A comprehensive review on anti-inflammatory, antibacterial, anticancer and antifungal properties of several bivalent transition metal complexes

Transition metal complexes have been recognized as possible therapeutic agents, attributed to their special biological actions, including anti-inflammatory, antibacterial, antifungal, and anticancer. The pharmacological perspective connected with Copper (Cu), Cobalt (Co), Nickel (Ni), Manganese (Mn), Palladium (Pd), Zinc (Zn), and Platinum (Pt) metal(II) complexes is comprehensively explored in-depth in this research. The complexes show unique coordination chemistry and modes of action that help interactions with biological targets, including DNA binding, enzyme inhibition, and the formation of reactive oxygen species. All the metal(II) complexes showed notable potential impact in their perspective activity. Conspicuously, Co(II) and Ni(II) complexes show better antibacterial and antifungal action, while Cu(II) and Zn(II) combinations show higher anti-inflammatory activity. While research is constantly investigating alternative metal-based anticancer drugs like Pd(II), which seem to have lowered side effects, Pt(II) complexes especially cisplatin continue to be the benchmark in cancer treatment. Although the possible pharmacological actions are motivating, problems with toxicity and biocompatibility still provide major difficulties, especially in relation to Cd(II) and Hg(II) complexes. Strategies like ligand modification, nanoparticle-based delivery, and prodrug methods are used to increase selectivity and reduce side effects related to metal complexes. This review compiles the most recent developments and continuous research, thereby shedding light on the potential revolutionary power of metal(II) complexes in medical therapy. Understanding their mechanisms and enhancing their safety profiles will help us open the path to creative ideas for addressing some of the most urgent medical issues of today.

Innovative rheumatoid arthritis management using injection replacement approach via dual therapeutic effects of hyalurosomes-encapsulated luteolin and dexamethasone

Rheumatoid arthritis is a highly prevalent debilitating condition linked to inflammation. The effectiveness of the present therapeutic techniques is constrained; so, there is an urgent requirement for a novel nanoplatform entailing drugs with proven efficacy. The current work highlighted the development of dexamethasone and luteolin co-encapsulated hyalurosomes (LUT-DEX hyalurosomes). High entrapment efficiency of 92.79 % and 81.21 % for DEX and LUT, respectively in addition to sustained release of both drugs were attained, where only 45 % DEX and 75.87 % LUT were released after 24 h indicating the possibility of a persistent therapeutic impact. A spherical nano-system with smooth edges and a characteristic layer of hyaluronic acid surrounding the core of the particles was evidenced by a transmission electron microscope. The efficacy of LUT-DEX hyalurosomes was evaluated in-vision vivo using a rat model of rheumatoid arthritis initiated by Complete Freund's Adjuvant (CFA). Histological examination and serum concentrations of malondialdehyde (MDA), interleukin 1ß (IL1ß), tumour necrosis factor-alpha (TNF-α), interleukin 3 (MMP-3), and nuclear factor (erythroid-derived) Like 2 NRF2) were also evaluated. The dual drug-loaded hyalurosomes demonstrated 2.9-, 3.2-, 2.5- and 2.7-fold decreases in MMP3, TNF-α, MDA and IL1, respectively, compared with the positive control group. Conversely, the negative control group demonstrated the highest NRF2 level followed by LUT-DEX hyalurosomes, comparison compared to the positive control group which demonstrated the lowest NRF2 level. The histological examination of the joints confirmed the superior effect of the dual drug encapsulated nano delivery system in reducing joint swelling and inflammation achieving similar results as the negative control group. Ultimately, the developed hyalurosomes co-encapsulating dexamethasone and luteolin, possess the potential to serve as a highly auspicious innovative strategy for managing rheumatoid arthritis.

Quercetin and luteolin complexation with first-row transition metals in purely aqueous solutions: stoichiometry and binding site selectivity

The complexation behaviour of quercetin and luteolin with first-row transition metals (Cr(III), Mn(II), Co(II), Ni(II), and Zn(II)) in aqueous solutions was systematically investigated using potentiometric titrations, UV-Vis and FT-IR spectroscopy, and density functional theory (DFT) calculations. This study aimed to elucidate the stability, stoichiometry, and preferred binding sites of these flavonoid-metal complexes in an entirely aqueous solution at 37 °C as a function of pH under controlled ionic strength. Speciation analysis revealed the formation of 1 : 1, 1 : 2, and 1 : 3 metal-to-ligand complexes, with coordination occurring primarily at the 4,5- or 3,4-binding site, depending on the metal ion and ligand structure. UV-Vis and IR spectral changes confirmed complex formation, while computational modeling provided insights into binding site selectivity and free energy changes associated with coordination. Results highlight the influence of the ligand structure on metal affinity and stability, with quercetin forming more stable complexes than those formed by luteolin owing to the presence of an additional hydroxyl group at position 3. These findings contribute to a deeper understanding of flavonoid-metal interactions, with potential implications for antioxidant activity, metal chelation therapy, and environmental applications.

Protein bioactive complexes promote osteogenesis under microgravity environment

The space microgravity environment and cosmic radiation pose a significant threat to musculoskeletal health, particularly bone mass. However, the critical mechanism underlying space-induced bone loss and its relation to cellular oxidative stress remains unclear. Currently used bone-loss-reversing drugs face limitations like poor efficacy and metabolic defects. Herein, we revealed that simulated microgravity (SMG) induces reactive oxygen species (ROS), negatively impacting osteoblasts, causing cytoskeletal damage, and downregulating osteogenic genes. To combat this, we designed protein-zein nanocages loaded with a chimeric non-enzymatic cocktail (ZNAC) containing ascorbic acid, resveratrol, luteolin, coenzyme Q, and glutathione. These nanocages (~200 nm) demonstrated excellent stability, biocompatibility, and antioxidant properties compared to free drugs. We investigated the effects of ZNAC under SMG using two experimental models: MC3T3 pre-osteoblast/MG63 osteoblasts and regenerating zebrafish scales that represent compositional and physiological/pathophysiological analogy with mammalian system. ZNAC effectively reduced SMG-induced ROS, preserved cytoskeletal integrity, and enhanced alkaline phosphatase (ALP) activity along with the expression of osteogenic genes such as RUNX2 and Col1A1. In zebrafish scales, it increased osteogenic gene expression, calcification, and the calcium/phosphorus ratio, indicating enhanced scale regeneration. These findings suggest that ZNAC is a promising candidate for bone regeneration, offering potential solutions for maintaining astronaut health during extended space missions.

Copper-luteolin nanocomplexes for Mediating multifaceted regulation of oxidative stress, intestinal barrier, and gut microbiota in inflammatory bowel disease

Oxidative stress, dysbiosis, and immune dysregulation have been confirmed to play pivotal roles in the complex pathogenesis of inflammatory bowel disease (IBD). Herein, we design copper ion-luteolin nanocomplexes (CuL NCs) through a metal-polyphenol coordination strategy, which plays a multifaceted role in the amelioration of IBD. The fabricated CuL NCs function as therapeutic agents with exceptional antioxidant and anti-inflammatory capabilities because of their great stability and capacity to scavenge reactive oxygen species (ROS). It can effectively modulate the inflammatory microenvironment including facilitating the efficient reduction of pro-inflammatory cytokine levels, protecting intestinal epithelial cells, promoting mucosal barrier repair and regulating intestinal microbiota. In addition, CuL NCs have been found to enhance cellular antioxidant and anti-inflammatory capacities by regulating the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) oxidative stress pathway and nuclear factor kappa B (NF-κB) signaling pathway, respectively. Notably, CuL NCs demonstrate significant prophylactic and therapeutic efficacy in mouse models with typical IBD, including ulcerative colitis (UC) and Crohn's disease (CD). This study provides a new approach for building multifaceted therapeutic platforms for natural products to treat IBD.

Luteolin-Manganese Nanozyme Induces Apoptosis and Ferroptosis for Enhanced Cancer Therapy

Cancer presents a significant global public health challenge that impacts millions of individuals worldwide. The incorporation of natural products into cancer treatment has the potential to mitigate many of the side effects commonly associated with chemotherapy. This study builds on the advantages of enhancing the anticancer activity of natural flavonoids through metal chelation by synthesizing a natural antioxidant flavonoid complex, termed Lu-Mn nanozyme, which involves the chelation of luteolin with manganese ions. In vitro experiments demonstrated that Lu-Mn exhibits a strong affinity for hydrogen peroxide (H2O2) and effectively catalyzes the generation of hydroxyl radicals (•OH) from H2O2 within the tumor microenvironment. The administration of the Lu-Mn nanozyme not only induced apoptosis in tumor cells by upregulating the expression of cleaved caspase3 and caspase9 but also activated ferroptosis through downregulation of the NRF2-GPX4 signaling pathway. Furthermore, animal studies have shown that Lu-Mn possesses significant antitumor efficacy and a favorable safety profile. Collectively, these findings suggest that luteolin, through its chelation with metal ions, has considerable potential for application in cancer treatment.

Metallo-Organic Complexes Containing Transition Metals; Synthetic Approaches and Pharmaceutical Aspects

Coordination compounds offer a flexible framework for the thoughtful design of novel therapeutic-metallodrugs because of the unique properties of metal ions, such as their ability to coordinate with a wide range of organic ligands, variable oxidation states, a wide range of geometries, and coordination numbers. The pharmaceutical potential of a metal ion and associated substances is validated by the prevalence of various disease states linked to a metal ion's excess or deficiency within the biological system. Researchers have sought more selective, efficacious metallodrugs that cause fewer adverse effects. Attempts have resulted in considering a large range of organic ligands, preferably polydentate ligands with demonstrated biological activity, and a large range of metals from the periodic table, primarily from the d-block. In this review, we have outlined the key coordination complexes comprising N-, O-, and S-donor ligands reported in the last six years to demonstrate the potential applications of these metallo-organic complexes. The synthetic pathways of ligands, their complexes, and their potential for therapeutic applications are highlighted.

Flavonoids and their metal complexes as potential agents for diabetes mellitus with future perspectives

Type 2 diabetes mellitus (T2DM) is a global health burden, with hyperglycemia as the main hallmark. This review commences with a concise overview of the intricate mechanisms underlying glucose uptake and utilization in organisms. Notably, we emphasize that T2DM management strategies pivot on delaying carbohydrate digestion, augmenting insulin secretion, and enhancing insulin sensitivity in target tissues. Unfortunately, the drugs currently available in the market for the treatment of T2DM have unpleasant side effects, spurring an urgent quest for safer and more efficacious alternatives. Flavonoids, emerging as a promising class of bioactive compounds derived from plants, offer a multi-faceted approach to diabetes treatment. Specifically, they potently inhibit enzymes such as α-amylase, α-glucosidase, dipeptidyl peptidase-4 (DPP-4), glycogen phosphorylase (GP) and protein-tyrosine phosphatase-1B (PTP1B). Through an in-depth analysis, this review not only summarizes these inhibitory actions but also establishes the structure-activity relationship (SAR), providing a blueprint for rational drug design. However, the clinical translation of flavonoids has been hampered by their suboptimal water solubility and bioavailability, attributable to the characteristic carbonyl and hydroxyl groups. Ingeniously, this chemical quirk has been harnessed to engineer metal chelates, which exhibit enhanced pharmacokinetic profiles. Herein, we offer an exhaustive overview of the latest advancements in flavonoid metal complexes research, spotlighting their potential as next-generation diabetes therapeutics. Available data are poised to galvanize the development of novel flavonoid derivatives, be it as potent drugs or functional foods, for combating T2DM.

Antioxidative and Anticancer Potential of Luteolin: A Comprehensive Approach Against Wide Range of Human Malignancies

Luteolin is widely distributed phytochemical, a flavonoid, in kingdom plantae. Luteolin with potential antioxidant activity prevent ROS-induced damages and reduce oxidative stress which is mainly responsible in pathogenesis of many diseases. Several chemo preventive activities and therapeutic benefits are associated with luteolin. Luteolin prevents cancer via modulation of numerous pathways, that is, by inactivating proteins; such as procaspase-9, CDC2 and cyclin B or upregulation of caspase-9 and caspase-3, cytochrome C, cyclin A, CDK2, and APAF-1, in turn inducing cell cycle arrest as well as apoptosis. It also enhances phosphorylation of p53 and expression level of p53-targeted downstream gene. By Increasing BAX protein expression; decreasing VEGF and Bcl-2 expression it can initiate cell cycle arrest and apoptosis. Luteolin can stimulate mitochondrial-modulated functions to cause cellular death. It can also reduce expression levels of p-Akt, p-EGFR, p-Erk1/2, and p-STAT3. Luteolin plays positive role against cardiovascular disorders by improving cardiac function, decreasing the release of inflammatory cytokines and cardiac enzymes, prevention of cardiac fibrosis and hypertrophy; enhances level of CTGF, TGFβ1, ANP, Nox2, Nox4 gene expressions. Meanwhile suppresses TGFβ1 expression and phosphorylation of JNK. Luteolin helps fight diabetes via inhibition of alpha-glucosidase and ChE activity. It can reduce activity levels of catalase, superoxide dismutase, and GS4. It can improve blood glucose, insulin, HOMA-IR, and HbA1c levels. This review is an attempt to elaborate molecular targets of luteolin and its role in modulating irregularities in cellular pathways to overcome severe outcomes during diseases including cancer, cardiovascular disorders, diabetes, obesity, inflammation, Alzheimer's disease, Parkinson's disease, hepatic disorders, renal disorders, brain injury, and asthma. As luteolin has enormous therapeutic benefits, it could be a potential candidate in future drug development strategies.

Structural and biochemical basis for regiospecificity of the flavonoid glycosyltransferase UGT95A1

Glycosylation is a predominant strategy plants use to fine-tune the properties of small molecule metabolites to affect their bioactivity, transport, and storage. It is also important in biotechnology and medicine as many glycosides are utilized in human health. Small molecule glycosylation is largely carried out by family 1 glycosyltransferases. Here, we report a structural and biochemical investigation of UGT95A1, a family 1 GT enzyme from Pilosella officinarum that exhibits a strong, unusual regiospecificity for the 3'-O position of flavonoid acceptor substrate luteolin. We obtained an apo crystal structure to help drive the analyses of a series of binding site mutants, revealing that while most residues are tolerant to mutations, key residues M145 and D464 are important for overall glycosylation activity. Interestingly, E347 is crucial for maintaining the strong preference for 3'-O glycosylation, while R462 can be mutated to increase regioselectivity. The structural determinants of regioselectivity were further confirmed in homologous enzymes. Our study also suggests that the enzyme contains large, highly dynamic, disordered regions. We showed that while most disordered regions of the protein have little to no implication in catalysis, the disordered regions conserved among investigated homologs are important to both the overall efficiency and regiospecificity of the enzyme. This report represents a comprehensive in-depth analysis of a family 1 GT enzyme with a unique substrate regiospecificity and may provide a basis for enzyme functional prediction and engineering.

Luteolin: A promising multifunctional natural flavonoid for human diseases

Natural products are closely associated with human health. Luteolin (LUT), a flavonoid polyphenolic compound, is widely found in fruits, vegetables, flowers, and herbs. It is noteworthy that LUT exhibits a variety of beneficial pharmacological properties and holds significant potential for clinical applications, particularly in antitumor, anti-convulsion, diabetes control, anti-inflammatory, neuroprotection, anti-oxidation, anti-cardiovascular, and other aspects. The potential mechanism of action has been partially elucidated, including the mediation of NF-κB, toll-like receptor, MAPK, Wnt/β-catenin, PI3K/Akt, AMPK/mTOR, and Nrf-2, among others. The review that aimed to comprehensively consolidate essential information on natural sources, pharmacological effects, therapeutic and preventive potential, as well as potential mechanisms of LUT. The objective is to establish a theoretical basis for the continued development and application of LUT.

An insight into the antioxidant activities and the exploration of record high quantities of quercetin and luteolin in the plant parts of Myxopyrum smilacifolium (wall.) Blume

This study attempts to reveal antioxidants in the plant parts of Myxopyrum smilacifolium (Wall.) Blume using antioxidant assays and LC-MS/MS analysis. Methanol is the most effective solvent for collecting antioxidants. The roots-derived methanol extract demonstrates the greatest antioxidant activity, corresponding to the extremely low IC50 values of 16.39 µg/mL and 19.80 µg/mL for DPPH and ABTS radicals, respectively. The high phenolic and flavonoid contents are the primary reason for outstanding total antioxidant capacity (TAC; i.e. 247.73 ± 1.62 mg GA/g or 163.93 ± 0.83 mg AS/g) of the root extract. LC-MS/MS quantification of five phenolic compounds reveals exceptionally high amounts of quercetin and luteolin in the root extract, ranging from 238.86 ± 5.74 to 310.99 ± 1.44 µg/g and from 201.49 ± 7.84 to 234.10 ± 2.54 µg/g, respectively, in the root-derived methanol extract. The achievement highlights M. smilacifolium as a promising source of natural antioxidants for large-scale medical applications.

Isolation, characterization and anti-inflammatory activity of compounds from the Vernonia amygdalina

The need to explore the abundance of natural products cannot be overemphasized particularly in the management of various disease conditions. In traditional medical practice, Vernonia amygdalina has been widely adopted in the management of various inflammatory disorders. The objective of this investigation was to isolate the bioactive principles from the stem-bark and root of V. amygdalina and assess the anti-inflammatory (in vitro) activity of both the crude extracts and the isolated compounds. Following extraction with the methanol, the extract was subjected to gravity column chromatography and the resultant fractions was further purified to obtained pure compounds. The structural elucidation of the compounds were based on data obtained from 1H to 13C nuclear magnetic resonance (NMR) spectroscopies as well as fourier transform infrared (FT-IR). Using diclofenac as a control drug, the albumin denaturation assay was used to determine the in vitro anti-inflammatory activity of the extracts and isolates. Three distinct compounds characterized are vernoamyoside D, luteolin-7-α-o-glucuronide, and vernotolaside, a new glycoside. When compared to diclofenac, which has an IC50 of 167.8 μg/mL, luteolin-7-α-o-glucuronide, vernoamyoside D, and vernotolaside all showed significant inhibitions with respective IC50 values 549.8, 379.5, and 201.7 μg/mL. Vernotolaside is reported for the first time from the root. The assertion that the plant is used in traditional medicine for the management of inflammatory disorder is somewhat validated by the confirmation of the existence of the compounds with the biochemical actions. Further validation of the isolated compounds would be required in animal studies.

Controlled release, chitosan-tethered luteolin phytocubosomes; Formulation optimization to in-vivo antiglaucoma and anti-inflammatory ocular evaluation

A chitosan-coated luteolin-loaded phytocubosomal system was prepared to improve the pharmacodynamic performance of luteolin in the treatment of glaucoma and ocular inflammation after topical ocular administration. Luteolin, a potent anti-oxidant herbal drug with poor aqueous solubility, was complexed with phospholipid. The prepared phytocubosomes were coated with chitosan, producing homogenously distributed nanosized particles (258 ± 9.05 nm) with a positive charge (+49 ± 6.09 mV), improved EE% (96 %), and increased concentration of encapsulated drug to 288 μg/ml. Polarized light microscopy revealed a cubic phase. Chitosan-coated phytocubosomes showed a sustained drug release profile (38 % over 24 h) and improved anti-oxidant activity (IC50 of 32 μg/ml). Ex vivo transcorneal permeation was higher by 3.60 folds compared to luteolin suspension. Irritancy tests confirmed their safety in ocular tissues after single and multiple administrations. The pharmacodynamic studies on glaucomatous rabbit eyes demonstrated 6.46-, 3.88-, and 1.89-fold reductions in IOP of chitosan-coated phytocubosomes compared to luteolin suspension, cubosomes, and phytocubosomes, respectively. Pharmacodynamic anti-inflammatory studies revealed faster recovery capabilities of chitosan-coated phytocubosomes over other formulations. Thus, chitosan-coated phytocubosomes could be a promising ocular hybrid system for delivering herbal lipophilic drugs such as luteolin.

Carrageenan tethered ion sensitive smart nanogel containing oleophytocubosomes for improved ocular luteolin delivery

Ophthalmic delivery of luteolin (LU) was studied after formulating a carrageenan-based novel ion-sensitive in situ gel (ISG) incorporating oleophytocubosomes for prolonged ocular residence time and improved ocular bioavailability of the poorly absorbed herbal drug luteolin. The prepared oleophytocubosomes and ISG were compared with LU suspension. Optimized oleophytocubosomes possessed small, homogenously distributed negatively charged particles with high entrapment efficiency. Polarized light microscope revealed a cubic phase. Optimized ISG matrix composed of 0.4% kappa carrageenan (KC), and 2% hydroxypropylmethylcellulose (HPMC) demonstrated rapid gelation, high resistance to dilution, increased viscosity after gelation, and strong mucoadhesive properties. oleophytocubosomes exerted improved drug release, while a more sustained release was observed for ISG oleophytocubosomes. The antioxidant activity of both formulations was significantly higher than that of LU suspension. Oleophytocubosome and ISG oleophytocubosome revealed significantly higher apparent permeability coefficients of 3.62 and 2.90 folds, respectively, compared to LU suspension. Irritation tests showed the safety of both formulations for single- and multiple-ocular administration. In-vivo studies demonstrated that the ISG system showed prolonged antiglaucoma effects and a faster anti-inflammatory effect, followed by oleophytocubosomes.

Phytochemical Composition and Antioxidant and Anti-Inflammatory Activities of Humboldtia sanjappae Sasidh. & Sujanapal, an Endemic Medicinal Plant to the Western Ghats

Ethnomedicinal plants are important sources of drug candidates, and many of these plants, especially in the Western Ghats, are underexplored. Humboldtia, a genus within the Fabaceae family, thrives in the biodiversity of the Western Ghats, Kerala, India, and holds significant ethnobotanical importance. However, many Humboldtia species remain understudied in terms of their biological efficacy, while some lack scientific validation for their traditional uses. However, Humboldtia sanjappae, an underexplored plant, was investigated for the phytochemical composition of the plant, and its antioxidant, enzyme-inhibitory, anti-inflammatory, and antibacterial activities were assessed. The LC-MS analysis indicated the presence of several bioactive substances, such as Naringenin, Luteolin, and Pomiferin. The results revealed that the ethanol extract of H. sanjappae exhibited significant in vitro DPPH scavenging activity (6.53 ± 1.49 µg/mL). Additionally, it demonstrated noteworthy FRAP (Ferric Reducing Antioxidant Power) activity (8.46 ± 1.38 µg/mL). Moreover, the ethanol extract of H. sanjappae exhibited notable efficacy in inhibiting the activities of α-amylase (47.60 ± 0.19µg/mL) and β-glucosidase (32.09 ± 0.54 µg/mL). The pre-treatment with the extract decreased the LPS-stimulated release of cytokines in the Raw 264.7 macrophages, demonstrating the anti-inflammatory potential. Further, the antibacterial properties were also evident in both Gram-positive and Gram-negative bacteria. The observed high zone of inhibition in the disc diffusion assay and MIC values were also promising. H. sanjappae displays significant anti-inflammatory, antioxidant, antidiabetic, and antibacterial properties, likely attributable to its rich composition of various biological compounds such as Naringenin, Luteolin, Epicatechin, Maritemin, and Pomiferin. Serving as a promising reservoir of these beneficial molecules, the potential of H. sanjappae as a valuable source for bioactive ingredients within the realms of nutraceutical and pharmaceutical industries is underscored, showcasing its potential for diverse applications.

Biomedical applications of selective metal complexes of indole, benzimidazole, benzothiazole and benzoxazole: A review (From 2015 to 2022)

Indole, benzoxazole benzothiazole and benzimidazole are excellent classes of organic heterocyclic compounds. These compounds show significant application in pharmacy, industries, dyes, medicine, polymers and food packages. These compounds also form metal complexes with copper, zinc, cadmium, nickel, cobalt, platinum, gold, palladium chromium, silver, iron, and other metals that have shown to be significant applications. Recently, researchers have attracted enormous attention toward heterocyclic compounds such as indole, benzimidazole, benzothiazole, benzoxazole, and their complexes due to their excellent medicinal applications such as anti-ulcerogenic, anti-cancer, antihypertensive, antifungal, anti-inflammatory, antitubercular, antiparasitic, anti-obesity, antimalarial, antiglycation, antiviral potency, antineuropathic, analgesic antioxidant, antihistaminic, and antibacterial potentials. In this article, we summarize the medicinal applications of these compounds as well as their metal complexes. We hope this article will help researchers in designing and synthesizing novel and potent compounds with significant applications in various fields.

Preparation, structural analysis and physicochemical properties of the Cordyceps cicadae exopolysaccharide iron complex

In this study, EPS-Fe(III) complexes were synthesized, and their structural characteristics, thermal stability, antioxidant activity and digestive properties were evaluated. The content of iron in the EPS-Fe(III) complex was 6.34 ± 1.43 %. The absorbance bands of EPS and EPS-Fe(III) complexes were easily changed, indicating that iron ions can interact with the hydroxyl or carboxyl groups of EPS. Energy spectrometric analysis showed that a strong iron signal was observed in the EPS-Fe(III) complex. The IC₅₀ values of the EPS-Fe(III) complex for DPPH, hydroxyl radical and ABTS were 1.52 mg/mL, 2.63 mg/mL and 1.20 mg/mL, respectively. Under oxidative stress, EPS-Fe(III) can prolong the lifespan of nematodes through the DAF-16 and SKN-1 pathways. Under the condition of gastric juice and intestinal juice, the iron content released from artificial intestinal juice reached 66 %. In addition, the negative effect of trypsin or polyphenols on the solubility of iron in EPS-Fe(III) digestive solution was lower than that in ferric chloride digestive solution. In conclusion, the EPS-Fe(III) complex can be used as a new type of iron supplement, which has good antioxidant activity, high stability and good water solubility.

Synthesis and Characterization of Quercetin-Iron Complex Nanoparticles for Overcoming Drug Resistance

Quercetin, one of the major natural flavonoids, has demonstrated great pharmacological potential as an antioxidant and in overcoming drug resistance. However, its low aqueous solubility and poor stability limit its potential applications. Previous studies suggest that the formation of quercetin-metal complexes could increase quercetin stability and biological activity. In this paper, we systematically investigated the formation of quercetin-iron complex nanoparticles by varying the ligand-to-metal ratios with the goal of increasing the aqueous solubility and stability of quercetin. It was found that quercetin-iron complex nanoparticles could be reproducibly synthesized with several ligand-to-iron ratios at room temperature. The UV-Vis spectra of the nanoparticles indicated that nanoparticle formation greatly increased the stability and solubility of quercetin. Compared to free quercetin, the quercetin-iron complex nanoparticles exhibited enhanced antioxidant activities and elongated effects. Our preliminary cellular evaluation suggests that these nanoparticles had minimal cytotoxicity and could effectively block the efflux pump of cells, indicating their potential for cancer treatment.

Antioxidant and antimicrobial characteristics of ethyl acetate polar fractions from walnut green husk

Walnut green husk (WGH) is rich in natural compounds and is valued as a potential source of antioxidant and antimicrobial properties. In this study, the antioxidant and antimicrobial activities of petroleum ether polar fraction, dichloromethane polar fraction, ethyl acetate polar fraction (EAPF), and n-butanol polar fraction from WGH were analyzed. The results showed that EAPF exhibited the highest total flavonoid content (65.74 ± 1.01 mg rutin equivalents [RE]/g dry weight [DW]) and total phenol content (48.73 ± 1.09 mg gallic acid equivalent [GAE]/g DW), with the highest 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical (•OH), and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonate scavenging activity compared with other fractions. EAPF also showed good antibacterial activity against Escherichia coli and Bacillus cereus vegetative cells, with a diameter of inhibition zones of 33.5 and 37.6 mm, respectively, a minimum inhibitory concentration of 31.25 mg/ml and a minimum bactericidal concentration of 62.5 mg/ml, which inhibited the growth of both bacteria. Analysis of the antibacterial mechanism demonstrated that EAPF damaged the integrity of the cell membrane, increased the membrane permeability, and triggered the leakage of intracellular material. In addition, ultrahigh performance liquid chromatography-tandem with mass spectrometry analysis revealed that 8 polyphenols and 14 flavonoids were mainly present in EAPF, such as chlorogenic acid (C₁₆ H₁₈ O₉ ), gallic acid (C₇ H₆ O₅ ), vanillic acid (C₈ H₈ O₄ ), ferulic acid (C₁₀ H₁₀ O₄ ), epicatechin (C₁₅ H₁₄ O₆ ), catechin (C₁₅ H₁₄ O₆ ), hesperetin (C₁₆ H₁₄ O₆ ), naringenin (C₁₅ H₁₂ O₅ ), hyperin (C₂₁ H₂₀ O₁₂ ), luteolin (C1₅ H₁₀ O₆ ), and so on. Therefore, WGH had the potential to be developed as a natural antioxidant and antibacterial material. PRACTICAL APPLICATION: Our work indicates that WGH contains abundant flavonoids and polyphenols compounds. Therefore, the plant byproducts like WGH may have a promising application as a source of antimicrobial and antioxidant additives.

Multiscale Modeling Unravels the Influence of Biomembranes on the Photochemical Properties of Embedded Anti-Oxidative Polyphenolic and Phenanthroline Chelating Dyes

The embedding of caffeate methyl ester, the flavonoids luteolin and quercetin, and the o-phenanthroline and neocuproine in a liquid disordered lipid bilayer has been studied through extensive atomistic calculations. The location and the orientation of these bio-active antioxidants are explained and analyzed. While the two phenanthrolines strongly associate with the lipid tail region, the other three compounds are rather found among the head groups. The simulations showcase conformational changes of the flavonoids. Through the use of a hybrid quantum mechanics-molecular mechanics scheme and supported by a profound benchmarking of the electronic excited-state method for these compounds, the influence of the anisotropic environment on the compounds' optical properties is analyzed. Influences of surrounding water molecules and of the polar parts of the lipids on the transition dipole moments and excited-state dipole moments are weighted with respect to a change in conformation. The current study highlights the importance of the mapping of molecular interactions in model membranes and pinpoints properties, which can be biomedically used to discriminate and detect different lipid environments.

Luteolin: a flavonoid with a multifaceted anticancer potential

Therapeutic effect of phytochemicals has been emphasized in the traditional medicine owing to the presence of bioactive molecules, such as polyphenols. Luteolin is a flavone belonging to the flavonoid class of polyphenolic phytochemicals with healing effect on hypertension, inflammatory disorders, and cancer due to its action as pro-oxidants and antioxidants. The anticancer profile of luteolin is of interest due to the toxic effect of contemporary chemotherapy paradigm, leading to the pressing need for the development and identification of physiologically benevolent anticancer agents and molecules. Luteolin exerts anticancer activity by downregulation of key regulatory pathways associated with oncogenesis, in addition to the induction of oxidative stress, cell cycle arrest, upregulation of apoptotic genes, and inhibition of cell proliferation and angiogenesis in cancer cells. In this review, we discuss about the anticancer profile of luteolin.

Self-Emulsifying Phospholipid Preconcentrates for the Enhanced Photoprotection of Luteolin

Exposure to ultraviolet B (UVB) leads to the overproduction of reactive oxygen species (ROS), causing higher risks of skin disorders. Luteolin (Lut) is a naturally occurring antioxidant that can absorb a broad range of ultraviolet light, but its water solubility and skin permeability are limited and insufficient. The aim of the current study was to develop a Lut-loaded self-emulsifying phospholipid preconcentrate (LSEPP) for enhancing the solubility, permeability, and photoprotective activity of Lut. The designed formulations were firstly examined for their droplet size, zeta potential, dispersity, and in vitro corneum permeability after dispensing the preconcentrate to form an emulsion; the optimized formulation was further characterized for its emulsified morphology, compatibility with excipients, stability in the preconcentrate form, and photoprotective activity by the HaCaT cell model under the emulsified status. The optimized LSEPP formulation attained a smaller droplet size (140.6 ± 24.2 nm) with the addition of 1,8-cineole and increased the permeability of Lut by 7-fold. As evidenced in the cell model studies, the optimized LSEPP formulation can efficiently deliver Lut into HaCaT cells after emulsification and result in a 115% better cell viability as well as a 203% stronger ROS scavenging capability, compared with those of unformulated Lut after UVB irradiation. To sum up, we have successfully developed an LSEPP formulation, which is a safe and promising topical delivery system for enhancing the photoprotective effects of Lut.

Flavonoids-Rich Plant Extracts Against Helicobacter pylori Infection as Prevention to Gastric Cancer

Gastric cancer is the fifth most common and fourth type to cause the highest mortality rates worldwide. The leading cause is related to Helicobacter pylori (H. pylori) infection. Unfortunately, current treatments have low success rates, highlighting the need for alternative treatments against carcinogenic agents, specifically H. pylori. Noteworthy, natural origin products contain pharmacologically active metabolites such as flavonoids, with potential antimicrobial applications.

Objective: This article overviews flavonoid-rich extracts’ biological and pharmacological activities. It focuses on using these substances against Helicobacter pylori infection to prevent gastric cancer. For this, PubMed and Science Direct databases were searched for studies that reported the activity of flavonoids against H. pylori, published within a 10-year time frame (2010 to August 2020). It resulted in 1,773 publications, of which 44 were selected according to the search criteria. The plant family primarily found in publications was Fabaceae (9.61%). Among the flavonoids identified after extraction, the most prevalent were quercetin (19.61%), catechin (13.72), epicatechin (11.76), and rutin (11.76). The potential mechanisms associated with anti-H. pylori activity to the extracts were: inhibition of urease, damage to genetic material, inhibition of protein synthesis, and adhesion of the microorganism to host cells.

Conclusion: Plant extracts rich in flavonoids with anti-H. pylori potential proved to be a promising alternative therapy source, reinforcing the relevance of studies with natural products.

Formulation of Apigenin-Cyclodextrin-Chitosan Ternary Complex: Physicochemical Characterization, In Vitro and In Vivo Studies

The current investigation was performed with an aim to improve the aqueous solubility, dissolution rate, and thus the biological activity of apigenin (APG) using the solubilizers hydroxypropyl beta-cyclodextrin (HPβCD) and chitosan (CTSN). A binary and ternary inclusion complexes of APG with HPβCD and CTSN were prepared by physical mixing, fusion, and solvent evaporation methods. The liquid state characterization of the APG, the solubilizers, and the physical and chemical interactions between them was done through phase solubility approach. The solid-state characterization was performed by proton nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The in vitro dissolution test and antioxidant activity and in vivo anti-inflammatory activity of the ternary inclusion complex in albino rats were performed to assess the performance of the APG. Phase solubility study results revealed a remarkable increase in apparent stability constant (Kc) and complexation efficiency (CE) of HPβCD in presence of CTSN in ternary complex with above 8 folds more increment in solubility of APG than its binary complex. The in vitro dissolution rate, antioxidant activity, and the anti-inflammatory effect of the APG ternary inclusion complex were found to be significantly higher than that of pure APG. Solid state characterization confirmed the formation of a ternary inclusion complex. 1H-NMR study gave more insight at molecular level into how different groups of APG were responsible for complex formation with the HPβCD and how CTSN was significantly influencing on the APG-HPβCD complex formed. Nevertheless, pharmacokinetic and histopathological studies of our APG-HPβCD-CTSN ternary complex would yield much rewarding results.

Preparation and In Vitro-In Vivo Evaluation of Luteolin Loaded Gastroretentive Microsponge for the Eradication of Helicobacter pylori Infections

The current study aimed to develop a luteolin gastric floating microsponge for targeting Helicobacter pylori. The microsponge formulations were prepared by a quasi-emulsion method, and then evaluated for various physicochemical variables. The best microsponge was further assessed for drug-polymer interactions, surface morphology, in vivo floating, and in vitro anti H. pylori activity. The formulation which exhibited comparatively good production yield (64.45% ± 0.83), high entrapment efficiency (67.33% ± 3.79), prolonged in vitro floating time (>8 h), and sustained in-vitro drug release was selected as the best microsponge. The SEM study revealed that the best microsponge was spherical in shape and has a porous surface with interconnecting channels. DSC and XRD studies demonstrated the dispersion of luteolin in the polymeric matrix of the microsponge. Ultrasonography confirmed that the best microsponge could in the rat stomach for 4 h. The in vitro MIC results indicate that the anti H. pylori activity of the best microsponge was almost doubled and more sustained compared to pure luteolin. To conclude, it can be said that the developed luteolin gastric floating microsponge could be a better option to effectively eradicate H. pylori infections and the histopathological and pharmacodynamic assessments of our best microsponge can be expected to provide a rewarding outcome.

The Synergistic Beneficial Effect of Thyme Honey and Olive Oil against Diabetes and Its Complications Induced by Alloxan in Wistar Rats

Diabetes is a metabolic disorder characterized by a chronic increase in blood glucose. Owing to the limitations observed with antidiabetics in modern medicine, medicinal plants and bee products are known as good matrices for the search for new antidiabetic molecules. The present study focused on the evaluation of the hypoglycemic and the protective properties of two natural products widely used in complementary and alternative medicine (thyme honey and olive oil). To achieve this, the study was carried out on Wistar rats rendered diabetic by the injection of a single dose of alloxan monohydrate (65 mg/kg body weight (BW)). First, the physicochemical characterization and the phytochemical analysis of thyme honey and olive oil were carried out, and then in vivo study was conducted on 42 Wistar rats divided into seven groups: three groups were normal, one group was untreated diabetic, and three groups were diabetic rats treated with thyme honey (2 g/kg BW) or olive oil (10 mL/kg BW) or their combination ((1 g/kg BW of thyme honey) and (5 mL/kg BW of olive oil)). During the experiment, the glycemia was measured regularly every 10 days. After 30 days of treatment, the rats were sacrificed. The serum and urine were analyzed to determine hepatic enzymes levels (AST, ALT, ALP, and LDH), lipidic profile (total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein), and kidney parameters (urea, uric acid, creatinine, total protein, sodium, potassium, and chloride). The liver, pancreas, and kidneys were analyzed to evaluate their histological changes and to determine their enzymatic antioxidant content (catalase, GSH, and GPx) and the levels of MDA. The results obtained showed that thyme honey or olive oil, and especially their combination, improved significantly the blood glucose levels and they protect against metabolic changes and the complications induced by diabetes.

Crystal Structure, Spectroscopic Characterization, Antioxidant and Cytotoxic Activity of New Mg(II) and Mn(II)/Na(I) Complexes of Isoferulic Acid

The Mg(II) and heterometallic Mn(II)/Na(I) complexes of isoferulic acid (3-hydroxy-4-methoxycinnamic acid, IFA) were synthesized and characterized by infrared spectroscopy FT-IR, FT-Raman, electronic absorption spectroscopy UV/VIS, and single-crystal X-ray diffraction. The reaction of MgCl2 with isoferulic acid in the aqueous solutions of NaOH resulted in synthesis of the complex salt of the general formula of [Mg(H2O)6]⋅(C10H9O4)2⋅6H2O. The crystal structure of this compound consists of discrete octahedral [Mg(H2O)6]2+ cations, isoferulic acid anions and solvent water molecules. The hydrated metal cations are arranged among the organic layers. The multiple hydrogen-bonding interactions established between the coordinated and lattice water molecules and the functional groups of the ligand stabilize the 3D architecture of the crystal. The use of MnCl2 instead of MgCl2 led to the formation of the Mn(II)/Na(I) complex of the general formula [Mn3Na2(C10H7O4)8(H2O)8]. The compound is a 3D coordination polymer composed of centrosymmetric pentanuclear subunits. The antioxidant activity of these compounds was evaluated by assays based on different antioxidant mechanisms of action, i.e., with •OH, DPPH• and ABTS•+ radicals as well as CUPRAC (cupric ions reducing power) and lipid peroxidation inhibition assays. The pro-oxidant property of compounds was measured as the rate of oxidation of Trolox. The Mg(II) and Mn(II)/Na(I) complexes with isoferulic acid showed higher antioxidant activity than ligand alone in DPPH (IFA, IC50 = 365.27 μM, Mg(II) IFA IC50 = 153.50 μM, Mn(II)/Na(I) IFA IC50 = 149.00 μM) and CUPRAC assays (IFA 40.92 μM of Trolox, Mg(II) IFA 87.93 μM and Mn(II)/Na(I) IFA 105.85 μM of Trolox; for compounds' concentration 10 μM). Mg(II) IFA is a better scavenger of •OH than IFA and Mn(II)/Na(I) IFA complex. There was no distinct difference in ABTS•+ and lipid peroxidation assays between isoferulic acid and its Mg(II) complex, while Mn(II)/Na(I) complex showed lower activity than these compounds. The tested complexes displayed only slight antiproliferative activity tested in HaCaT human immortalized keratinocyte cell line within the solubility range. The Mn(II)/Na(I) IFA (16 μM in medium) caused an 87% (±5%) decrease in cell viability, the Mg salt caused a comparable, i.e., 87% (±4%) viability decrease in a concentration of 45 μM, while IFA caused this level of cell activity attenuation (87% ± 5%) at the concentration of 1582 μM (significant at α = 0.05).

Diversity of Chemical Structures and Biosynthesis of Polyphenols in Nut-Bearing Species

Nuts, such as peanut, almond, and chestnut, are valuable food crops for humans being important sources of fatty acids, vitamins, minerals, and polyphenols. Polyphenols, such as flavonoids, stilbenoids, and hydroxycinnamates, represent a group of plant-specialized (secondary) metabolites which are characterized as health-beneficial antioxidants within the human diet as well as physiological stress protectants within the plant. In food chemistry research, a multitude of polyphenols contained in culinary nuts have been studied leading to the identification of their chemical properties and bioactivities. Although functional elucidation of the biosynthetic genes of polyphenols in nut species is crucially important for crop improvement in the creation of higher-quality nuts and stress-tolerant cultivars, the chemical diversity of nut polyphenols and the key biosynthetic genes responsible for their production are still largely uncharacterized. However, current technical advances in whole-genome sequencing have facilitated that nut plant species became model plants for omics-based approaches. Here, we review the chemical diversity of seed polyphenols in majorly consumed nut species coupled to insights into their biological activities. Furthermore, we present an example of the annotation of key genes involved in polyphenolic biosynthesis in peanut using comparative genomics as a case study outlining how we are approaching omics-based approaches of the nut plant species.

Characterization and Quantification of Luteolin-Metal Complexes in Aqueous Extract of Lonicerae Japonicae Flos and Huangshan Wild Chrysanthemum

Luteolin is a flavonoid compound widely found in vegetables, fruits, and medicinal plants. In this study, the reaction conditions for luteolin and five metal ions (Ca²⁺, Mg²⁺, Zn²⁺, Fe³⁺, and Cu²⁺) to form complexes in hot water were optimized, which was at a molar ratio of 1 : 1 for luteolin and metal ions at 90°C in a volume of 20 mL for 2 h, and the ability of luteolin to form complexes with Cu²⁺ was the strongest. The DPPH scavenging test showed that luteolin exerted a dose-dependent effect on the clearance of free radicals; luteolin-Cu²⁺ complexes and luteolin-Fe³⁺ complexes accentuated the clearance of free radicals. Furthermore, we used high performance liquid chromatography (HPLC) to analyze luteolin in samples from two medicinal plants, obtained from the dissolution of aqueous extracts in two different solvents. The results showed that the peak areas for luteolin in the samples dissolved in 20% formic acid-methanol were significantly larger than those from the samples dissolved in methanol alone, with increases in the peak area being 135.6% (Lonicerae Japonicae Flos), and 161.16% (Huangshan wild chrysanthemum). The aforementioned results indicate that complexes formed from organic compounds and metal ions are present in the decoction of a plant.

Yellow Lake Pigments from Weld in Art: Investigating the Winsor & Newton 19th Century Archive

Weld (Reseda luteola) was one of the main sources of yellow dyes used for dyeing textiles and to prepare artists’ pigments in Europe until the 19th century. For the first time, this work explores the technology of preparing weld lake pigments in the 19th century by Winsor & Newton (W&N), a renowned supplier of artists’ materials. Five recipes were discovered in the W&N 19th century Archive Database and reconstructed in the laboratory. W&N was extracting weld in neutral and basic media, and preparing the insoluble lake by complexation with Al3+ in the form of alum (KAl(SO4)2•12H2O) or hydrated alumina (Al(OH)3). Five yellow lake pigments were successfully obtained and characterized by High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) and Fourier Transform Infrared Spectroscopy (FTIR). Their chromatographic profiles display as main yellows, luteolin 7-O-glucoside (Lut-7-O-glu) or both Lut-7-O-glu plus luteolin 3′,7-O-glucoside (Lut-3’,7-O-glu). In two of the processes, the presence of gypsum (CaSO4•2H2O) was unequivocally detected by FTIR, being formed as a by-product. This work offers the first identification of weld lake pigments’ characteristic infrared bands. The W&N Database proved again to be a unique source of information on 19th-century artists’ materials and their commercial preparation. The knowledge gain is essential to ensure effective conservation and authentication procedures.

Dietary Luteolin: A Narrative Review Focusing on Its Pharmacokinetic Properties and Effects on Glycolipid Metabolism

Luteolin, a flavone subclass of flavonoids, is commonly found in food plants and has multiple biological activities. Recently, evidence is growing with regard to the potential of luteolin intake to beneficially affect glycolipid metabolism disorders (GLMDs), particularly insulin resistance, diabetes, and obesity. The aim of this contribution is to provide an overview of recent advances in identifying and understanding the pharmacokinetic properties (absorption, metabolism, and bioavailability) of luteolin, its regulatory effects on glycolipid metabolism, and the underlying mechanisms of action of luteolin in the brain, liver, adipose tissues, and other tissues/organs. Collectively, luteolin or its principal metabolites may contribute to counteracting GLMDs, especially for human obesity and diabetes.

Water Soldier Stratiotes aloides L.-Forgotten Famine Plant With Unique Composition and Antioxidant Properties

Stratiotes aloides L. is common water plant in central Poland. Due to its expansive character, S. aloides L. can strongly affect the functioning of aquatic ecosystems. S. aloides L. was an important famine plant in central Poland. This plant was commonly collected and cooked until the turn of the 20th century. It has also been used to heal wounds, especially when these are made by an iron implement. The objective of the present work was to study the phenolic profile in the leaves and roots of S. aloides as well as their antioxidant potential and ability to inhibit lipoxygenase (LOX) in the light of their potential bioaccessibility. The dominant compound in its leaves was luteolin-7-O-hexoside-glucuronide (5.84 mg/g DW), whereas the dominant root component was chrysoeriol-7-O-hexoside-glucuronide (0.83 mg/g DW). Infusions from leaves, roots, and their 1:1 (v/v) mixture contained potentially bioaccessible antiradical compounds. S. aloides is a good source of water-extractable reductive compounds. Especially valuable are the leaves of this plant. The roots of S. aloides contained very active hydrophilic compounds able to chelate metal ions. However, their potential bioaccessibility was relatively low. The hydrophilic compounds from the leaves were the most effective XO inhibitors (EC₅₀ = 9.91 mg DW/mL). The water-extractable compounds derived from the leaves and roots acted as uncompetitive LOX inhibitors.

Formulation of Curcumin-β-cyclodextrin-polyvinylpyrrolidone supramolecular inclusion complex: experimental, molecular docking, and preclinical anti-inflammatory assessment

This research planned to ameliorate an aqueous solubility and dissolution of Curcumin (CUR) by the formulation of inclusion complex with β-cyclodextrin (β-CD) and polyvinylpyrrolidone (PVP). The phase solubility study was performed to assess the solubility of CUR. The prepared CUR complex assessed for dissolution study, physicochemical evaluation, in-vitro antioxidant activity, molecular modeling, and anti-inflammatory assessment. The pivotal findings of phase-solubility studies demonstrate apparent stability constant (Kc) and complexation efficiency (CE) values for CUR-β-CD and CUR-β-CD-PVP complex was 175.4 M ^-1, 1.15% and 833.3.2 M ^-1 and 5.21%, respectively. The characterization results revealed amorphization of crystalline state (CUR) into amorphous state. The maximum drug release found with the ternary CUR complex (F7), i.e. 45.41 ± 3.78% in 6 h study. The chemical shift in the NMR supports that the aromatic ring of CUR is completely complexed inside the β-CD cavity. The antioxidant activity of pure CUR was found to be 58.02 ± 2.21% and CUR ternary complex (F7) showed significantly higher activity to 96.02 ± 2.46%. The in-vivo effect of CUR complex (F7) was also found significantly higher than that of pure CUR. The molecular modeling study depicted that PVP increased the stability of the ternary complex by forming the link between CUR and β-CD. Thus, the ternary inclusion complex of CUR-β-CD-PVP could contribute as an innovative outcome in the enhancement of solubility and in-vivo activity.

Recent Studies on the Antimicrobial Activity of Transition Metal Complexes of Groups 6–12

Antimicrobial resistance is an increasingly serious threat to global public health that requires innovative solutions to counteract new resistance mechanisms emerging and spreading globally in infectious pathogens. Classic organic antibiotics are rapidly exhausting the structural variations available for an effective antimicrobial drug and new compounds emerging from the industrial pharmaceutical pipeline will likely have a short-term and limited impact before the pathogens can adapt. Inorganic and organometallic complexes offer the opportunity to discover and develop new active antimicrobial agents by exploiting their wide range of three-dimensional geometries and virtually infinite design possibilities that can affect their substitution kinetics, charge, lipophilicity, biological targets and modes of action. This review describes recent studies on the antimicrobial activity of transition metal complexes of groups 6–12. It focuses on the effectiveness of the metal complexes in relation to the rich structural chemical variations of the same. The aim is to provide a short vade mecum for the readers interested in the subject that can complement other reviews.

Effects of honeybush (Cyclopia subternata) extract on physico-chemical, oxidative and sensory traits of typical Italian salami

Honeybush (Cyclopia subternata Vogel) is an indigenous South African shrub enjoyed as hot brewed tea. "Unfermented" honeybush is also a potential antioxidant bioactive extract for foodstuffs due to its polyphenol content. The effect of "unfermented" honeybush extract (Hob; 0.5%) was evaluated in typical Italian salami and compared with nitrate (Nit; 100 mg/kg) and a control (Ctl; without nitrate or honeybush). After 35 days of ripening, Hob had a higher (p < .01) water activity (0.928), compared with Ctl (0.923) and Nit (0.924). Final pH (5.35-5.24) was not affected by treatments. Lower lipid oxidation was observed in Hob and Nit treatments (p < .001) compared with Ctl. Internal color and odor intensity were similar among treatments. Salami with honeybush extract had less spontaneous outer surface mold growth whereas the Ctl showed intermediate growth (p < .05). Honeybush extract seems a promising natural ingredient with antioxidant action.

Enhanced Dissolution of Luteolin by Solid Dispersion Prepared by Different Methods: Physicochemical Characterization and Antioxidant Activity

Luteolin (LT) is a poorly soluble bioactive compound that suffered bioavailability problems after oral administration. Hence, the aim of the proposed research work was to formulate and investigate various solid dispersions (SDs) of LT in order to enhance its dissolution and bioactivity. LT-SD was prepared using polyethylene glycol 4000 (PEG 4000) as a carrier at the mass ratios of 1:1, 1:2, and 1:4. LT-SD was prepared using different methods including fusion (FU), solvent evaporation (SE), and microwave irradiation (MI) methods. The prepared LT-SD was duly characterized in terms of differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) and evaluated for dissolution and in vitro antioxidant activity. The results of DSC, XRD, SEM, IR, and NMR suggested the formation of LT-SD. After 90 min of the dissolution study, the results displayed that the % release of LT from prepared SD was significantly higher compared with the pure LT and its physical mixture dispersion (PMD). LT-SD prepared using the MI method displayed the maximum release of LT (i.e., 97.78 ± 4.41%) at a 1:2 mass ratio of LT:PEG 4000. The LT-SD prepared using the SE method displayed the maximum release of 93.78 ± 3.98% at a mass ratio of 1:4 of LT:PEG 4000. The SD prepared by the MI method showed enhanced dissolution due to higher aqueous solubility and the reduction of particle size. The solid-state characterization studies (DSC, XRD, SEM, IR, and NMR studies) suggested the morphological conversion of LT into the amorphous form from the crystalline state. The results of the antioxidant study revealed that the formation LT-SD displayed significantly higher radical scavenging activity than the pure LT. Therefore, SD obtained using PEG 4000 could be a potential strategy for maximizing the solubility, in vitro dissolution, and therapeutic efficacy of LT.

From Xanthine Oxidase Inhibition to In Vivo Hypouricemic Effect: An Integrated Overview of In Vitro and In Vivo Studies with Focus on Natural Molecules and Analogues

Hyperuricemia is characterized by elevated uric acid (UA) levels on blood, which can lead to gout, a common pathology. These high UA levels are associated with increased purine ingestion and metabolization and/or its decreased excretion. In this field, xanthine oxidase (XO), by converting hypoxanthine and xanthine to UA, plays an important role in hyperuricemia control. Based on limitations and adverse effects associated with the use of allopurinol and febuxostat, the most known approved drugs with XO inhibitory effect, the search for new molecules with XO activity is growing. However, despite the high number of studies, it was found that the majority of tested products with relevant XO inhibition were left out, and no further pharmacological evaluation was performed. Thus, in the present review, available information published in the past six years concerning isolated molecules with in vitro XO inhibition complemented with cytotoxicity evaluation as well as other relevant studies, including in vivo hypouricemic effect, and pharmacokinetic/pharmacodynamic profile was compiled. Interestingly, the analysis of data collected demonstrated that molecules from natural sources or their mimetics and semisynthetic derivatives constitute the majority of compounds being explored at the moment by means of in vitro and in vivo animal studies. Therefore, several of these molecules can be useful as lead compounds and some of them can even have the potential to be considered in the future clinical candidates for the treatment of hyperuricemia.