Anti-inflammatory Effects and Mechanisms of Rhein, an Anthraquinone Compound, and Its Applications in Treating Arthritis: A Review

Abstract

Inflammation is a defensive response of living tissues to damaging agents, which exists in two forms, acute inflammation and chronic inflammation, and chronic inflammation is closely related to arthritis. Currently, the commonly prescribed anti-inflammatory medications are greatly limited by high incidence of gastrointestinal erosions in the clinical applications. Rhein, a bioactive constituent of anthraquinone, exhibits excellent anti-inflammatory activities and therapeutic effects on arthritis with less gastrointestinal damages. Although there are numbers of studies on anti-inflammatory effects and mechanisms of rhein in the last few decades, to the best of our knowledge, only a few review articles pay attention to the interactive relationships of rhein on multiple inflammatory signaling pathways and cellular processes from a comprehensive perspective. Herein, we summarized anti-inflammatory effects and mechanisms of rhein and its practical applications in the treatment of arthritis, thereby providing a reference for its basic researches and clinical applications.

Obtusifolin, an Anthraquinone Extracted from Senna obtusifolia (L.) H.S.Irwin & Barneby, Reduces Inflammation in a Mouse Osteoarthritis Model

“…Reportedly, several anthraquinone substances are present in the seeds of S. obtusifolia , of which aurantio-obtusin is the most abundant [ 39 ]. Furthermore, other substances such as rhein, aloe-emodin, and emodin are also known to have arthritis-related anti-inflammatory properties [ 19 , 41 , 42 , 43 ]. These anthraquinones and their derivatives are commonly used as pharmaceutical ingredients [ 16 , 19 ].…”

“…However, the function of obtusifolin in OA is currently unknown. As studies have shown that anthraquinones have anti-inflammatory effects [ 16 , 19 , 41 , 42 , 43 ] and the NF-κB pathway is regulated by obtusifolin [ 27 ], we hypothesized that obtusifolin would have a sufficient OA inhibitory effect.…”

Update on Pharmacological Activities, Security, and Pharmacokinetics of Rhein

“…The I κ B kinase P (IKK β )/nuclear transcription factor (NF- κ B) pathway is known as the most promising target for anti-inflammatory drug in recent studies. Rhein is the active metabolite of diacerein, which exerts anti-inflammatory activity mainly through the IKK β /NF- κ B pathway without gastrointestinal damage [ 77 ].…”

Antagonism of the ATP-gated P2X7 receptor: a potential therapeutic strategy for cancer

“…Several naturally occurring compounds have also been shown to antagonise P2X7R with the potential to be therapeutically valuable. This includes compounds such as Rhein, Emodin, Teniposide, and Baicalein which have all been demonstrated to inhibit P2X7R function in different contexts [112][113][114][115][116]. Whilst these compounds all show P2X7R antagonising properties, there has been limited studies completed in the context of cancer, with only Emodin specifically being investigated in breast cancer cells and shown to limit cancer cell invasion [117].…”