Efficacy of silver nanoparticles mediated by Jania rubens and Sargassum dentifolium macroalgae; Characterization and biomedical applications

Macroalgae as biofactories of metal nanoparticles; biosynthesis and food applications

Nanotechnology has opened a new frontier in recent years, capable of providing new ways of controlling and structuring products with greater market value and offering significant opportunities for the development of innovative applications in food processing, preservation, and packaging. Macroalgae (MAG) are the major photoautotrophic group of living beings known as a potential source of secondary metabolites, namely phenolic compounds, pigments, and polysaccharides. Biosynthesis based on the abilities of MAG as "nanobiofactories" targets the use of algal secondary metabolites as reducing agents to stabilize nanoparticles (NPs). Nowadays, most of the studies are focused on the use of metal (Ag, Au) and metal-oxide (CuO, ZnO) NPs derived from algae. The eco-friendly biosynthesis of metal NPs reduces the cost and production time and increases their biocompatibility, due to the presence of bioactive compounds in MAG, making them suitable for a wide variety of applications. These compounds have been attributed to the antimicrobial and antioxidant properties responsible for their application through innovative technologies such as nanoencapsulation, nanocomposites, or biosensors in the food industry. Nevertheless, toxicity is a key factor that should be considered, so the applicable regulation needs to guarantee the safe use of metal NPs. Consequently, the aim of this review will be to compile the available information on MAG-mediated metal NPs, their biosynthesis, and potential food applications.

The Lebanese Red Algae Jania rubens: Promising Biomolecules against Colon Cancer Cells

Colorectal cancer (CRC) is ranked the second most lethal type of tumor globally. Thus, developing novel anti-cancer therapeutics that are less aggressive and more potent is needed. Recently, natural bioactive molecules are gaining interest as complementary and supportive antineoplastic treatments due to their safety, effectiveness, and low cost. Jania rubens (J. rubens) is a red coral seaweed abundant in the Mediterranean and bears a significant pharmacological essence. Despite its therapeutic potential, the natural biomolecules extracted from this alga are poorly identified. In this study, the proximal analysis revealed high levels of total ash content (66%), 11.3% proteins, 14.5% carbohydrates, and only 4.5% lipids. The elemental identification showed magnesium and calcium were high among its macro minerals, (24 ± 0.5 mg/g) and (33 ± 0.5 mg/g), respectively. The Chlorophyll of J. rubens was dominated by other pigments with (0.82 ± 0.02 mg/g). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay identified effective antioxidant activity in various J. rubens extracts. More importantly, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium reduction and wound healing assays indicate that organic extracts from J. rubens significantly counteract the proliferation of colon cancer cell lines (HCT-116 and HT-29) and inhibit their migratory and metastatic properties in a dose and time-dependent manner. Overall, this study provides insight into the physicochemical properties of red seaweed, J. rubens, and identifies its significant antioxidant, cytotoxic, and anti-migratory potential on two colorectal cell lines, HCT-116 and HT-29.

Production, Characterization, and Cytotoxicity Effects of Silver Nanoparticles from Brown Alga (Cystoseira myrica)

A green, eco-friendly approach to biosynthesizing silver nanoparticles has been reported for marine macroalga (Cystoseira myrica) extract as a reducing agent. Different pH and temperature impact the green synthesis of silver nanoparticles suggesting that the synthesis depends greatly on pH and temperature. The structure and characters of synthesized nanoparticles were confirmed using HR-TEM, DLS, XRD, and FTIR. Cytotoxicity was indicated using provided cell lines of breast carcinoma cells (MCF-7) and human hepatocellular carcinoma cells (HepG2). Shape of silver nanoparticles at pH 9 and 75°C for 30 min was found to be suitable for the biosynthesis process and the AgNPs exhibited a characteristic absorption peak at 434 nm. High Resolution Electron Microscope Transmission reported polydisperse and spherical shapes ranging from 8 to 15 nm. High attractive and repulsive forces between each nanoparticle were recorded with an average zeta-potential value of approximately −29.3 mV. The X-ray diffraction study revealed the crystalline structure of silver nanoparticles. FTIR has shown the bioreduction of silver ions to silver nanoparticles through biomolecules found in algal extract. Silver nanoparticles have been found to have anticancer activity. The cytotoxicity assay was studied against MCF-7 and HepG2 at various concentrations (100, 50, 25, 12.5, 6.25, 3.125, 1.56, 0.78, 0.39, 0.2, and 0.1 μg/mL). By increasing the concentration of AgNPs from 0.1 to 100 μg/mL, the maximum percentage of viability against MCF-7 and HepG2 cell line decreased from 94.55 ± 7.55 to 19.879 ± 0.503 and from 78.56 ± 11.36 to 25.81 ± 2.66 after time exposure, respectively.

Apoptotic and Antioxidant Activity of Gold Nanoparticles Synthesized Using Marine Brown Seaweed: An In Vitro Study

A major paradigm shift in the field of nanobiotechnology is the invention of an eco-friendly, economical, and green approach for synthesis of metal nanoparticles. In the present study, we have synthesized gold nanoparticles (AuNPs) using aqueous extracts of marine brown seaweed Sargassum longifolium. The synthesized nanoparticle was subjected to characterization using different techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, atomic force microscope, scanning electron microscope, transmission electron microscope, and elemental dispersive X-ray diffraction. Further, the seaweed extract and the synthesized AuNPs were evaluated for its anticancer effect using MG-63 human osteosarcoma cells besides in vitro antioxidant effect. The formation of S. longifolium-mediated synthesis of gold nanoparticles was demonstrated by UV-Vis spectroscopy. Presence of elemental gold was confirmed by EDX analysis. TEM analysis demonstrated spherical morphology of the synthesized AuNPs and SEM analysis revealed the particle size to be in the range of 10-60 nm. The FTIR showed the presence of hydroxyl functional groups. The toxicity of S. longifolium extract and the synthesized AuNPs was tested using brine shrimp lethality assay at different concentrations with results showing both seaweed extract and AuNPs to be nontoxic. Both S. longifolium and AuNPs exhibited significant antioxidant activity by scavenging DPPH free radicals and H2O2 radicals. Significant antiproliferative effect was observed against MG-63 osteosarcoma cells. It was also shown that the seaweed extract and the AuNPs induced cytotoxicity in cell lines by mechanism of apoptosis. In conclusion, this study provided insight on AuNPs synthesized from S. longifolium as a potent antioxidant and anticancer agent.

Molecular epidemiology of virulent E. coli among rural small scale dairy herds and shops: Efficacy of selected marine algal extracts and disinfectants

Virulent pathotypes of E. coli seriously affect the livestock regarding the misuse of antibiotics. All 180 samples collected from cow's environment and dairy shops in Qena, Egypt were serologically and molecularly positive for coliforms. Enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli (STEC), Enteroinvasive E. coli (EIEC) and Enterotoxigenic E. coli (ETEC) pathotypes were isolated from water and milk-related samples. STEC serogroups O26, O55, O111, O113, O145 were also recovered. The non-O157 STEC serotypes were recovered from human diarrheagenic patients contacting cattle or consuming contaminated water/milk products. Bla_CTX-M and bla_TEM genes were detected in 25.5% and 100%, respectively. Disinfectants and algal extracts, identified by GC-MS, were evaluated in vitro for antibacterial activities. TH4+® disinfectant and methanol extract of Turbinaria decurrens reduced E. coli at 13 log10 at 1.5% and 3 mg/ml concentrations, respectively. Ag-NPs/T. decurrens showed 8-9 log10 reduction at concentration of 1.6 × 10⁵ NPs/ml. Examined water sources, milk and milk products were potential reservoirs for virulent antibiotic-resistant E.coli which may impose animal and public health threats.Abbreviations: APEC: Avian pathogenic E. coli; bla_CTX-M: β-lactamase inhibitors-Cefotaximase gene; bla_TEM: β-lactamase inhibitors-Temoneira gene; CFU: Colony-forming unit; DAEC: Diffusely adherent E. coli; DEC: Diarrheagenic Escherichia coli; DEMSO: Dimethyl sulfoxide; eaeA: Intimin or E. coli attaching gene; EAEC: Enteroaggregative E. coli; EHEC: Enterohemorrhagic E. coli; EIEC: Enteroinvasive E. coli; EOSQC: Egyptian Organization for Standardization and Quality Control; EPEC: Enteropathogenic E. coli; ETEC: Enterotoxigenic E. coli; ExPEC: Extra-intestinal pathogenic E. coli; GC-MS: Gas chromatography-mass spectrometry technique; hly: Hemolysin gene; STEC: Shiga like producing E. coli; stx1: Shiga-toxin 1 gene; ESBLs: Extended-spectrum beta-lactamases.

Control of Virulent Listeria monocytogenes Originating from Dairy Products and Cattle Environment Using Marine Algal Extracts, Silver Nanoparticles Thereof, and Quaternary Disinfectants

Introduction

Listeria monocytogenes is an important foodborne pathogen of public- and animal-health concern globally. The persistence of L. monocytogenes in the dairy-processing environment has multifactorial causes, including lack of hygiene, inefficient cleaning, and improper disinfection practices.

Materials and Methods

A total of 300 dairy-product and environmental samples were collected from dairy-cattle facilities and local dairy shops and vendors in Qena, Egypt. Samples were screened for the incidence of Listeria spp. and to detect virulence determinants and disinfectant-resistance genes. Three marine algal species - Caulerpa racemosa, Jania rubens, and Padina pavonica - were collected from Hurghada on the Red Sea coast. Algal extracts were screened using gas chromatography-mass spectrometry. The antimicrobial activity of some marine algal extracts, nanoparticles derived therefrom, and some disinfectants against L. monocytogenes strains were assessed in vitro using agar-well diffusion and liquid-broth methods. The impact of P. pavonica extract on the growth and survival of virulent L. monocytogenes in cheese and whey were clarified.

Results and Discussion

The incidence of L. monocytogenes in dairy products and environmental samples was 15.5% and 19%, respectively. The most common toxigenic gene profile found among the isolates was hlyA ⁺-inlA ⁺-prfA ⁺. The sensitivity pattern of L. monocytogenes strains to disinfectant containing alkyl (C_12-16) dimethyl BAC was high compared to other tested quaternary ammonium compounds (QAC) disinfectants tested, which showed lower log reductions against resistant strains. The QAC disinfectant-resistance gene qacH was detected in 40% of the isolates. Potent bactericidal activity of a petroleum ether extract of P. pavonica and silver nanoparticles of P. pavonica were obtained against the virulent L. monocytogenes strain. The population of L. monocytogenes in cheese curd and whey after 14 days was reduced at a rate of 9 log CFU/g and 8 log CFU/mL, respectively due to the effect of P. pavonica extract. After 28 days of storage, L. monocytogenes was completely inactivated in those dairy products.

Conclusion

P. pavonica extract showed promising antimicrobial properties, calling for further comprehensive studies prior to it being applied in the food industry to enhance the safety, quality, and shelf life of products and protect public health.

Optimizing and purifying extracellular amylase from soil bacteria to inhibit clinical biofilm-forming bacteria

BACKGROUND

Bacterial biofilms have become a major threat to human health. The objective of this study was to isolate amylase-producing bacteria from soil to determine the overall inhibition of certain pathogenic bacterial biofilms.

METHODS

We used serial dilution and the streaking method to obtain a total of 75 positive amylase isolates. The starch-agar plate method was used to screen the amylolytic activities of these isolates, and we used morphological and biochemical methods to characterize the isolates. Optimal conditions for amylase production and purification using Sephadex G-200 and SDS-PAGE were monitored. We screened these isolates' antagonistic activities and the purified amylase against pathogenic and multi-drug-resistant human bacteria using the agar disk diffusion method. Some standard antibiotics were controlled according to their degree of sensitivity. Finally, we used spectrophotometric methods to screen the antibiofilm 24 and 48 h after application of filtering and purifying enzymes in order to determine its efficacy at human pathogenic bacteria.

RESULTS

The isolated Bacillus species were Bacillus megaterium (26.7%), Bacillus subtilis (16%), Bacillus cereus (13.3%), Bacillus thuringiesis (10.7%), Bacillus lentus (10.7%), Bacillus mycoides (5.3%), Bacillus alvei (5.3%), Bacillus polymyxa (4%), Bacillus circulans (4%), and Micrococcus roseus (4%). Interestingly, all isolates showed a high antagonism to target pathogens. B. alevi had the highest recorded activity (48 mm) and B. polymyxa had the lowest recorded activity (12 mm) against Staphylococcus aureus (MRSA) and Escherichia coli, respectively. On the other hand, we detected no antibacterial activity for purified amylase. The supernatant of the isolated amylase-producing bacteria and its purified amylase showed significant inhibition for biofilm: 93.7% and 78.8%, respectively. This suggests that supernatant and purified amylase may be effective for clinical and environmental biofilm control.

DISCUSSION

Our results showed that soil bacterial isolates such as Bacillus sp. supernatant and its purified amylase are good antibiofilm tools that can inhibit multidrug-resistant former strains. They could be beneficial for pharmaceutical use. While purified amylase was effective as an antibiofilm, the isolated supernatant showed better results.

Defect minimized Ag-ZnO microneedles for photocatalysis

A facile solution processing strategy has been developed for the formation of Ag-modified ZnO microneedles at various calcination temperatures such as 300, 500, and 700 °C (AZ3, AZ5, and AZ7 respectively). Due to the heavy doping of AgNO₃, Ag⁺ ions have been incorporated in to the crystal lattice of ZnO in all the Ag-ZnO samples, which facilitated the formation of Ag-ZnO microneedle morphology with minimized defect states, and obviously, the plasmon peaks were observed due to Ag modification. These Ag-ZnO microneedle structures have been evaluated for their photocatalytic performance using methylene blue as model target contaminant and their activity was compared with the commercially available titania P25 photocatalyst. The photoactivity of all the Ag-ZnO microneedle structures was significantly higher than that of the commercially available P25 photocatalyst with the most active Ag-ZnO material having a photocatalytic activity ~ 1.4 times greater than that of P25 titania.

Phycocosmetics and Other Marine Cosmetics, Specific Cosmetics Formulated Using Marine Resources

Marine resources exist in vast numbers and show enormous diversity. As a result, there are likely many possible applications for marine molecules of interest in the cosmetic industry, whether as excipients or additives, but especially as active substances. It is possible to obtain extracts from active substances; for example, quite a few algae species can be used in moisturizing or anti-ageing products. In the field of topical photoprotection, mycosporine-like amino acids and gadusol are important lines of enquiry that should not be overlooked. In the field of additives, the demonstration that certain seaweed (algae) extracts have antimicrobial properties suggests that they could provide alternatives to currently authorized preservatives. These promising leads must be explored, but it should be kept in mind that it is a long process to bring ingredients to market that are both effective and safe to use.