Atherosclerosis is the commonest and most important vascular disease. Andrographolide (AND) is the main bioactive component of the medicinal plant Andrographis paniculata and is used in traditional medicine. This study was aimed to evaluate the antiatherogenic effect of AND against atherosclerosis induced by Porphyromonas gingivalis in White New Zealand rabbits. Thirty rabbits were divided into five groups as follows: G1, normal group; G2-5, were orally challenged with P. gingivalis five times a week over 12 weeks; G2, atherogenic control group; G3, standard group treated with atorvastatin (AV) 5 mg/kg; and G4 and G5, treatment groups treated with AND 10 and 20 mg/kg, respectively over 12 weeks. Serums were subjected to antioxidant enzymatic and anti-inflammatory activities, and the aorta was subjected to histological analyses. Groups treated with AND showed a significant reversal of liver and renal biochemical changes, compared with the atherogenic control group. In the same groups, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), total glutathione (GSH) levels in serum were significantly increased (P < 0.05), and lipid peroxidation (malondialdehyde (MDA)) levels were significantly decreased (P < 0.05), respectively. Furthermore, treated groups with AV and AND showed significant decrease in the level of VCAM-1 and ICAM-1 compared with the atherogenic control group. In aortic homogenate, the level of nitrotyrosine was significantly increased, while the level of MCP1 was significantly decreased in AV and AND groups compared with the atherogenic control group. In addition, staining the aorta with Sudan IV showed a reduction in intimal thickening plaque in AV and AND groups compared with the atherogenic control group. AND has showed an antiatherogenic property as well as the capability to reduce lipid, liver, and kidney biomarkers in atherogenic serum that prevents atherosclerosis complications caused by P. gingivalis.
Developments in nanotechnology field, specifically, metal oxide nanoparticles have attracted the attention of researchers due to their unique sensing, electronic, drug delivery, catalysis, optoelectronics, cosmetics, and space applications. Physicochemical methods are used to fabricate nanosized metal oxides; however, drawbacks such as high cost and toxic chemical involvement prevail. Recent researches focus on synthesizing metal oxide nanoparticles through green chemistry which helps in avoiding the involvement of toxic chemicals in the synthesis process. Bacteria, fungi, and plants are the biological sources that are utilized for the green nanoparticle synthesis. Due to drawbacks such as tedious maintenance and the time needed for the nanoparticle formation, plant extracts are widely used in nanoparticle production. In addition, plants are available all over the world and phytosynthesized nanoparticles show comparatively less toxicity towards mammalian cells. Secondary metabolites including flavonoids, terpenoids, and saponins are present in plant extracts, and these are highly responsible for nanoparticle formation and reduction of toxicity. Hence, this article gives an overview of recent developments in the phytosynthesis of metal oxide nanoparticles and their toxic analysis in various cells and animal models. Also, their possible mechanism in normal and cancer cells, pharmaceutical applications, and their efficiency in disease treatment are also discussed.
Lung cancer is the most common type of cancer, with over 2.1 million cases diagnosed annually worldwide. It has a high incidence and mortality rate, leading to extensive research into various treatment options, including the use of nanomaterial-based carriers for drug delivery. With regard to cancer treatment, the distinct biological and physico-chemical features of nano-structures have acquired considerable impetus as drug delivery system (DDS) for delivering medication combinations or combining diagnostics and targeted therapy. This review focuses on the use of nanomedicine-based drug delivery systems in the treatment of lung cancer, including the use of lipid, polymer, and carbon-based nanomaterials for traditional therapies such as chemotherapy, radiotherapy, and phototherapy. The review also discusses the potential of stimuli-responsive nanomaterials for drug delivery in lung cancer, and the limitations and opportunities for improving the design of nano-based materials for the treatment of non-small cell lung cancer (NSCLC).
Circular RNAs (circRNAs) have emerged as pivotal regulators of gene expression and cellular processes in various physiological and pathological conditions. In recent years, there has been a growing interest in investigating the role of circRNAs in inflammatory lung diseases, owing to their potential to modulate inflammation-associated pathways and contribute to disease pathogenesis. Inflammatory lung diseases, like asthma, chronic obstructive pulmonary disease (COPD), and COVID-19, pose significant global health challenges. The dysregulation of inflammatory responses demonstrates a pivotal function in advancing these diseases. CircRNAs have been identified as important players in regulating inflammation by functioning as miRNA sponges, engaging with RNA-binding proteins, and participating in intricate ceRNA networks. These interactions enable circRNAs to regulate the manifestation of key inflammatory genes and signaling pathways. Furthermore, emerging evidence suggests that specific circRNAs are differentially expressed in response to inflammatory stimuli and exhibit distinct patterns in various lung diseases. Their involvement in immune cell activation, cytokine production, and tissue remodeling processes underscores their possible capabilities as therapeutic targets and diagnostic biomarkers. Harnessing the knowledge of circRNA-mediated regulation in inflammatory lung diseases could lead to the development of innovative strategies for disease management and intervention. This review summarizes the current understanding of the role of circRNAs in inflammatory lung diseases, focusing on their regulatory mechanisms and functional implications.
The rationale of designing compounds containing a (3,4,5-trimethoxybenzyloxy) phenyl moiety is largely due to its potential antioxidant and cytotoxic activities. A previous study focused on its antioxidant mechanism, whereas in this study, we investigated the cytotoxicity of a series of 28 analogues and the mechanism of apoptosis of the most cytotoxic compound against wild-type (HCT-116) and p53 mutant (HT-29) colorectal cancer cell lines. The series of analogues comprise of different families, namely hydrazone, oxadiazole, thiosemicarbazides and triazoles. In the initial cytotoxicity screening, N-(3,4,5-trimethoxybenzylidene)-4-(3,4,5-trimethoxybenzyloxy) benzohydrazide, henceforth known as, P5H, was found to be most cytotoxic against human colorectal cancer cell lines (IC50 for HCT-116 = 11.79 μM and HT-29 = 18.52 μM). Additionally, P5H was found to have some degree of selectivity towards cancer cells compared to normal human colon cells (CCD-112 CoN). Subsequent investigation had brought insight on P5H ability to induce apoptosis in both HCT-116 and HT-29 cell lines. Cell cycle analysis showed both cell lines were arrested at the G2/M phase upon treatment. Our study concluded that P5H induced the death receptor, DR5 in HCT-116 and mitochondria-mediated apoptosis pathway in HT-29. Therefore, P5H may be a promising candidate as a chemotherapy agent against colon cancer. Graphical abstract The apoptotic pathways induced in HT-29 and HCT-116 cells upon P5H treatment.
Cancer is a complex disease characterized by dysregulated cell growth and division, posing significant challenges for effective treatment. Hispidulin, a flavonoid compound, has shown promising biological effects, particularly in the field of anticancer research. The main objective of this study is to investigate the anticancer properties of hispidulin and gain insight into its mechanistic targets in cancer cells. A comprehensive literature review was conducted to collect data on the anticancer effects of hispidulin. In vitro and in vivo studies were analyzed to identify the molecular targets and underlying mechanisms through which hispidulin exerts its anticancer activities. Hispidulin has shown significant effects on various aspects of cancer, including cell growth, proliferation, cell cycle regulation, angiogenesis, metastasis, and apoptosis. It has been observed to target both extrinsic and intrinsic apoptotic pathways, regulate cell cycle arrest, and modulate cancer progression pathways. The existing literature highlights the potential of hispidulin as a potent anticancer agent. Hispidulin exhibits promising potential as a therapeutic agent for cancer treatment. Its ability to induce apoptosis and modulate key molecular targets involved in cancer progression makes it a valuable candidate for further investigation. Additional pharmacological studies are needed to fully understand the specific targets and signaling pathways influenced by hispidulin in different types of cancer. Further research will contribute to the successful translation of hispidulin into clinical settings, allowing its utilization in conventional and advanced cancer therapies with improved therapeutic outcomes and reduced side effects.
The gut microbiome is involved in the pathogenesis of many diseases including polycystic ovarian syndrome (PCOS). Modulating the gut microbiome can lead to eubiosis and treatment of various metabolic conditions. However, there is no proper study assessing the delivery of microbial technology for the treatment of such conditions. The present study involves the development of guar gum-pectin-based solid self-nanoemulsifying drug delivery system (S-SNEDDS) containing curcumin (CCM) and fecal microbiota extract (FME) for the treatment of PCOS. The optimized S-SNEDDS containing FME and CCM was prepared by dissolving CCM (25 mg) in an isotropic mixture consisting of Labrafil M 1944 CS, Transcutol P, and Tween-80 and solidified using lactose monohydrate, aerosil-200, guar gum, and pectin (colon-targeted CCM solid self-nanoemulsifying drug delivery system [CCM-CT-S-SNEDDS]). Pharmacokinetic and pharmacodynamic evaluation was carried out on letrozole-induced female Wistar rats. The results of pharmacokinetic studies indicated about 13.11 and 23.48-fold increase in AUC of CCM-loaded colon-targeted S-SNEDDS without FME (CCM-CT-S-SNEDDS (WFME)) and CCM-loaded colon-targeted S-SNEDDS with FME [(CCM-CT-S-SNEDDS (FME)) as compared to unprocessed CCM. The pharmacodynamic study indicated excellent recovery/reversal in the rats treated with CCM-CT-S-SNEDDS low and high dose containing FME (group 13 and group 14) in a dose-dependent manner. The developed formulation showcasing its improved bioavailability, targeted action, and therapeutic activity in ameliorating PCOS can be utilized as an adjuvant therapy for developing a dosage form, scale-up, and technology transfer.
Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) are among the leading causes of mortality worldwide. Cigarette smoking is among the main aetiologic factors for both ailments. These diseases share common pathogenetic mechanisms including inflammation, oxidative stress, and tissue remodelling. Current therapeutic approaches are limited by low efficacy and adverse effects. Consequentially, LC has a 5-year survival of < 20%, while COPD is incurable, underlining the necessity for innovative treatment strategies. Two promising emerging classes of therapy against these diseases include plant-derived molecules (phytoceuticals) and nucleic acid-based therapies. The clinical application of both is limited by issues including poor solubility, poor permeability, and, in the case of nucleic acids, susceptibility to enzymatic degradation, large size, and electrostatic charge density. Nanoparticle-based advanced drug delivery systems are currently being explored as flexible systems allowing to overcome these limitations. In this review, an updated summary of the most recent studies using nanoparticle-based advanced drug delivery systems to improve the delivery of nucleic acids and phytoceuticals for the treatment of LC and COPD is provided. This review highlights the enormous relevance of these delivery systems as tools that are set to facilitate the clinical application of novel categories of therapeutics with poor pharmacokinetic properties. This picture was generated with BioRender.
One major source of inter-individual variability in drug pharmacokinetics is genetic polymorphism of the cytochrome P450 (CYP) genes. This study aimed to elucidate the enzyme kinetic and molecular basis for altered activity in three major alleles of CYP2D6, namely CYP2D6*2, CYP2D6*10 and CYP2D6*17. The E. coli-expressed allelic variants were examined using substrate (venlafaxine and 3-cyano-7-ethoxycoumarin[CEC]) and inhibitor (quinidine, fluoxetine, paroxetine, terbinafine) probes in enzyme assays as well as molecular docking. The kinetics data indicated that R296C and S486T mutations in CYP2D6*2 have caused enhanced ligand binding (enhanced intrinsic clearance for venlafaxine and reduced IC50 for quinidine, paroxetine and terbinafine), suggesting morphological changes within the active site cavity that favoured ligand docking and binding. Mutations in CYP2D6*10 and CYP2D6*17 tended to cause deleterious effect on catalysis, with reduced clearance for venlafaxine and CEC. Molecular docking indicated that P34S and T107I, the unique mutations in the alleles, have negatively impacted activity by affecting ligand access and binding due to alteration of the substrate access channel and active site morphology. IC50 values however were quite variable for quinidine, fluoxetine and terbinafine, and a general decrease in IC50 was observed for paroxetine, suggesting ligand-specific altered susceptibility to inhibition in the alleles. This study indicates that CYP2D6 allele selectivity for ligands was not solely governed by changes in the active site architecture induced by the mutations, but that the intrinsic properties of the substrates and inhibitors also played vital role.
Moringa oleifera Lam. is a pan-tropical plant well known to the ancient world for its extensive therapeutic benefits in the Ayurvedic and Unani medical systems. The ancient world was familiar with this tree, but it has only lately been rediscovered as a multifunctional species with a huge range of possible therapeutic applications. It is a folk remedy for skin diseases, edema, sore gums, etc. This review comprises the history, ethnomedicinal applications, botanical characteristics, geographic distribution, propagation, nutritional and phytochemical profile, dermatological effects, and commercially available cosmeceuticals of Moringa oleifera Lam.Compilation of all the presented data has been done by employing various search engines like Science Direct, Google, PubMed, Research Gate, EBSCO, SciVal, SCOPUS, and Google Scholar.Studies on phytochemistry claim the presence of a variety of substances, including fatty acids, phenolic acids, sterols, oxalates, tocopherols, carotenoids, flavonoids, flavonols glycosides, tannins, terpenoids, terpene, saponins, phylates, alkaloids, glucosinolates, glycosides, and isothiocyanate. The pharmacological studies have shown the efficacy of Moringa oleifera Lam. as an antibacterial, antifungal, anti-inflammatory, antioxidant, anti-atopic dermatitis, antipsoriatic, promoter of wound healing, effective in treating herpes simplex virus, photoprotective, and UV protective. As a moisturizer, conditioner, hair growth promoter, cleanser, antiwrinkle, anti-aging, anti-acne, scar removal, pigmentation, and control for skin infection, sores, as well as sweating, it has also been utilized in a range of cosmeceuticals.he Moringa oleifera Lam. due to its broad range of phytochemicals can be proven boon for the treatment of dermatological disorders.
Asthma, lung cancer, cystic fibrosis, tuberculosis, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and COVID-19 are few examples of inflammatory lung conditions that cause cytokine release syndrome. It can initiate a widespread inflammatory response and may activate several inflammatory pathways that cause multiple organ failures leading to increased number of deaths and increased prevalence rates around the world. Nanotechnology-based therapeutic modalities such as nanoparticles, liposomes, nanosuspension, monoclonal antibodies, and vaccines can be used in the effective treatment of inflammatory lung diseases at both cellular and molecular levels. This would also help significantly in the reduction of patient mortality. Therefore, nanotechnology could be a potent platform for repurposing current medications in the treatment of inflammatory lung diseases. The aim and approach of this article are to highlight the clinical manifestations of cytokine storm in inflammatory lung diseases along with the advances and potential applications of nanotechnology-based therapeutics in the management of cytokine storm. Further in-depth studies are required to understand the molecular pathophysiology, and how nanotechnology-based therapeutics can help to effectively combat this problem.
Inflammation and compromised immune responses often increase colorectal cancer (CRC) risk. The immune-modulating effects of limonin on carcinogen/inflammation-induced colorectal cancer (CRC) were studied in mice. Male Balb/c mice were randomly assorted into three groups (n = 6): healthy control, non-treated CRC-induced (azoxymethane/dextran-sulfate-sodium AOM/DSS) control, and CRC-induced + 50 mg limonin/kg body weight. The CRC developments were monitored via macroscopic, histopathological, ELISA, and mRNA expression analyses. Limonin downregulated inflammation (TNF-α, tumor necrosis factor-α), enhanced the adaptive immune responses (CD8, CD4, and CD19), and upregulated antioxidant defense (Nrf2, SOD2) mRNA expressions. Limonin reduced serum malondialdehyde (MDA, lipid peroxidation biomarker), prostaglandin E2, and histopathology inflammation scores, while increasing reduced glutathione (GSH) in CRC-induced mice. Limonin significantly (p
Saussurea costus (Falc.) Lipsch., commonly known as costus, is a perennial herb that has been traditionally used in various indigenous medicinal systems across Asia. Its historical prominence in traditional remedies underscores the need to explore its phytochemical composition, pharmacological properties, and potential therapeutic benefits. This review aims to provide a comprehensive overview of the available literature on the pharmacological properties, phytochemical constituents, ethnobotanical uses, and therapeutic potential of S. costus. An exhaustive search was performed across multiple electronic databases, including PubMed/MedLine, Google Scholar, Web of Science, Scopus, TRIP database, and Science Direct. Both experimental and clinical studies, as well as traditional ethnobotanical records, were considered for inclusion. The phytochemical analysis revealed that S. costus contains a plethora of bioactive compounds, including sesquiterpenes, flavonoids, and essential oils, which are responsible for its myriad of medicinal properties. The pharmacological studies have demonstrated its anti-inflammatory, anti-oxidant, anti-cancer, hepatoprotective, and immunomodulatory effects, among others. Ethnobotanical data showcased its extensive use in treating ailments like asthma, digestive disorders, and skin conditions. Some clinical trials also underscore its efficacy in certain health conditions, corroborating its traditional uses. S. costus possesses significant therapeutic potential, largely attributable to its rich phytochemical composition; the convergence of its traditional uses and modern pharmacological findings suggests promising avenues for future research, especially in drug development and understanding its mechanism of action in various ailments.
SRS27, an andrographolide analogue, had been proven to have therapeutic properties at a dose of 3 mg/kg in both in vitro and in vivo asthma models of our previous study. The present study focuses on the pharmacokinetic and toxicity profile of this compound to provide further evidence for the development of this compound as an anti-asthma agent. A simple pharmacokinetic study was performed in female BALB/c mice to measure blood plasma concentration of the compound at therapeutic dose. At a single dose of 3 mg/kg, SRS27 had a relatively short half-life but was able to achieve a concentration range of 13-19 μM that is related to its in vitro bioactivities. With regard to toxicity profile, SRS27 appears to be safe, as no histopathological changes were observed in the liver, kidneys and ovaries of SRS27-treated female BALB/c mice. In addition, there was no significant change in the mean body weight and organ weight of the animals in the SRS27-treated groups compared with the vehicle-treated control group at the end of the treatment. This fully supports the absence of any significant changes in peripheral blood leukocyte counts of SRS27-treated mice. Rewardingly, this acute toxicity study also revealed that SRS27 has a wide therapeutic window as no toxicity symptoms were detected with a dose up to 60 mg/kg daily when tested for 14 days. These results provide strong justification for further investigation of SRS27 as a potential new anti-asthma agent.
The cathepsin B inhibitor benzyloxycarbonyl-phenylalanine-alanine-chloromethyl ketone (z-FA-CMK) was recently found to induce apoptosis at low concentrations in Jurkat T cells, while at higher concentrations, the cells die of necrosis. In the present study, we showed that z-FA-CMK readily depletes intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) generation. The toxicity of z-FA-CMK in Jurkat T cells was completely abrogated by N-acetylcysteine (NAC), suggesting that the toxicity mediated by z-FA-CMK is due to oxidative stress. We found that L-buthionine sulfoximine (BSO) which depletes intracellular GSH through the inhibition of GSH biosynthesis in Jurkat T cells did not promote ROS increase or induce cell death. However, NAC was still able to block z-FA-CMK toxicity in Jurkat T cells in the presence of BSO, indicating that the protective effect of NAC does not involve GSH biosynthesis. This is further corroborated by the protective effect of the non-metabolically active D-cysteine on z-FA-CMK toxicity. Furthermore, in BSO-treated cells, z-FA-CMK-induced ROS increased which remains unchanged, suggesting that the depletion of GSH and increase in ROS generation mediated by z-FA-CMK may be two separate events. Collectively, our results demonstrated that z-FA-CMK toxicity is mediated by oxidative stress through the increase in ROS generation.
The functional responses of different overnight-stored in vitro tissues are not clearly described in any animal model. The influence of overnight storage in an animal model may vary between tissue types. We employed Sprague-Dawley rat as our animal model and investigated the functional changes of rat aorta, trachea, bronchus and bladder that were used (i) immediately after surgical removal (denoted as fresh) and (ii) after storage in aerated (95% O2, 5% CO2) Krebs-Ringer bicarbonate solution at 4 °C for 24 h (denoted as stored). The aorta ring was pre-contracted with phenylephrine, and the functional response of the tissue was investigated using isoprenaline, forskolin and carbachol. Carbachol was also used to increase the tone in trachea, bronchus rings and bladder strips. A clear reduced function of endothelium, with a minor if any effect in the smooth muscle function in rat aorta was observed after overnight storage. The contractile response of overnight-stored rat airway (trachea and bronchus) and bladder smooth muscles remained unchanged. Among all tested tissues, only bronchus showed a reduced response rate (only 40% responded) after storage. In vitro rat tissues that are stored in Krebs solution at 4 °C for 24 h can still be used to investigate smooth muscle responses, however, not endothelium-mediated responses for aorta. The influence of overnight storage on different tissues from an animal model (Sprague-Dawley rat in our study) also provides an insight in maximising the use of sacrificed animals.
Lung cancer (LC) is the leading cause of cancer-related deaths globally. It accounts for more than 1.9 million cases each year due to its complex and poorly understood molecular mechanisms that result in unregulated cell proliferation and metastasis. β-Catenin is a developmentally active protein that controls cell proliferation, metastasis, polarity and cell fate during homeostasis and aids in cancer progression via epithelial-mesenchymal transition. Therefore, inhibition of the β-catenin pathway could attenuate the progression of LC. Berberine, an isoquinoline alkaloid which is known for its anti-cancer and anti-inflammatory properties, demonstrates poor solubility and bioavailability. In our study, we have encapsulated berberine into liquid crystalline nanoparticles to improve its physiochemical functions and studied if these nanoparticles target the β-catenin pathway to inhibit the human lung adenocarcinoma cell line (A549) at both gene and protein levels. We observed for the first time that berberine liquid crystalline nanoparticles at 5 µM significantly attenuate the expression of the β-catenin gene and protein. The interaction between berberine and β-catenin was further validated by molecular simulation studies. Targeting β-catenin with berberine nanoparticles represents a promising strategy for the management of lung cancer progression.
Lung cancer is the second most prevalent type of cancer and is responsible for the highest number of cancer-related deaths worldwide. Non-small-cell lung cancer (NSCLC) makes up the majority of lung cancer cases. Zerumbone (ZER) is natural compound commonly found in the roots of Zingiber zerumbet which has recently demonstrated anti-cancer activity in both in vitro and in vivo studies. Despite their medical benefits, ZER has low aqueous solubility, poor GI absorption and oral bioavailability that hinders its effectiveness. Liquid crystalline nanoparticles (LCNs) are novel drug delivery carrier that have tuneable characteristics to enhance and ease the delivery of bioactive compounds. This study aimed to formulate ZER-loaded LCNs and investigate their effectiveness against NSCLC in vitro using A549 lung cancer cells. ZER-LCNs, prepared in the study, inhibited the proliferation and migration of A549 cells. These inhibitory effects were superior to the effects of ZER alone at a concentration 10 times lower than that of free ZER, demonstrating a potent anti-cancer activity of ZER-LCNs. The underlying mechanisms of the anti-cancer effects by ZER-LCNs were associated with the transcriptional regulation of tumor suppressor genes P53 and PTEN, and metastasis-associated gene KRT18. The protein array data showed downregulation of several proliferation associated proteins such as AXL, HER1, PGRN, and BIRC5 and metastasis-associated proteins such as DKK1, CAPG, CTSS, CTSB, CTSD, and PLAU. This study provides evidence of potential for increasing the potency and effectiveness of ZER with LCN formulation and developing ZER-LCNs as a treatment strategy for mitigation and treatment of NSCLC.
Diabetes mellitus (DM) often causes ocular disorders leading to vision loss. Metformin is commonly prescribed for type 2 diabetes. This study assessed the effect of metformin on hyperglycemic histopathological eye abnormalities and some possible pathways involved. Male rats were divided into 3 groups (N = 6), namely, healthy control, hyperglycemic non-treated control, and hyperglycemic rats treated with 200 mg/kg metformin. Two weeks after diabetes induction by an intraperitoneal streptozotocin (60 mg streptozotocin (STZ)/kg) injection, the rats develop ocular abnormalities, and metformin (200 mg/kg) treatment was administered daily. Rats underwent dilated retinal digital ophthalmoscope examination and graded for diabetic retinopathy. Rats were sacrificed at 12 weeks, and the cornea, lens, sclera, ciliary body, iris, conjunctiva, retinal, and optic nerve were examined histologically. Rats' fasting blood glucose and body weight were monitored. Serum tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), claudin-1, and glutathione/malondialdehyde ratios were analyzed. Metformin significantly attenuated diabetes-related histopathological ocular deteriorations in the cornea, lens, sclera, ciliary body, iris, conjunctiva, retina, and optic nerve partly by restoring serum TNF-α, VEGF, claudin-1, and glutathione/malondialdehyde ratios without significantly affecting the fasting blood glucose levels or body weight in these hyperglycemic rats. Metformin attenuated hyperglycemia-associated histopathological eye deteriorations, possibly partly by ameliorating vascular leakage, oxidative stress, inflammation, and neovascularization, without affecting the fasting blood glucose levels or body weights in these STZ-induced diabetic rats.
The inhibitory effects of five flavonoids with distinct chemical classes (flavones [luteolin], flavonols [quercetin and quercitrin], and flavanones [hesperetin and hespiridin]) on cDNA-expressed CYP2C8 were investigated. CYP2C8 was co-expressed with NADPH-cytochrome P450 reductase in Escherichia coli and used to characterise potency and mechanism of these flavonoids on the isoform. Tolbutamide 4-methylhydroxylase, a high-performance liquid chromatography-based assay, was selected as marker activity for CYP2C8. Our results indicated that the flavonoids inhibited CYP2C8 with different potency. The order of inhibitory activities was quercetin > luteolin > hesperetin > hesperidin > quercitrin. All of these compounds however exhibited mechanism-based inhibition. A number of structural factors were found to be important for inhibition; these include the molecular shape (volume to surface ratio), the number of hydroxyl groups as well as glycosylation of the hydroxyl group. Quercetin was the most potent inhibitor among the flavonoids examined in this study, and our data suggest that it should be examined for potential pharmacokinetic drug interactions pertaining to CYP2C8 substrates in vivo.