Nitric oxide (NO) and salicylic acid (SA): A framework for their relationship in plant development under abiotic stress.

The free radical nitric oxide (NO) and the phenolic phytohormone salicylic acid (SA) are signal molecules which exert key functions at biochemical and physiological levels. Abiotic stresses, especially in early plant development, impose the biggest threats to agricultural systems and crop yield. These stresses impair plant growth and subsequently cause a reduction in root development, affecting nutrient uptake and crop productivity. The molecules NO and SA have been identified as robust tools for efficiently mitigating the negative effects of abiotic stress in plants. SA is engaged in an array of tasks under adverse environmental situations. The function of NO depends on its cellular concentration; at a low level, it acts as a signal molecule, while at a high level, it triggers nitro-oxidative stress. The crosstalk between NO and SA involving different signalling molecules and regulatory factors modulate plant function during stressful situations. Crosstalk between these two signalling molecules induces plant tolerance to abiotic stress and needs further investigation. This review aims to highlight signalling aspects of NO and SA in higher plants and critically discusses the roles of these two molecules in alleviating abiotic stress.

Synthesis, Characterization and Screening for Analgesic and Anti-inflammatory activities of 2, 5-disubstituted 1, 3, 4-oxadiazole derivatives.

The aim of the present investigation was to synthesize, characterize and evaluate analgesic and anti- inflammatory activities of 2, 5-disubstituted 1, 3, 4-oxadiazole derivatives. The reaction of starting material 4-chloro-m-cresol with ethyl chloroacetate in dry acetone affords ethyl (4-chloro-3-methylphenoxy) acetate, which after reacting with the hydrazine hydrate in ethanol yields 2(4-chloro-3-methylphenoxy) acetohydrazide. When 2(4-chloro-3-methylphenoxy) acetohydrazide was treated with different aromatic aldehydes, aromatic acids and carbon disulfide in alcoholic solution, different 3-acetyl-5-[(4-chloro-3-methylphenoxy) methyl]-2-aryl-2, 3-dihydro-1, 3, 4-oxadiazole and 2-[(4-chloro-3-methylphenoxy) methyl]-5-aryl-1, 3, 4-oxadiazole derivatives were obtained. Purity of the derivatives was confirmed by thin layer chromatography and melting point. Structure of these derivatives was set up by determining infrared spectroscopy, nuclear magnetic resonance spectroscopy and mass spectroscopy. Further, the synthesized derivatives were evaluated for their analgesic and anti-inflammatory activities in rodents. In animal studies, the derivatives 3-acetyl-5-[(4-chloro-3- methylphenoxy)methyl]-2-(4-methoxyphenyl)-2,3-dihydro-1, 3, 4-oxadiazole and 4-{5-[(4-chloro-3- methylphenoxy)methyl]-1, 3, 4-oxadiazol-2-yl}pyridine show more potent analgesic activity and the derivatives 2-{3-acetyl-5-[(4-chloro-3-methylphenoxy)methyl]-2,3-dihydro-1, 3, 4-oxadiazol-2-yl}phenol and 3-acetyl-5- [(4-chloro-3-methylphenoxy)methyl]-2-(4-methoxyphenyl)-2,3-dihydro-1, 3, 4-oxadiazole exhibit more potent anti-inflammatory effect as compared to other derivatives. The results of the current study indicate that cyclization of acetohydrazide produces novel oxadiazole derivatives with potent analgesic and anti-inflammatory activities.

Sustained Release of Diltiazem Hydrochloride from Cross-linked Biodegradable IPN Hydrogel Beads of Pectin and Modified Xanthan Gum.

Interpenetrating polymer network hydrogel beads of pectin and sodium carboxymethyl xanthan were prepared by ionotropic gelation with Al(+3) ions and covalent cross-linking with glutaraldehyde for sustained delivery of diltiazem hydrochloride. Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning colorimetry and scanning electron microscopy were used to characterise the hydrogel beads. The swelling of the hydrogel and the release of drug were relatively low in pH 1.2 buffer solutions. However, higher swelling and drug release were observed in pH 6.8 buffer solutions. The carboxyl functional groups of hydrogels undergo ionisation and the osmotic pressure inside the beads increases resulting in higher swelling and drug release in higher pH. The release of drug depends on concentration of polymer, amount and exposure time of cross-linker and drug content in the hydrogel matrices. The present study indicated that the hydrogel beads minimised the drug release in pH 1.2 buffer solutions and to prolong the drug release in pH 6.8 buffer solutions.