Alisol B 23-Acetate Increases the Antitumor Effect of Bufalin on Liver Cancer through Inactivating Wnt/β-Catenin Axis

An overview of the past decade of bufalin in the treatment of refractory and drug-resistant cancers: current status, challenges, and future perspectives

Profound progress has been made in cancer treatment in the past three decades. However, drug resistance remains prevalent and a critical challenge. Drug resistance can be attributed to oncogenes mutations, activated defensive mechanisms, ATP-bind cassette transporters overexpression, cancer stem cells, etc. Chinese traditional medicine toad venom has been used for centuries for different diseases, including resistant cancers. Bufalin is one of the bufadienolides in toad venom that has been extensively studied for its potential in refractory and drug-resistant cancer treatments in vitro and in vivo. In this work, we would like to critically review the progress made in the past decade (2013-2022) of bufalin in overcoming drug resistance in cancers. Generally, bufalin shows high potential in killing certain refractory and resistant cancer cells via multiple mechanisms. More importantly, bufalin can work as a chemo-sensitizer that enhances the sensitivity of certain conventional and targeted therapies at low concentrations. In addition, the development of bufalin derivatives was also briefly summarized and discussed. We also analyzed the obstacles and challenges and provided possible solutions for future perspectives. We hope that the collective information may help evoke more effort for more in-depth studies and evaluation of bufalin in both lab and possible clinical trials.

Retracted: Alisol B 23-Acetate Increases the Antitumor Effect of Bufalin on Liver Cancer through Inactivating Wnt/β-Catenin Axis

[This retracts the article DOI: 10.1155/2022/6249534.].

The roles of serine hydrolases and serum albumin in alisol B 23-acetate hydrolysis in humans

Introduction: Alisol B 23-acetate (AB23A), a major bioactive constituent in the Chinese herb Zexie (Rhizoma Alismatis), has been found with multiple pharmacological activities. AB23A can be readily hydrolyzed to alisol B in mammals, but the hydrolytic pathways of AB23A in humans and the key enzymes responsible for AB23A hydrolysis are still unrevealed. This study aims to reveal the metabolic organs and the crucial enzymes responsible for AB23A hydrolysis in human biological systems, as well as to decipher the impact of AB23A hydrolysis on its biological effects. Methods: The hydrolytic pathways of AB23A in human plasma and tissue preparations were carefully investigated by using Q-Exactive quadrupole-Orbitrap mass spectrometer and LC-UV, while the key enzymes responsible for AB23A hydrolysis were studied via performing a set of assays including reaction phenotyping assays, chemical inhibition assays, and enzyme kinetics analyses. Finally, the agonist effects of both AB23A and its hydrolytic metabolite(s) on FXR were tested at the cellular level. Results: AB23A could be readily hydrolyzed to form alisol B in human plasma, intestinal and hepatic preparations, while human butyrylcholinesterase (hBchE) and human carboxylesterases played key roles in AB23A hydrolysis in human plasma and tissue preparations, respectively. It was also found that human serum albumin (hSA) could catalyze AB23A hydrolysis, while multiple lysine residues of hSA were covalently modified by AB23A, suggesting that hSA catalyzed AB23A hydrolysis via its pseudo-esterase activity. Biological tests revealed that both AB23A and alisol B exhibited similar FXR agonist effects, indicating AB23A hydrolysis did not affect its FXR agonist effect. Discussion: This study deciphers the hydrolytic pathways of AB23A in human biological systems, which is very helpful for deep understanding of the metabolic rates of AB23A in humans, and useful for developing novel prodrugs of alisol B with desirable pharmacokinetic behaviors.

Pharmacological Properties and Molecular Targets of Alisol Triterpenoids from Alismatis Rhizoma

More than 100 protostane triterpenoids have been isolated from the dried rhizomes of Alisma species, designated Alismatis rhizoma (AR), commonly used in Asian traditional medicine to treat inflammatory and vascular diseases. The main products are the alisols, with the lead compounds alisol-A/-B and their acetate derivatives being the most abundant products in the plant and the best-known bioactive products. The pharmacological effects of Ali-A, Ali-A 24-acetate, Ali-B, Ali-B 23-acetate, and derivatives have been analyzed to provide an overview of the medicinal properties, signaling pathways, and molecular targets at the origin of those activities. Diverse protein targets have been proposed for these natural products, including the farnesoid X receptor, soluble epoxide hydrolase, and other enzymes (AMPK, HCE-2) and functional proteins (YAP, LXR) at the origin of the anti-atherosclerosis, anti-inflammatory, antioxidant, anti-fibrotic, and anti-proliferative activities. Activities were classified in two groups. The lipid-lowering and anti-atherosclerosis effects benefit from robust in vitro and in vivo data (group 1). The anticancer effects of alisols have been largely reported, but, essentially, studies using tumor cell lines and solid in vivo data are lacking (group 2). The survey shed light on the pharmacological properties of alisol triterpenoids frequently found in traditional phytomedicines.