Antioxidant and Anti-Inflammatory Effects of Garlic in Ischemic Stroke: Proposal of a New Mechanism of Protection through Regulation of Neuroplasticity

Stroke represents one of the main causes of death and disability in the world; despite this, pharmacological therapies against stroke remain insufficient. Ischemic stroke is the leading etiology of stroke. Different molecular mechanisms, such as excitotoxicity, oxidative stress, and inflammation, participate in cell death and tissue damage. At a preclinical level, different garlic compounds have been evaluated against these mechanisms. Additionally, there is evidence supporting the participation of garlic compounds in other mechanisms that contribute to brain tissue recovery, such as neuroplasticity. After ischemia, neuroplasticity is activated to recover cognitive and motor function. Some garlic-derived compounds and preparations have shown the ability to promote neuroplasticity under physiological conditions and, more importantly, in cerebral damage models. This work describes damage/repair mechanisms and the importance of garlic as a source of antioxidant and anti-inflammatory agents against damage. Moreover, we examine the less-explored neurotrophic properties of garlic, culminating in proposals and observations based on our review of the available information. The aim of the present study is to propose that garlic compounds and preparations could contribute to the treatment of ischemic stroke through their neurotrophic effects.

The antinociceptive effect of garlic, garlic preparations, and derivative compounds

The antinociceptive effects of garlic have shown promise in treating different chronic diseases in humans, such as knee osteoarthritis, rheumatoid arthritis, and peripheral arterial occlusive disease stage II. The most common garlic products are garlic powder (dried garlic), steam distilled garlic oils, garlic oil macerate, and aged garlic extract. These commercial products contain organosulfur compounds (OSC) that have been extensively evaluated in preclinical models and some clinical assays to treat different diseases against pain. In this review, we describe the importance of some bioactive compounds found in garlic and its role in treating pain. A systematic search of the literature in Dimensions, PubMed, Scopus, Web of Science was performed. Terms and preselected keywords relating to garlic, its derivates and organusulfur compunds in pain, were used to perform a systematic literature search. Two independent reviewers screened papers for inclusion and assessed the methodological quality. The antinociceptive activity of garlic and its OSC is related to its antioxidant and anti-inflammatory properties, which may be explained by the ability to block the synthesis of PGs, pro-inflammatory cytokines and interferon-γ, by the reduction COX- 2 activity and by increases the levels of anti-inflammatory cytokines. Besides, garlic extract is an activator of TRPA1 and TRPV1, where the principal responsible for this activation are OSC. The relationship between these pathways allows a better understanding how garlic and its derivates could be carrying out its pharmacological action over the management of acute and chronic pain and provide a base by further investigations.

Antitumor Effects of Natural Compounds Derived from Allium sativum on Neuroblastoma: An Overview

Garlic (Allium sativum) has been used in alternative medicine to treat several diseases, such as cardiovascular and neurodegenerative diseases, cancer, and hepatic diseases. Several publications have highlighted other features of garlic, including its antibacterial, antioxidative, antihypertensive, and antithrombotic properties. The properties of garlic result from the combination of natural compounds that act synergistically and cause different effects. Some garlic-derived compounds have been studied for the treatment of several types of cancer; however, reports on the effects of garlic on neuroblastoma are scarce. Neuroblastoma is a prevalent childhood tumor for which the search for therapeutic alternatives to improve treatment without affecting the patients’ quality of life continues. Garlic-derived compounds hold potential for the treatment of this type of cancer. A review of articles published to date on some garlic compounds and their effect on neuroblastoma was undertaken to comprehend the possible therapeutic role of these compounds. This review aimed to analyze the impact of some garlic compounds on cells derived from neuroblastoma.

Canonical and non-canonical mechanisms of Nrf2 activation

Nuclear Factor Erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates the expression of genes involved in the metabolism, immune response, cellular proliferation, and other processes; however, the attention has been focused on the study of its ability to induce the expression of proteins involved in the antioxidant defense. Nrf2 is mainly regulated by Kelch-like ECH-associated protein 1 (Keap1), an adapter substrate of Cullin 3 (Cul3) ubiquitin E3 ligase complex. Keap1 represses Nrf2 activity in the cytoplasm by its sequestering, ubiquitination and proteosomal degradation. Nrf2 activation, through the canonical mechanism, is carried out by electrophilic compounds and oxidative stress where some cysteine residues in Keap1 are oxidized, resulting in a decrease in Nrf2 ubiquitination and an increase in its nuclear translocation and activation. In the nucleus, Nrf2 induces a variety of genes involved in the antioxidant defense. Recently a new mechanism of Nrf2 activation has been described, called the non-canonical pathway, where proteins such as p62, p21, dipeptidyl peptidase III (DPP3), wilms tumor gene on X chromosome (WTX) and others are able to disrupt the Nrf2-Keap1 complex, by direct interaction with Keap1 decreasing Nrf2 ubiquitination and increasing its nuclear translocation and activation. In this review, the regulatory mechanisms involved in both canonical and non-canonical Nrf2 activation are discussed.