Green solutions: evaluating the impact of Chlorella sorokiniana and Anabaena laxa on captan phycoremediation.

This study explores the use of algae for phycoremediation, focusing on how Chlorella sorokiniana and Anabaena laxa detoxify water contaminated with captan, a common fungicide. The efficiency of these species in absorbing captan and the associated biochemical changes were evaluated to assess their potential for environmental protection. Microalgae were exposed to captan concentrations of 15 and 30 mg/L, and various parameters, including captan uptake, chlorophyll (Chl) a, carotenoid levels, and changes in metabolic profiles (soluble carbohydrates, organic acids, amino acids, and fatty acids), were measured. Results showed Anabaena had a higher captan absorption capacity (141.7 µg/g at 15 mg/L and 239.3 µg/g at 30 mg/L) compared to Chlorella (74.43 µg/g and 162 µg/g). Increased captan uptake reduced the growth of both species, as indicated by lower Chl a levels. Both species accumulated osmo-protectants and antioxidants as defense mechanisms, with soluble sugars increasing by 83.49% in Chlorella and 68.87% in Anabaena, and carotenoids increasing by 60.42% and 46.24%, respectively. Principal component analysis revealed distinct species-level responses, with Anabaena showing greater tolerance. The study concludes that both species can effectively remediate captan, with Anabaena being more efficient, indicating their potential for mitigating agrochemical impacts in aquatic environments and promoting sustainable agriculture and water management.

This study uniquely demonstrates the superior capability of Anabaena laxa over Chlorella sorokiniana in remediating captan-contaminated water, highlighting distinct biochemical responses and enhanced tolerance mechanisms. By detailing species-specific metabolic adaptations, it underscores the potential of Anabaena for more effective phycoremediation. This novel insight into the differential resilience of microalgae species offers a promising approach to mitigating agrochemical pollution, advancing sustainable agriculture, and improving water management practices.

Assessing thallium phycoremediation by applying Anabaena laxa and Nostoc muscorum and exploring its effect on cellular growth, antioxidant, and metabolic profile.

Thallium (Tl), a key element in high-tech industries, is recognized as a priority pollutant by the US EPA and EC. Tl accumulation threatens aquatic ecosystems. Despite its toxicity, little is known about its impact on cyanobacteria. This study explores the biochemical mechanisms of Tl(I) toxicity in cyanobacteria, focusing on physiology, metabolism, oxidative damage, and antioxidant responses. To this end, Anabaena and Nostoc were exposed to 400 µg/L, and 800 µg/L of Tl(I) over seven days. Anabaena showed superior Tl(I) accumulation with 7.8% removal at 400 µg/L and 9.5% at 800 µg/L, while Nostoc removed 2.2% and 7.4%, respectively. Tl(I) exposure significantly reduced the photosynthesis rate and function, more than in Nostoc. It also altered primary metabolism, increasing sugar levels and led to higher amino and fatty acids levels. While Tl(I) induced cellular damage in both species, Anabaena was less affected. Both species enhanced their antioxidant defense systems, with Anabaena showing a 175.6% increase in SOD levels under a high Tl(I) dose. This suggests that Anabaena's robust biosorption and antioxidant systems could be effective for Tl(I) removal. The study improves our understanding of Tl(I) toxicity, tolerance, and phycoremediation in cyanobacteria, aiding future bioremediation strategies.

This study presents novel insights into thallium (Tl) phycoremediation using Anabaena laxa and Nostoc muscorum, crucial for addressing the increasing contamination concerns stemming from high-tech industries. Elucidating the tolerance mechanisms and physiological responses of these cyanobacterial species to Tl(I) exposure. It highlights the potential of Anabaena laxa as an effective bio-remediator, offering a sustainable solution to mitigate Tl(I) environmental impact.

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.

Exploring Exogenous Indole-3-acetic Acid's Effect on the Growth and Biochemical Profiles of Synechocystis sp. PAK13 and Chlorella variabilis.

Microalgae have garnered scientific interest for their potential to produce bioactive compounds. However, the large-scale industrial utilization of microalgae faces challenges related to production costs and achieving optimal growth conditions. Thus, this study aimed to investigate the potential role of exogenous indole-3-acetic acid (IAA) application in improving the growth and production of bioactive metabolites in microalgae. To this end, the study employed different concentrations of exogenously administered IAA ranging from 0.36 µM to 5.69 µM to assess its influence on the growth and biochemical composition of Synechocystis and Chlorella. IAA exposure significantly increased IAA levels in both strains. Consequentially, improved biomass accumulation in parallel with increased total pigment content by approximately eleven-fold in both strains was observed. Furthermore, the application of IAA stimulated the accumulation of primary metabolites. Sugar levels were augmented, providing a carbon source that facilitated amino acid and fatty acid biosynthesis. As a result, amino acid levels were enhanced as well, leading to a 1.55-fold increase in total amino acid content in Synechocystis and a 1.42-fold increase in Chlorella. Total fatty acids content increased by 1.92-fold in Synechocystis and by 2.16-fold in Chlorella. Overall, the study demonstrated the effectiveness of exogenously adding IAA as a strategy for enhancing the accumulation of microalgae biomass and biomolecules. These findings contribute to the advancement of microalgae-based technologies, opening new avenues to produce economically important compounds derived from microalgae.

The inhibitory effect of some natural bioactive compounds against SARS-CoV-2 main protease: insights from molecular docking analysis and molecular dynamic simulation.

This work aimed at evaluating the inhibitory effect of ten natural bioactive compounds (1-10) as potential inhibitors of SARS-CoV-2-3CL main protease (PDB ID: 6LU7) and SARS-CoV main proteases (PDB IDs: 2GTB and 3TNT) by molecular docking analysis. The inhibitory effect of all studied compounds was studied with compared to some proposed antiviral drugs which currently used in COVID-19 treatment such as chloroquine, hydroxychloroquine, azithromycin, remdesivir, baloxvir, lopinavir, and favipiravir. Homology modeling and sequence alignment was computed to evaluate the similarity between the SARS-CoV-2-3CL main protease and other SARS-CoV receptors. ADMET properties of all studied compounds were computed and reported. Also, molecular dynamic (MD) simulation was performed on the compound which has the highest binding affinity inside 6LU7 obtained from molecular docking analysis to study it is stability inside receptor in explicit water solvent. Based on molecular docking analysis, we found that caulerpin has the highest binding affinity inside all studied receptors compared to other bioactive compounds and studied drugs. Our homology modeling and sequence alignment showed that SARS-CoV main protease (PDB ID: 3TNT) shares high similarity with 3CLpro (96.00%). Also, ADMET properties confirmed that caulerpin obeys Lipinski's rule and passes ADMET property, which make it a promising compound to act as a new safe natural drug against SARS-CoV-2-3CL main protease. Finally, MD simulation confirmed that the complex formed between caulerpin and 3CLpro is stable in water explicit and had no major effect on the flexibility of the protein throughout the simulations and provided a suitable basis for our study. Also, binding free energy between caulerpin and 6LU7 confirmed the efficacy of the caulerpin molecule against SARS-CoV-2 main protease. So, this study suggested that caulerpin could be used as a potential candidate in COVID-19 treatment.

Urea intercalated encapsulated microalgae composite hydrogels for slow-release fertilizers.

In agriculture, hydrogels can be addressed for effective operation of water and controlled-release fertilizers. Hydrogels have a significant ability for retaining water and improving nutrient availability in soil, enhancing plant growth while reducing water and fertilizer usage. This work aimed to prepare a hydrogel composite based on microalgae and biopolymers including chitosan and starch for use as a soil conditioner. The hydrogel composite was characterized by FTIR, XRD, and SEM. All hydrogel properties were studied including swelling degree, biodegradability, water-holding capacity, water retention, and re-swelling capacity in soil and water. The urea fertilizer loading and releasing behavior of the prepared hydrogels were investigated. The results revealed that the range of the maximal urea loading was between 99 and 440%, and the kinetics of loading was fitted with Freundlich model. The urea release % exhibited 78-95%, after 30 days, and the kinetics of release was fitted with zero-order, Higuchi, and Korsmeyer-Peppas models. Furthermore, the prepared hydrogels obtained a significant water-holding capacity, after blending soil (50 g) with small amount of hydrogels (1 g), the capacity increased in the range of 99.4-101.5%. In sum, the prepared hydrogels have the potential to be applied as a soil conditioner.

Evaluation of Cytotoxicity and Metabolic Profiling of Synechocystis sp. Extract Encapsulated in Nano-Liposomes and Nano-Niosomes Using LC-MS, Complemented by Molecular Docking Studies.

Liposomes and niosomes can be considered excellent drug delivery systems due to their ability to load all compounds, whether hydrophobic or hydrophilic. In addition, they can reduce the toxicity of the loaded drug without reducing its effectiveness. Synechocystis sp. is a unicellular, freshwater cyanobacteria strain that contains many bioactive compounds that qualify its use in industrial, pharmaceutical, and many other fields. This study investigated the potential of nano-liposomes (L) and nano-niosomes (N) for delivering Synechocystis sp. extract against cancer cell lines. Four different types of nanoparticles were prepared using a dry powder formulation and ethanol extract of Synechocystis sp. in both nanovesicles (N1 and N2, respectively) and liposomes (L1 and L2, respectively). Analysis of the formed vesicles using zeta analysis, SEM morphological analysis, and visual examination confirmed their stability and efficiency. L1 and L2 in this investigation had effective diameters of 419 and 847 nm, respectively, with PDI values of 0.24 and 0.27. Furthermore, the zeta potentials were found to range from -31.6 mV to -43.7 mV. Regarding N1 and N2, their effective diameters were 541 nm and 1051 nm, respectively, with PDI values of 0.31 and 0.35, and zeta potentials reported from -31.6 mV to -22.2 mV, respectively. Metabolic profiling tentatively identified 22 metabolites (1-22) from the ethanolic extract. Its effect against representative human cancers was studied in vitro, specifically against colon (Caco2), ovarian (OVCAR4), and breast (MCF7) cancer cell lines. The results showed the potential activities of the prepared N1, N2, L1, and L2 against the three cell lines, where L1 had cytotoxicity IC50 values of 19.56, 33.52, and 9.24 µg/mL compared to 26.27, 56.23, and 19.61 µg/mL for L2 against Caco2, OVCAR4, and MCF7, respectively. On the other hand, N1 exhibited IC50 values of 9.09, 11.42, and 2.38 µg/mL, while N2 showed values of 15.57, 18.17, and 35.31 µg/mL against Caco2, OVCAR4, and MCF7, respectively. Meanwhile, the formulations showed little effect on normal cell lines (FHC, OCE1, and MCF10a). All of the compounds were evaluated in silico against the epidermal growth factor receptor tyrosine kinase (EGFR). The molecular docking results showed that compound 21 (1-hexadecanoyl-2-(9Z-hexadecenoyl)-3-(6'-sulfo-alpha-D-quinovosyl)-sn-glycerol), followed by compounds 6 (Sulfoquinovosyl monoacylgycerol), 7 (3-Hydroxymyristic acid), 8 (Glycolipid PF2), 12 (Palmitoleic acid), and 19 (Glyceryl monostearate), showed the highest binding affinities. These compounds formed good hydrogen bond interactions with the key amino acid Lys721 as the co-crystallized ligand. These results suggest that nano-liposomes and nano-niosomes loaded with Synechocystis sp. extract hold promise for future cancer treatment development. Further research should focus on clinical trials, stability assessments, and pharmacological profiles to translate this approach into effective anticancer drugs.

New insights into enhancement of bio-hydrogen production through encapsulated microalgae with alginate under visible light irradiation.

The production of green hydrogen is a promising alternative to fossil fuels. The current study focuses on the design of microalgae as a catalyst in bioelectrochemical systems for the generation of biohydrogen. Furthermore, the abovementioned target could be achieved by optimizing different parameters, including strains of microalgae, different optical filters, and their shapes. Synechocystis sp. PAK13 (Ba9), Micractinium sp. YACCYB33 (R4), and Desmodesmus intermedius (Sh42) were used and designed as free cells and immobilized microalgae for evaluating their performance for hydrogen production. Alginate was applied for immobilization not only for protecting the immobilized microalgae from stress but also for inhibiting the agglomeration of microalgae and improving stability. The amount of studied immobilized microalgae was 0.01 g/5 ml algae-dissolved in 10 ml alginate gel at 28 °C, 12 h of light (light intensity 30.4 µmol m-2 s-1), and 12 h of darkness with continual aeration (air bump in every strain flask) at pH = 7.2 ± 0.2 in 0.05 %wuxal buffer which has 3.7 ionic strength. Different modalities, including FTIR, UV, and SEM, were performed for the description of selected microalgae. The surface morphology of Ba9 with alginate composite (immobilized Ba9) appeared as a stacked layer with high homogeneity, which facilitates hydrogen production from water. The conversion efficiencies of the immobilized microalgae were evaluated by incident photon-to-current efficiency (IPCE). Under optical filters, the optimum IPCE value was ∼ 7 % at 460 nm for immobilized Ba9. Also, its number of hydrogen moles was calculated to be 16.03 mmol h-1 cm-2 under optical filters. The electrochemical stability of immobilized Ba9 was evaluated through repetitive 100 cycles as a short-term stability test, and the curve of chrono-amperometry after 30 min in 0.05 %wuxal at a constant potential of 0.9 V for 30 min of all studied samples confirmed the high stability of all sample and the immobilized Ba9 has superior activity than others.

Glycine differentially improved the growth and biochemical composition of Synechocystis sp. PAK13 and Chlorella variabilis DT025.

The potential of microalgae to produce valuable compounds has garnered considerable attention. However, there are various challenges that hinder their large-scale industrial utilization, such as high production costs and the complexities associated with achieving optimal growth conditions. Therefore, we investigated the effects of glycine at different concentrations on the growth and bioactive compounds production of Synechocystis sp. PAK13 and Chlorella variabilis cultivated under nitrogen availability. Glycine supplementation resulted in increased biomass and bioactive primary metabolites accumulation in both species. Sugar production, particularly glucose content, significantly improved in Synechocystis at 3.33 mM glycine (1.4 mg/g). This led to enhanced organic acid, particularly malic acid, and amino acids production. Glycine stress also influenced the concentration of indole-3-acetic acid, which was significantly higher in both species compared to the control. Furthermore, fatty acids content increased by 2.5-fold in Synechocystis and by 1.36-fold in Chlorella. Overall, the exogenous application of glycine is a cheap, safe, and effective approach to enhancing sustainable microalgal biomass and bioproducts production.

Seasonal Changes in the Biochemical Composition of Dominant Macroalgal Species along the Egyptian Red Sea Shore.

Macroalgae are significant biological resources in coastal marine ecosystems. Seasonality influences macroalgae biochemical characteristics, which consequentially affect their ecological and economic values. Here, macroalgae were surveyed from summer 2017 to spring 2018 at three sites at 7 km (south) from El Qusier, 52 km (north) from Marsa Alam and 70 km (south) from Safaga along the Red Sea coast, Egypt. Across all the macroalgae collected, Caulerpa prolifera (green macroalgae), Acanthophora spicifera (red macroalgae) and Cystoseira myrica, Cystoseira trinodis and Turbinaria ornata (brown macroalgae) were the most dominant macroalgal species. These macroalgae were identified at morphological and molecular (18s rRNA) levels. Then, the seasonal variations in macroalgal minerals and biochemical composition were quantified to determine the apt period for harvesting based on the nutritional requirements for commercial utilizations. The chemical composition of macroalgae proved the species and seasonal variation. For instance, minerals were more accumulated in macroalgae C. prolifera, A. spicifera and T. ornata in the winter season, but they were accumulated in both C. myrica and C. trinodis in the summer season. Total sugars, amino acids, fatty acids and phenolic contents were higher in the summer season. Accordingly, macroalgae collected during the summer can be used as food and animal feed. Overall, we suggest the harvesting of macroalgae for different nutrients and metabolites in the respective seasons.

Applying an internal transcribed spacer as a single molecular marker to differentiate between Tetraselmis and Chlorella species.

In the realm of applied phycology, algal physiology, and biochemistry publications, the absence of proper identification and documentation of microalgae is a common concern. This poses a significant challenge for non-specialists who struggle to identify numerous eukaryotic microalgae. However, a promising solution lies in employing an appropriate DNA barcoding technique and establishing comprehensive databases of reference sequences. To address this issue, we conducted a study focusing on the molecular characterization and strain identification of Tetraselmis and Chlorella species, utilizing the internal transcribed spacer (ITS) barcode approach. By analyzing the full nuclear ITS region through the Sanger sequencing approach, we obtained ITS barcodes that were subsequently compared with other ITS sequences of various Tetraselmis and Chlorella species. To ensure the reliability of our identification procedure, we conducted a meticulous comparison of the DNA alignment, constructed a phylogenetic tree, and determined the percentage of identical nucleotides. The findings of our study reveal the significant value of the ITS genomic region as a tool for distinguishing and identifying morphologically similar chlorophyta. Moreover, our results demonstrate that both the ITS1 and ITS2 regions are capable of effectively discriminating isolates from one another; however, ITS2 is preferred due to its greater intraspecific variation. These results underscore the indispensability of employing ITS barcoding in microalgae identification, highlighting the limitations of relying solely on morphological characterization.

Antibacterial, Antifungal, and Anticancer Effects of Camel Milk Exosomes: An In Vitro Study.

Camel milk (CM) has potent antibacterial and antifungal effects and camel milk exosomes (CM-EXO) have been shown to inhibit the proliferation of a large variety of cancer cells including HepaRG, MCF7, Hl60, and PANC1. However, little is known regarding the effects of CM-EXO on bacteria, fungi, HepG2, CaCo2, and Vero cells. Therefore, this study aimed to evaluate the antibacterial, antifungal, and anticancer effects of CM-EXO. EXOs were isolated from CM by ultracentrifugation and characterized by transmission electron microscope and flow cytometry. Unlike CM, CM-EXO (6 mg/mL) had no bactericidal effects on Gram-positive bacteria (Staphylococcus aureus, Micrococcus luteus, and Enterococcus feacalis) but they had bacteriostatic effects, especially against Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis), and fungistatic effects on Candida albicans. HepG2, CaCo2, and Vero cells were respectively treated with CM-EXOs at low (6.17, 3.60, 75.35 µg/mL), moderate (12.34, 7.20, 150.70 µg/mL), and high (24.68, 14.40, 301.40 µg/mL) doses and the results revealed that CM-EXOs triggered apoptosis in HepG2 and CaCo2 cells, but not in normal Vero cells, as revealed by high Bax expression and caspase 3 activities and lower expression of Bcl2. Interestingly, CM-EXOs also induced the elevation of intracellular reactive oxygen species and downregulated the expression of antioxidant-related genes (NrF2 and HO-1) in cancer cells but not in normal cells. CM-EXOs have antibacterial and antifungal effects as well as a selective anticancer effect against HepG2 and CaCo2 cells with a higher safety margin on normal cells.

In vitro antioxidant, anticancer, anti-inflammatory, anti-diabetic and anti-Alzheimer potentials of innovative macroalgae bio-capped silver nanoparticles.

The antagonistic side effects of chemical medications led to the search for safe strategies such as biogenic agents. Correspondingly, this study aims to create biogenic, appropriate, auspicious and innovative therapeutic agents like Galaxaura elongata {GE}, Turbinaria ornata {TO} and Enteromorpha flexuosa {EF} macroalgae-based silver nanoparticles (Ag-NPs). The Ag+ reduction and the creation of Ag[GE]-NPs, Ag[TO]-NPs and Ag[EF]-NPs have been validated using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and zeta potential analysis, and the chemical composition of macroalgae crude extracts was estimated through gas chromatography-mass spectrometry (GC-MS). Further, macroalgae-based Ag-NPs were tested for their free radical scavenging activity DPPH, ABTS, anticancer activity in human liver carcinoma (HepG2) cell line, distinctive inflammation forms and elevated α-amylase. Results showed that the biosynthesized Ag-NPs have unique mechanical and physicochemical characters attributed to their high relative surface area, nanosized dimensions and spherical shape. At dose of 200 µg/mL, the DPPH radical scavenging capacity was maximized with Ag[TO]-NPs (67.26%); however, Ag[EF]-NPs was the most potent as ABTs scavenger (97.74%). Additionally, Ag[GE]-NPs had the maximum proteinase inhibitory action with 59.78%. The 1000 µg/mL of Ag[GE]-NPs, Ag[TO]-NPs and Ag[EF]-NPs revealed significant inhibitions of cell growth of HepG2 resulting in cell viabilities 5.92%, 4.44% and 11.33%, respectively. These findings suggest that macroalgae bio-capped Ag-NPs have magnificent biological potentials for safe biomedical applications.

Photocatalytic Activity of Revolutionary Galaxaura elongata, Turbinaria ornata, and Enteromorpha flexuosa's Bio-Capped Silver Nanoparticles for Industrial Wastewater Treatment.

More suitable wastewater treatment schemes need to be developed to get rid of harmful dyes and pigments before they are discharged, primarily from apparel and textile factories, into water bodies. Silver nanoparticles (Ag-NPs) are very effective, reductive nanocatalysts that can degrade many organic dyes. In this study, Ag-NPs are stabilized and capped with bioactive compounds such as Galaxaura elongata, Turbinaria ornata, and Enteromorpha flexuosa from marine macroalgae extracts to produce Ag[GE], Ag[TE], and Ag[EE] NPs. The reduction of Ag ions and the production of Ag[GE], Ag[TE], and Ag[EE] NPs have been substantiated by UV-Vis spectroscopy, SEM, EDX, and XRD tests. The NPs are sphere and crystalline shaped in nature with dimensions ranging from 20 to 25 nm. The biosynthesized Ag[GE], Ag[TE], Ag[EE] NPs were applied to photodegrade hazardous pigments such as methylene blue, Congo red, safranine O, and crystal violet under sunlight irradiation. In addition to the stability analysis, various experimental parameters, including dye concentration, exposure period, photocatalyst dose, and temperature, were optimized to achieve 100% photodegradation of the dyes. Moreover, the thermodynamic and kinetic parameters were calculated and the impact of scavengers on the photocatalytic mechanism was also investigated.

Bis-indole alkaloid caulerpin from a new source Sargassum platycarpum: isolation, characterization, in vitro anticancer activity, binding with nucleobases by DFT calculations and MD simulation.

Caulerpin, a bis-indole alkaloid is isolated from a new source Sargassum platycarpum, brown alga (family Sargassaceae) for the first time. The structure of caulerpin was characterized by IR, H1NMR, C13 NMR, HSQC, HMBC, EI-MS spectroscopy. Antifungal results suggest that caulerpin has been inhibited Cryptococcus neoformas (12 mm) and Candida albicans (7 mm) than other microbes. In vitro anticancer activity of caulerpin has been explored by cell viability assay against new human cancer cell line (liver-HepG2). The results show that caulerpin has low IC50 value (24.6 ± 2.1 µg/mL) against HepG-2. Based on the least toxic activity of caulerpin, these results encourage for future in vivo anticancer study. The binding of caulerpin molecule with the two nucleobases (T/U) bases has been studied by DFT methods. According to the AIM analysis, there are two types of interactions between caulerpin and T/U bases partially covalent partially electrostatic and electrostatic in gas and water phases. Based on NBO analysis, the charges were transferred from the lone-pair (n) in orbitals of O atoms of caulerpin to the σ* orbitals of T/U bases atoms. ΔEbin in the state of caulerpin-T bases complexes are lower than those in the caulerpin-U bases complexes in both gas and water phase. MD simulation supported that caulerpin-T/U bases complexes are stable in presence of explicit water phase. Thus, the findings of our study will be useful for giving an insight into the caulerpin/bases complexes that could be helpful in future experimental studies to develop the performance of caulerpin molecules as natural candidate drug. Communicated by Ramaswamy H. Sarma.

Cytotoxic activity, molecular docking, pharmacokinetic properties and quantum mechanics calculations of the brown macroalga Cystoseira trinodis compounds.

In this study, nine compounds were isolated, eight of them were isolated for the first time from Cystoseira trinodis. The biological activity of the extract, fractions and pure compounds was evaluated. The antimicrobial activity was investigated against 3 fungi species, 3 gram + ve and 3 gram -ve bacteria. The crude extract and fractions showed moderate inhibition against some of the tested microorganisms, especially the butanol fraction exhibited the maximum inhibition zone against Salmonella typhimurium (16 ± 0.60 mm). Cytotoxicity was evaluated against HepG-2 and MCF-7 cell lines. Hexane fraction exhibited the highest cytotoxic effect against HepG-2 and MCF-7 cell lines with an IC50 value of 14.3 ± 0.8 and 19.2 ± 0.7 µg/ml, respectively with compared to other fractions. The isolates were identified as octacosanoic acid (1), glyceryl trilinoleate (2), oleic acid (3), and the epimeric mixture of saringosterols (4, 5), ß-sitosterol (6), glycoglycerolipid (7) and a mixture of kjellmanianone and loliolide (8, 9) by spectroscopic analysis. Among the all tested compounds kjellmanianone and loliolide mixture exhibited significant cytotoxic activity with an IC50 value of 7.27 µg/ml against HepG-2 cells. The major and minor constituents of the extract and fractions were identified using GC-MS analysis. Molecular docking analysis confirmed that most of the studied compounds especially compounds 8 and 9 strongly interact with TPK and VEGFR-2 with highest binding energies supported that the high cytotoxicity of these compounds against human hepatocellular cancer in the experimental part. The energetic, geometric and topological properties of compounds 8 and 9 binding with cytosine base were computed by DFT methods. Molecular properties descriptors, bioactivity score and ADMET analysis confirmed that most of the studied compounds especially compounds 8 and 9 exhibit significant biological activities and have a better chance to be developed as drug leads. Communicated by Ramaswamy H. Sarma.

Combination and tricombination therapy to destabilize the structural integrity of COVID-19 by some bioactive compounds with antiviral drugs: insights from molecular docking study.

Recently, the SARS-CoV-2 (COVID-19) pandemic virus has been spreading throughout the world. Until now, no certified drugs have been discovered to efficiently inhibit the virus. The scientists are struggling to find new safe bioactive inhibitors of this deadly virus. In this study, we aim to find antagonists that may inhibit the activity of the three major viral targets: SARS-CoV-2 3-chymotrypsin-like protease (6LU7), SARS-CoV-2 spike protein (6VYB), and a host target human angiotensin-converting enzyme 2 (ACE2) receptor (1R42), which is the entry point for the viral encounter, were studied with the prospects of identifying significant drug candidate(s) against COVID-19 infection. Then, the protein stability produced score of less than 0.6 for all residues of all studied receptors. This confirmed that these receptors are extremely stable proteins, so it is very difficult to unstable the stability of these proteins through utilizing individual drugs. Hence, we studied the combination and tricombination therapy between bioactive compounds which have the best binding affinity and some antiviral drugs like chloroquine, hydroxychloroquine, azithromycin, simeprevir, baloxavir, lopinavir, and favipiravir to show the effect of combination and tricombination therapy to disrupt the stability of the three major viral targets that are mentioned previously. Also, ADMET study suggested that most of all studied bioactive compounds are safe and nontoxic compounds. All results confirmed that caulerpin can be utilized as a combination and tricombination therapy along with the studied antiviral drugs for disrupting the stability of the three major viral receptors (6LU7, 6VYB, and 1R42). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11224-020-01723-5.

Destabilizing the structural integrity of COVID-19 by caulerpin and its derivatives along with some antiviral drugs: An in silico approaches for a combination therapy.

Presently, the SARS-CoV-2 (COVID-19) pandemic has been spreading throughout the world. Some drugs such as lopinavir, simeprevir, hydroxychloroquine, chloroquine, and amprenavir have been recommended for COVID-19 treatment by some researchers, but these drugs were not effective enough against this virus. This study based on in silico approaches was aimed to increase the anti-COVID-19 activities of these drugs by using caulerpin and its derivatives as an adjunct drug against SARS-CoV-2 receptor proteins: the SARS-CoV-2 main protease and the SARS-CoV-2 spike protein. Caulerpin exhibited antiviral activities against chikungunya virus and herpes simplex virus type 1. Caulerpin and some of its derivatives showed inhibitory activity against Alzheimer's disease. The web server ANCHOR revealed higher protein stability for the two receptors with disordered score (< 0.6). Molecular docking analysis showed that the binding energies of most of the caulerpin derivatives were higher than all the suggested drugs for the two receptors. Also, we deduced that inserting NH2, halogen, and vinyl groups can increase the binding affinity of caulerpin toward 6VYB and 6LU7, while inserting an alkyl group decreases the binding affinity of caulerpin toward 6VYB and 6LU7. So, we can modify the inhibitory effect of caulerpin against 6VYB and 6LU7 by inserting NH2, halogen, and vinyl groups. Based on the protein disordered results, the SARS-CoV-2 main protease and SARS-CoV-2 spike protein domain are highly stable proteins, so it is quite difficult to unstabilize their integrity by using individual drugs. Also, molecular dynamics (MD) simulation indicates that binding of the combination therapy of simeprevir and the candidate studied compounds to the receptors was stable and had no major effect on the flexibility of the protein throughout the simulations and provided a suitable basis for our study. So, this study suggested that caulerpin and its derivatives could be used as a combination therapy along with lopinavir, simeprevir, hydroxychloroquine, chloroquine, and amprenavir for disrupting the stability of SARS-CoV2 receptor proteins to increase the antiviral activity of these drugs.