ABSTRACT
Two prenylated flavanones have been isolated from the hexane extract of Phyllanthus niruri plant. The structure of these flavanones were established as 8-(3-Methyl-but-2-enyl)-2-phenyl chroman-4-one (1) and 2-(4-hydroxyphenyl)-8-(3-methyl-but-2-enyl)-chroman-4-one (2) on the basis of spectral analysis. These were evaluated for nematicidal activity against root-knot, Meloidogyne incognita, and reniform, Rotylenchulus reniformis, nematodes. Compound 2 exhibited nematicidal activity at par with the standard carbofuran (LC50 3.3 and 3.1ppm, respectively) when tested against reniform nematode. The LC50 value against root-knot nematode was found to be 14.5ppm. Compound 1 however, showed moderate activity against both the test nematodes.
Subject(s)
Antinematodal Agents/pharmacology , Chromans/chemistry , Flavanones/pharmacology , Nematoda/drug effects , Phyllanthus/chemistry , Plant Roots/parasitology , Animals , Antinematodal Agents/chemistry , Antinematodal Agents/isolation & purification , Chromans/isolation & purification , Flavanones/chemistry , Flavanones/isolation & purification , Molecular Structure , Nematoda/chemistry , Plant Roots/drug effects , Plant Roots/growth & development , Species Specificity , StereoisomerismABSTRACT
Eleven sesquiterpene lactone derivatives of parthenin (1), obtained from wild feverfew, Parthenium hysterophorus, were prepared by chemical and photochemical transformations. The compounds tested were a pyrazoline adduct (2) of parthenin, its cyclopropyl (3) and propenyl (4) derivatives, anhydroparthenin (5), a dihydro-deoxygenated product (6), a formate (7) and its corresponding alcohol (8) and acetate (9), a rearranged product (10), lactone (11) and hemiacetal (12). All these derivatives, along with parthenin, were tried for their antifeedant action against sixth-instar larvae of Spodoptera litura, for insecticidal activity against the adults of store grain pest Callosobruchus maculatus, for phytotoxic activity against Cassia tora, and for nematicidal activity against the juvenile stage-II (J2) of the root knot nematode Meloidogyne incognita. Antifeedent bioassay revealed that parthenin is moderately antifeedant. Among the derivatives, the saturated lactone (11) was found to be about 2.25 times more active than parthenin. The pyrazoline adduct (2) was found to be the most effective as an insecticide, with LC50 values after 24, 48 and 72 h of 96, 43 and 32 mg litre-1, respectively, which are comparable with neem extract. Compound 4 was found to be the most effective inhibitor of germination and seedling growth of C tora, with ID50 values for germination, plumule length and radicle length of 136, 326 and 172 compared with 364, 738 and 427 mg litre-1, respectively, for parthenin. Compound 10 was found to be the most effective in terms of nematicidal activity. The LC50 values for this compound were 273 and 104 mg litre-1, respectively, after 48 and 72 h compared with 862 and 512 mg litre-1 observed for parthenin after 48 and 72 h.
Subject(s)
Antinematodal Agents/pharmacology , Insecticides/pharmacology , Limonins , Plants, Medicinal , Sesquiterpenes/pharmacology , Tanacetum parthenium/chemistry , Triterpenes/pharmacology , Uncoupling Agents/pharmacology , Animals , Antinematodal Agents/chemical synthesis , Antinematodal Agents/chemistry , Biological Assay , Coleoptera/drug effects , Feeding Behavior/drug effects , Insecticides/chemical synthesis , Insecticides/isolation & purification , Lactones/chemistry , Lactones/pharmacology , Lepidoptera/drug effects , Molecular Conformation , Nematoda/drug effects , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Rosales/drug effects , Sesquiterpenes/chemistry , Sesquiterpenes/isolation & purification , Triterpenes/chemical synthesis , Uncoupling Agents/isolation & purificationABSTRACT
The allelopathic effects ofProsopis juliflora were studied both in the laboratory and in nature and compared with that ofProsopis cineraria to understand the chemical nature of allelochemics. Both species occupy the same habitats butP. cineraria does not appear to have any toxic effect on other plants under its canopy.P. juliflora is highly allelopathic and does not allow the growth of any other species. Leaf extracts and leaf leachates ofP. juliflora were inhibitory. Decaying leaves were also inhibitory at early stages of decomposition. Live roots were not found to be inhibitory in cogermination and interplanting of seeds. Chemical investigation of the extracts showed the allelopathic compounds to be phenolic in nature in both the species. Slow decomposition and heavy accumulation of leaf litter belowP. juliflora may possibly result in accumulation of toxic substances in soil layers, inhibiting growth of other species.
ABSTRACT
Six essential oils of Mentha arvensis, Mentha piperita, Anethum sowa, Cymbopogon winterianus, Nardostachys jatamansi, and Commiphora mukul were selected and tested for their efficacy against Aspergillus flavus, A. fumigatus, A. sulphureus, Mucor fragilis, and Rhizopus stolonifer. These oils were fungistatic or fungicidal to one or the other molds, depending upon the concentrations.
