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Günther Raspotnig - One of the best experts on this subject based on the ideXlab platform.
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The scent gland chemistry of neogoveid cyphophthalmids (Opiliones): an unusual methyljuglone from Metasiro savannahensis
Chemoecology, 2019Co-Authors: Günther Raspotnig, Felix Anderl, Ronald M. ClouseAbstract:While the chemistries of scent gland secretions from a few selected species of three families of Cyphophthalmi, namely Sironidae, Pettalidae, and Stylocellidae, have already been reported and found to consist of complex blends of Naphthoquinones and methyl ketones, nothing is known about the other families. We here report on the secretions of Metasiro savannahensis Clouse and Wheeler (Zootaxa 3814:177–201, 2014), a first representative of the family Neogoveidae. The secretions from males, females and one juvenile were extracted and analyzed by gas chromatography–mass spectrometry. Twenty-five compounds were identified, all of which belong to the chemical classes of Naphthoquinones and methyl ketones, confirming a hypothesized chemical uniformity of cyphophthalmid exudates. One major Naphthoquinone compound, however, was new for cyphophthalmids and for arthropod exocrine secretions in general: a methyljuglone isomer, 6-methyljuglone (= 6-MJ; iupac name: 5-hydroxy-6-methyl-1,4-Naphthoquinone), amounted for about 20% of the secretion and was eventually identified by synthesis. Hydroxy-Naphthoquinones and their derivatives are known to possess a variety of antibiotic effects, probably enhancing the antimicrobial/antifungal potential of the Metasiro -secretion. Currently, without further data on neogoveids, the compound represents a chemical autapomorphy of M. savannahensis , and—just as the strange chloro-Naphthoquinones of Sironidae and Pettalidae—adds to the repertoire of unusual Naphthoquinone compounds across the Cyphophthalmi.
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Methyl-ketones in the scent glands of Opiliones: a chemical trait of cyphophthalmi retrieved in the dyspnoan Nemastoma triste
Chemoecology, 2018Co-Authors: Miriam Schaider, Hans-jörg Leis, Tone Novak, Christian Komposch, Günther RaspotnigAbstract:The homologous and phylogenetically old scent glands of harvestmen—also called defensive or repugnatorial glands—represent an ideal system for a model reconstruction of the evolutionary history of exocrine secretion chemistry (“phylogenetic chemosystematics”). While the secretions of Laniatores (mainly phenols, benzoquinones), Cyphophthalmi (Naphthoquinones, chloro-Naphthoquinones, methyl-ketones) and some Eupnoi (Naphthoquinones, ethyl-ketones) are fairly well studied, one open question refers to the still largely enigmatic scent gland chemistry of representatives of the suborder Dyspnoi and the relation of dyspnoan chemistry to the remaining suborders. We here report on the secretion of a nemastomatid Dyspnoi, Nemastoma triste, which is composed of straight-chain methyl-ketones (heptan-2-one, nonan-2-one, 6-tridecen-2-one, 8-tridecen-2-one), methyl-branched methyl-ketones (5-methyl-heptan-2-one, 6-methyl-nonan-2-one), Naphthoquinones (1,4-Naphthoquinone, 6-methyl-1,4-Naphthoquinone) and chloro-Naphthoquinones (4-chloro-1,2-Naphthoquinone, 4-chloro-6-methyl-1,2-Naphthoquinone). Chemically, the secretions of N. triste are remarkably reminiscent of those found in Cyphophthalmi. While Naphthoquinones are widely distributed across the scent gland secretions of harvestmen (all suborders except Laniatores), methyl-ketones and chloro-Naphthoquinones arise as linking elements between cyphophthalmid and dyspnoan scent gland chemistry.
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On the enigmatic scent glands of dyspnoan harvestmen (Arachnida, Opiliones): first evidence for the production of volatile secretions
Chemoecology, 2014Co-Authors: Günther Raspotnig, Miriam Schaider, Hans-jörg Leis, Edith Stabentheiner, Ivo KaramanAbstract:While considerable knowledge on the chemistry of the scent gland secretions from the opilionid suborders Laniatores and Cyphophthalmi has been compiled, it is the Palpatores (Eupnoi and Dyspnoi) where chemical data are scarce. In particular, the Dyspnoi have remained nearly unstudied, mainly due to their reported general reluctance to release secretions as well as to the phenomenon of production of insoluble—and inaccessible—solid secretion. We here show that at least certain nemastomatid Dyspnoi, namely all three species of genus Carinostoma , indeed produce a volatile secretion, comprising octan-3-one, 6-methyl-5-hepten-2-one and acetophenone in species-specific combinations. In all Carinostoma spp., these volatiles are embedded in a semi-volatile, Naphthoquinone matrix (mainly 1,4-Naphthoquinone and 6-methyl-1,4-Naphthoquinone). In detail, acetophenone and traces of Naphthoquinones characterize the secretions of Carinostoma carinatum . A mixture of octan-3-one, 6-methyl-5-hepten-2-one and large amounts of Naphthoquinones were found in C. elegans , and 6-methyl-5-hepten-2-one together with small amounts of Naphthoquinones in the secretions of C. ornatum . So far, exclusively Naphthoquinones had been reported from a single dyspnoan hitherto studied, Paranemastoma quadripunctatum .
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Naphthoquinones and Anthraquinones from Scent Glands of a Dyspnoid Harvestman, Paranemastoma quadripunctatum
Journal of Chemical Ecology, 2010Co-Authors: Günther Raspotnig, Miriam Schaider, Verena Leutgeb, Christian KomposchAbstract:Extracts of Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae) contained seven components, all of which likely originated from the secretion of well-developed prosomal scent glands. The two main components (together accounting for more than 90% of the secretion) were identified as 1,4-Naphthoquinone and 6-methyl-1,4-Naphthoquinone. The minor components were 1,4-naphthalenediol, two methoxy-Naphthoquinones (2-methoxy-1,4-Naphthoquinone, and 2-methoxy-6-methyl-1,4-Naphthoquinone) and two anthraquinones (2-methyl-9,10-anthraquinone and a dimethyl-9,10-anthraquinone). While some chemical data on scent gland secretions of the other suborders of Opiliones (Cyphophthalmi, palpatorean Eupnoi, and Laniatores) already exist, this is the first report on the scent gland chemistry in the Dyspnoi. Naphthoquinones are known scent gland exudates of Cyphophthalmi and certain Eupnoi, methoxy-Naphthoquinones and anthraquinones are new for opilionid scent gland secretions.
P.k. Shukla - One of the best experts on this subject based on the ideXlab platform.
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design synthesis and biological evaluation of novel nitrogen and sulfur containing hetero 1 4 Naphthoquinones as potent antifungal and antibacterial agents
European Journal of Medicinal Chemistry, 2009Co-Authors: Vishnu K Tandon, Hardesh K Maurya, Nripendra N Mishra, P.k. ShuklaAbstract:Abstract A series of 2-Arylamino-3-chloro-1,4-Naphthoquinones (3), 2-Amino-3-arylsulfanyl-1,4-Naphthoquinones (5), 2-Arylamino-3-arylsulfanyl-1,4-Naphthoquinones (6), Dihydrobenzo[f]naphtho[2,3-b][1,4]thiazepine-6,11-diones (9) (via Pictet–Spengler cyclization), Isoindoline-1,3-dione derivatives of 1,4-Naphthoquinone (13), 2,2′-(1,4-Dioxo-1,4-dihydronaphthalene-2,3-diyl)bis(methylene)dibenzonitrile (14), 13-Amino-12-substituted-6H-benzo[e]naphtho [2,3-b][1,4]diazepine-6,11(12H)-diones (15–16), 2-Chloro-3-arylsulfanyl-1,4-Naphthoquinones (17–18) and 3-Methyl-6H-benzo[b]phenothiazine-6,11(12H)-dione (19) were synthesized and studied for their antifungal and antibacterial activities. The results indicate that compounds 3b, 5a and 5b have potent antifungal activity. Amongst the most promising antifungal compounds, 3b showed better antifungal activity than clinically prevalent antifungal drug Fluconazole (MIC50 = 2.0 μg/mL) against Sporothrix schenckii (MIC50 = 1.56 μg/mL), significant profile against Candida albicans (MIC50 = 1.56 μg/mL), Cryptococcus neoformans (MIC50 = 0.78 μg/mL) and Trichophyton mentagraphytes (MIC50 = 1.56 μg/mL) and same antifungal activity when compared with Amphotericin-B against C. neoformans (MIC50 = 0.78 μg/mL). Compounds 3b, 5a and 5b also showed promising antibacterial activity.
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synthesis and biological evaluation of novel l α amino acid methyl ester heteroalkyl and aryl substituted 1 4 Naphthoquinone derivatives as antifungal and antibacterial agents
Bioorganic & Medicinal Chemistry Letters, 2005Co-Authors: Vishnu K Tando, Ravindra V Singh, Dharmendra Yadav, Ashok K Chaturvedi, P.k. ShuklaAbstract:Abstract A series of ( S )- N -(1,4-naphthoquinon-2-yl)-α-amino acid methyl esters 3 – 9 , 2- N , N -dialkylamino-1,4-Naphthoquinones 10 – 11 and 2-hydroxy-3-(2′-mercaptoimidazolyl)-1,4-Naphthoquinones and their cyclic analogs 12 – 15 were synthesized and evaluated for antifungal and antibacterial activities. The structure–activity relationships of these compounds were studied and the results show that the compounds 9b and 13c exhibited in vitro antifungal activity against Candida albicans , Cryptococcus neoformans , and Sporothrix schenckii , whereas compound 6a showed in vitro antibacterial activity against Streptococcus faecalis , K. pneumoniae , Escherichia coli , and Staphylococcus aureus .
Vinod K Singh - One of the best experts on this subject based on the ideXlab platform.
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highly enantioselective synthesis of Naphthoquinones and pyranoNaphthoquinones catalyzed by bifunctional chiral bis squaramides
Organic and Biomolecular Chemistry, 2015Co-Authors: Nagaraju Molleti, Vinod K SinghAbstract:A variety of enantioenriched Naphthoquinones have been synthesized in high yields and excellent enantioselectivities (up to >99% ee) using a bifunctional chiral bis-squaramide catalyzed conjugate addition of 2-hydroxy-1,4-Naphthoquinone to 2-enoylpyridines. Some of the Michael products have been successfully converted into various enantioenriched pyranoNaphthoquinone derivatives. The protocol is further extended to the synthesis of various 4-hydroxycoumarin derivatives under mild conditions.
Vishnu K Tandon - One of the best experts on this subject based on the ideXlab platform.
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design synthesis and biological evaluation of novel nitrogen and sulfur containing hetero 1 4 Naphthoquinones as potent antifungal and antibacterial agents
European Journal of Medicinal Chemistry, 2009Co-Authors: Vishnu K Tandon, Hardesh K Maurya, Nripendra N Mishra, P.k. ShuklaAbstract:Abstract A series of 2-Arylamino-3-chloro-1,4-Naphthoquinones (3), 2-Amino-3-arylsulfanyl-1,4-Naphthoquinones (5), 2-Arylamino-3-arylsulfanyl-1,4-Naphthoquinones (6), Dihydrobenzo[f]naphtho[2,3-b][1,4]thiazepine-6,11-diones (9) (via Pictet–Spengler cyclization), Isoindoline-1,3-dione derivatives of 1,4-Naphthoquinone (13), 2,2′-(1,4-Dioxo-1,4-dihydronaphthalene-2,3-diyl)bis(methylene)dibenzonitrile (14), 13-Amino-12-substituted-6H-benzo[e]naphtho [2,3-b][1,4]diazepine-6,11(12H)-diones (15–16), 2-Chloro-3-arylsulfanyl-1,4-Naphthoquinones (17–18) and 3-Methyl-6H-benzo[b]phenothiazine-6,11(12H)-dione (19) were synthesized and studied for their antifungal and antibacterial activities. The results indicate that compounds 3b, 5a and 5b have potent antifungal activity. Amongst the most promising antifungal compounds, 3b showed better antifungal activity than clinically prevalent antifungal drug Fluconazole (MIC50 = 2.0 μg/mL) against Sporothrix schenckii (MIC50 = 1.56 μg/mL), significant profile against Candida albicans (MIC50 = 1.56 μg/mL), Cryptococcus neoformans (MIC50 = 0.78 μg/mL) and Trichophyton mentagraphytes (MIC50 = 1.56 μg/mL) and same antifungal activity when compared with Amphotericin-B against C. neoformans (MIC50 = 0.78 μg/mL). Compounds 3b, 5a and 5b also showed promising antibacterial activity.
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synthesis and evaluation of novel 1 4 Naphthoquinone derivatives as antiviral antifungal and anticancer agents
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Vishnu K Tandon, Ravindra V Singh, Dharmendra B YadavAbstract:Abstract The synthesis and evaluation of some 2-substituted-1,4-Naphthoquinones 2 , S -(1,4-naphthoquinon-2-yl)-mercaptoalkanoic acid amides 4 , related benzoquinone and Naphthoquinone derivatives 6 – 9 and 2,3-disubstituted 1,4-Naphthoquinones 10 – 11 were carried out. The antifungal, antibacterial, antiviral and anticancer activities were determined by using the standard assay. The results show that compounds 2b and 10a showed in vitro antiviral activity against Inflenza-A Virus and Herpes Simplex Virus and possess pronounced antifungal profile whereas 4a showed anticancer activites against Lymphoid Leukaemia P 388 .
Liqiang Wu - One of the best experts on this subject based on the ideXlab platform.
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synthesis and biological evaluation of novel 1 2 Naphthoquinones possessing tetrazolo 1 5 a pyrimidine scaffolds as potent antitumor agents
RSC Advances, 2015Co-Authors: Liqiang WuAbstract:A series of novel 1,2-Naphthoquinones possessing tetrazolo[1,5-a]pyrimidine scaffolds were synthesized in very good yields using one-pot condensation of 2-hydroxy-1,4-Naphthoquinone, aldehydes, and 5-aminotetrazole. All the synthesized compounds were evaluated for their antitumor activity in vitro against HCT116 (human colon cancer) and HepG2 (human hepatoma) cell lines. Among the screened compounds, 4o, 4k, 4g, 4q, and 4s showed significant inhibitory activity against the two human cell lines.
