Author
Manjusha Sarkar
Bio: Manjusha Sarkar is an academic researcher from University of Calcutta. The author has contributed to research in topics: Piper retrofractum & Carbon-13 NMR. The author has an hindex of 4, co-authored 6 publications receiving 85 citations.
Papers
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TL;DR: In this article, two unsaturated amides, retrofractamides A and C, were isolated from the total aboveground parts of Piper retroractum and were shown to be N -isobutyl-9(3′,4′-methylenedioxyphenyl)2 E,4 E,8 E -nonatrienamide from spectroscopic and chemical investigations.
42 citations
TL;DR: Three unsaturated amides, designatedBrachystamides-C, D and E have been characterised from Piper brachystachyum Wall, which yielded retrofractamide-D, which has been fully characterised.
22 citations
TL;DR: The structure of a 2,3,4 trisubstituted furanoid lignan, designated sylvone, was established as 1 from detailed spectroscopical and chemical studies as discussed by the authors.
19 citations
TL;DR: In this article, the authors complete the composition and composes apparentes d'apres les schemas de decomposition des spectres couples, de l'application des relations d'additivite and des comparaisons internes des deplacements chimiques.
Abstract: Attribution complete du spectre de ce compose et de composes apparentes d'apres les schemas de decomposition des spectres couples, de l'application des relations d'additivite et des comparaisons internes des deplacements chimiques
5 citations
TL;DR: Three unsaturated amides, designated brachystamides-C, D and E have been characterised from Piper brachyachyum Wall as mentioned in this paper, and two of them have been fully characterised.
Abstract: Three unsaturated amides, designated brachystamides-C, D and E have been characterised from Piper brachystachyum Wall. Brachystamide-C, shown to be N-isobutyl-15-(3',4'-methylenedioxyphenyl)-2E,4E,13E-pentadecatrienamide, was unusual in having a non-conjugated double bond. Piper retrofractum Vahl. yielded retrofractamide-D, which has been fully characterised.
3 citations
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TL;DR: The secondary metabolites isolated from Piper species for the period 1907 to June 1996 have been reviewed in this paper, where nearly six hundred chemical constituents belonging to different classes of bioactive compounds are listed together with their source(s) and references.
849 citations
TL;DR: Structural-activity relationships indicate that the N-isobutylamine moiety might play a crucial role in the larvicidal activity, but the methylenedioxyphenyl moiety does not appear essential for toxicity.
Abstract: The insecticidal activity of materials derived from the fruits of Piper nigrum against third instar larvae of Culex pipiens pallens, Aedes aegypti, and A. togoi was examined and compared with that of commercially available piperine, a known insecticidal compound from Piper species. The biologically active constituents of P. nigrum fruits were characterized as the isobutylamide alkaloids pellitorine, guineensine, pipercide, and retrofractamide A by spectroscopic analysis. Retrofractamide A was isolated from P. nigrum fruits as a new insecticidal principle. On the basis of 48-h LC(50) values, the compound most toxic to C. pipiens pallens larvae was pipercide (0.004 ppm) followed by retrofractamide A (0.028 ppm), guineensine (0.17 ppm), and pellitorine (0.86 ppm). Piperine (3.21 ppm) was least toxic. Against A. aegypti larvae, larvicidal activity was more pronounced in retrofractamide A (0.039 ppm) than in pipercide (0.1 ppm), guineensine (0.89 ppm), and pellitorine (0.92 ppm). Piperine (5.1 ppm) was relatively ineffective. Against A. togoi larvae, retrofractamide A (0.01 ppm) was much more effective, compared with pipercide (0.26 ppm), pellitorine (0.71 ppm), and guineensine (0.75 ppm). Again, very low activity was observed with piperine (4.6 ppm). Structure-activity relationships indicate that the N-isobutylamine moiety might play a crucial role in the larvicidal activity, but the methylenedioxyphenyl moiety does not appear essential for toxicity. Naturally occurring Piper fruit-derived compounds merit further study as potential mosquito larval control agents or as lead compounds.
203 citations
TL;DR: Piper crassinervium, P. aduncum,P.
Abstract: Piper crassinervium, P aduncum, P hostmannianum, and P gaudichaudianum contain the new benzoic acid derivatives crassinervic acid (1), aduncumene (8), hostmaniane (18), and gaudichaudianic acid (20), respectively, as major secondary metabolites Additionally, 19 known compounds such as benzoic acids, chromenes, and flavonoids were isolated and identified The antifungal activity of these compounds was evaluated by bioautographic TLC assay against Cladosporium cladosporioides and C sphaerospermum
184 citations
TL;DR: The n-hexane extracts of 19 Piper species, predominantly from China, were screened for their 5-lipoxygenase (5-LOX) and cyclo oxygengenase-1 (COX-1) inhibitory potential and showed considerable inhibitory activity against at least one of these two key enzymes of the arachidonic acid metabolism.
152 citations
01 Jan 2004
131 citations