Advances in the study of emodin: an update on pharmacological properties and mechanistic basis

Abstract

Rhei Radix et Rhizoma, also known as rhubarb or Da Huang, has been widely used as a spice and as traditional herbal medicine for centuries, and is currently marketed in China as the principal herbs in various prescriptions, such as Da-Huang-Zhe-Chong pills and Da-Huang-Qing-Wei pills. Emodin, a major bioactive anthraquinone derivative extracted from rhubarb, represents multiple health benefits in the treatment of a host of diseases, such as immune-inflammatory abnormality, tumor progression, bacterial or viral infections, and metabolic syndrome. Emerging evidence has made great strides in clarifying the multi-targeting therapeutic mechanisms underlying the efficacious therapeutic potential of emodin, including anti-inflammatory, immunomodulatory, anti-fibrosis, anti-tumor, anti-viral, anti-bacterial, and anti-diabetic properties. This comprehensive review aims to provide an updated summary of recent developments on these pharmacological efficacies and molecular mechanisms of emodin, with a focus on the underlying molecular targets and signaling networks. We also reviewed recent attempts to improve the pharmacokinetic properties and biological activities of emodin by structural modification and novel material-based targeted delivery. In conclusion, emodin still has great potential to become promising therapeutic options to immune and inflammation abnormality, organ fibrosis, common malignancy, pathogenic bacteria or virus infections, and endocrine disease or disorder. Scientifically addressing concerns regarding the poor bioavailability and vague molecular targets would significantly contribute to the widespread acceptance of rhubarb not only as a dietary supplement in food flavorings and colorings but also as a health-promoting TCM in the coming years.

Enzymatic Synthesis of Bioactive O-Glucuronides Using Plant Glucuronosyltransferases

“…31 Emodin ( 12) is an important component of the traditional Chinese herb Rhubarb (Da Huang) and has various efficacies, including causing bacteriostasis, anti-inflammatory effects, and protective effects on the liver and kidney. 32 Magnolol ( 13) is an active antibacterial component in Magnolia of f icinalis Rehd. et Wils with special, long-lasting muscle relaxant effects.…”

Recent Advances in the Role of Nuclear Factor Erythroid-2-Related Factor 2 in Spinal Cord Injury: Regulatory Mechanisms and Therapeutic Options

“…It is widely used as a spice and traditional herb which exists in the rhizomes and roots of Polygonaceae plants Rheum palmatum and Rheum tanguticum in free and glycoside form. Emodin has been proven to have a variety of pharmacological effects, including anti-inflammatory, immunomodulatory, anti-fibrosis, anti-tumor, anti-viral, antibacterial, and anti-diabetic effects (Zheng Q. et al, 2021). Zeng et al (2018) studied the effect of emodin on oxidative stress and inflammatory damage in acute SCI rats.…”

Promising Role of Emodin as Therapeutics to Against Viral Infections

“…The chemical structure of emodin is depicted in Figure 1 . In general, emodin exerts its pharmacological activity at concentrations of a few tens of μM ( Zheng et al, 2021 ). In pharmacokinetic experiments, after intragastric administration, emodin was quickly absorbed from the gastrointestinal tract and then rapidly metabolized to form its glucuronide, and the parent form of emodin was barely detectable in vivo ( Shia et al, 2010 ).…”

“…Urinary excretion was 18 and 22% at 24 and 72 h, respectively, free emodin and emodin acid were principal metabolites found in the pooled urine ( Mueller et al, 1999 ; Monisha et al, 2016 ). Although emodin is known to be rapidly soluble in DMSO, ethanol or alkaline solutions, it is practically insoluble in water ( Zheng et al, 2021 ). In addition to this, the significant first-pass elimination effect of emodin in the liver and intestine determines its low oral bioavailability ( Teng et al, 2012 ).…”

“…Emodin (1,3,8-trihydroxy-6-methylanthraquinone, C15H10O5) is an anthraquinone derivative, which has been identified in 17 families of natural plants ( Zheng et al, 2021 ), including Rheum palmatum , Polygonum cuspidatum , Polygonum multiflorum ( Ahn et al, 2016 ; Li et al, 2016 ), Cassiae semen ( Yang et al, 2019 ), etc. These herbs have long been used as antibacterial, anti-inflammatory, anti-fibrotic and anticancer, anti-aging, anti-hyperlipidaemia, antidiabetic, neuroprotective, hepatoprotective, antioxidant, laxative and hypotensive activities and treatment of infection medicine in China ( Peng et al, 2013 ; Lin L et al, 2015 ; Dong et al, 2017 ; Xiang et al, 2020 ).…”