No abstract

In the present study, mace-mediated silver nanoparticles (mace-AgNPs) were synthesized, characterized, and evaluated against an array of pathogenic microorganisms. Mace, the arils of Myristica fragrans, are a rich source of several bioactive compounds, including polyphenols and aromatic compounds. During nano synthesis, the bioactive compounds in mace aqueous extracts serve as excellent bio reductants, stabilizers, and capping agents. The UV-VIS spectroscopy of the synthesized NPs showed an intense and broad SPR absorption peak at 456 nm. Dynamic light scattering (DLS) analysis showed the size with a Z average of 50 nm, while transmission electron microscopy (TEM) studies depicted the round shape and small size of the NPs, which ranged between 5–28 nm. The peaks related to important functional groups, such as phenols, alcohols, carbonyl groups, amides, alkanes and alkenes, were obtained on a Fourier-transform infrared spectroscopy (FTIR) spectrum. The peak at 3 keV on the energy dispersive X-ray spectrum (EDX) validated the presence of silver (Ag). Mace-silver nanoparticles exhibited potent antifungal and antibacterial activity against several pathogenic microorganisms. Additionally, the synthesized mace-AgNPs displayed an excellent cytotoxic effect against the human cervical cancer cell line. The mace-AgNPs demonstrated robust antibacterial, antifungal, and cytotoxic activity, indicating that the mace-AgNPs might be used in the agrochemical industry, pharmaceutical industry, and biomedical applications. However, future studies to understand its mode of action are needed.

The aim of this study was to assess Annona muricata L. fruit extracts as an alternative to synthetic fungicide against Alternaria alternata (Fries) Keissler, the causative agent of black spots of tomato fruit. Antifungal activities of A. muricata pulp and seed extracts were tested both in vitro and in vivo. The seed extracts were more potent at inhibiting A. alternata than the pulp extracts. The in vitro assay showed maximum inhibition of radial mycelial growth of A. alternata (90%) by methanol seed extracts, at the highest concentration of 6%. Similarly, the in vivo assay showed marked reduction in lesion diameter (2.1 mm) and consequent disease inhibition (84%) on the tomato fruit treated with methanol seed extracts. Scanning electron microscopy showed that A. muricata extracts significantly damaged the morphology of hyphae and conidial structures. The FT-IR spectrum obtained from methanol extracts showed bands representing important bioactive compounds that possess antifungal activity. Based on our findings, Annona muricata fruit extracts can be further explored as a potential, excellent alternative approach to control the postharvest Alternaria spots of tomato fruit.

Recent studies have shown that green synthesis of silver nanoparticles (AgNPs) and their application in the control of phytopathogenic fungi is a burgeoning field. Sisymbrium irio (Si) (London rocket) is a well-known weed that grows abundantly in Saudi Arabia from February to May. The present study is concerned with the rapid synthesis of silver nanoparticles from the aqueous seed extract of Si) in the presence of sunlight. The biosynthesized Si-AgNPs were characterized using UV-Visible spectroscopy (UV-Vis), energy dispersive X-ray (EDX) microanalysis, dynamic light scattering analysis (DLS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy analysis (FTIR). The UV-Vis spectrum revealed a prominent surface plasmon resonance (SPR) absorption band (∼439 nm) characteristic of AgNPs. As revealed by TEM analysis, the Si-AgNPs were predominantly spheroidal in shape and measured between 4 and 51 nm, while the Z average of nanoparticles was 94.81 nm as revealed by the DLS spectrum. The FTIR spectrum displayed peaks related to important functional groups (amines, phenols, carboxylic acids, flavonoids, aromatic compounds, and esters) that aid in the reduction, encapsulation, and stability of AgNPs. The Si-AgNPs were further investigated against a panel of potent fungal phytopathogens that included Alternaria alternata, A. brassicae, Fusarium solani, F. oxysporum, and Trichoderma harzianum. The cytotoxic activity of the biosynthesized nanoparticles against human cervical cancer cell lines (HeLa) was also tested. Si-AgNPs at 80 µg·mL−1 demonstrated a marked reduction in mycelial growth and spore germination. Similarly, Si-AgNPs exhibited dose-dependent cytotoxic activity against the HeLa cell line, with an IC50 value of 21.83 ± 0.76 µg·mL−1. The results of the present study demonstrate the robust cytotoxic and antifungal activities of Si-AgNPs. Based on the findings, Si-AgNPs can be exploited to design formulations that can effectively act as anticancer agents, controlling the proliferation of cancer cells while also combating fungal phytopathogens. However, future research to understand their toxicity mechanisms is needed.