Antimicrobial Activity of Arthrospira platensis-Mediated Gold Nanoparticles against Streptococcus pneumoniae: A Metabolomic and Docking Study.

The emergence of antibiotic-resistant Streptococcus pneumoniae necessitates the discovery of novel therapeutic agents. This study investigated the antimicrobial potential of green-synthesized gold nanoparticles (AuNPs) fabricated using Arthrospira platensis extract. Characterization using Fourier transform infrared spectroscopy revealed the presence of functional groups such as ketones, aldehydes, and carboxylic acids in the capping agents, suggesting their role in AuNP stabilization. Transmission electron microscopy demonstrated the formation of rod-shaped AuNPs with a mean diameter of 134.8 nm, as determined by dynamic light scattering, and a zeta potential of -27.2 mV, indicating good colloidal stability. The synthesized AuNPs exhibited potent antibacterial activity against S. pneumoniae, with a minimum inhibitory concentration (MIC) of 12 µg/mL, surpassing the efficacy of the control antibiotic, tigecycline. To elucidate the underlying mechanisms of action, an untargeted metabolomic analysis of the A. platensis extract was performed, identifying 26 potential bioactive compounds belonging to diverse chemical classes. In silico studies focused on molecular docking simulations revealed that compound 22 exhibited a strong binding affinity to S. pneumoniae topoisomerase IV, a critical enzyme for bacterial DNA replication. Molecular dynamics simulations further validated the stability of this protein-ligand complex. These findings collectively highlight the promising antimicrobial potential of A. platensis-derived AuNPs and their constituent compounds, warranting further investigation for the development of novel anti-pneumococcal therapeutics.

Unlocking the potential of microalgae cultivated on wastewater combined with salinity stress to improve biodiesel production.

Microalgae have the potential as a source of biofuels due to their high biomass productivity and ability to grow in a wide range of conditions, including wastewater. This study investigated cultivating two microalgae species, Oocystis pusilla and Chlorococcus infusionum, in wastewater for biodiesel production. Compared to Kühl medium, KC medium resulted in a significant fold increase in cellular dry weight production for both O. pusilla and C. infusionum, with an increase of 1.66 and 1.39, respectively. A concentration of 100% wastewater resulted in the highest growth for O. pusilla, with an increase in biomass and lipid content compared to the KC medium. C. infusionum could not survive in these conditions. For further increase in biomass and lipid yield of O. pusilla, different total dissolved solids (TDS) levels were used. Maximum biomass and lipid productivities were achieved at 3000 ppm TDS, resulting in a 28% increase in biomass (2.50 g/L) and a 158% increase in lipid yield (536.88 mg/g) compared to KC medium. The fatty acid profile of O. pusilla cultivated on aerated wastewater at 3000 ppm TDS showed a high proportion of desirable saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) for biodiesel production. Cultivating microalgae in wastewater for biodiesel production can be cost-effective, especially for microalgae adapted to harsh conditions. It could be concluded that O. pusilla is a promising candidate for biodiesel production using wastewater as a growth medium, as it has high biomass productivity and lipid yield, and its fatty acid profile meets the standard values of American and European biodiesel standards. This approach offers a sustainable and environmentally friendly solution for producing biofuels while reducing the environmental impact of wastewater disposal.

Potential Activity of Arthrospira platensis as Antioxidant, Cytotoxic and Antifungal against Some Skin Diseases: Topical Cream Application.

This research evaluated the antifungal effectiveness of Arthrospira platensis ethanol, methanol, ethyl acetate and acetone extracts against the tested pathogenic fungi (Candida albicans, Trichophyton rubrum and Malassezia furfur). Antioxidant and cytotoxicity effectiveness of A. platensis extracts against four distinct cell lines were also assessed. Methanol extract of A. platensis exhibited the highest inhibition zones against Candida albicans as measured by the well diffusion method. A transmission electron micrograph of the treated group of Candida cells with A. platensis methanolic extract showed mild lysis and vacuolation of the cytoplasmic organelles. In vivo, after induced infection of mice by C. albicans and treatment with A. platensis methanolic extract cream, the skin layer emerged with the removal of Candida spherical plastopores. The extract of A. platensis recorded the highest antioxidant activity using the DPPH (2, 2- diphenyl-1-picrylhydrazyl) scavenging method (IC50 28 mg/mL). A cytotoxicity test using a MTT assay showed that the A. platensis extract had strong cytotoxic activity against the HepG2 cell line (IC50 20.56 ± 1.7 µg/mL) and moderate cytotoxic activity against MCF7 and the Hela cell (IC50 27.99 ± 2.1 µg/mL). Gas Chromatography/Mass Spectroscopy (GC/MS) results revealed that the effective activity of A. platensis extract could be linked to a synergistic impact between their prominent composition as alkaloids, phytol, fatty acids hydrocarbons, phenolics and phthalates. A. platensis extract contains active metabolites that constitute a promising source of antifungal, antioxidant and anti-proliferative compounds for the pharmaceutical drug industry.

Antioxidant and Antidiabetic Activity of Algae.

Currently, algae arouse a growing interest in the pharmaceutical and cosmetic area due to the fact that they have a great diversity of bioactive compounds with the potential for pharmacological and nutraceutical applications. Due to lifestyle modifications brought on by rapid urbanization, diabetes mellitus, a metabolic illness, is the third largest cause of death globally. The hunt for an efficient natural-based antidiabetic therapy is crucial to battling diabetes and the associated consequences due to the unfavorable side effects of currently available antidiabetic medications. Finding the possible advantages of algae for the control of diabetes is crucial for the creation of natural drugs. Many of algae's metabolic processes produce bioactive secondary metabolites, which give algae their diverse chemical and biological features. Numerous studies have demonstrated the antioxidant and antidiabetic benefits of algae, mostly by blocking carbohydrate hydrolyzing enzyme activity, such as α-amylase and α-glucosidase. Additionally, bioactive components from algae can lessen diabetic symptoms in vivo. Therefore, the current review concentrates on the role of various secondary bioactive substances found naturally in algae and their potential as antioxidants and antidiabetic materials, as well as the urgent need to apply these substances in the pharmaceutical industry.

Potential effect of Turbinaria decurrens acetone extract on the biochemical and histological parameters of alloxan-induced diabetic rats.

Upon Seeking natural and safe alternatives for synthetic medicines to treat many chronic diseases, seaweeds have offered a promising resource to produce numerous bioactive secondary metabolites. Through in vivo investigations, Turbinaria decurrens acetone extract (AE) revealed its antidiabetic activity against alloxan-induced diabetic rats. Treatment of rats with T. decurrens AE at 300 and 150 mg/Kg doses revealed antihyperglycemic activity by reducing the elevated blood glucose level. A remarkable decrease in the liver, kidney functions, and hyperlipidemia related to diabetes were also detected. Administration of the same extract also showed a recovery in body weight loss, total protein, albumin, and haemoglobin levels compared with untreated diabetic rats. Furthermore, treatment of rats with the same extract improved liver and pancreas histopathological disorders related to diabetes. These effects may be attributed to the presence of bioactive phytochemicals and antioxidant components in T. decurrens AE mainly cyclotrisiloxane, hexamethyl, and cyclic diterpene 3,7,11,15-tetramethyl-2-hexadecen-1-ol (phytol alcohol). Besides, other valuable secondary metabolites, as phenols, flavonoids, alkaloids, terpenoids, steroid and glycosides, which were documented and published by the same authors in a previous study. The obtained results in the present study recommended using T. decurrens AE in developing medicinal preparations for treatment of diabetes and its related symptoms.

Antidiabetic and antioxidant activity of phlorotannins extracted from the brown seaweed Cystoseira compressa in streptozotocin-induced diabetic rats.

Diabetes mellitus is considered a set of diseases that lead to high glucose level due to the absolute or relative absence of insulin. The study investigated the antioxidant activity and antidiabetic effect of phlorotannins extracted from brown seaweed Cystoseira compressa. Phlorotannins were extracted from C. compressa. It was confirmed by 2,4 dimethoxy benzaldehyde assay (DMBA), ultraviolet spectra, Fourier transform infrared spectroscopy, and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The free radical scavenging activity of phlorotannins was estimated by total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity, and 2,2 azino-bis3-ethylbenthiazoline-6-sulfonic acid assays. Four groups of albino rats used in this study include control normal, control phlorotannins extract, diabetic by intraperitoneally administering of streptozotocin, and diabetic treatment with 60 mg/kg of phlorotannin extract after 4 weeks of diabetes induction. The main compound identified by UPLC-MS/MS in C. compressa extract belonged to the fuhalol. C. compressa extract showed high antioxidant properties. Phlorotannins significantly decreased serum glucose, liver malondialdehyde, and α-amylase, glucosidase activities. However, total antioxidant capacity, serum insulin, hepatic glutathione, and AMPKα2 expression in skeletal muscle were improved compared to the diabetic group. The histopathological examination showed that phlorotannins markedly reduced damage in ß cells of pancreases. Phlorotannins from C. compressa have efficient antioxidant activity and the antidiabetic effect that may be utilized in human health.

Efficacy of two seaweeds dry mass in bioremediation of heavy metal polluted soil and growth of radish (Raphanus sativus L.) plant.

This study investigated the effect of Ulva fasciata and Sargassum lacerifolium seaweeds as heavy metal remediators for soil and on the growth of radish (Raphanus sativus L.). The soil was inoculated by dry biomass of each seaweed alone and by their mixture. Seaweeds inoculation increased the organic matter content, clay-size fraction, and nutrients in the soil. Seaweeds mixture treatment caused a significant reduction in the contents of Pb, Cu, Zn and Ni in the soil samples and reduced them to the tolerable limits (40.2, 49.3, 43.8 and 1.1 mg kg-1, respectively), while Cd, Cr, Fe, and Mn contents were closely decreased to the tolerable limits. Biosorption of soil heavy metals by seaweeds decreased the bioaccumulated concentrations of metals in radish plant roots and/or translocated to its shoots compared to control. For seaweeds mixture-treated soil, cultivated radish roots were able to phyto-extract Cd, Cu, Cr, and Ni from the soil (bioaccumulation factor values > 1) of 7.45, 1.18, 3.13, and 26.6, respectively. Seaweeds inoculation promoted the growth of cultivated radish and improved the germination percentage and the morphological and biochemical growth parameters compared to control plants. The achieved soil remediation by dried seaweeds might be due to their efficient metal biosorption capacity due to the existence of active functional groups on their cell wall surfaces. Increased growth observed in radish was as a result of nutrients and growth hormones (gibberellins, indole acetic acid, and cytokinins) present in dried seaweeds. This study shows the efficiency of seaweeds as eco-friendly bioremediators for controlling soil pollution.

Natural products from some soil cyanobacterial extracts with potent antimicrobial, antioxidant and cytotoxic activities.

The ethyl acetate, n hexane and methanol extracts of six cyanobacterial species isolated from paddy fields in Egypt were assessed for their antimicrobial activity, using disc diffusion method. Oscillatoria acuminata, Oscillatoria amphigranulata and Spirulina platensis methanolic extracts showed the highest inhibition zones. Minimum inhibitory concentration of O. amphigranulata extract recorded lower values using agar streak dilution method. O. acuminata methanolic extract exhibited the highest antioxidant activity (6.58 and 34.60 % using DPPH (2, 2- diphenyl-1- picrylhydrazyl) and ABTS+ (2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) methods, respectively, followed by O. amphigranulata then S. platensis. Similarly, O. acuminata methanolic extract showed very strong cytotoxicity activity against HepG2 and HCT-116 cell lines and strong activity with MCF-7 cell lines. O. amphigranulata extract showed strong cytotoxicity for HepG2 and HCT-116 as well as moderate cytotoxicity for MCF-7 cell line. Whereas, S. platensis extract exhibited moderate cytotoxicity for all cell lines. Results of gas chromatography/mass spectroscopy analysis pointed out that the potential activity of these cyanobacterial extracts might be attributed to a synergistic effect between their pronounced contents of fatty acids, alkaloids, phytol, hydrocarbons, phenolics and phthalates, especially fatty acids. We recommend cyanobacteria as a rich source of natural products with potent pharmacological and medical applications.

Outdoor cultivation of the green microalga Chlorella vulgaris under stress conditions as a feedstock for biofuel.

The present work investigated the potential of the green alga Chlorella vulgaris to produce high-quality biofuel under culture stress conditions. The cultivation was carried out in a 1000 l open plate tank system, which provides biomass yields comparable to open pond systems, but with less area needed. Algal biomass and lipid content were measured repeatedly. We compared the two solvent systems n-hexane and hexane/isopropanol (HIP) for extraction efficiency of lipids and applied three different extraction methods Soxhlet, soaking, and soaking followed by Soxhlet (soak-Sox). The combination of the HIP solvent and the soak-Sox provided the highest lipid yield (15.8 ± 0.174). Volumetric biomass and lipid productivity were 0.201 g l-1 day-1 and 31.71 mg l-1 day-1, respectively, whereas areal biomass and lipid productivity were 25.73 g m-2 day-1 and 4.066 g m-2 day-1, respectively. The fatty acid profile by means of gas chromatography resulted in seven fatty acids from C12 to C18. The most abundant fatty acid methyl esters (FAMES) were palmitic (C16:0), oleic (C18:1), and stearic (C18:0) acids. Lipid synthesis enhanced by optimizing the Kuhl growth medium with replacing nitrate by urea (50% N compared to the original recipe) increased salt content (10 g/l NaCl), ferrous sulfate (0.5 g/l), and sodium acetate addition (1 g/l). With regard to density, kinematic viscosity, gravity, pour point, flash point, and cetane number, the Chlorella-biodiesel comply with ASTM and EN standards thus pointing at the high potential of lipids synthesized by Chlorella as a feedstock for biodiesel production.

Antiviral Profile of Brown and Red Seaweed Polysaccharides Against Hepatitis C Virus.

Hepatitis C virus (HCV) has infected 3% of the population worldwide and 20% of the population in Egypt. HCV infection can lead to hepatocellular carcinoma and death. The presently available treatment with interferon plus ribavirin, has limited benefits due to adverse side effects. Seaweeds have become a major source of new compounds to treat viral diseases. This work aimed to study the effect of four species of seaweeds as anti- HCV. The inhibition of lipid peroxidation was measured by evaluating the ability of seaweed extracts to scavenge the free radicals. The HepG2 cells were infected with the HCV and treated with each seaweed polysaccharide. Inhibition of viral replication was detected using the Real Time PCR (RT) qPCR. To explain the mode of the seaweed action on HCV, three modes of virus infections and seaweed polysaccharide treatments were applied. All treatments had the ability to inhibit the HCV with priority to Laurencia obtusa (82.36%), while the potentiality to scavenge the free radicals reached up to 81.5% with the Sargassumvulgare. Seaweed polysaccharide extracts may be helpful in exploring further gateways for antiviral therapy against HCV.