Inhibition of microsomal lipid peroxidation by baicalein: a possible formation of an iron-baicalein complex

The metabolites from traditional Chinese medicine targeting ferroptosis for cancer therapy

Cancer is a major disease with ever-increasing morbidity and mortality. The metabolites derived from traditional Chinese medicine (TCM) have played a significant role in combating cancers with curative efficacy and unique advantages. Ferroptosis, an iron-dependent programmed death characterized by the accumulation of lipid peroxide, stands out from the conventional forms of cell death, such as apoptosis, pyroptosis, necrosis, and autophagy. Recent evidence has demonstrated the potential of TCM metabolites targeting ferroptosis for cancer therapy. We collected and screened related articles published in or before June 2023 using PubMed, Google Scholar, and Web of Science. The searched keywords in scientific databases were ferroptosis, cancer, tumor, traditional Chinese medicine, botanical drugs, and phytomedicine. Only research related to ferroptosis, the metabolites from TCM, and cancer was considered. In this review, we introduce an overview of the current knowledge regarding the ferroptosis mechanisms and review the research advances on the metabolites of TCM inhibiting cancer by targeting ferroptosis.

Pathophysiological aspects of transferrin-A potential nano-based drug delivery signaling molecule in therapeutic target for varied diseases

Transferrin (Tf), widely known for its role as an iron-binding protein, exemplifies multitasking in biological processes. The role of Tf in iron metabolism involves both the uptake of iron from Tf by various cells, as well as the endocytosis mediated by the complex of Tf and the transferrin receptor (TfR). The direct conjugation of the therapeutic compound and immunotoxin studies using Tf peptide or anti-Tf receptor antibodies as targeting moieties aims to prolong drug circulation time and augment efficient cellular drug uptake, diminish systemic toxicity, traverse the blood-brain barrier, restrict systemic exposure, overcome multidrug resistance, and enhance therapeutic efficacy with disease specificity. This review primarily discusses the various biological actions of Tf, as well as the development of Tf-targeted nano-based drug delivery systems. The goal is to establish the use of Tf as a disease-targeting component, accentuating the potential therapeutic applications of this protein.

The Regulatory Effects and the Signaling Pathways of Natural Bioactive Compounds on Ferroptosis

Natural bioactive compounds abundantly presented in foods and medicinal plants have recently received a remarkable attention because of their various biological activities and minimal toxicity. In recent years, many natural compounds appear to offer significant effects in the regulation of ferroptosis. Ferroptosis is the forefront of international scientific research which has been exponential growth since the term was coined. This type of regulated cell death is driven by iron-dependent phospholipid peroxidation. Recent studies have shown that numerous organ injuries and pathophysiological processes of many diseases are driven by ferroptosis, such as cancer, arteriosclerosis, neurodegenerative disease, diabetes, ischemia-reperfusion injury and acute renal failure. It is reported that the initiation and inhibition of ferroptosis plays a pivotal role in lipid peroxidation, organ damage, neurodegeneration and cancer growth and progression. Recently, many natural phytochemicals extracted from edible plants have been demonstrated to be novel ferroptosis regulators and have the potential to treat ferroptosis-related diseases. This review provides an updated overview on the role of natural bioactive compounds and the potential signaling pathways in the regulation of ferroptosis.

Prolyl oligopeptidase and its role in the organism: attention to the most promising and clinically relevant inhibitors

Prolyl oligopeptidase (POP), also called prolyl endopeptidase, is a cytosolic enzyme investigated by several research groups. It has been proposed to play an important role in physiological processes such as modulation of the levels of several neuronal peptides and hormones containing a proline residue. Due to its proteolytic activity and physiological role in cell signaling pathways, inhibition of POP offers an emerging approach for the treatment of Alzheimer's and Parkinson's diseases as well as other diseases related to cognitive impairment. Furthermore, it may also represent an interesting target for treatment of neuropsychiatric disorders, and as an antiangiogenesis or antineoplastic agent. In this review paper, we summarized naturally occurring POP inhibitors together with peptide-like inhibitors and their biological effects. Some of them have shown promising results and interesting pharmacological profiles. However, to date, there is no POP inhibitor available on the market although several clinical trials have been undertaken.

Neuroprotective herbs and foods from different traditional medicines and diets

Plant secondary metabolites include an array of bioactive constituents form both medicinal and food plants able to improve human health. The exposure to these phytochemicals, including phenylpropanoids, isoprenoids and alkaloids, through correct dietary habits, may promote health benefits, protecting against the chronic degenerative disorders mainly seen in Western industrialized countries, such as cancer, cardiovascular and neurodegenerative diseases. In this review, we briefly deal with some plant foods and herbs of traditional medicines and diets, focusing on their neuroprotective active components. Because oxidative stress and neuroinflammation resulting from neuroglial activation, at the level of neurons, microglial cells and astrocytes, are key factors in the etiopathogenesis of both neurodegenerative and neurological diseases, emphasis will be placed on the antioxidant and anti-inflammatory activity exerted by specific molecules present in food plants or in remedies prescribed by herbal medicines.

Iron-binding and anti-Fenton properties of baicalein and baicalin

Baicalein and baicalin, the major bioactive compounds found in the Chinese herb Scutellaria baicalensis, have been shown to be effective against cancer, bacterial infections and oxidative stress diseases. However, little is known about their mechanisms of action. To probe whether iron homeostasis modulation may play a role in their bioactivity, we have investigated their iron binding characteristics under physiologically relevant conditions. A 2:1 baicalein-ferrous complex was readily formed in 20mM phosphate buffer, pH 7.2, with a binding constant approximately 2-9 x 10(11)M(-2), whereas a 1:1 baicalein-ferric complex was formed, under the same conditions, with an apparent binding constant approximately 1-3 x 10(6)M(-1). Baicalein appears to bind the ferrous ion more strongly than ferrozine, a well known iron(II) chelator. Using (1) H NMR and Zn(2+) and Ga(3+) as probes, the iron-binding site on baicalein was elucidated to be at the O6/O7 oxygen atoms of the A-ring. No binding was observed for baicalin under the same NMR conditions. Furthermore, baicalein strongly inhibits the Fe-promoted Fenton chemistry via a combination of chelation and radical scavenging mechanism while baicalin can provide only partial protection against radical damage. These results indicate that baicalein is a strong iron chelator under physiological conditions and hence may play a vital role in modulating the body's iron homeostasis. Modulation of metal homeostasis and the inhibition of Fenton chemistry may be one of the possible mechanisms for herbal medicine.

[Alloxan radical-induced generation of reactive oxygen species in the reaction system of alloxan with ascorbate]

The diabetogenic action of alloxan is thought to be initiated by generation of reactive oxygen species (ROS). Ascorbate can be an antioxidant in a predominantly aqueous environment, such as plasma and extracellular fluids. We have investigated the generation of ROS in the interaction of alloxan with ascorbate. Rapid oxygen consumption was observed in the reactin system of alloxan with ascorbate. The oxygen consumption was suppressed by superoxide dismutase and catalase, suggesting that superoxide and hydrogen peroxide could be generated in the reaction system. In addition, the generation of alloxan radical, an electron reductance of alloxan, and ascorbate free radical (AFR), an electron oxidant of ascorbate, was observed using electron spin resonance (ESR). Under anaerobic conditions, the ESR signal intensity of alloxan radical was significantly increased in comparison with that under aerobic conditions, whereas the intensity of AFR was significantly decreased. These results suggest that alloxan radical and AFR were generated in the reaction system of alloxan with ascorbate, and that the alloxan radical but not AFR reacted with molecular oxygen, resulting in the generation of ROS.