Antimicrobial Activity Research Articles

Green synthesis of CdS/flaxseed mucilage nanocomposite films using gamma irradiation for packaging applications

Abstract The most common ways to produce nanoparticles are through chemical and physical processes, which can be expensive and environmentally hazardous. Using plant extracts (green synthesis) as reducing and capping agents is a simple, cost-effective, and environmentally friendly method of lowering the usage of dangerous chemicals in the synthesis of metal nanoparticles. This study covers the environmentally friendly synthesis of cadmium sulphide nanoparticles (CdS NPs) using a blend of flaxseed extracts (FM), polyvinyl alcohol (PVA), and chitosan (Cs). The composites are then exposed to gamma irradiation at doses of 20 kGy and 40 kGy. UV–VIS absorption spectroscopy, SEM, HRTEM, EDX, and FTIR were used to analyse the produced nanocomposite films. UV–Vis absorption spectra showed considerable surface Plasmon resonance (SPR) bands at 396–440 nm, indicating that CdS NPs had been successfully synthesized. A progressive red shift in wavelength was noted, along with the broadening of the absorption band as the irradiation dose increased. Transmission electron microscopy pictures revealed that the generated CdS nanostructures were dispersed as spherical nanoparticles with remarkable structural homogeneity. Tensile strength and elongation measurements of the films revealed that the inclusion of CdS NPs improved their mechanical properties. The addition of CdS NPs to the current blends limits biodegradation in soil. Thermal gravimetric analysis findings showed that CdS NPs included in FM/PVA films had improved thermal stability. The antimicrobial activities of the tested films were performed against Staphylococcus aureus, Escherichia coli, and Candida albicans. The results revealed that all of the films exhibited more antibacterial activity against S. aureus than the two others, with the highest activity observed in nanocomposites with a high concentration of CdS.

Hidden Treasure: Halophilic Fungi as a Repository of Bioactive Lead Compounds

The pressing demand for novel compounds to address contemporary health challenges has prompted researchers to venture into uncharted territory, including extreme ecosystems, in search of new natural pharmaceuticals. Fungi capable of tolerating extreme conditions, known as extremophilic fungi, have garnered attention for their ability to produce unique secondary metabolites crucial for defense and communication, some of which exhibit promising clinical significance. Among these, halophilic fungi thriving in high-salinity environments have particularly piqued interest for their production of bioactive molecules. This review highlights the recent discoveries regarding novel compounds from halotolerant fungal strains isolated from various saline habitats. From diverse fungal species including Aspergillus, Penicillium, Alternaria, Myrothecium, and Cladosporium, a plethora of intriguing molecules have been elucidated, showcasing diverse chemical structures and bioactivity. These compounds exhibit cytotoxicity against cancer cell lines such as A549, HL60, and K-562, antimicrobial activity against pathogens like Escherichia coli, Bacillus subtilis, and Candida albicans, as well as radical-scavenging properties. Notable examples include variecolorins, sclerotides, alternarosides, and chrysogesides, among others. Additionally, several compounds display unique structural motifs, such as spiro-anthronopyranoid diketopiperazines and pentacyclic triterpenoids. The results emphasize the significant promise of halotolerant fungi in providing bioactive compounds for pharmaceutical, agricultural, and biotechnological uses. However, despite their potential, halophilic fungi are still largely unexplored as sources of valuable compounds.

Novel Tannic Acid-Modified Cobalt-Based Metal–Organic Framework: Synthesis, Characterization, and Antimicrobial Activity

Novel Tannic Acid-Modified Cobalt-Based Metal–Organic Framework: Synthesis, Characterization, and Antimicrobial Activity

Profiling Key Aroma Compounds of Senecio glaucus L. and their Antimicrobial and Antioxidant Activities: Multiplex of GC-MS, NMR and In Silico Studies.

The essential oils of Senecio plants have been used to treat a wide range of ailments. The current study aimed to extract the essential oil of Senecio glaucus obtained from Egypt's Nile delta and determine its chemical profile using GC-MS and NMR analysis. Then, the antimicrobial activity of the oil has been investigated against different fungal and bacterial strains. In addition, its activity as radical scavenger has been evaluated using DPPH, ABTS, and metal chelating techniques. The results revealed the identification of 50 compounds representing 98.80 % of the oil total mass. Sesquiterpenes, including dehydrofukinone (27.15 %) and 4,5-di-epi-aristolochene (10.27 %), as well as monoterpenes, including p-cymene (4.77 %), represented the most predominant constituents. The dehydrofukinone has been isolated and structurally confirmed using 1D and 2D NMR techniques. The oil has showed remarkable antifungal activity against Candida glabrata and C. albicans where the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values were 3.13 μg/mL and 1.50 μg/mL and 12.50 μg/mL and 6.30 μg/mL, respectively that could be attributed to the sesquiterpene ketones present in the aerial tissues of the plant. Also, this oil inhibited the growth of the tested bacteria with MIC ranging from 12.50-100.00 μg/mL. In comparison to ascorbic acid and Trolox, the EO had remarkable scavenging activity of DPPH, ABTS and metal chelating with IC50 values of 313.17±13.4, 493.83±20.1, and 409.13±16.7 μg/mL. The docking studies of the identified compounds of the oil to different microbial targets, including Gyrase B and α-sterol demethylase, showed that the phytol possessed the best binding affinities toward the active sites of both enzymes with ΔG=-7.42 and -7.78 kcal/mol, respectively. In addition, the phytol revealed the highest binding affinity to tyrosine kinase Hck with ΔG=-7.44 kcal/mol.

Multicentre double-blind randomised placebo-controlled trial evaluating the efficacy of the meningococcal B vaccine, 4CMenB (Bexsero), against Neisseria gonorrhoeae infection in men who have sex with men: the GoGoVax study protocol

IntroductionGonorrhoea, the sexually transmissible infection caused by Neisseria gonorrhoeae, has a substantial impact on sexual and reproductive health globally with an estimated 82 million new infections each year worldwide. N....

Chemical Characterization and Evaluation of the Antimicrobial Activity of Extracts from Two Cultivars of Cannabis sativa L. (Tisza and Kompolti) Grown in Sardinia

The present work was aimed at the chemical characterization and antimicrobial activity of some extracts of aerial parts (essential oils from leaves and inflorescences and resins from inflorescences) of two legal hemp (Cannabis sativa) varieties, Tisza and Kompolti, grown in Sardinia. Chemical characterization was carried out by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) techniques. The main constituent was myrcene (11.75% in Tisza and 18.21% in Kompolti); delta-9-tetrahydrocannabinol (THC) was not found, while cannabidiol was present up to 0.36% in Tisza and up to 2.80% in Kompolti. The antimicrobial activity of these extracts against a panel of microorganisms was also determined via minimum inhibitory concentration (M.I.C.) determination. While the results showed minor or negligible antimicrobial activity of the extracts against the Gram+ and Candida strains (M.I.C. values equal to or greater than 4 mg/mL), good antibacterial activity (especially of resins) was recorded against S. aureus (M.I.C. 0.015–0.031 mg/mL); no substantial differences were detected between the chemical compositions of the two Cannabis varieties.

Further Insights on Honey and Propolis from Gerês (Portugal) and Their Bioactivities: Unraveling the Impact of Beehive Relocation

Propolis, a bee product, is known for its variability of chemical and bioactive profiles. However, Portuguese propolis from Gerês, normally obtained by mixing propolis from three places—Bugalho, Felgueiras and Toutelo—has shown similar chemical and biological profiles over the years. Recently, a new propolis place—Roca—was added to the apiary to replace Bugalho, lost to the 2017 wildfires, hence questioning the previously claimed constancy of Gerês propolis. To unravel to what extent the beehive relocation affected this constancy, we studied different Gerês propolis samples collected in three consecutive years (2017–2019) composed of different combinations of source places. Two honey samples, collected before (2017) and after (2018) the occurrence of the wildfire, were also investigated. Total phenolics, flavonoids and ortho-diphenols contents were determined and the antioxidant and antimicrobial activities were evaluated, using the DPPH assay and the agar dilution method, respectively. Although both antimicrobial and antioxidant activities were generally in the ranges usually obtained from Gerês propolis, some variations were detected for the samples, with different compositions when compared to previous years. This work reinforces the importance of the consistency of a combination of several factors for the protection and preservation of the flora near the hives, providing bee products with more constant chemical and biological profiles over the years.

Zinc Oxide-Based Nanomaterials for Microbiostatic Activities: A Review

The world is fighting infectious diseases. Therefore, effective antimicrobials are required to prevent the spread of microbes and protect human health. Zinc oxide (ZnO) nano-materials are known for their antimicrobial activities. Because of their distinctive physical and chemical characteristics, they can be used in medical and environmental applications. ZnO-based composites are among the leading sources of antimicrobial research. They are effective at killing (microbicidal) and inhibiting the growth (microbiostatic) of numerous microorganisms, such as bacteria, viruses, and fungi. Although most studies have focused on the microbicidal features, there is a lack of reviews on their microbiostatic effects. This review provides a detailed overview of available reports on the microbiostatic activities of ZnO-based nano-materials against different microorganisms. Additionally, the factors that affect the efficacy of these materials, their time course, and a comparison of the available antimicrobials are highlighted in this review. The basic properties of ZnO, challenges of working with microorganisms, and working mechanisms of microbiostatic activities are also examined. This review underscores the importance of further research to better understand ZnO-based nano-materials for controlling microbial growth.

Interaction of Valine with Biometal Chlorides in an Aqueous Environment at 25°C

Research in medical biology and pharmacology can expand understanding of the interactions of biometals with amino acids, which are key components of biological systems. This may lead to the development of new complexes that can be used in medicine, for example, to develop new drugs with antimicrobial activity or to maintain metabolic balance in the body. Research purpose:obtaining complex compounds of biometals, cobalt chloride, nickel chloride and manganese chloride with the amino acid valine, as well as the study of their physicochemical and biological properties. For the analysis, the Kjeldahl method was used to determine the nitrogen content. The composition of the formed crystals was analyzed by IR spectroscopy. The structure and shape of cobalt, nickel and manganese crystals were determined using a microscope. The identity of the obtained compounds was confirmed by IR spectroscopy and microscopic analyses. We can conclude that valine in the complex is coordinated to metal ions through the oxygen atoms of the carboxyl and nitrogen groups of the amine groups.

Screening Studies of the Antimicrobial Activity of the Pyrimidine Compound 2,2-[6-Bromo-2,4-Dioxoquinazoline-1,3(2H)diyl]bis(N-Carbamimidoylacetamide)

The aim of this study was to screen the antimicrobial activity of a pyrimidine compound under the laboratory code VMA-21-01. Antimicrobial activity was studied in relation to: Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumonia, and Proteus mirabilis. The antimicrobial activity of 2,2-[6-Bromo-2,4-dioxoquinazoline- 1,3(2H)diyl]bis(N-carbamimidoylacetamide) was carried out in vitro by serial dilution and determination of its minimum inhibitory concentration. The sensitivity of microorganisms to the test substance was determined in a meat-peptone broth (visual assessment), followed by reinoculation on meat-peptone agar and colony count. DMSO tubes were used as a control. A 4% gentamicin solution was used as a comparison drug. In an in vitro experiment, it was found that the pyrimidine compound 2,2-[6-Bromo-2,4-dioxyquinazoline-1,3(2H)diyl]bis(N-carbamimidoylacetamide) under the laboratory cipher VMA21-01 has bactericidal activity against K. pneumonia comparable to the comparison drug gentamicin, as well as bacteriostatic activity against S. aureus, S. pneumoniae, E. coli, and P. mirabilis. 

Influential lead uptake using dried and inactivated-fungal biomass obtained from Panaeolus papilionaceus: biological activity, equilibrium, and mechanism

AbstractIn this study, the use of fungal (Panaeolus papilionaceus) biomass as a biosorbent was investigated to effectively remove Pb2+ ions from aquatic medium. The removal of Pb2+ ions using a fungal biosorbent was examined in a batch system in terms of initial solution pH, temperature, time, and initial Pb2+ concentration. Optimal operating conditions for biosorption of Pb2+ ions; pH: 4.5, T: 25 °C, and t: 24 h. The max biosorption capacity for Pb2+ ions was found to be 31.2 mg g−1 from the Langmuir model. Thermodynamic studies showed that Pb2+ ions biosorption into fungal biomass was possible, spontaneous, and endothermic. Additionally, the antimicrobial activity and antibiofilm activity of the extract of fungus were also investigated. It was determined that the fungal extract did not have antimicrobial properties. On the other hand, the extract has been shown to have the potential to prevent biofilm formation. 1 mg of the extract prevented the biofilm formation of Staphylococcus aureus by 87.85%. It has been observed that the biosorption mechanism of Pb2+ ions into fungal biomass includes the steps of surface biosorption, film diffusion, and intra-particle diffusion.

Antibacterial, antibiofilm, and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant bacteria.

To evaluate the antibacterial, antibiofilm and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant (MDR) bacteria. Antimicrobial assays included determination of the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration of Biofilm (MICB50), as well as synergistic and antivirulence assays for eight diterpenes against MDR. The tests revealed that two diterpenes (named 1 and 5) showed the best results, with MIC and MBC between 12.5 and 50μg/mL against most MDR bacteria. These diterpenes exhibited promising MICB50 in concentration between 3.12-25μg/mL but showed no synergistic antimicrobial activity. In the assessment of antivirulence activity, diterpenes 1 and 5 inhibited only one of the virulence factors evaluated (Dnase) produced by some strains of S. aureus at subinhibitory concentration (6.25μg/mL). Results obtained indicated that diterpenes isolated from Copaifera oleoresin plays an important part in the search of new antibacterial and antibiofilm agents that can act against MDR bacteria.

Optimizing Wound Healing: Examining the Influence of Biopolymers Through a Comprehensive Review of Nanohydrogel-Embedded Nanoparticles in Advancing Regenerative Medicine.

Nanohydrogel wound healing refers to the use of nanotechnology-based hydrogel materials to promote the healing of wounds. Hydrogel dressings are made up of a three-dimensional network of hydrophilic polymers that can absorb and retain large amounts of water or other fluids. Nanohydrogels take this concept further by incorporating nanoscale particles or structures into the hydrogel matrix. These nanoparticles can be made of various materials, such as silver, zinc oxide, or nanoparticles derived from natural substances like chitosan. The inclusion of nanoparticles can provide additional properties and benefits to the hydrogel dressings. Nanohydrogels can be designed to release bioactive substances, such as growth factors or drugs, in a controlled manner. This allows for targeted delivery of therapeutics to the wound site, promoting healing and reducing inflammation. Nanoparticles can reinforce the structure of hydrogels, improving their mechanical strength and stability. Nanohydrogels often incorporate antimicrobial nanoparticles, such as silver or zinc oxide. These nanoparticles have shown effective antimicrobial activity against a wide range of bacteria, fungi, and other pathogens. By incorporating them into hydrogel dressings, nanohydrogels can help prevent or reduce the risk of infection in wounds. Nanohydrogels can be designed to encapsulate and release bioactive substances, such as growth factors, peptides, or drugs, in a controlled and sustained manner. This targeted delivery of therapeutic agents promotes wound healing by facilitating cell proliferation, reducing inflammation, and supporting tissue regeneration. The unique properties of nanohydrogels, including their ability to maintain a moist environment and deliver bioactive agents, can help accelerate the wound healing process. By creating an optimal environment for cell growth and tissue repair, nanohydrogels can promote faster and more efficient healing of wounds.

A literature review on various agents which can be used as a mouthwash for effective oral care

There are various types of mouthwashes available in the market, which contains different types of ingredients in it, which are active and inactive in nature. A mouthwash can perform various functions like, it can provide an antimicrobial activity, can be used as a topical anti-inflammatory agent, as a topical analgesic and most commonly and importantly for the prevention of the occurrence of the caries in the oral cavity. Mouthwashes are the most common types of agents, which came in direct contact with the oral mucous membrane and can be absorbed directly into the blood stream. Different agents which can be used in the preparation of the oral mouthwashes are chlorhexidine, benzydamine hydrochloride, cetylpyridinium chloride and sodium benzoate, triclosan, oxygenating agents, sodium bicarbonate, alcohol, while on the other side the main content of the poly herbal mouth washes are clove, peppermint, green tea, ajwain, neem, tulsi and leaf of guava fruit. Usually, most therapeutic oral rinses or natural mouth rinses usually does not contain any alcohol or sugar or any type of artificial sweetener in it.

Reinforcement of biodegradable SiO2NPs-modified cellulose-gelatin hydrogel films with antioxidant and antibacterial properties as potential food packaging composite

AbstractThis study proposed an innovative approach to the development of sustainable and biodegradable food packaging materials by incorporating inexpensive nano-silica (SiO2NPs) in designed hydrogel (CSG) film employing biodegradable polymers: synthetic polymer polyvinyl alcohol (PVA), natural polymer - carboxymethyl cellulose (CMC) and protein-based bio-polymer –gelatine, and a commercial crosslinker, tetraethoxysilane (TEOS) through a conventional air-dry casting technique. The CSG hydrogel blends were modified with varying amounts of SiO2NPs (0.05g, 0.1g, 0.15g and 0.2g) and compared with the blend without SiO2NPs to determine the effect of SiO2NPs loading through various characterisation techniques and applications including antioxidant and antimicrobial activity. Comprehensive characterizations of the CSG films revealed that CSG 0.1 (containing 0.1g SiO2NPs) exhibited the most favourable functional properties, low crystallinity, high flexibility, suitable pore size, thermal stability, adequate tensile strength, elongation at the breaking point and maximum stability by swelling and diffusion test. The addition of SiO2NPs consistently enhanced thermal and mechanical stability in all CSG films. Further, these CSG films were implemented for antioxidant test and antimicrobial activity against gram-positive Bacillus cereus and gram-negative Escherichia coli. SiO2NPs integration significantly elevated the antioxidant capacity in all films, with CSG 0.1 showing ⁓7% improvement. The antimicrobial activity of SiO2NPs-modified CSG films was also notable, with CSG 0.1 effectively inhibiting B. cereus by 1.2cm zone and E. coli by 0.5cm zone. A soil burial test was performed to pattern the biodegradability of CSG hydrogels. Therefore, the outstanding improvements in the intrinsic properties of CSG films, owing to SiO2NPs modification, positioned these CSG hydrogels as promising candidates for advanced food packaging materials in various industries.

Glucose-Binding Dioclea bicolor Lectin (DBL): Purification, Characterization, Structural Analysis, and Antibacterial Properties.

In this study, we purified a lectin isolated from the seeds of Dioclea bicolor (DBL) via affinity purification. Electrophoresis analysis revealed that DBL had three bands, α, β, and γ chains, with molecular masses of approximately 29, 14, and 12kDa, respectively. Gel filtration chromatography revealed that the native form of DBL had a molecular mass of approximately 100kDa, indicating that it is a tetramer. Interestingly, DBL-induced hemagglutination was inhibited by several glucosides, mannosides, ampicillin, and tetracycline with minimum inhibitory concentration (MIC) values of 1.56-50mM. Analysis of the complete amino acid sequence of DBL revealed the presence of 237 amino acids with high similarity to other Diocleinae lectins. Circular dichroism showed the prominent β-sheet secondary structure of DBL. Furthermore, DBL structure prediction revealed a Discrete Optimized Protein Energy (DOPE) score of -26,642.69141/Normalized DOPE score of -1.84041. The DBL monomer was found to consist a β-sandwich based on its 3D structure. Molecular docking showed the interactions between DBL and α-D-glucose, N-acetyl-D-glucosamine, α-D-mannose, α-methyl-D-mannoside, ampicillin, and tetracycline. In addition, DBL showed antimicrobial activity with an MIC of 125μg/mL and exerted synergistic effects in combination with ampicillin and tetracycline (fractional inhibitory concentration index ≤ 0.5). Additionally, DBL significantly inhibited biofilm formation and showed no toxicity in murine fibroblasts (p < 0.05). These results suggest that DBL exhibits antimicrobial activity and works synergistically with antibiotics.

Metabolomic profiling of wild rooibos (Aspalathus linearis) ecotypes and their antioxidant-derived phytopharmaceutical potential.

Aspalathus linearis (commonly known as rooibos) is endemic to the Cape Floristic Region of South Africa and is a popular herbal drink and skin phytotherapeutic ingredient, with health benefits derived primarily from its unique phenolic content. Several, seemingly habitat-specific ecotypes from the Cederberg (Western Cape) and Northern Cape have morphological, ecological, genetic and biochemical differences. Despite the commercial popularity of the cultivated variety, the uncultivated ecotypes are largely understudied. To address gaps in knowledge about the biochemical constituency, ultra-performance liquid chromatography-mass spectrometry analysis of fifteen populations was performed, enabling high-throughput metabolomic fingerprinting of 50% (v/v) methanolic extracts. Antioxidant screening of selected populations was performed via three assays and antimicrobial activity on two microbial species was assessed. The metabolomic results were corroborated with total phenolic and flavonoid screening of the extracts. Site-specific chemical lineages of rooibos ecotypes were confirmed via multivariate data analyses. Important features identified via PLS-DA disclosed higher relative abundances of certain tentative metabolites (e.g., rutin, aspalathin and apiin) present in the Dobbelaarskop, Blomfontein, Welbedacht and Eselbank sites, in comparison to other locations. Several unknown novel metabolites (e.g., m/z 155.0369, 231.0513, 443.1197, 695.2883) are responsible for metabolomic separation of the populations, four of which showed higher amounts of key metabolites and were thus selected for bioactivity analysis. The Welbedacht and Eselbank site 2 populations consistently displayed higher antioxidant activities, with 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities of 679.894 ± 3.427µmol Trolox/g dry matter and 635.066 ± 5.140µmol Trolox/g dry matter, respectively, in correlation with a high number of phenolic and flavonoid compounds. The contribution of the individual metabolites to the pharmacological effectiveness of rooibos remains unknown and as such, further structural elucidation and phytopharmacological testing is thus urgently needed.

A Comparative Analysis of Polysaccharides and Ethanolic Extracts from Two Egyptian Sweet Potato Cultivars, Abees and A 195: Chemical Characterization and Immunostimulant Activities

Sweet potato (Ipomoea batatas (L.) Lam.) belongs to family Convolvulaceae. The plant is distributed worldwide and consumed, especially for its edible tubers. Many studies have proved that the plant has variable biological activities such as antidiabetic, anti-cancer, antihypertensive, antimicrobial, and immunostimulant activities. The roots of sweet potatoes are rich in valuable phytochemical constituents that vary according to the flesh color. Our investigation focused on the chemical profiling of two Egyptian sweet potato cultivars, Abees and A 195, using UPLC-QTOF and the analysis of their polysaccharide fractions by GC-MS. Furthermore, we assessed the immunostimulant properties of these extracts in immunosuppressed mice. The study revealed that sweet potato roots contain significant concentrations of phenolic acids, including caffeoylquinic, caffeic, caffeoyl-feruloyl quinic, and p-coumaric acids, as well as certain flavonoids, such as diosmin, diosmetin, and jaceosidin, and coumarins, such as scopoletin and umbelliferone. Moreover, polysaccharides prepared from both studied cultivars were analyzed using GC-MS. Further biological analysis demonstrated that all the tested extracts possessed immunostimulant properties by elevating the level of WBCs, IL-2, TNF, and IFN-γ in the immunosuppressed mice relative to the control group with the highest values in polysaccharide fractions of A195 (the ethanolic extract showed a higher effect on TNF and IFN-γ, while its polysaccharide fraction exhibited a promising effect on IL-2 and WBCs). In conclusion, the roots of the Egyptian sweet potato cultivars Abees and A 195 demonstrated significant immunostimulant activities, which warrants further investigation through clinical studies.

Qualitative and Quantitative Phytochemicals Screening of Aqueous, Methanol and Hexane Leaves Extracts of Senna Occidentalis

The Senna occidentalis tree is an incredible plant with incredible antimicrobial, antifungal and antimalarial activities used traditionally. The study was carried out to determine the phytochemical content responsible for these activities  Fresh leaves were collected, aqueous, methanolic and hexane extracts of leaves were prepared, and the extracts were screened for phytochemical constituents using standard methods. Results of the phytochemical screening of all the crude extracts revealed the presence of saponins, tannins, steroids, phenol, alkaloid and flavonoid. In aqeuose extract, flavonoid show higher content of 2,47%, followed by tepernoid with 2.27%, methanol with higher content of tepernoid with 2.60%, and hexane with the highest in tepernoid with only 2.38%. Based on the present study, it can be concluded that the extracts of Senna occidentalis are rich source of phytochemicals and F flavonoid is found to be most abundant phytochemical presence of bioactive constituents that could be the reason for pharmacological activity that is used traditionally by many people as an alternative treatment for a variety of health diseases.

Quest for a stable Cu-ligand complex with a high catalytic activity to produce ROS.

Metal ion-catalysed overproduction of reactive oxygen species (ROS) are believed to contribute significantly to oxidative stress and be involved in several biological processes, from immune defence to development of diseases. Among the essential metal ions, copper is one of the most efficient catalysts in ROS production in the presence of O2 and a physiological reducing agent such as ascorbate. To control this chemistry, Cu ions are tightly coordinated to biomolecules. Free or loosely bound Cu ions are generally avoided to prevent their toxicity. In the present report, we aim to find stable Cu-ligand complexes (Cu-L) that can catalyse efficiently the production of ROS in presence of ascorbate under aerobic conditions. Thermodynamic stability would be needed to avoid dissociation in biological environment and high ROS catalysis is of interest for applications as in antimicrobial or anticancer agents. A series of Cu complexes with the well-known tripodal and tetradentate ligands containing a central amine linked to three pyridyl-alkyl arms of different lengths were investigated. The two of them with mixed armlength showed higher catalytic activity in oxidation of ascorbate and subsequent ROS production than Cu salts in buffer, which is an unprecedented result. Despite these high catalytic activities, no increased antimicrobial activity towards E. coli or cytotoxicity against eukaryotic AGS cells in culture related to Cu-L based ROS production could be observed. The potential reasons for discrepancy between in vitro and in cell data will be discussed.