The biosynthesis of nanoparticles has been proposed as a cost effective and environmentally benevolent alternative to chemical and physical methods. In the present study, microwave assisted synthesis of silver nanoparticles (AgNPs) has been demonstrated using leaf extract of Fraxinus excelsior reducing aqueous AgNO₃ solution. The synthesized nanoparticles have been characterized on the basis of fourier transform infrared spectroscopy (FT-IR), UV–Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. The presence of a characteristic surface plasmon resonance (SPR) absorption band at 425 nm in UV–Vis reveals the reduction of silver metal ions into silver nanoparticles. FT-IR analysis was carried out to probe the possible functional group involved in the synthesis of AgNPs. Further leaf extracts and AgNPs were evaluated for antiradical scavenging activity by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay.

The methanolic extract of the leaves of Peltophorum vogelianum (Caesalpiniaceae) afforded a new phytoconstituent, 2-methoxy-4,5-dihydroxy-1(7,8-dihydroxyethylene)-8-β-D-glucuropyranoside named as peltophorumyl-β-D-glucuropyranoside (5), along with four known phytoconstituents, 1-pentatriacontanol (1), friedelin (2), β-sitosterol (3) and β-sitosterol-β-D-glucopyranoside (4), which have not been isolated previously from this plant. Their structures were established on the basis of chemical and physical evidence (IR, ¹H-NMR, ¹³C-NMR, DEPT, HSQC, HMBC and MS). Moreover, compound 5 showed significant antimicrobial activity.

In the present study, a focused library of multi functionalized 1-substituted-1H-tetrazole analogues 4(a–o) were synthesized, which were typically accessed via a facile, solvent-free and green synthetic protocol. The reaction involves expeditious reusable catalyst (SiO₂–H₃BO₃) promoted condensation between a variety of heterocyclic/aromatic amines, sodium azide and triethyl ortho-formate, eliminating the use of an environmentally toxic solvent. This new eco-friendly and sustainable protocol resulted in a remarkable enhancement in the synthetic efficiency (90–97%, yield) with high purity. This silica–boric acid catalyst is air and water stable and easy to prepare from cheap silica and boric acid. The present methodology is a green protocol offering several advantages such as an excellent yield of products, a simple operational procedure, minimizing production of chemical wastes, mild reaction conditions, a shorter reaction profile, easy preparation of the catalyst and its recyclability up to five cycles without any appreciable loss in catalytic activity. The optimization conditions achieved in the present study revealed that 2.5 mol% of the SiO₂–H₃BO₃ catalyst under solvent-free conditions at 90 °C are the best suited conditions for the synthesis of tetrazole derivatives in excellent yields. The present protocol is applicable to a broader substrate scope (electron-rich and electron-deficient). Compounds possessing a nicotinic acid nucleus (4e, 4f, 4g) displayed strongest inhibition against AChE with IC₅₀ values of 0.43 μM, 0.21 μM and 0.26 μM, respectively. The results revealed that the electronic effect of substituents inflicts a prominent effect on AChE activity.