Cardiovascular protective effects of cinnamic acid as a natural phenolic acid: a review

Phenolic acids derived from plants have beneficial effects on cardiovascular diseases (CVD). Cinnamic acid (CA) is a crucial phenolic acid that can form numerous hydroxycinnamic derivate found in many food groups. We review current data on the cardiovascular pharmacology of CA with a focus on CVD and their risk factors including hyperlipidaemia, obesity, hyperglycaemia, cardiomyopathy and myocardial ischaemia, vascular dysfunction, oxidative stress and inflammation. Both in vivo and in vitro laboratory studies demonstrate the lipid-lowering, anti-obesity, anti-hyperglycemic, cardio-protective and vasorelaxant activities of CA. The protective impacts of CA against CVD occur by inhibiting inflammatory, oxidative, and apoptotic pathways, regulating the genes and enzymes involved in glucose and lipid metabolisms, and promoting vasodilation. This review showed that the most studied and prominent effects of CA are anti-hyperlipidemic and anti-diabetic properties. In conclusion, intake of plant foods rich in CA may reduce CVD risk especially through regulating blood glucose and lipids levels.

Unveiling the Detrimental Effect of Glipizide on Structure and Function of Catalase: Spectroscopic, Thermodynamics and Simulation Studies

Free radicals, products of oxidative processes, induce cellular damage linked to diseases like Parkinson's and diabetes due to increased reactive oxygen species (ROS) levels. Catalase, crucial for scavenging ROS, emerges as a therapeutic agent against ailments including atherosclerosis and tumor progression. Its primary function involves breaking down hydrogen peroxide into water and oxygen. Research on catalase-drug interactions reveals structural changes under specific conditions, affecting its activity and cellular antioxidant balance, highlighting its pivotal role in defending against oxidative stress-related diseases. Hence, targeting catalase is considered an effective strategy for controlling ROS-induced cellular damage. This study investigates the interaction between bovine liver catalase and glipizide using spectroscopic and computational methods. It also explores glipizide's effect on catalase activity. More than 20% inhibition of catalase enzymatic activity was recorded in the presence of 50 µM glipizide. To investigate the inhibition of catalase activity by glipizide, we performed a series of binding studies. Glipizide was found to form a complex with catalase with moderate affinity and binding constant in the range of 3.822 to 5.063 × 104 M-1. The binding was spontaneous and entropically favourable. The α-helical content of catalase increased from 24.04 to 29.53% upon glipizide complexation. Glipizide binding does not alter the local environment surrounding the tyrosine residues while a notable decrease in polarity around the tryptophan residues of catalase was recorded. Glipizide interacted with numerous active site residues of catalase including His361, Tyr357, Ala332, Asn147, Arg71, and Thr360. Molecular simulations revealed that the catalase-glipizide complex remained relatively stable in an aqueous environment. The binding of glipizide had a negligible effect on the secondary structure of catalase, and hydrogen bonds persisted consistently throughout the trajectory. These results could aid in the development of glipizide as a potent catalase inhibitor, potentially reducing the impact of reactive oxygen species (ROS) in the human body.

Implication of Caffeic Acid for the Prevention and Treatment of Alzheimer's Disease: Understanding the Binding with Human Transferrin Using In Silico and In Vitro Approaches

In present times, a switch from chemical molecules towards natural products is taking place, and the latter is being increasingly explored in the management of diseases due to their broad range of therapeutic potential. Consumption of coffee is thought to reduce Alzheimer's disease (AD); however, the mechanism is still unexplored. Primarily, it is thought that components of coffee are the key players in making it a neuroprotectant. Caffeic acid (CA) is found in high quantities in coffee; thus, it is being increasingly explored to decipher its neuroprotection by various mechanisms. Iron is a toxic element in a free form capable of causing oxidative damage and ultimately contributing to the pathogenesis of AD. Thus, maintaining the proper iron levels is vital and human transferrin (Htf), a glycoprotein, is a key player in this aspect. In this work, we explored the binding mechanism of CA with Htf at the atomistic level, employing molecular docking and extensive molecular dynamics simulation (MD) approaches coupled with spectroscopic techniques in a bid to decipher the mode of interaction of CA with Htf. Molecular docking results demonstrated a strong binding affinity between CA and Htf. Furthermore, MD study highlighted the Htf-CA complex's stability and the ligand's minimal impact on Htf's overall structure. In silico approaches were further backed up by experimental approaches. Strong binding of CA with Htf was ascertained by UV-visible and fluorescence spectroscopy observations. Together, the study provides a comprehensive understanding of the Htf-CA interaction, adding to the knowledge of the use of CA in the treatment of AD, thereby adding another feather to its already known neuroprotective role.

Computational and physicochemical insight into 4-hydroxy-2-nonenal induced structural and functional perturbations in human low-density lipoprotein

Lipid peroxidation (LPO) is a biological process that frequently occurs under physiological conditions. Undue oxidative stress increases the level of LPO; which may further contribute to the development of cancer. 4-Hydroxy-2-nonenal (HNE), one of the principal by-products of LPO, is present in high concentrations in oxidatively stressed cells. HNE rapidly reacts with various biological components, including DNA and proteins; however, the extent of protein degradation by lipid electrophiles is not well understood. The influence of HNE on protein structures will likely have a considerable therapeutic value. This research elucidates the potential of HNE, one of the most researched phospholipid peroxidation products, in modifying low-density lipoprotein (LDL). In this study, we tracked the structural alterations in LDL by HNE using various physicochemical techniques. To comprehend the stability, binding mechanism and conformational dynamics of the HNE-LDL complex, computational investigations were carried out. LDL was altered in vitro by HNE, and the secondary and tertiary structural alterations were examined using spectroscopic methods, such as UV-visible, fluorescence, circular dichroism and fourier transform infrared spectroscopy. Carbonyl content, thiobarbituric acid-reactive-substance (TBARS) and nitroblue tetrazolium (NBT) reduction assays were used to examine changes in the oxidation status of LDL. Thioflavin T (ThT), 1-anilinonaphthalene-8-sulfonic (ANS) binding assay and electron microscopy were used to investigate aggregates formation. According to our research, LDL modified by HNE results in changes in structural dynamics, oxidative stress and the formation of LDL aggregates. The current investigation must characterize HNE's interactions with LDL and comprehend how it can change their physiological or pathological functions.Communicated by Ramaswamy H. Sarma.

Insight into the interaction of isochroman with bovine serum albumin: extensive experimental and computational investigations

The way therapeutic compounds interact with serum protein provides valuable information on their pharmacokinetics, toxicity, effectiveness, and even their structural-related information. Isochroman (IC) is a phytochemical compound obtained from the leaves of Olea europea plant. The derivatives of IC have various pharmacological properties including antidepressants, antihistamines, antiinflammation, anticonvulsants, appetite depressants, etc. The binding of small molecules to bovine serum albumin (BSA) is useful to ensure their efficacy. Thus, in this study, we have found out the binding mode of IC with BSA using several spectroscopic and in silico studies. UV and fluorescence spectroscopy suggested the complex formation between IC and BSA with a binding constant of 103 M-1. IC resulted in fluorescence quenching in BSA through static mechanism. The microenvironmental and conformational changes in BSA were confirmed using synchronous and three-dimensional studies. Site marker experiment revealed the IC binding in site-III of BSA. The influence of vitamins, metals and β-cyclodextrin (β-CD) on binding constant of IC-BSA complex was also examined. Circular dichroism spectra showed that α-helical of BSA decreased upon interaction with IC. Computational and experimental results were complimentary with one another and assisted in determining the binding sites, nature of bonds and amino acids included in the IC-BSA complex formation.Communicated by Ramaswamy H. Sarma.

Inhibitory effect of baicalein against glycation in HSA: an in vitro approach

Hyperglycaemia accelerates the aging process significantly. Diabetes problems can be mitigated by inhibiting glycation. To learn more about glycation and antiglycation mediated by methyl glyoxal and baicalein, we studied human serum albumin as a model protein. A Methylglyoxal (MGO) incubation period of seven days at 37 degrees Celsius induced glycation of Human Serum Albumin.s Hyperchromicity, decreased tryptophan and intrinsic fluorescence, increased AGE-specific fluorescence, and reduced mobility were all seen in glycated human serum albumin (MGO-HSA) in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Fourier transform infrared spectroscopy (FT-IR) and then far ultraviolet dichroism were used to detect secondary and tertiary structural perturbations (CD). The Congo red assay (CR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) all verified the presence of amyloid-like clumps. Structure (carbonyl groups on ketoamine moieties) (CO), physiological problems including diabetes mellitus, and cardiovascular disease, etc. are linked to the structural and functional changes in glycated HSA, as proven by these studies.Communicated by Ramaswamy H. Sarma.

Antiglycation and antioxidant potential of coumaric acid isomers: a comparative in-vitro study

Advanced glycation end products (AGEs) are the product of non-enzymatic glycation of serum proteins. AGEs increase reactive oxygen species (ROS) formation, which leads to diabetic complications. Phytochemicals exhibit lesser side effects as compared to conventional therapy. In this study, three isomers of coumaric acid (ortho, meta, para) were used to deduce the better one in terms of reducing diabetic complications. For this purpose, human serum albumin (HSA) was incubated with glucose in the absence and presence of isomers for 28 days. To avoid any growth, NaN3 was added and temperature was kept constant throughout the incubation period. Studies like fluorescence, circular dichroism spectroscopy, fructosamine analysis, free lysine estimation, free thiol group estimation were done. To investigate the ROS production, fluorescence microscopy of isolated lymphocytes using DAPI and dichloro-dihydro-fluorescein diacetate were performed. Molecular docking and molecular dynamic simulations (root-mean-square deviation, root-mean-square fluctuations, radius of gyration and solvent-accessible surface area) of HSA and peroxisome proliferator activated receptor (PPAR) alpha and gamma were also done. It was observed that in glycated protein samples, the level of absorbance, fluorescence, fructosamine and carbonyl group increased along with the loss of secondary structure, free lysine and thiol group. These parameters were found gradually recovered in treated samples. ROS production and apoptosis were found to be reduced in lymphocytes treated with p-Coumaric acid (pCA)-treated protein samples as compared to lymphocyte treated with glycated protein. Computational modelling suggested a stable complex formation of HSA and PPARs with pCA. Results with pCA at 200 µM were consistently better than other two isomers. Our next step is to evaluate this study in rats.Communicated by Ramaswamy H. Sarma.

An insight into the binding and inhibition of eye ζ-crystallin by the environmental toxin arsenic: implications in eye diseases

Arsenic contamination is highly prevalent in food chain, soil and groundwater. Continuous exposure to elevated levels of this environmental toxin is a global concern. Studies have reported enriched accumulation of arsenic in the eyes compared to other body organs leading to various eye diseases. Here, the impact of arsenic exposure on the enzymatic eye ζ-crystallin has been investigated. Arsenic inhibited the activity of the enzyme with an IC50 value of 35 µM. It decreased the free thiol group content of ζ-crystallin due to protein oxidation. The binding of arsenic with ζ-crystallin was explored using biophysical and computational tools. The enzyme undergoes some conformational changes upon arsenic binding. The binding constant (Kb) was determined to be 1.2 × 102 M-1. Thermodynamic parameters were determined by isothermal titration calorimetry (ITC) and the binding energy (ΔG) was calculated to be -3.52 kcal/mol. Molecular docking studies helped in visualizing the amino acid residues (especially Cys165) of the enzyme involved in binding with arsenic. Continuous arsenic exposure is expected to increase the eye crystallin-related abnormalities, elevating the risk of cataractogenesis. Therefore, proper measures need to be taken by authorities to control the contamination of arsenic in the environment and groundwater.Communicated by Ramaswamy H. Sarma.

Discovery of novel glucosinolates inhibiting advanced glycation end products: Virtual screening and molecular dynamic simulation

Protein glycation can result in the formation of advanced glycation end products (AGEs), which pose a potential health risk due to their association with diabetic complications. Natural products are a source of drugs discovery and the search for potential natural inhibitors of AGEs is of great significance. Glucosinolates (GSLs) mainly from cruciferous plants have potential antioxidant, anti-inflammatory, and anti-glycation activities. In this study, the inhibitory activity of GSLs on bovine serum albumin (BSA) along with its mechanism was investigated by virtual screening and various computational simulation techniques. Virtual screening revealed that 174 GSLs were screened using Maestro based on the glide score and 89% of the compounds were found to have potential anti-glycation ability with the docking scores less than -5 kcal/mol. Molecular docking showed that the top 10 GSLs were bound to the IIA structural domain of BSA. Among them, glucohesperin (1) and 2-hydroxyethyl glucosinolate (2) had the lowest docking scores of -9.428 and -9.333 kcal/mol, respectively, reflecting their good binding affinity. Molecular dynamics simulations of 1 (ΔG = -43.46 kcal/mol) and 2 (ΔG = -43.71 kcal/mol) revealed that the complexes of these two compounds with proteins had good stability. Further binding site analysis suggested that the mechanism of inhibition of protein glycation by these two active ingredients might be through competitive hydrogen bonding to maintain the structural integrity of the protein, thus inhibiting glycation reaction. Moreover, the ADMET values and CYP450 metabolism prediction data were within the recommended values. Therefore, it can be concluded that 1 and 2 may act as potential anti-glycation agents.

Skin health properties of Paeonia lactiflora flower extracts and tyrosinase inhibitors and free radical scavengers identified by HPLC post-column bioactivity assays

Skin health is a major concern across the world. The Paeonia lactiflora Pall. flower (PLPF) is well-known in China as an edible ornamental flower, that has been traditionally prescribed for the treatment of irregular menstruation and dysmenorrhea. However, its chemical constituents and bioactivities have not been systematically stuided. This study tentatively identified 27 compounds in aqueous and ethanol extracts of PLPF using ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry, including four monoterpene glycosides, six phenols, six tannins, ten flavonoids and a hydroxycinnamic acid amide. Online antioxidant and tyrosinase inhibitor screening assays based on post-column bioactivity tests were used to screen for bioactive compounds in the extracts. Online and offline bioactivity assays showed that both extracts exhibited notable antioxidant properties against DPPH, ABTS, and FRAP, potent antiglycation capacity, and significant inhibition of tyrosinase, cyclooxygenase-2, and collagenase. Gallic acid derivatives were the main contributors to the antioxidant and antityrosinase capacity and may also inhibit cyclooxygenase-2 and collagenase, but they exhibited weak antiglycation capacity. The antiglycation effects may be due to the synergistic action of gallic acid and specific flavonoids. PLPF is a promising source of bioactive compounds for the development of natural skin health products.

Inhibitory potential of N-acetylaspartate against protein glycation, AGEs formation and aggregation: Implication of brain osmolyte in glycation-related complications

Protein glycation and aggregation have a pivotal role in many diseases including diabetes and neurodegenerative disorders. N-acetyl aspartate (NAA), an osmolyte derived from L-aspartic acid, is one of the most abundant metabolites in the mammalian brain. Although NAA is supposed to be a substitute for a neuronal marker, its function is not fully elucidated. Herein, we have investigated the effect of NAA on glycation, AGEs formation and aggregation of irisin. AGE-specific fluorescence showed the strong inhibition of AGEs formation in the presence of NAA, demonstrating its anti-glycating property. The aggregates present in MG-modified irisin were also reduced by NAA, which was confirmed by Thioflavin T fluorescence and fluorescence microscopy. Further, for the explanation of the strong anti-glycating potential of NAA, the interaction between irisin and NAA was also examined. Interaction studies involving steady-state fluorescence and molecular docking demonstrated that hydrogen bonding and salt bridges by NAA stabilize the irisin. It was found that glycation-prone residues i.e., lysine and arginine are specifically involved in the interaction which might prevent them from getting modified during the process of glycation. This study for the first time reported the antiglycating potential of NAA which can be implicated in the therapeutic management of various glycation-related complications.

Mannose 2, 3, 4, 5, 6-O-pentasulfate (MPS): a partial activator of human heparin cofactor II with anticoagulation potential

Thromboembolic diseases are a major cause of mortality in human and the currently available anticoagulants are associated with various drawbacks, therefore the search for anticoagulants that have better safety profile is highly desirable. Compounds that are part of the dietary routine can be modified to possibly increase their anticoagulant potential. We show mannose 2,3,4,5,6-O-pentasulfate (MPS) as a synthetically modified form of mannose that has appreciable anticoagulation properties. An in silico study identified that mannose in sulfated form can bind effectively to the heparin-binding site of antithrombin (ATIII) and heparin cofactor II (HCII). Mannose was sulfated using a simple sulfation strategy-involving triethylamine-sulfur trioxide adduct. HCII and ATIII were purified from human plasma and the binding analysis using fluorometer and isothermal calorimetry showed that MPS binds at a unique site. A thrombin inhibition analysis using the chromogenic substrate showed that MPS partially enhances the activity of HCII. Further an assessment of in vitro blood coagulation assays using human plasma showed that the activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged in the presence of MPS. A molecular dynamics simulation analysis of the HCII-MPS complex showed fluctuations in a N-terminal loop and the cofactor binding site of HCII. The results indicate that MPS is a promising lead due to its effect on the in vitro coagulation rate.Communicated by Ramaswamy H. Sarma.

Studying the Mechanism of Interaction of Doxofylline with Human Lysozyme: A Biophysical and In Silico Approach

In this study, multiple spectroscopic and computational methods were utilized to investigate the binding mechanism of doxofylline with lysozyme. The in vitro methods were used to obtain the binding kinetics and thermodynamics. UV-vis spectroscopy indicated the formation of complex between doxofylline and lysozyme. The Gibb's free energy and binding constant from UV-vis data was obtained as -7.20 kcal M^-1 and 1.929 × 10⁵ M^-1, respectively. Doxofylline successfully quenched the fluorescence of lysozyme, confirming the formation of complex. The k_q and K_sv values for the quenching of lysozyme's fluorescence by doxofylline were 5.74 × 10¹¹ M^-1 s^-1 and 3.32 × 10³ M^-1, respectively. These values signified a moderate binding affinity between doxofylline and lysozyme. In synchronous spectroscopy, red shifts were observed for indicating the changes in microenvironment of lysozyme following the binding of doxofylline. The secondary structural analysis was determined using circular dichroism (CD) which revealed an increase in % α-helical as a result of doxofylline interaction. The binding affinity and flexibility of lysozyme upon complexation have been revealed via molecular docking and molecular dynamic (MD) simulations, respectively. According to the many parameters of the MD simulation, the lysozyme-doxofylline complex was stable under physiological conditions. All during the simulation time, hydrogen bonds were continuously present. The MM-PBSA binding energy for lysozyme and doxofylline binding was found to be -30.55 kcal mol^-1.

Anti-cyclooxygenase, anti-glycation, and anti-skin aging effect of Dendrobium officinale flowers’ aqueous extract and its phytochemical validation in aging

Introduction

Dendrobium officinale Kimura et Migo (D. officinale) , widely called as “life-saving immortal grass” by Chinese folk, is a scarce and endangered species. The edible stems of D. officinale have been extensively studied for active chemical components and various bioactivities. However, few studies have reported the well-being beneficial effects of D. officinale flowers (DOF). Therefore, the present study aimed to investigate the in vitro biological potency of its aqueous extract and screen its active components.

Methods

Antioxidant tests, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), the ferric reducing ability of plasma (FRAP), and intracellular reactive oxygen species (ROS) level analyses in primary human epidermal keratinocytes, anti-cyclooxygenase2 (COX-2) assay, anti-glycation assay (both fluorescent AGEs formation in a BSA fructose/glucose system and glycation cell assay), and anti-aging assay (quantification of collagen types I and III, and SA-β-gal staining assay) were conducted to determine the potential biological effects of DOF extracts and its major compounds. Ultra-performance liquid chromatography-electrospray ionisation-quadrupole-time-of-flight-mass spectrometry (UPLC-ESI-QTOF-MS/MS) was performed to investigate the composition of DOF extracts. Online antioxidant post-column bioassay tests were applied to rapidly screen major antioxidants in DOF extracts.

Results and discussion

The aqueous extract of D. officinale flowers was found to have potential antioxidant capacity, anti-cyclooxygenase2 (COX-2) effect, anti-glycation potency, and anti-aging effects. A total of 34 compounds were identified using UPLC-ESI-QTOF-MS/MS. Online ABTS radical analysis demonstrated that 1-O-caffeoyl-β-D-glucoside, vicenin-2, luteolin-6-C-β-D-xyloside-8-C-β--D-glucoside, quercetin-3-O-sophoroside, rutin, isoquercitrin, and quercetin 3-O-(6″-O-malonyl)-β-D-glucoside are the major potential antioxidants. In addition, all selected 16 compounds exerted significant ABTS radical scavenging ability and effective AGE suppressive activities. However, only certain compounds, such as rutin and isoquercitrin, displayed selective and significant antioxidant abilities, as shown by DPPH and FRAP, as well as potent COX-2 inhibitory capacity, whereas the remaining compounds displayed relatively weak or no effects. This indicates that specific components contributed to different functionalities. Our findings justified that DOF and its active compound targeted related enzymes and highlighted their potential application in anti-aging.

Effect of crocin on glycated human low-density lipoprotein: A protective and mechanistic approach

Human low-density lipoprotein (LDL) is known to have a role in coronary artery diseases when it undergoes modification due to hyperglycaemic conditions. Plant products like crocin play an essential role in protecting against oxidative stress and in the production of advanced glycation end-products (A.G.E.s). In this study, the anti-glycating effect of crocin was analyzed using various biochemical, spectroscopic, and in silico approaches. Glycation-mediated oxidative stress was confirmed by nitroblue tetrazolium, carbonyl content, and lipid peroxidation assays, and it was efficiently protected by crocin in a concentration-dependent manner. A.N.S. fluorescence, thioflavin T (ThT) assay, and electron microscopy confirmed that the structural changes in LDL during glycation lead to the formation of fibrillar aggregates, which can be minimized by crocin treatment. Moreover, secondary structural perturbations in LDL were observed using circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), where crocin was found to prevent the loss of secondary structure in glycated LDL. Spectroscopic studies like U.V. absorbance, fluorescence spectroscopy, CD, FTIR, and fluorescence resonance energy transfer (FRET) provided insights into the interaction mechanism between LDL and crocin. Molecular docking supports these results with a highly negative binding energy of -10.3 kcal/mol, suggesting the formation of a stable ldl-crocin complex. Our study indicates that crocin may be a potent protective agent against coronary artery diseases by limiting the glycation of LDL in people with such disorders.

Studies on the synergistic action of methylglyoxal and peroxynitrite on structure and function of human serum albumin

Albumin, an important serum protein, is continuously exposed to various oxidizing/nitrating and glycating agents. Depending upon the nature/concentration of reactive species present, the protein may be glycated, oxidized/nitroxidized or glyco-nitro-oxidized. Peroxynitrite is a powerful nitroxidant and has been reported to damage a wide array of macromolecules. On the other hand, methylglyoxal is a very strong reactive dicarbonyl and a potent precursor for the formation of advanced glycation end products under pathological conditions. In certain pathological conditions albumin may be modified by peroxynitrite and methylglyoxal simultaneously. There is dearth of literature suggests that structural/conformational and functional alteration in albumin upon glycation and oxidation/nitroxidation, however the alterations produced by glyco-nitro-oxidation has not yet been explored. Therefore, in this study, simultaneous effect of glycation and nitroxidation on the structure and conformation, vis-a-vis function of albumin was explored. Glyco-nitro-oxidized albumin showed decreased free amino acid content together with decreased affinity of albumin towards cobalt. Molecular docking model and molecular dynamic simulations showed close interaction and formation of stable complexes between methylglyoxal, peroxynitrite and albumin. Formation of carboxymethyl lysine and 3-nitrotyrosine in glyco-nitro-oxidized albumin were confirmed by MALDI-TOF MS and UP-LC MS. Aggregate formation in glyco-nitro-oxidized albumin was visualized by transmission electron microscopy. On the basis of these results, it may be speculated that, albumin modified with endogenously generated methylglyoxal and peroxynitrite might be a driving factor in the progression of heightened inflammatory autoimmune responses. The work presents a ground to study the role of glyco-nitro-oxidized albumin in the pathogenesis and progression of various autoimmune diseases including rheumatoid arthritis. Communicated by Ramaswamy H. Sarma.

Ameliorative effects of endogenous and exogenous indole-3-acetic acid on atrazine stressed paddy field cyanobacterial biofertilizer Cylindrospermum stagnale

Across the world, paddy fields naturally harbour cyanobacteria that function as biofertilizers and secrete various compounds like Indole-3-acetic acid (IAA) that help organisms in regulating their growth. Also, paddy field farming utilizes large amounts of pesticides (e.g. atrazine); but their continued application in the agricultural field causes toxicity in non-target cyanobacterial species that hinder their performance as a biofertilizer. Hence, the current study is an attempt to ameliorate the atrazine stress in cyanobacterium Cylindrospermum stagnale by addition of IAA (1 mM each) under different atrazine levels (0, 60, 80, 100, 120, 140 µg/l). Atrazine toxicity affected C. stagnale in a dose-dependent manner further experiments revealed that both the exogenous and endogenous IAA mitigated the detrimental effects of atrazine. It reduced MDA content and simultaneously increased chlorophyll content, total protein content, and multiple antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] at 140 µg/l. A molecular docking study revealed that the pesticide binds to the D1 protein of the photoelectric chain in photosynthesis. Hence, the application of IAA or cyanobacterial biofertilizer that secretes a sufficient amount of IAA may assist sustainable agriculture in counteracting the atrazine toxicity.

Ameliorative effect of pioglitazone on glucose induced glycation of α-crystallin: Management of complications associated with diabetic retinopathy

The glycation and aggregation of lens proteins significantly contribute to the onset of diabetic cataracts as well as the retinopathy. The glycation exerts numerous alterations in the tertiary structural of proteins. Moreover, the covalent crosslinking of lens crystallins also contribute to the cataract formation. In this article, the effect of pioglitazone on glucose induced glycation and aggregation α-crystallin was examined. A remarkable inhibition of early glycation products (~80%) and advanced glycation products (~75%) was recorded by the treatment of pioglitazone. There was >75% recovery in biochemical marker (carbonyl content). The presence of 150 μM of pioglitazone reduced the free lysine modifications to 35%. Treatment of pioglitazone also protected the secondary structural alterations induced by glycation and inhibited the formation of protein aggregates. The interaction studies showed that pioglitazone interacted with α-crystallin via moderate binding affinity. The interaction between pioglitazone interacted and α-crystallin was energetically and entropically favourable. The complex of pioglitazone with studied protein stable in which RMSF, R_g, SASA, RMSD, and the secondary structural components was not affected. The findings show antiglycation activity of pioglitazone along with its mechanism of action highlighting the ability of drug to be possibly developed novel as glycation inhibitor.

Depicting the DNA Binding and Cytotoxicity Studies against Human Colorectal Cancer of Aquabis (1-Formyl-2-Naphtholato-k2O,O′) Copper(II): A Biophysical and Molecular Docking Perspective

In this study, we attempted to examine the biological activity of the copper(II)–based small molecule aquabis (1-formyl-2-naphtholato-k2O,O′)copper(II) (1) against colon cancer. The characterization of complex 1 was established by analytical and spectral methods in accordance with the single-crystal X-ray results. A monomeric unit of complex 1 exists in an O4 (H2O) coordination environment with slightly distorted square pyramidal geometry (τ = ~0.1). The interaction of complex 1 with calf thymus DNA (ctDNA) was determined by employing various biophysical techniques, which revealed that complex 1 binds to ctDNA at the minor groove with a binding constant of 2.38 × 105 M–1. The cytotoxicity of complex 1 towards human colorectal cell line (HCT116) was evaluated by the MTT assay, which showed an IC50 value of 11.6 μM after treatment with complex 1 for 24 h. Furthermore, the apoptotic effect induced by complex 1 was validated by DNA fragmentation pattern, which clarified that apoptosis might be regulated through the mitochondrial-mediated production of reactive oxygen species (ROS) causing DNA damage pathway. Additionally, molecular docking was also carried out to confirm the recognition of complex 1 at the minor groove.

Diet-Derived Advanced Glycation End Products (dAGEs) Induce Proinflammatory Cytokine Expression in Cardiac and Renal Tissues of Experimental Mice: Protective Effect of Curcumin

The beneficial effect of curcumin (CU) on dietary AGEs (dAGEs) involves blocking the overexpression of proinflammatory cytokine genes in the heart and kidney tissues of experimental mice. The animals were divided into six groups (n = 6/group) and were fed a heat-exposed diet (dAGEs) with or without CU for 6 months. Their blood pressure (BP) was monitored by a computerized tail-cuff BP-monitoring system. The mRNA and protein expression levels of proinflammatory genes were analyzed by RT-PCR and western blot, respectively. A marked increase in BP (108 ± 12 mmHg vs 149 ± 15 mmHg) accompanied by a marked increase in the heart and kidney weight ratio was noted in the dAGE-fed mice. Furthermore, the plasma levels of proinflammatory molecules (C5a, ICAM-1, IL-6, MCP-1, IL-1β and TNF-α) were found to be elevated (3-fold) in dAGE-fed mice. mRNA expression analysis revealed a significant increase in the expression levels of inflammatory markers (Cox-2, iNOS, and NF-κB) (3-fold) in cardiac and renal tissues of dAGE-fed mice. Moreover, increased expression of RAGE and downregulation of AGER-1 (p < 0.001) were noticed in the heart and kidney tissues of dAGE-fed mice. Interestingly, the dAGE-induced proinflammatory genes and inflammatory responses were neutralized upon cotreatment with CU. The present study demonstrates that dietary supplementation with CU has the ability to neutralize dAGE-induced adverse effects and alleviate proinflammatory gene expression in the heart and kidney tissues of experimental mice.

Plumbagin inhibits quorum sensing-regulated virulence and biofilms of Gram-negative bacteria: in vitro and in silico investigations

The global rise in antimicrobial resistance and lack of discovery of new antimicrobials have created serious concerns. Targeting quorum sensing (QS) and biofilms of pathogenic bacteria is considered a promising approach in antimicrobial drug discovery. This study explored the inhibitory effect of plumbagin against biofilms and QS of Chromobacterium violaceum, Serratia marcescens and Pseudomonas aeruginosa. Violacein production in C. violaceum 12472 was reduced by >80%. The virulent traits of P. aeruginosa PAO1 such as pyocyanin, rhamnolipid and proteases were also inhibited at sub-minimum inhibitory concentrations. Moreover, the biofilms of the test bacteria were reduced by 56-70%. Plumbagin reduced the bacterial adherence and colonization on solid surface. Computational studies gave closer insights regarding the possible modes of action. Molecular dynamics simulations revealed that the protein complexes were quite stable under physiological conditions. This study provides both experimental and computational evidence regarding the efficacy of plumbagin against biofilms and the QS-controlled virulence factors of Gram-negative bacteria.

Design, synthesis and molecular modeling studies of novel mesalamine linked coumarin for treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are continuous idiopathic inflammation of GIT. Ulcerative colitis, inflammation of the colonic or rectal mucosa has no known medical cure and its treatment is aimed at reducing the signs and symptoms associated with the disorders, induction and maintenance of remission. In this study, we have reported the synthesis of mesalamine and coumarin linked together by a diazo group. The compound was characterized by various spectroscopic methods. Therapeutic potential of the synthesized compound was investigated through acetic acid induced ulcerative rat model. Pharmacokinetic properties were predicted for the compounds by ADMET related descriptors. Molecular docking studies were conducted with four proteins (COX-2, MMP-9, TNF-α and MPO) to examine the interaction of mesalamine (MS) and mesalamine coumarin derivative (MS-CU). Moreover, molecular dynamic simulations were carried out to study the dynamics and stability of the complexes in solvent system. The binding energy of MS-CU with MPO, COX-2, MMP-9 and TNF-α was found to be -9.5, -10.4, -9.2 and -8.4 kcal/mol respectively. MS-CU exhibited higher binding affinity towards all tested proteins than MS. Molecular dynamic simulation reveals that both MS and MS-CU formed a stable complex with all test proteins in aqueous system. Overall binding energy of MS-CU was more than MS showing stronger affinity towards the test portions. In conclusion, Mesalamine-coumarin derivative reduces colonic damage in acetic acid induced ulcerative colitis in rat model, and therefore may prove to be effective in the management of IBD.

Insight into the In Vitro Antiglycation and In Vivo Antidiabetic Effects of Thiamine: Implications of Vitamin B1 in Controlling Diabetes

Hyperglycemia is considered to be a driving factor for advanced glycated end products (AGEs) formation. Inhibition of this process plays a vital role in reducing the problems of diabetes. This study aimed to explore the in vitro antiglycation and in vivo antidiabetic effect of thiamine. Human serum albumin (HSA) was used as a model protein to delineate the antiglycation potential of thiamine. Fructosamine levels were low in the presence of thiamine, implying the inhibition of early stages of glycation by thiamine. Furthermore, HSA-glucose assays depict the inhibition of post-Amadori products by thiamine. CD spectroscopy suggested fewer alterations in the secondary structure in the presence of thiamine. It was found that the administration of thiamine to diabetic rats leads to an increase in hexokinase activity and increased insulin secretion coupled with glycolysis utilization of glucose. Moreover, the activity of glucose-6-phosphatase and fructose- 1-6-phosphatase (increased in the liver and kidney of diabetic rats) is restored to near-normal levels upon thiamine administration. Histopathological studies also advocated that thiamine supplementation decreases the pathological abnormalities associated with diabetes in the liver and kidney. This study provides a rationale that vitamins can be implicated in controlling diabetes.

Mechanistic insight into glycation inhibition of human serum albumin by vitamin B9: Multispectroscopic and molecular docking approach

Advanced glycation end products (AGEs) formation produces free radicals that play a role in diabetes mellitus; hence inhibition of glycation plays a part in minimizing diabetes-related complications. This study was intended to examine the AGEs formation of HSA upon prolonged incubation of 28 days at 37 °C and further investigate the antiglycation potential of folic acid (FA). FA shows a significant binding affinity to the HSA with a binding constant (K) of 10⁴ M^-1. The evaluation of enthalpy change (∆H⁰) and entropy change (∆S^o) implied that the HSA-FA complex is stabilized primarily by hydrophobic interaction and hydrogen bonding. Molecular docking analysis depicted that FA binds with HSA in subdomain IIA (Sudlow's site I) with a binding energy of -7.0 kcal mol^-1. AGEs were characterized by free lysine and thiol groups, carbonyl content, and AGEs specific fluorescence. The presence of FA significantly decreased glycation from free lysine and carbonyl content estimation and AGEs specific fluorescence. Multispectroscopic observations and molecular docking and examination of various biomarkers demonstrate the antiglycation activity of FA and its capacity to prevent disease progression in diabetes.

Inhibition of non-enzymatic glycation by capsaicin: targeting AGE-induced diabetic complications

Capsaicin inhibits the non-enzymatic glycation of human serum albumin.

Glyburide inhibits non-enzymatic glycation of HSA: An approach for the management of AGEs associated diabetic complications

Advanced glycation endproducts (AGEs) are the final product of glycation, highly reactive in nature and contribute directly or indirectly to numerous complications related to diabetes. In this study, the antiglycation activity of glyburide was investigated using HSA as model protein, both against glucose and methylglyoxal mediated glycation. The possible mechanism of action was also deciphered using biophysical and computational tools. Approximately 70% inhibition of both early and advanced glycation end products were recorded in the presence of glyburide. Free lysine modification was reduced by glyburide treatment and improvement in biochemical markers such as free thiol groups and carbonyl content was observed. Interaction studies revealed that glyburide showed moderate to strong binding affinity towards HSA with binding constant in the order of 10⁶ M^-1. The interaction of glyburide with HSA was entropically favourable and spontaneous in nature. Molecular dynamics simulation deciphered that glyburide-HSA complex was quite stable where RMSD, RMSF, R_g, SASA, and secondary structure of HSA remained approximately same over the entire simulation period. The average binding energy of the MD simulation for glyburide-HSA complex was found to be -15.386 kJ mol^-1. The findings demonstrate the antiglycation potential of glyburide and its possible mechanism of action.

Carbamylation of human serum albumin generates high-molecular weight aggregates: fine characterization by multi-spectroscopic methods and electron microscopy

Carbamylation is the non-enzymatic reaction between isocyanic acid and macromolecules (mainly proteins) which results in carbamylation-derived products (CDPs) generation, wherein the macromolecules show altered structure and function. In this study, we examined the modifications caused in human serum albumin (HSA) upon interaction with potassium cyanate (KCNO). HSA was incubated with varying concentrations of KCNO for 6 h at 37 °C. The resultant product was characterized by biochemical and biophysical techniques. Among other changes, the carbamylated-HSA showed homocitrulline generation (LC-MS), increase in mass (DLS), and amyloidogenic aggregate formation (Congo red, SEM, TEM). The Gibb's free energy was calculated to be -2.91 to -3.95 kcal mol^-1, suggesting that the binding was spontaneous and energetically favourable. The results indicate that in chronic kidney disease patients, elevated levels of isocyanic acid (formed from urea) may modify the albumin structure and lead to its conversion into amyloidogenic aggregates, thus accelerating kidney damage.

Study on the interaction between 4-(1H-indol-3-yl)-2-(p-tolyl)quinazoline-3-oxide and human serum albumin

An organic small-molecular drug, 4-(1H-indol-3-yl)-2-(p-tolyl)quinazoline-3-oxide 1a was synthesized. It was employed to investigate the binding interaction and mechanism with human serum albumin (HSA). The experimental results indicated that the fluorescence quenching of HSA by 1a is a static quenching process and formation 1a-HSA complex. The site competition experiments revealed that the combination of 1a on HSA are hydrophobic interactions in the IIA domain and hydrogen bonds in IIIA domain of HSA, and the hydrophobic interactions of 1a on HSA are stronger than that of hydrogen bonds. These results were also confirmed by molecular docking theoretic analysis and ANS-hydrophobic fluorescent probe experiment. Synchronous fluorescence experiments showed that the polarity of HSA microenvironment was increase in the interaction process of 1a with HSA. The results of binding distance explored indicated that the combination distance between 1a and HSA is 3.63 nm, which is between 0.5R₀ and 1.5R₀, revealing the energy transfer between HSA and 1a is non-radiative. These results are very helpful for people to screen out high efficient indoloquinazoline drugs.

Biomolecular interactions and binding dynamics of tyrosine kinase inhibitor erdafitinib, with human serum albumin

Erdafitinib is an approved tyrosine kinase inhibitor that inhibits fibroblast growth factor receptor. It has been described as one of the potent anti-tumor drugs especially for the treatment of urothelial carcinoma. In this study, we have investigated the binding dynamics of erdafitinib with human serum albumin (HSA) using multiple spectroscopic techniques. The outcome of the results suggests the occurrence of static quenching during the interaction of HSA with erdafitinib which leads to the formation of non-fluorescent HSA-erdafitinib ground state complex. Formation of HSA-erdafitinib complex was also confirmed from the findings of absorption spectral analysis. The changes in microenvironment around hydrophobic domains (especially tryptophan and tyrosine) were deciphered from fluorescence spectroscopy which was further confirmed by synchronous spectral analysis. In order to gain insight into the binding site of erdafitinib in HSA, molecular docking combined with competitive displacement assay was performed. The modified form of Stern Volmer equation was used to estimate various binding parameters including number of binding sites. The findings are indicative of a single binding site (n = 1) with binding constant in the order of 10⁴. The negative values of thermodynamic parameters like ΔG, ΔH and ΔS were suggestive of the binding reaction being spontaneous and exothermic, while the hydrogen bonds and Van der Waals interactions being the major forces present between HSA and erdafitinib. Circular dichroism spectral analysis revealed the alterations in the conformation of HSA structure and reduction in its α-helical content.Communicated by Ramaswamy H. Sarma[Formula: see text].

The inefficacy of donepezil on glycated-AChE inhibition: Binding affinity, complex stability and mechanism

Donepezil (DPZ) is a well-known drug for Alzheimer's disease that inhibits acetylcholinesterase activity (AChE). In the present study, the inhibitory effect of DPZ on non-enzymatic glycated-AChE (GLY-AChE) was studied by different experimental and simulation techniques. The initial investigation revealed that glycation process could reduce AChE activity approximately 60% in the pure enzyme and 38% in the extracted crude AChE from neural cells cultured in the presence of high glucose (HG) concentration. It is suggested that glycation of lysine residues on the structure of AChE could change the conformation of the active site (Trp-86 and His-447) in a way that the orientation of acetylcholine interrupted. The further studies indicated that DPZ is although a strong inhibitor for the native enzyme, it is not able to affect the GLY-AChE activity. The K_D values of AChE-DPZ and GLY-AChE-DPZ complexes were estimated to be 1.88 × 10^-9 and 2.10 × 10^-6, respectively. The stability assessment showed that AChE-DPZ complex is more stable than the glycated complex. Our results indicate that, glycation process could impact on the conformation of the residues involved in the DPZ binding cavity on α-helix domain. Therefore, DPZ is not able to bind its specific cavity to induce its inhibitory effects on GLY-AChE.

Effects of piceatannol on the structure and activities of bovine serum albumin: A multi-spectral and molecular modeling studies

Piceatannol (PIC) displays a wide spectrum of biological activities, such as antioxidation, antibacterial activity and anti-inflammation, but the biochemical and molecular mechanism is not fully understood. In this study, the interaction of PIC with bovine serum albumin (BSA) was studied by fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism spectroscopy and molecular simulation. The effects of PIC on BSA non-enzymatic glycosylation, fibrillation, thermal stability, and structure information were also studied. The results showed that the formation of PIC-BSA complex by mainly hydrogen-bonding forces resulted in the conformational changes of protein. PIC inhibited the formation of β-sheets structures of BSA. BSA still maintained the esterase-like good activity in the presence of PIC. In addition, PIC significantly reduced the degree of BSA glycosylation. These results provided a basis for the molecular interaction between PIC and protein, and suggested the potential effect of PIC in preventing the progression of diabetes mellitus.

Interactions of Designed Trp-Containing Antimicrobial Peptides with DNA of Multidrug-Resistant Pseudomonas aeruginosa

To investigate the intracellular mechanisms of seven Trp-containing peptides in clinically isolated multidrug-resistant Pseudomonas aeruginosa (MRPA0108). The results showed that the Trp-containing peptides had high antibacterial activity against the MRPA0108 strain, with minimal inhibitory concentration (MIC) values ranging from 6.25 to 25 μM. The peptides rapidly and completely killed the MRPA0108 at a concentration of 16 × MIC at 60-90 min. The Trp-containing peptides were found to penetrate the bacterial cell membrane and accumulate in the cells. A DNA gel retardation assay indicated that the peptides were able to bind with the genomic DNA of MRPA0108 cells; L5W exhibited a stronger DNA binding ability than that of the other peptides, and the ratio of peptide to DNA was 0.62/1. Next, the UV absorption spectrum of the DNA indicated that L5W interacted with the MRPA0108 genomic DNA and intercalated into the groove of the DNA molecule, resulting in loosening of the double-helical structure of the originally contracted DNA and leading to the occurrence of a hyperchromic effect. The circular dichroism spectrum suggested that I1W and L5W associated with the DNA via a trench combination mode resulting from the compact structure of the DNA double helix and reduction in ππ accumulation between base pairs. Furthermore, real-time quantitative PCR demonstrated that the Trp-containing peptides could downregulate the expression of DNA replication-initiating genes in MRPA0108 cells. MRPA0108 DNA may be a potential active target for the antimicrobial activity of Trp-containing peptides.

Unravelling the interaction of glipizide with human serum albumin using various spectroscopic techniques and molecular dynamics studies

Glipizide is known to stimulate insulin secretion by β-cells of the pancreas. It is a second-generation sulfonylurea drug used in the management of type 2 diabetes. The shorter biological half-life makes it a suitable candidate to be designed as a controlled release formulation. Human serum albumin (HSA), a major plasma protein plays a crucial role in the transportation of drugs, hormones, fatty acids, and many other molecules and determines their physiological fate and biodistribution. In this study, the interaction of glipizide with HSA was investigated under physiological conditions using multi-spectroscopic techniques corroborated with molecular docking and dynamics approach. It was found that glipizide integrates to HSA with a binding constant in the order of 10⁵ M^-1. The mode of fluorescence quenching by glipizide is static in nature with one binding site. Glipizide preferentially interacts with sub-domain IIA of HSA and their complexion is thermodynamically favorable. This interaction results in the loss of α-helical content of HSA. The energy transfer efficiency from HSA to glipizide was found to be 26.72%. In silico molecular docking and simulation studies ratified in vitro findings and revealed that hydrogen bonds and hydrophobic interactions are accountable for glipizide-HSA complex formation.Communicated by Ramaswamy H. Sarma.

Deciphering the interaction of food additive, vanillin with DNA: A biophysical and computational study

Communicated by Ramaswamy H. Sarma.

Mechanism of non-enzymatic antiglycation action by coumarin: a biophysical study

Coumarin inhibited non-enzymatic glycation by masking the free amino groups and scavenging carbonyl groups of protein.

Secondary metabolites from lichen as potent inhibitors of advanced glycation end products and vasodilative agents

Secondary metabolites from lichens are known for exhibiting various biological effects such as anti-inflammatory, antioxidant and antibacterial activities. Despite this wide range of reported biological effects, their impact on the formation of advanced glycation end products (AGEs) remains vastly unexplored. The latter are known contributors to lifestyle and age-related diseases such as Alzheimer and Parkinson. Moreover, the development of atherosclerosis and arterial stiffness is causally linked to the formation of AGEs. With this in mind, the present work evaluated the inhibitory effects of secondary lichen metabolites on the formation of pentosidine-like AGEs' by using an in vitro, Maillard reaction based, fluorescence assay. Overall, thirty-seven natural and five synthetically modified compounds were tested, eighteen of which exhibiting IC₅₀ values in the range of 0.05 to 0.70 mM. This corresponds to 2 to 32 fold of the inhibitory activity of aminoguanidine. Targeting one major inhibiting mechanism of AGEs formation, all compounds were additionally evaluated on their radical scavenging capacities in an DPPH assay. Furthermore, as both AGEs' formation and hypertension are major risk factors for atherosclerosis, compounds that were available in sufficient amounts were also tested for their vasodilative effects. Overall, and though some of the active compounds were previously reported cytotoxic, present results highlight the interesting potential of secondary lichen metabolites as anti-AGEs and vasodilative agents.