Farhana Afshan

Two insecticidal tetranortriterpenoids from Azadirachta indica

Two new triterpenoids, 6 alpha-O-acetyl-7-deacetylnimocinol [24,25,26,27-tetra-norapotirucalla-(apoeupha)-6 alpha-acetoxy-7 alpha-hydroxy-1,14,20,22-tetraen-21,23-epoxy-3-one] (1) and meliacinol [24,25,26,27-tetranorapotirucalla-(apoeupha)-1 alpha-trimethylacryloxy-21,23-6 alpha,28-diepoxy-16-oxo-17-oxa-14,20,22-trien-3 alpha,7 alpha-diol] (2) were isolated from the methanolic extract of the fresh leaves of Azadirachta indica (neem). Their structures have been elucidated through spectral studies, including 2D-NMR (COSY-45, NOESY, HMQC and HMBC). The bioactivity of these as well as of nimocinol, reported earlier from the same source, is reported. The first compound and nimocinol showed toxicity on fourth instar larvae of mosquitoes (Aedes aegypti) with LC50 values of 21 and 83 ppm, respectively. The second compound had no effect upto 100 ppm.

Phytochemical studies on the seed extract of Piper nigrum Linn.

The petroleum ether extract of dried ground seeds of Piper nigrum Linn. and some column fractions of this extract were subjected to GC and GC-MS analysis, resulting in the identification of fourteen compounds (1–14) by using NIST Mass spectral search program 1998 and the Kovats retention indices. Ten of the compounds (1, 2, 4–12) are reported for the first time from this plant. All the fractions showed insecticidal activity against the fourth instar larvae of Aedes aegypti and against the fourth instar larvae of Anopheles stephensi Liston, determined by the WHO method.

Insecticidal amides from fruits of Piper Nigrum Linn.

The petroleum ether and ethyl acetate fractions of dried ground seeds of Piper nigrum Linn. afforded sixteen compounds (1–16) including one new insecticidal amide, pipwaqarine (1) and six constituents (3,4,6,7,11,15) previously unreported from this plant. The structure of (1) has been elucidated through extensive 1D-, 2D-NMR spectral studies as, 1-[13-(3′,4′-methylenedioxyphenyl)-2E,4E,12E-tridecatrienoyl]-N-isopentylamide, while those of known constituents through comparison of spectral data. 1 exhibited toxicity of 30 ppm against fourth instar larvae of Aedes aegypti Liston determined by WHO method. A portion of petroleum ether fraction was also subjected to GC and GC-MS analysis resulting in the identification of three compounds (17–19) using the NIST Mass spectral search program 1998 and Kovats retention indices. Two of these compounds, 17 and 18, are reported for the first time from this plant.

Piptigrine, a new Insecticidal Amide from Piper Nigrum Linn.

A new insecticidal amide piptigrine (1) possessing highly extended conjugation was isolated from the dried ground seeds of Piper nigrum Linn. along with the known amides piperine and wisanine (hitherto unreported from this plant). The structure of 1 has been elucidated as 1-[9-(3′,4′-methylenedioxyphenyl)-4E,6E,8E-nonatrienoyl]piperidine through extensive 1D- and 2D-NMR (COSY-45, NOESY, J-resolved, HMQC, HMBC and NOESY studies. The known compounds have been identified through comparison of their spectral data with those reported in literature. 1 exhibited toxicity of 15.0 ppm against fourth instar larvae of Aedes aegypti Liston.

Withanolides from Datura innoxia

The methanolic extract of the aerial parts of Datura innoxia afforded two new withanolides namely witharifeen (1) and daturalicin (2). Their structures were established as 11α 12β-dihydroxy (20R, 22R)-21,24-epoxy-1-oxowitha-2, 5, 25(27)-trien-22, 26-olide (1) and (20R, 22R)-5β, 6β-14α,15α-21,24-triepoxyl-oxowitha-2,25(27)-dien-22,26-olide (2) respectively by analysis of spectroscopic data.

Three novel tetracyclic triterpenoids of biogenetic interest from the leaves of Azadirachta indica

Abstract From the methanolic extract of Azadirachta indica leaves, we have isolated three new tetracyclic triterpenoids of biogenetic interest, namely, melianol 1 , desfurano-desacetylnimbin-17-one 2 and meliatetraone 3 . The structure elucidation is based on extensive spectral studies including 1 H– 1 H-COSY, NOESY, HMQC, and HMBC experiments.

New insect-growth-regulator meliacin butenolides from the leaves of Azadirachta indica A. Juss

Two new triterpenoids, 23-O-methylnimocinolide [7α-acetoxy-6α-hydroxy-23ξ-methoxy-3-oxo-24,25,26,27-tetranorapotirucalla(apoeupha)-1,14,20(22)-trieno-21,23-lactone] 1, 7-O-deacetyl-23-O-methyl-7α-O-senecioylnimocinolide [6α-hydroxy-23ξ-methoxy-3-oxo-7α-senecioyloxy-24,25,26,27-tetranorapotirucalla(apoeupha)-1,14,20(22)-trieno-21,23-lactone] 2 have been isolated from the methanolic extract of the fresh leaves of Azadirachta indica (neem). Their structures were elucidated through spectral studies, including 2D NMR (NOESY, COSY-45, HMQC and HMBC). Compounds 1 and 2 show insect-growth-regulating effect on mosquitoes (Aedes aegypti) with LC50 53 ppm and 2.14 ppm, respectively. The senecioyloxy substituent at C-7 in 2 results in a significant increase of activity.

A new natural product and insecticidal amides from seeds of Piper nigrum Linn.

Studies on the petroleum ether soluble and insoluble fraction of ethanol extract of dried ground seeds of Piper nigrum resulted in the isolation and structure elucidation of 1 new and 11 known compounds which include 3 hitherto unreported constituents, namely, cinnamylideneacetone, 3,4-methylenedioxyphenylpropiophenone and 2-hydroxy-4,5-methylenedioxypropiophenone from this plant.

A new tetracyclic triterpenoid from the leaves of Azadirachta indica.

A new tetracyclic triterpenoid zeeshanol [25,26,27-trinor-apotirucalla-(apoeupha)-6α-, 21-dihydroxy, 7α-acetoxy, 1,14,22-tri-en-3, 16-dione] (1) along with a known constituent desfurano-6α-hydroxyazadiradione (2) have been isolated from the methanolic extract of the leaves of Azadirachta indica. The structure and the relative configurations of 1 were determined by the spectroscopic method (1H- and 13C-NMR, IR, and MS) and 2D-NMR experiments.

Medicinal Plants - A Source of Potential Chemicals of Diverse Structures and Biological Activity

Biodiversity is defined as the total diversity and variability of living thing and of the system of which they are a part. This covers the total range of variation in and variability among systems and organisms, at the bioregional, landscape, ecosystem and habitat levels, at the various organism levels down to species, population and genes. The variability that we observe among individuals (phenotype) results from the interaction of genetic differences (genotype) with their surrounding environments. Genetic diversity can be assayed directly by surveying the actual genetic material (i.e. the genotype). The genetic diversity occurs in the form of nucleotide variation within the genome sometimes causing a change in a given protein. Hence we observe chemical diversity through biosynthetic processes controlled by specific enzymes (proteins).