In vitro anti-Pythium insidiosum activity of biogenic silver nanoparticles

Abstract

Pythium insidiosum belongs to the phylum Oomycota. It is capable of infecting mammals causing a serious condition called pythiosis, which affects mainly horses in Brazil and humans in Thailand. The objective of the present study was to verify the in vitro anti-P. insidiosum activity of a biogenic silver nanoparticle (bio-AgNP) formulation. The in vitro assays were evaluated on P. insidiosum isolates (n = 38) following the M38-A2 protocol. Damage to the P. insidiosum hyphae ultrastructure was verified by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bio-AgNP inhibition concentrations on P. insidiosum isolates ranged from 0.06 to 0.47 μg/ml. It was observed through SEM that P. insidiosum hyphae treated showed surface roughness, as well as cell walls with multiple retraction areas, loss of continuity, and rupture in some areas. The TEM of treated hyphae did not differentiate organelle structures; also, the cellular wall was rarefied, showing wrinkled and partly ruptured borders. The bio-AgNP evaluated has excellent in vitro anti-P. insidiosum activity. However, further studies on its in vivo action are necessary as so to determine the possibility of its use in the treatment of the disease in affected hosts.

Biogenic silver nanoparticle (Bio‐AgNP) has an antibacterial effect against carbapenem‐resistant Acinetobacter baumannii with synergism and additivity when combined with polymyxin B

“…The main reasons for the differences in the antibacterial activity of AgNPs would be related to four mechanisms: (1) the adhesion of AgNPs to the cell wall and membrane surface, (2) the penetration of AgNPs causing damage to intracellular structures (i.e. ribosomes) and biomolecules (proteins, lipids and DNA), (3) AgNPs inducing cellular toxicity and oxidative damage by generating reactive oxygen species (ROS) and free radicals and (4) modulating signal transduction pathways (Bocate et al, 2019; Dakal et al, 2016; Valente et al, 2018; Durán et al, 2019; Figueiredo et al, 2019; Scandorieiro et al, 2016; Zhang et al, 2016). Silver ions delivered by the nanoparticles to bacteria increase membrane permeability, interrupting the formation of disulfide bonds in the inner membrane leading to the production of ROS and promoting lysis, a process by which cells die (Abbasi et al, 2016; Hossain et al, 2019; Jasim et al, 2017; Lu et al, 2020).…”

“…A recent study evaluated the toxic effect of Bio‐AgNPs in mammalian cells, and the results of the selectivity index (SI) showed their viable application in the medical area (Figueiredo et al, 2019). In another study, the cytotoxicity of Bio‐AgNPs was evaluated in RK13 cells (rabbit kidney cell), which evidenced a cytotoxicity threshold between 0.6 and 5 µg/ml within 24 h, suggesting that these concentrations of Bio‐AgNPs pose no risk of toxicity to mammalian cells (Valente et al, 2018). In our study, both Bio‐AgNP and polymyxin B exhibited a concentration‐dependent cytotoxic activity.…”

“…The synthesis of AgNPs can be applied by a series of methodologies, but biological synthesis stands out as the best approach since its routes have several advantages; it is simple, economical and ecologically correct and shows high performance. Also, it uses the so‐called green or biogenic technology that generates nontoxic products (Valente et al, 2018; Siddiqi et al, 2018).…”

Evaluation of antifungal effect and toxicity of xanthyletin and two bacterial metabolites against Thai isolates of Pythium insidiosum

“…It is well known that the therapy of pythiosis has posed a challenge in recent decades as the current treatment options are highly variable and often lead to failure 14 . Therefore, many studies have searched for antimicrobial agents, natural compounds or secondary metabolites from microorganisms against P. insidiosum and results of in vitro testing are quite promising 6,7,[15][16][17][18][19][20][21] . The present study evaluated antimicrobial effects against P. insidiosum of xanthyletin and two fractions of the crude extracts from P. stutzeri ST1302 and K. pneumoniae ST2501.…”

Nanotechnology in veterinary medicine: a review

“…These include antineoplastic drugs (HOFHEINZ et al, 2005), antimicrobials (CORDEIRO et al, 2000), analgesics (ROSE et al, 2005), and anti-inflammatory drugs (METSELAAR et al, 2003). In veterinary medicine, nanoparticles of various substances have been tested for antibacterial (OLIVEIRA et al, 2013;SAGAVE et al, 2015;JAGUEZESKI et al, 2019;ACOSTA et al, 2020), antiviral (GREENWOOD et al, 2008ZHAO et al, 2016;ZHAO et al, 2018), anthelmintic (KHAN et al, 2015TOMAR et al, 2017;REHMAN et al, 2019), antiprotozoal (KROUBI et al, 2010HASSAN et al, 2019), antifungal (BANSOD et al, 2015, antioomycetes (VALENTE et al, 2016;VALENTE et al, 2019;VALENTE et al, 2020), anti-algae (JAGIELSKI et al, 2018;ELy et al, 2020), andantineoplastic (ROCHA et al, 2019) activities.…”