Protective effects of luteolin on the venous endothelium

Luteolin, a flavone ingredient: Anticancer mechanisms, combined medication strategy, pharmacokinetics, clinical trials, and pharmaceutical researches

Current pharmaceutical research is energetically excavating the pharmacotherapeutic role of herb-derived ingredients in multiple malignancies' targeting. Luteolin is one of the major phytochemical components that exist in various traditional Chinese medicine or medical herbs. Mounting evidence reveals that this phytoconstituent endows prominent therapeutic actions on diverse malignancies, with the underlying mechanisms, combined medication strategy, and pharmacokinetics elusive. Additionally, the clinical trial and pharmaceutical investigation of luteolin remain to be systematically delineated. The present review aimed to comprehensively summarize the updated information with regard to the anticancer mechanism, combined medication strategies, pharmacokinetics, clinical trials, and pharmaceutical researches of luteolin. The survey corroborates that luteolin executes multiple anticancer effects mainly by dampening proliferation and invasion, spurring apoptosis, intercepting cell cycle, regulating autophagy and immune, inhibiting inflammatory response, inducing ferroptosis, and pyroptosis, as well as epigenetic modification, and so on. Luteolin can be applied in combination with numerous clinical anticarcinogens and natural ingredients to synergistically enhance the therapeutic efficacy of malignancies while reducing adverse reactions. For pharmacokinetics, luteolin has an unfavorable oral bioavailability, it mainly persists in plasma as glucuronides and sulfate-conjugates after being metabolized, and is regarded as potent inhibitors of OATP1B1 and OATP2B1, which may be messed with the pharmacokinetic interactions of miscellaneous bioactive substances in vivo. Besides, pharmaceutical innovation of luteolin with leading-edge drug delivery systems such as host-guest complexes, nanoparticles, liposomes, nanoemulsion, microspheres, and hydrogels are beneficial to the exploitation of luteolin-based products. Moreover, some registered clinical trials on luteolin are being carried out, yet clinical research on anticancer effects should be continuously promoted.

Luteolin Attenuates Oxidative Stress and Colonic Hypermobility in Water Avoidance Stress Rats by Activating the Nrf2 Signaling Pathway

SCOPE

Irritable bowel syndrome (IBS) is an intestinal disorder, whose symptoms can be alleviated by certain dietary phytochemicals. This study explores the role and potential mechanisms of a natural flavonoid luteolin (LUT) in alleviating the excessive motility of colonic smooth muscles and reducing oxidative stress in IBS with diarrhea (IBS-D) rats.

METHODS AND RESULTS

LUT reduces excessive intestinal motility and lowers reactive oxygen species (ROS) levels in a water avoidance stress (WAS) rat model. Moreover, LUT increases the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), activates the nuclear translocation of Nrf2, and greatly reduces the hydrogen peroxide (H2 O2 )-induced oxidative damage in intestinal epithelial cells.

CONCLUSIONS

LUT, a phyto-active component, protects against excessive intestinal motility and diarrhea by regulating the Nrf2 signaling pathway and effectively reduces oxidative stress damage in the colon.

The protective effect of luteolin on the depression-related dry eye disorder through Sirt1/NF-κB/NLRP3 pathway

Luteolin has been reported to exhibit therapeutic effect on depressive-like behaviors in mice. Nevertheless, the therapeutic effect of luteolin on the depression-related dry eye disorder remains inconclusive. In this study, C57 mice were subjected to chronic unpredictable mild stress in a dry environment (relative humidity in the cage <40%). The behavioral test and phenol red cotton thread test were employed to select the mice with both dry eye and depression-like behavior. The mechanism of luteolin on depression-related dry eye disorder was assessed by the Sirt1 selective inhibitor EX-527. Luteolin alleviated depressive-like behaviors induced by CUMS, increased tear secretion and restored corneal defects in mice. The secretions of pro-inflammatory factors IL-1β, IL-6, IL-18 and TNF-α were decreased in hippocampi and corneal tissues by Luteolin treatment. Luteolin treatment up-regulated Sirt1 expression and down-regulated Ac-NF-κB, NLRP3, Ac-Caspase-1, GSDMD-N, Cleaved IL-1β, and Cleaved IL-18 expressions. In addition, the selective inhibition of Sirt1 could weaken the therapeutic effect of luteolin on depression-related dry eye disorder. The beneficial effect of luteolin through Sirt1/NF-κB/NLRP3 signaling pathway might be a therapeutic strategy for the depression-related dry eye disorder.

Phytochemicals, Biological Activities, Molecular Mechanisms, and Future Prospects of Plantago asiatica L

Plantago asiatica L. has been used as a vegetable and nutritious food in Asia for thousands of years. According to recent phytochemical and pharmacological research, the active compositions of the plant contribute to various health benefits, such as antioxidant, anti-inflammatory, antibacterial, antiviral, and anticancer. This article reviews the 87 components of the plant and their structures, as well as their biological activities and molecular research progress, in detail. This review provides valuable reference material for further study, production, and application of P. asiatica, as well as its components in functional foods and therapeutic agents.

Venous endothelial function in cardiovascular disease

The essential role of the endothelium in vascular homeostasis is associated with the release of endothelium-dependent relaxing and contractile factors (EDRF and EDCF, respectively). Different from arteries, where these factors are widely studied, the vasoactive factors derived from the venous endothelium have been given less attention. There is evidence for a role of the nitric oxide (NO), endothelium-dependent hyperpolarization (EDH) mechanism, and cyclooxygenase (COX)-derived metabolites as EDRFs; while the EDCFs need to be better evaluated since no consensus has been reached about their identity in venous vessels. The imbalance between the synthesis, bioavailability, and/or action of EDRFs and/or EDCFs results in a pathological process known as endothelial dysfunction, which leads to reduced vasodilation and/or increased vasoconstriction. In the venous system, endothelial dysfunction is relevant since reduced venodilation may increase venous tone and decrease venous compliance, thus enhancing mean circulatory filling pressure, which maintains or modify cardiac workload contributing to the etiology of cardiovascular diseases. Interestingly, some alterations in venous function appear at the early stages (or even before) the establishment of these diseases. However, if the venous endothelium dysfunction is involved in these alterations is not yet fully understood and requires further studies. In this sense, the present study aims to review the current knowledge on venous endothelial function and dysfunction, and the general state of the venous tone in two important cardiovascular diseases of high incidence and morbimortality worldwide: hypertension and heart failure.

Biosynthesis of a water solubility-enhanced succinyl glucoside derivative of luteolin and its neuroprotective effect

The natural flavonoids luteolin and luteoloside have anti-bacterial, anti-inflammatory, anti-oxidant, anti-tumour, hypolipidemic, cholesterol lowering and neuroprotective effects, but their poor water solubility limits their application in industrial production and the pharmaceutical industry. In this study, luteolin-7-O-β-(6″-O-succinyl)-d-glucoside, a new compound that was prepared by succinyl glycosylation of luteolin by the organic solvent tolerant bacterium Bacillus amyloliquefaciens FJ18 in an 8.0% DMSO (v/v) system, was obtained and identified. Its greater water solubility (2293 times that of luteolin and 12 232 times that of luteoloside) provides the solution to the application problems of luteolin and luteoloside. The conversion rate of luteolin (1.0 g l^-1 ) was almost 100% at 24 h, while the yield of luteolin-7-O-β-(6″-O-succinyl)-d-glucoside reached 76.2%. In experiments involving the oxygen glucose deprivation/reoxygenation injury model of mouse hippocampal neuron cells, the cell viability was significantly improved with luteolin-7-O-β-(6″-O-succinyl)-d-glucoside dosing, and the expressions of the anti-oxidant enzyme HO-1 in the nucleus increased, providing a neuroprotective effect for ischemic cerebral cells. The availability of biosynthetic luteolin-7-O-β-(6″-O-succinyl)-d-glucoside, which is expected to replace luteolin and luteoloside, would effectively expand the clinical application value of luteolin derivatives.

Pharmacokinetic, Metabolism, and Metabolomic Strategies Provide Deep Insight Into the Underlying Mechanism of Ginkgo biloba Flavonoids in the Treatment of Cardiovascular Disease

Ginkgo biloba, known as the “living fossil,” has a long history of being used as botanical drug for treating cardiovascular diseases and the content of flavonoids as high as 24%. More than 110 different kinds of flavonoids and their derivatives have been separated from G. biloba, including flavones, flavonols, biflavonoids, catechins, and their glycosides, etc., all of which display the ability to dilate blood vessels, regulate blood lipids, and antagonize platelet activating factor, and protect against ischemic damage. At present, many types of preparations based on G. biloba extract or the bioactive flavonoids of it have been developed, which are mostly used for the treatment of cardiovascular diseases. We herein review recent progress in understanding the metabolic regulatory processes and gene regulation of cellular metabolism in cardiovascular diseases of G. biloba flavonoids. First, we present the cardioprotective flavonoids of G. biloba and their possible pharmacological mechanism. Then, it is the pharmacokinetic and liver and gut microbial metabolism pathways that enable the flavonoids to reach the target organ to exert effect that is analyzed. In the end, we review the possible endogenous pathways toward restoring lipid metabolism and energy metabolism as well as detail novel metabolomic methods for probing the cardioprotective effect of flavonoids of G. biloba.