Plant extract effect on seed-borne pathogenic fungi from seeds of paddy grown in Southern India

A total of 40 seed samples of different cultivars of paddy, collected from southern part of India, were mycologicaly analyzed by agar plating method on Czapek's-Dox-Agar (CzA) medium and Standard Blotter Method (SBM), revealed the occurrence of 33 diverse fungal species belonging to 16 genera. The species of Drechslera oryzae (RP 82.5) was recorded with the incidence and relative preponderance (RP), followed by Curvularia lunata (RP 67.5) and Aspergillus niger (RP 65.0) respectively. The data on the diversity and incidence of fungal species would be a great importance in the region for predicting the extent of pre-and post-infections.In vitro antifungal activity assay of methanol extract of 12 plants belonging to different families were tested against eight pathogenic fungal species viz., Alternaria alternata, Aspergillus flavus, Curvularia lunata, Drechslera oryzae, D. halodes, Fusarium moniliforme, Pyricularia oryzae and Trichoconis padwickii by poisoned food technique. The results revealed that, methanol extract of Acacia nilotica, Caesalpinia coriaria, Decalepis hamiltonii, Emblica officinalis, Lawsonia inermis and Mimosops elengi showed significant antifungal activity at 3500 μg/ml concentration. Comparative evaluation of the extracts with the synthetic fungicides viz., bavistin, blitox, captan, dithane M-45 and thiram at the recommended dosage revealed that, antifungal activity of methanol extract of D. hamiltonii, L. inermis and M. elengi was almost equivalent. These plants can possibly be exploited in the management of seed-borne pathogenic fungi and prevention of biodeterioration of paddy in an eco-friendly way

Determination of Quantum Yield for the Photochemical Decomposition of Dichloramine-B and Dibromamine-B in Aqueous Acetic Acid Medium

The photolysis of dihaloamines (RNX2), viz., dichloramine-B (DCB) and dibromamine-B (DBB) in aqueous acetic acid (1:1 v/v) solutions has been studied with the UV light source (λ= 2537 Å). The experimental rate law obtained is - d [RNX2] / dt = k' Io / [RNX2], where Io is the intensity of incident light. The addition of benzenesulphonamide, the product of photolysis or uranyl ion had no significant effect on the rate of photochemical decomposition. A slight decrease in the rate has been observed by the addition of NaCl / NaBr to DCB / DBB solutions. The quantum yield (Φ) for the photolytic decomposition has been computed. A suitable photolytic mechanism and a rate law consistent with the observed results have been proposed

Mechanistic investigation of oxidation of phenylpropanolamine with n-bromobenzenesulfonamide in alkaline medium: A kinetic approach

The kinetics of oxidation of phenylpropanolamine (PPA) with sodium N-bromobenzenesulfonamide or bromamine-B (BAB) has been investigated in alkaline medium at 308 K. The oxidation reaction obeys the rate law, – d[BAB]/dt = k [BAB] [PPA]x [OH-], where x is less than unity. The variation of ionic strength of the medium, addition of the reduction product, benzenesulfonamide, and chloride ion had no pronounced effect on the reaction rate. Decrease of dielectric permittivity of the medium by increasing the CH3CN content increased the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated from the Arrhenius plot. The stiochiometry of the reaction was found to be 1:1, and the oxidation product of phenylpropanolamine was identified as benzaldehyde and ethylideneamine. The rate decreased in D2O medium and the normal isotope effect k' (H2O) / k' (D2O) is 2.18. Proton inventory studies have been made in H2O - D2O mixtures. Formation and decomposition constant of BAB-PPA complexes in the reaction scheme have been determined. The conjugate acid, C6H5SO2NHBr is assumed to be the reactive species. The proposed mechanism and the derived rate law are consistent with the observed experimental results

Ruthenium(III)-catalyzed oxidation of 2-phenylethylamine with sodium N-chlorobenzenesulphonamide in hydrochloric acid solution: A kinetic and mechanistic study

The kinetics of ruthenium(III)-catalyzed oxidation of 2-phenylethylamine (PEA) with sodium N-chlorobenzenesulphonamide or chloramine-B (CAB) in hydrochloric acid solution has been studied at 313K. The reaction rate shows first-order dependence each on CAB, H+ and Ru(III)Cl3 and fractional order on PEA and Cl−. Variation of ionic strength and addition of the reduction product of CAB has no significant effect on the rate. There is a negative effect of dielectric constant of the solvent. The stoichiometry of the reaction was found to be 1:1 and the oxidation product of 2-phenylethylamine was identified as phenyl acetaldehyde. The reaction was studied at different temperatures and the activation parameters have been evaluated from the Arrhenius plot. The reaction constants involved in the mechanisms were computed. RN+H2Cl has been postulated as the reactive oxidizing species. Mechanisms consistent with the observed kinetic data have been proposed and discussed

Ruthenium (iii) - catalyzed oxidatwe cleavage of phenylpropanolamine hydrochloride with sodium n-chorobezenesulfonamide in acid medium: a kinetic and mechanistic study

Phenylpropanolamine hydrochloride (2-amino-l-phenylpropanol hydrochloride) is a sympathomimetric drug used for nasal congestión associated with the common cold, allergies, high fever, or other respiratory illness. The kinetics of oxidation of phenylpropanolamine hydrochloride (PPA) with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) catalyzed by Ru (III) in hydrochloric acid médium has been studied at 308 K. The oxidation reaction follows the rate law, - d [CAB]/dt = k [CAB] [H+]x [PPA]y [Ru(III)]z, where x, y and z are less than unity. Addition of chloride ions, perchlorate ions and the reduction product of CAB, benzenesulfonamide (BSA), have no significant effect on the rate. Decrease of dielectric permittivity of the médium by increasing the CH3CN content increased the rate. The reaction was studied at different temperatures and the activation parameters have been computed from the Arrhenius plot. The stoichiometery of the reaction was foundto be 1:1 and the main oxidation producís of PPA were found to be benzaldehyde and acetaldehyde. The rate constant decreases in D20 médium and the normal isotope effect, k' (H20) / k' (D20) is 2.39. Proton inventory studies have been made in H20-D20 mixtures. Formation and decomposition constant of CAB-PPA complexes in the reaction scheme have been evaluated. The conjúgate acid C6H5S02NHC1 has been assumed to be the reactive species. The observed results have been explained by plausible mechanisms and relative rate law has been deduced

Mechanistic investigation of the oxidation of vitamin B1 with sodium N-chlorobenzenesulfonamide in presence of ruthenium(III) catalyst in hydrochloric acid medium: a kinetic approach

The oxidative cleavage of vitamin B1 (thiamine hydrochloride, THM) with sodium N-chlorobenzenesulfonamide (chloramine-B, CAB) has been kinetically investigated in HCl medium in presence of ruthenium(III) catalyst at 308 K. The oxidation reaction follows the rate law, −d[CAB]/dt = k [CAB] [Ru(III)] [H+] [THM]a [Cl−]b, where a and b are less than unity. Variation of ionic strength of the medium and addition of the reaction product, benzenesulfonamide (BSA) had no significant effect on the reaction rate. The change in relative permittivity of the medium affected by changing the solvent composition with acetonitrile has been studied. The stoichiometry of the reaction was found to be 1:1, and N-[(4-amino-2-methylpyrimidine-5-yl)methyl]benzensulfonamide and 2-(4-methylthiazol-5-yl)ethanol were identified as the oxidation products of vitamin B1. The reaction constants involved in the mechanism were computed. The reaction was studied at different temperatures and the overall activation parameters have been evaluated. C6H5SO2NHCl has been postulated as the reactive oxidizing species. The observed results have been explained by plausible mechanisms and the relative rate laws have been deduced

Mechanical properties of banana empty fruit bunch fibre reinforced polyester composites

162-167A light weight composite material has been prepared using banana empty fruit bunch fibre (banana-EFB) as reinforcement in polyester resin matrix, and its mechanical properties studied. The composites are formulated up to a maximum fibre volume fraction of about 0.37, resulting in a mean tensile strength of 43 MPa and tensile modulus of 1.06 GPa which are 36% and 68% higher than those of the plain polyester respectively. The flexural strength of banana-EFB composites is decreased, whereas flexural modulus has shown a mixed trend compared to that of plain polyester. The specific flexural modulus of the composite is 1.42 times to that of polyester resin and the work of fracture in impact is found to be 141.7 J/m

Determination of quantum yield for the photochemical decomposition of dichloramine-B and dibromamine-B in aqueous acetic acid medium

The photolysis of dihaloamines (RNX2), viz., dichloramine-B (DCB) and dibromamine-B (DBB) in aqueous acetic acid (1:1 v/v) solutions has been studied with the UV light source (λ= 2537 Å). The experimental rate law obtained is - d [RNX2] / dt = k' Io / [RNX2], where Io is the intensity of incident light. The addition of benzenesulphonamide, the product of photolysis or uranyl ion had no significant effect on the rate of photochemical decomposition. A slight decrease in the rate has been observed by the addition of NaCl / NaBr to DCB / DBB solutions. The quantum yield (Φ) for the photolytic decomposition has been computed. A suitable photolytic mechanism and a rate law consistent with the observed results have been proposed