alkaloids, from which didehydrostemofoline (asparagamine A) was the major compound of the roots of S. collinsae, exhibiting the highest toxicity in feeding assays. Saturation and hydroxylation of the side chain in the co-occurring stemofoline and 2'-hydroxystemofoline, respectively, led to an increasing loss of activity. Contact toxicity tests with stemofoline and didehydrostemofoline exhibited even higher activities than those of Pyrethrum extract. Tuberostemonine was the dominating alkaloid in the roots of S. tuberosa, showing outstanding repellency but no toxic effects.
    Journal of Agricultural and Food Chemistry 11/2002; 50(22):6383-8. · 3.11 Impact Factor
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    ABSTRACT: Fifteen new stilbenoids including 11 phenylbenzofurans, the stemofurans A-K (1-11), and four dihydrostilbenes, the stilbostemins A (15), C (17), E (19), and F (20), were isolated and identified from a methanolic extract of Stemona collinsae roots together with five known derivatives, the stilbenes pinosylvin (13) and 4'-methylpinosylvin (14), the dihydrostilbenes, stilbostemins B (16) and D (18), and the dihydrophenanthrene racemosol (12) as well as (+)-sesamin, coniferyl alcohol, and stigmasterol. Bioautographic tests with Cladosporium herbarum displayed antifungal activity for stilbenoids of all four structural types. Ten derivatives were tested against five microfungi using the microdilution technique linked with digital image analysis of germ tubes.
    Journal of Natural Products 07/2002; 65(6):820-7. · 3.29 Impact Factor
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    ABSTRACT: Nine new sulfur containing amides were isolated from the lipophilic leaf extracts of different varieties of Glycosmis chlorosperma and G. ex aff. pseudoracemosa mainly collected in Thailand. Their structures were elucidated by spectroscopic methods. All amides were shown to be characterized by a methylsulfonylpropenoic acid moiety linked to a p-geranyloxy- or p-prenyloxy-phenethylamide rest. The compounds differ by different states of oxidation (i) at the 2-position of the ethylamine unit, (ii) at the aromatic m-position of phenethylamine, or (iii) at the terminal methyl group of the geranyloxy side chain.
    Phytochemistry 06/2000; 54(2):207-13. · 3.05 Impact Factor
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    H Greger, T Pacher, S Vajrodaya, M Bacher, O Hofer
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    ABSTRACT: Six new amides, leptaglin (1), hemileptaglin (2), aglanthin (3), agleptin (4), isoagleptin (5), and leptanthin (6), together with known lignans yangambin, eudesmin, grandisin (7), epigrandisin (8), and dehydrodiconiferyl alcohol, were isolated and identified from the lipophilic leaf and stem bark extracts of Aglaia leptantha. The dominating sulfur-containing bisamides contained either putrescine or the corresponding pyrrolidine ring as the diamine part, linked to phenylacetic and/or methylthiopropenoic acid moieties showing a remarkable infraspecific variation in eight individuals from two different habitats. Structures were determined by MS and NMR, including lanthanide-induced shifts.
    Journal of Natural Products 06/2000; 63(5):616-20. · 3.29 Impact Factor
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    ABSTRACT: Eight flavaglines, six cyclopenta[b]benzofurans, a cyclopenta[bc]benzopyran, and a benzo[b]oxepine, together with an aromatic butyrolactone were isolated from Aglaia odorata, A. elaeagnoidea, and A. edulis (Meliaceae) and tested against the three plant pathogens Pyricularia grisea, Fusarium avenaceum, and Alternaria citri for antifungal properties. Using the microdilution technique linked with digital image analysis of germ tubes, the benzofurans displayed strong activity, whereas the benzopyran, benzoxepine, and butyrolactone were inactive at the highest concentration tested. P. grisea, responsible for rice blast disease, was the most susceptible fungus against all benzofurans, with rocaglaol as the most active derivative. Based on EC(50), EC(90), and MIC values, the antifungal activity of rocaglaol was clearly higher than of the reference compounds, blasticidin S and Benlate.
    Journal of Agricultural and Food Chemistry 05/2000; 48(4):1400-4. · 3.11 Impact Factor
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    ABSTRACT: Twelve new derivatives of bisamides [piriferinol (5), edulimide (7)], lignans [lariciresinol acetat (10)], triterpenes [4-bis-norcycloartane-type triterpenes (11a, 12a+b, 13a+b)], cyclopenta[b]benzofurans [pannellin (15), pannellin 1-O-acetate (16), 3'-methoxypannellin (17)], and an aromatic butyrolactone [aglalactone (18)] were isolated and identified from lipophilic leaf, stem, and root extracts of Aglaia spp. elaeagnoidea, edulis, grandis, silvestris, and tomentosa. Two cyclopenta[b]benzofurans (flavaglines), pannellin (15) and pannellin 1-O-acetate (16), displayed very strong insecticidal activity against Spodoptera littoralis and Lymantria dispar, comparable with the activity of azadirachtin.
    Journal of Natural Products 01/1999; 61(12):1482-90. · 3.29 Impact Factor
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    ABSTRACT: Nine new flavaglines, cyclopenta[bc]benzopyrans (thapsakins) and benzo[b]oxepines (thapoxepines), were isolated from the lipophilic root extract of Aglaia edulis together with two known cyclopenta[b]benzofurans, aglaroxin A and pannellin. The structures were established on the basis of extensive use of NMR spectroscopic methods (C,H-COSY, NOESY, HMBC, lanthanide induced shifts). Aglaroxin A and pannellin exhibited the strongest insect toxicity toward neonate larvae of Spodoptera littoralis. Possible biogenetic connections between the three skeletal types are outlined and chemosystematic implications of flavagline formation are discussed.
    Phytochemistry 01/1999; 52(2):253-263. · 3.05 Impact Factor
  • C Seger, S Vajrodaya, H Greger, O Hofer
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    ABSTRACT: A new quinazolone derivative, (Z)-3,4-dihydro-3-(2-phenyIethcnyl)-quinazolin-4-one was isolated from Glycosmis cf. chlorosperma SPRENG. (Rutaceae). The structure was elucidated on the basis of spectroscopic data and confirmed by comparison with synthetically obtained material. The compound showed bioactivity against different test organisms.
    CHEMICAL & PHARMACEUTICAL BULLETIN 12/1998; 46(12):1926-1928. · 1.56 Impact Factor
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    ABSTRACT: The lipophilic leaf, stem and root extracts of Glycosmis trichanthera are characterized by distinct chemical profiles, containing sulphur-containing amides in the leaves, prenylated acridone alkaloids in the stem bark, and quinoline alkaloids together with a 3,7-diprenylated indole in the root bark. Two isomeric sulphones derived from methylthio-propenoic acid phenethylamides, named trichanthin-A and -B, and the 3,7-diprenylated indole proved to be new natural products. Structure elucidation of the new compounds is described by spectroscopic evidence. Bioautographic tests with Cladosporium herbarum showed only moderate antifungal activity for trichanthin-B and methylgerambullin.
    Phytochemistry 01/1998; 48(5):897-902. · 3.05 Impact Factor
  • Otmar Hofer, Srunya Vajrodaya, Harald Greger
    Monatshefte Fur Chemie - MONATSH CHEM. 01/1998; 129(2):213-219.