Biogenic Ag2O nanoparticles with "Hoja Santa" (Piper auritum) extract: characterization and biological capabilities.

The 'sacred leaf' or "Hoja Santa" (Piper auritum Kunth) has a great value for Mexican culture and has gained popularity worldwide for its excellent properties from culinary to remedies. To contribute to its heritage, in this project we proposed the green synthesis of silver oxide nanoparticles (Ag2O NPs) using an extract of "Hoja Santa" (Piper auritum) as a reducing and stabilizing agent. The synthesized Ag2O NPs were characterized by UV-Visible spectroscopy (plasmon located at 405 nm), X-ray diffraction (XRD) (particle size diameter of 10 nm), scanning electron microscopy (SEM) (particle size diameter of 13.62 ± 4.61 nm), and Fourier-transform infrared spectroscopy (FTIR) (functional groups from "Hoja Santa" attached to nanoparticles). Antioxidant capacity was evaluated using DPPH, ABTS and FRAP methods. Furthermore, the antimicrobial activity of NPs against a panel of clinically relevant bacterial strains, including both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Salmonella Enteritidis and Escherichia coli O157:H7), was over 90% at concentrations of 200 µg/mL. Additionally, we assessed the antibiofilm activity of the NPs against Pseudomonas aeruginosa (reaching 98% of biofilm destruction at 800 µg/mL), as biofilm formation plays a crucial role in bacterial resistance and chronic infections. Moreover, we investigated the impact of Ag2O NPs on immune cell viability, respiratory burst, and phagocytic activity to understand their effects on the immune system.

Immunostimulant Activity of Bacteria Isolated from Extreme Environments in Baja California Sur, Mexico: A Bioprospecting Approach.

Excessive use of antibiotics has led to an increase of pathogenic bacteria with multiple antibiotic resistance. Hypersaline and hyperthermal environments promote the development of several microorganisms that can potentially act as immunostimulants. Thus, the aim of this study was bioprospecting marine bacteria from these environments using mouse leukocytes as a cell model for assess immunostimulatory activity. Samples were taken from two evaporation ponds with 4 and 8% salinity (p/v) in a marine solar saltern (MSS) at Laguna Ojo de Liebre, Guerrero Negro and a shallow hydrothermal vent (SHV), Bahía Concepción under a mangrove forest both off Baja California Sur, México. From total number of isolates (N = 340), 267 were obtained from the MSS and 73 from the SHV. The 10 isolates that induced nitric oxide (NO) production in mouse splenocytes were identified using the 16S rRNA gene, of which Halomonas elongata, Halomonas sp., Pseudoalteromonas ruthenica, Bacillus subtilis and three Bacillus strains were isolated from the MSS ponds at 8% salinity and three Marinobacter lutaoensis strains from the SHV. Most of the selected bacteria were not cytotoxic for mouse splenocytes and enhanced phagocytic respiratory burst and antioxidant enzyme activities compared to the control immunostimulant (lipopolysaccharide from Escherichia coli). Selected bacteria from 8% salinity ponds in the MSS in Guerrero Negro had immunostimulant activity in vitro in mouse splenocytes. In conclusion, Bacillus subtilis SA4 220, Bacillus sp. SA4 62A, P. ruthenica SA4 40 as well as Halomonas sp. SA4 207 and Halomonas elongata SA8 44 increased several immunological parameters. Further research is needed to evaluate their potential application in preclinical models to fight against infectious diseases. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-022-01002-3.

Gold nanoparticles (AuNP) exert immunostimulatory and protective effects in shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus.

Gold nanoparticles (AuNP) stimulate immune responses in mammals but they have not been tested in species of relevance in aquaculture. In this study the immunostimulant and protective potential of orally administered AuNP against V. parahaemolyticus, the causative agent of Acute Hepatopancreatic Necrosis Disease, was determined in shrimp. Synthetized AuNP (18.57 ±â€¯4.37 nm) were moderately dispersed with a negative ζ potential of -10.3 ±â€¯0.208 mV (pH = 7). AuNP were administered (single dose) at 0.2, 2, and 20 µg/g feed in shrimp. Hemolymph samples were withdrawn daily for 6 days. Hemolymph or hemocytes were used to determine total hemocyte counts, immune-related enzymatic activities, and expression of immune-relevant genes. Hepatopancreas was sampled for the analysis of AuNP biodistribution and histological examination. Survival was recorded daily. No mortality or toxicity signs in hepatopancreas were found. AuNP were detected in hepatopancreas. Early (24-48 h) immunostimulation was mainly related to immune gene up-regulation. Upon a challenge with V. parahaemolyticus, survival was higher (80%) and histopathological damages were lower in shrimp treated with the 2 µg/g dose when compared to the control. Therefore orally administered AuNP are proposed as immunostimulants that protect shrimp against V. parahaemolyticus infection.

In vivo and in vitro studies using larval and adult antigens from Neobenedenia melleni on immune response in yellowtail (Seriola lalandi).

Neobenedenia melleni is a monogenean parasite that causes significant mortality and economic losses in fish aquaculture. Changes in the antigenic composition of this parasite occur during its developmental stages. In this study, we evaluated humoral parameters in serum and transcriptional immune responses of yellowtail naturally infected with N. melleni. In addition, in vitro assays were performed to study the stimulatory effects of antigens from larvae and adults on spleen leucocytes from non-infected fish at 6 and 24 h post-stimulation. The results showed enhanced total protein, myeloperoxidase and antiprotease activities in N. melleni-infected fish compared with non-infected ones. The induction of Toll-like receptors (TLRs) and pro-inflammatory cytokines in spleen leucocytes during natural infection with N. melleni suggests that these immune-related genes play an important role in the initiation of the immune defence mechanism for controlling parasite infection. Interestingly, the magnitude of in vitro responses of spleen leucocytes was dependent on the parasitic stage. An important stimulation of gene expression by adult antigens on spleen leucocytes was observed. Differential expression patterns of TLRs and target cytokines in yellowtail leucocytes in both in vivo and in vitro studies suggest that the quality of yellowtail immune response is conditioned by N. melleni development.

Antioxidant enzymes in erythrocytes from goats seropositive to the sheep nose bot fly (Oestrus ovis L., Diptera: Oestridae) infection.

Oestrus ovis (Diptera: Oestridae) causes an important cosmopolitan parasitosis of the nasal and sinusal cavities of sheep and goats called oestrosis. Our objective was to analyze the participation of erythrocytes in the antioxidant system in goats seropositive to O. ovis infection under field conditions. Fifty female goats naturally exposed to O. ovis infection from Baja California Sur, México, were blood-sampled. Erythrocytic intracellular content was obtained from blood plasma. Oestrosis serodiagnosis was determined by ELISA. Protein, hemoglobin (Hb), superoxide dismutase (SOD), mieloperoxidase (MPO), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation in erythrocytes were determined in both seropositive and seronegative goats. Overall seroprevalence of O. ovis infection in goats was 56%. Positive significant (P<0.05) associations were observed among systemic IgG level and protein (0.34), hemoglobin (0.43), SOD (0.32), and MPO (0.41) in erythrocytes. Protein and hemoglobin concentrations, as well as SOD and MPO activities in erythrocytes were found significantly higher (P<0.05) in seropositive than in seronegative goats. By contrast, enzymatic activities of CAT and GST and lipid peroxidation values were similar in seropositive and seronegative groups. In conclusion, there was a systemic stimulation of Reactive Oxygen Species which was efficiently scavenged by erythrocytic antioxidant enzymes in goats seropositive to O. ovis infection.