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This research work aims to synthesize environmentally benign and cost-effective metal nanoparticles. In this current research scenario, the leaf extract of Cedrela toona was used as a reducing agent to biosynthesize silver nanoparticles (AgNPs). The synthesis of AgNPs was confirmed by the color shift of the reaction mixture, i.e., silver nitrate and plant extract, from yellow to dark brown colloidal suspension and was established by UV-visible analysis showing a surface plasmon resonance band at 434 nm. Different experimental factors were optimized for the formation and stability of AgNPs, and the optimum conditions were found to be 1 mM AgNO3 concentration, a 1:9 ratio of extract/precursor, and an incubation temperature of 70°C for 4 h. The Fourier transform infrared spectroscopy spectra indicated the presence of phytochemicals in the leaf extract that played the role of bioreducing agents in forming AgNPs. X-ray diffraction patterns confirmed the presence of AgNPs with a mean size of 25.9 nm. The size distribution and morphology of AgNPs were investigated by scanning electron microscopy, which clearly highlighted spherical nanoparticles with a size distribution of 22–30 nm with a mean average size of 25.5 nm. Moreover, prominent antibacterial activity was found against Enterococcus faecalis (21 ± 0.5 mm), Bacillus subtilis (20 ± 0.9 mm), Pseudomonas aeruginosa (18 ± 0.3 mm), Staphylococcus aureus (16 ± 0.7 mm), Klebsiella pneumoniae (16 ± 0.3 mm), and Escherichia coli (14 ± 0.7 mm). In addition, antioxidant activity was determined by DPPH and ABTS assays. Higher antioxidant activity was reported in AgNPs compared to the plant extract in both DPPH (IC50 = 69.62 µg·ml−1) and ABTS assays (IC50 = 47.90 µg·ml−1). Furthermore, cytotoxic activity was also investigated by the MTT assay against MCF-7 cells, and IC50 was found to be 32.55 ± 0.05 µg·ml−1. The crux of this research is that AgNPs synthesized from the Cedrela toona leaf extract could be employed as antibacterial, antioxidant, and anticancer agents for the treatment of bacterial, free radical-oriented, and cancerous diseases.

Recent advances in nanoscience and nanotechnology have revolutionized the medical field, particularly in the treatment and prevention of disease. Silver nanoparticles (AgNPs) are considered one of the best supreme and most important nanomaterials with a variety of compulsive nanomaterial having diverse array of multifunctional bioapplications. The current study focuses on the green biosynthesis of AgNPs using polysaccharides extracted from Olea europaea leaves. The synthesized AgNPs were thoroughly analyzed and characterized using various spectroscopic and microscopic techniques including, UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Energy dispersive X-ray (EDX), and Scanning electron microscopy (SEM). The absorption peak at 440 nm showed a high plasmon resonance band, confirming the formation of green AgNPs by the reduction of Ag+ ions to Ag0. FTIR analysis showed the appearance and extension of different functional groups. The results of EDX and SEM confirmed the synthesis of AgNPs with spherical shape, crystalline structure, and an average size of 64.42 nm. The biosynthesized AgNPs possessed improved antimicrobial activities, indicating the importance of biosynthesized NPs in the pharmaceutical industry. In addition, the biosynthesized AgNPs were biocompatible and exhibited anti-inflammatory activity (86.29%), almost similar to that of a standard drug (87.78%) at a concentration of 500 µL/mL. The polysaccharides obtained from O. europaea could be considered as effective reducing agent, leading to an environmentally friendly synthesis of stable and biologically important AgNPs with a wide range of applications.

This study aimed to examine the pollen and pollinia morpho-structure of 18 horticultural Apocynaceous species. Advanced light and scanning electron microscopy (LM and SEM) were used to elaborate on and examine the systematic importance of pollen and pollinia micromorphology. Pollen grains were first acetolysed, which was followed by visualisation of their sculpturing features. The quantified data were subjected to statistical tools to elucidate dendrogram clustering and principal component analysis to reveal pollen/pollinia morphotypes. The size of pollen is variable, ranging from 113.45 μm in Cascabela thevetia to 23.4 μm in Alstonia scholaris. The study revealed tetrad, tetraporate, and tricolporate grains. Sculpturing (exine ornamentation) varies from reticulate perforate to reticulate. Pollinum shape was observed to be narrow oblong, obovate, orbicular, and reniform. Reticulate-psilate sculptural features were prominent among pollinia surfaces. Based on examination, it was ascertained that the minimum exine thickness in Periploca aphylla was 4.9 μm, whereas the corresponding number in Cryptolepis dubia was 1.35 μm. Taxonomic identification keys were constructed separately based on pollen/pollinia characters to identify the Apocynaceous taxa. In the presented study, seven pollen shapes were observed: from oblate to per prolate. The findings confirm that morphopollinic traits differ amongst genera of Apocynaceous species. However, these features can be used to distinguish the Apocynaceous taxa. The results show that structural characteristics of pollen and pollinia can help accurately identify Apocynaceous species.