The Effects and Mechanisms of Xanthones in Alzheimer's Disease: A Systematic Review

Natural xanthones as modulators of the Nrf2/ARE signaling pathway and potential gastroprotective agents

Oxidative stress is implicated in the initiation, pathogenesis, and progression of various gastric inflammatory diseases (GID). The prevalence of these diseases remains a concern along with the increasing risks of adverse effects in current clinical interventions. Hence, new gastroprotective agents capable of inhibiting oxidative stress by modulating cellular defense systems such as the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway are critically needed to address these issues. A candidate to solve the present issue is xanthone, a natural compound that reportedly exerts gastroprotective effects via antioxidant, anti-inflammatory, and cytoprotective mechanisms. Moreover, xanthone derivatives were shown to modulate the Nrf2/ARE signaling pathway to counter oxidative stress in both in vitro and in vivo models. Thirteen natural xanthones have demonstrated the ability to modulate the Nrf2/ARE signaling pathway and have high potential as lead compounds for GID as indicated by their in vivo gastroprotective action-particularly mangiferin (2), α-mangostin (3), and γ-mangostin (4). Further studies on these compounds are recommended to validate the Nrf2 modulatory ability in relation to their gastroprotective action.

Navigating the Maze of Alzheimer's disease by exploring BACE1: Discovery, current scenario, and future prospects

Alzheimer's disease (AD) is a chronic neurological condition that has become a leading cause of cognitive decline in elder individuals. Hardly any effective medication has been developed to halt the progression of AD due to the disease's complexity. Several theories have been put forward to clarify the mechanisms underlying AD etiology. The identification of amyloid plaques as a hallmark of AD has sparked the development of numerous drugs targeting the players involved in the amyloidogenic pathway, such as the β-site of amyloid precursor protein cleavage enzyme 1 (BACE1) blockers. Over the last ten years, preclinical and early experimental research has led several pharmaceutical companies to prioritize producing BACE1 inhibitors. Despite all these efforts, earlier discovered inhibitors were discontinued in consideration of another second-generation small molecules and recent BACE1 antagonists failed in the final stages of clinical trials because of the complications associated either with toxicity or effectiveness. In addition to discussing the difficulties associated with development of BACE1 inhibitors, this review aims to provide an overview of BACE1 and offer perspectives on the causes behind the failure of five recent BACE1 inhibitors, that would be beneficial for choosing effective treatment approaches in the future.