Scopoletin and umbelliferone protect hepatocytes against palmitate- and bile acid-induced cell death by reducing endoplasmic reticulum stress and oxidative stress

Scopoletin: a review of its pharmacology, pharmacokinetics, and toxicity

Scopoletin is a coumarin synthesized by diverse medicinal and edible plants, which plays a vital role as a therapeutic and chemopreventive agent in the treatment of a variety of diseases. In this review, an overview of the pharmacology, pharmacokinetics, and toxicity of scopoletin is provided. In addition, the prospects and outlook for future studies are appraised. Scopoletin is indicated to have antimicrobial, anticancer, anti-inflammation, anti-angiogenesis, anti-oxidation, antidiabetic, antihypertensive, hepatoprotective, and neuroprotective properties and immunomodulatory effects in both in vitro and in vivo experimental trials. In addition, it is an inhibitor of various enzymes, including choline acetyltransferase, acetylcholinesterase, and monoamine oxidase. Pharmacokinetic studies have demonstrated the low bioavailability, rapid absorption, and extensive metabolism of scopoletin. These properties may be associated with its poor solubility in aqueous media. In addition, toxicity research indicates the non-toxicity of scopoletin to most cell types tested to date, suggesting that scopoletin will neither induce treatment-associated mortality nor abnormal performance with the test dose. Considering its favorable pharmacological activities, scopoletin has the potential to act as a drug candidate in the treatment of cancer, liver disease, diabetes, neurodegenerative disease, and mental disorders. In view of its merits and limitations, scopoletin is a suitable lead compound for the development of new, efficient, and low-toxicity derivatives. Additional studies are needed to explore its molecular mechanisms and targets, verify its toxicity, and promote its oral bioavailability.

Phosphorylation: new star of pathogenesis and treatment in steatotic liver disease

Steatotic liver disease poses a serious threat to human health and has emerged as one of the most significant burdens of chronic liver disease worldwide. Currently, the research mechanism is not clear, and there is no specific targeted drug for direct treatment. Phosphorylation is widely regarded as the most common type of protein modification, closely linked to steatotic liver disease in previous studies. However, there is no systematic review to clarify the relationship and investigate from the perspective of phosphorylation. Phosphorylation has been found to mainly regulate molecule stability, affect localization, transform molecular function, and cooperate with other protein modifications. Among them, adenosine 5'-monophosphate-activated protein kinase (AMPK), serine/threonine kinase (AKT), and nuclear factor kappa-B (NF-kB) are considered the core mechanisms in steatotic liver disease. As to treatment, lifestyle changes, prescription drugs, and herbal ingredients can alleviate symptoms by influencing phosphorylation. It demonstrates the significant role of phosphorylation as a mechanism occurrence and a therapeutic target in steatotic liver disease, which could be a new star for future exploration.

Liver-Targeting Composite Nanocarrier Delivery System Based on Chitosan Nanoparticles and Phospholipid Complexes

Liver fibrosis is mainly caused by excessive accumulation of extracellular matrix and structural changes in the liver, ultimately leading to cirrhosis if left untreated. Reducing hyaluronan synthesis by inhibiting hyaluronic acid deposition or regulating the expression of hyaluronic synthase can ameliorate liver fibrosis symptoms. In this study, we aimed to improve the bioavailability and liver-targeting capacity of hydroxymethyl coumarin (4-MU) using a newly developed phospholipid complex chitosan nanoparticle (4-MU PC/CNP) optimized using the Box-Behnken design. The composite nanocarrier delivery system was formulated using solvent evaporation technology, and formulation and process parameters were evaluated. Furthermore, 4-MU PC/CNPs and their pharmacokinetics were characterized. The established 4-MU PC/CNPs had an average particle size of 153.07 ± 0.29 nm, a polydispersity index value of 0.383, and a positive zeta potential of ∼35.4 mV. Compared with 4-MUs, 4-MU PC/CNPs exhibited significantly improved water solubility, faster plasma clearance and tissue distribution, and better liver targeting. Pharmacokinetic analysis showed that the oral bioavailability of 4-MU in 4-MU PC/CNPs was significantly higher than that of simple 4-MU. In conclusion, 4-MU PC improved drug lipid (oil-water distribution coefficient of 1.31 ± 0.03) and water solubilities (2.05 times the drug substance). 4-MU PC/CNPs significantly improved 4-MU oral bioavailability, representing a promising approach for enhancing drug solubility. This study demonstrates that the targeting parameters of 4-MU PC/CNPs in the liver were all greater than 1, indicating that they specifically targeted the liver, thereby potentially alleviating liver fibrosis.

The Dynamic Role of Endoplasmic Reticulum Stress in Chronic Liver Disease

Chronic liver disease (CLD) is a major worldwide public health threat, with an estimated prevalence of 1.5 billion individuals with CLD in 2020. Chronic activation of endoplasmic reticulum (ER) stress-related pathways is recognized as substantially contributing to the pathologic progression of CLD. The ER is an intracellular organelle that folds proteins into their correct three-dimensional shapes. ER-associated enzymes and chaperone proteins highly regulate this process. Perturbations in protein folding lead to misfolded or unfolded protein accumulation in the ER lumen, resulting in ER stress and concomitant activation of the unfolded protein response (UPR). The adaptive UPR is a set of signal transduction pathways evolved in mammalian cells that attempts to reestablish ER protein homeostasis by reducing protein load and increasing ER-associated degradation. However, maladaptive UPR responses in CLD occur due to prolonged UPR activation, leading to concomitant inflammation and cell death. This review assesses the current understanding of the cellular and molecular mechanisms that regulate ER stress and the UPR in the progression of various liver diseases and the potential pharmacologic and biological interventions that target the UPR.

Quercetin ameliorates nonalcoholic fatty liver disease (NAFLD) via the promotion of AMPK-mediated hepatic mitophagy

The global incidence of nonalcoholic fatty liver disease (NAFLD) has been surging in recent years, however, no drug is currently approved to treat this disease. Quercetin, a natural flavonoid abundant in plants and fruits, has been reported to alleviate NAFLD, however, the exact molecular mechanism remains unclear. This study aims to further elucidate its potential mechanism of action. The beneficial effects and the underlying mechanism of quercetin in alleviating NAFLD were explored both in vitro and in vivo, by employing chemical inhibitors of autophagosomes (3-methyladenine, 3-MA), autolysosomes (chloroquine, CQ), AMPK (Compound C, CC) and SIRT1 (selisistat, EX-527). The levels of intracellular lipids, reactive oxygen species, mitochondria function, autophagy, and mitophagy were assessed by fluorescent labeling and examined using flow cytometry or confocal microscopy. Key protein expressions of autophagy, mitophagy, and inflammation were also determined. In vivo, quercetin was shown to dose-dependently effectively alleviate NAFLD, but intraperitoneal injection of 3-MA could block the beneficial effects of quercetin on body weight, liver weight, serum ALT/AST, hepatic ROS and inflammation. In vitro, quercetin could reduce intracellular lipids (Nile Red staining) and ROS/DHE accumulation, which could be also blocked by 3-MA or CQ. Furthermore, we found that CC could abrogate the protective effects of quercetin on lipid and ROS accumulation in vitro. Also, CC abolished the proautophagic and anti-inflammatory effects of quercetin, as shown by western blot determination and Lyso-Tracker labeling. Importantly, mitophagy, a specific form of mitochondria-targeted autophagy, was enhanced by quercetin, as demonstrated by PINK1/Parkin protein variation and immunofluorescence colocalization of autophagosomes and mitochondria, which could also be blocked by the intervention of CC. This study demonstrates that quercetin prevents NAFLD through AMPK-mediated mitophagy and suggests that promoting mitophagy via an upregulation of AMPK may be a promising therapeutic strategy against NAFLD.

Umbelliferon: a review of its pharmacology, toxicity and pharmacokinetics

Coumarin, a plant secondary metabolite, has various pharmacological activities, including antioxidant stress and anti-inflammatory effects. Umbelliferone, a common coumarin compound found in almost all higher plants, has been extensively studied for its pharmacological effects in different disease models and doses with complex action mechanisms. This review aims to summarize these studies and provide useful information to relevant scholars. The pharmacological studies demonstrate that umbelliferone has diverse effects such as anti-diabetes, anti-cancer, anti-infection, anti-rheumatoid arthritis, neuroprotection, and improvement of liver, kidney, and myocardial tissue damage. The action mechanisms of umbelliferone include inhibition of oxidative stress, inflammation, and apoptosis, improvement of insulin resistance, myocardial hypertrophy, and tissue fibrosis, in addition to regulation of blood glucose and lipid metabolism. Among the action mechanisms, the inhibition of oxidative stress and inflammation is the most critical. In short, these pharmacological studies disclose that umbelliferone is expected to treat many diseases, and more research should be conducted.

Ferroptosis: a new strategy for Chinese herbal medicine treatment of diabetic nephropathy

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes. It has become a leading cause of death in patients with diabetes and end-stage renal disease. Ferroptosis is a newly discovered pattern of programmed cell death. Its main manifestation is the excessive accumulation of intracellular iron ion-dependent lipid peroxides. Recent studies have shown that ferroptosis is an important driving factor in the onset and development of DN. Ferroptosis is closely associated with renal intrinsic cell (including renal tubular epithelial cells, podocytes, and mesangial cells) damage in diabetes. Chinese herbal medicine is widely used in the treatment of DN, with a long history and definite curative effect. Accumulating evidence suggests that Chinese herbal medicine can modulate ferroptosis in renal intrinsic cells and show great potential for improving DN. In this review, we outline the key regulators and pathways of ferroptosis in DN and summarize the herbs, mainly monomers and extracts, that target the inhibition of ferroptosis.

Synthesis of 6-alkoxy and 6-hydroxy-alkyl amine derivatives of braylin as vasorelaxing agents

Braylin (10b) is a 8,8-dimethyl chromenocoumarin present in the plants of the family Rutaceae and Meliaceae and possesses vasorelaxing and anti-inflammatory activities. In this study, six 6-alkoxy (10b, 15-19), and twelve 6-hydroxy-alkyl amine (20a-20l) derivatives of braylin (11 and 12) were synthesized to delineate its structural requirement for vasorelaxing activity. The synthesized compounds were evaluated for vasorelaxation response in preconstricted intact rat Main Mesenteric Artery (MMA). The compounds showed l-type VDCC channel blockade depended and endothelium-independent vasorelaxation within the range of Emax < 50.00-96.70 % at 30 µM. Amongst all, 6-alkoxy derivatives were more active than 6-hydroxy-alkyl amine derivatives. The structural refinements about braylin showed that deletion of its methoxy group or homologation beyond ethoxy group presented deleterious effect on vasorelaxation response of braylin. Interestingly, substituting the ethoxy group in 10b presented the best activity and selectivity towards l-type VDCC channel blockade, a specific target cardiovascular function.

Planting conditions can enhance the bioactivity of mulberry by affecting its composition

Mulberry (Morus alba L.) has a special significance in the history of agriculture and economic plant cultivation. Mulberry has strong environmental adaptability, a wide planting range, and abundant output. It is not only an important resource for silkworm breeding but also a raw ingredient for various foods and has great potential for the development of biological resources. The bioactivities of mulberry in different planting areas are not the same, which is an obstacle to the development of mulberry. This study collected information on the planting conditions of mulberry branches in 12 planting areas, such as altitude, temperature difference, and precipitation. A comparison of the levels of 12 constituents of mulberry branches from mulberry grown in different planting areas was then made. An in vitro model was used to study the bioactivities of mulberry branches in the 12 planting areas, and mathematical analysis was used to explain the possible reasons for the differences in the composition and bioactivities of mulberry branches in different planting areas. After studying mulberry samples from 12 planting areas in China, it was found that a small temperature difference could affect the antiapoptotic effect of mulberry branch on microvascular endothelial cells by changing the levels and proportions of rutin, hyperoside, and morusin. Adequate irrigation can promote the antioxidation of the mulberry branch on microvascular endothelial cells by changing the levels and proportions of scopoletin and quercitrin. The results of the analysis of planting conditions and the levels of active constituents and their correlation with bioactivities support the improvement of mulberry planting conditions and have great significance in the rational development of mulberry resources. This is the first time that a mathematical analysis method was used to analyze the effects of planting conditions on mulberry biological activity.

Natural Compounds with Aldose Reductase (AR) Inhibition: A Class of Medicative Agents for Fatty Liver Disease

Fatty liver disease (FLD), which includes both non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (ALD), is a worldwide health concern. The etiology of ALD is long-term alcohol consumption, while NAFLD is defined as an abnormal amount of lipid present in liver cells, which is not caused by alcohol intake and has recently been identified as a hepatic manifestation of metabolic syndrome (such as type 2 diabetes, obesity, hypertension, and obesity). Inflammation, oxidative stress, and lipid metabolic dysregulation are all known to play a role in FLD progression. Alternative and natural therapies are desperately needed to treat this disease since existing pharmaceuticals are mostly ineffective. The aldose reductase (AR)/polyol pathway has recently been shown to play a role in developing FLD by contributing to inflammation, oxidative stress, apoptosis, and fat accumulation. Herein, we review the effects of plantderived compounds capable of inhibiting AR in FLD models. Natural AR inhibitors have been found to improve FLD in part by suppressing inflammation, oxidative stress, and steatosis via the regulation of several critical pathways, including the peroxisome proliferator-activated receptor (PPAR) pathway, cytochrome P450 2E1 (CYP2E1) pathway, AMP-activated protein kinase (AMPK) pathway, etc. This review revealed that natural compounds with AR inhibitory effects are a promising class of therapeutic agents for FLD.