Key factors which concur to the correct therapeutic evaluation of herbal products in free radical-induced diseases

Curcumin and Heme Oxygenase: Neuroprotection and Beyond

Curcumin is a natural polyphenol component of Curcuma longa Linn, which is currently considered one of the most effective nutritional antioxidants for counteracting free radical-related diseases. Several experimental data have highlighted the pleiotropic neuroprotective effects of curcumin, due to its activity in multiple antioxidant and anti-inflammatory pathways involved in neurodegeneration. Although its poor systemic bioavailability after oral administration and low plasma concentrations represent restrictive factors for curcumin therapeutic efficacy, innovative delivery formulations have been developed in order to overwhelm these limitations. This review provides a summary of the main findings involving the heme oxygenase/biliverdin reductase system as a valid target in mediating the potential neuroprotective properties of curcumin. Furthermore, pharmacokinetic properties and concerns about curcumin's safety profile have been addressed.

Ginsenosides, catechins, quercetin and gut microbiota: Current evidence of challenging interactions

Recent studies have shown the role of gut microbiota in favoring the absorption of herbal products and the transformation of their active principles into metabolites endowed with biological activity. This review focuses on the evidence supporting the changes occurring, after metabolic reactions by specific bacteria that colonize the human gut, to ginseng-derived ginsenosides, green tea-derived catechins, and quercetin, this latter being a flavonoid aglycon bound to sugars and abundant in some vegetables and roots. Furthermore, the results of several studies demonstrating the potential beneficial effects of the active metabolites generated by these biotransformations on ginsenosides, catechins and quercetin will be reported.

Pioglitazone Represents an Effective Therapeutic Target in Preventing Oxidative/Inflammatory Cochlear Damage Induced by Noise Exposure

Recent progress in hearing loss research has provided strong evidence for the imbalance of cellular redox status and inflammation as common predominant mechanisms of damage affecting the organ of Corti including noise induced hearing loss. The discovery of a protective molecule acting on both mechanisms is challenging. The thiazolidinediones, a class of antidiabetic drugs including pioglitazone and rosiglitazone, have demonstrated diverse pleiotrophic effects in many tissues where they exhibit anti-inflammatory, anti-proliferative, tissue protective effects and regulators of redox balance acting as agonist of peroxisome proliferator-activated receptors (PPARs). They are members of the family of ligand regulated nuclear hormone receptors that are also expressed in several cochlear cell types, including the outer hair cells. In this study, we investigated the protective capacity of pioglitazone in a model of noise-induced hearing loss in Wistar rats and the molecular mechanisms underlying this protective effects. Specifically, we employed a formulation of pioglitazone in a biocompatible thermogel providing rapid, uniform and sustained inner ear drug delivery via transtympanic injection. Following noise exposure (120 dB, 10 kHz, 1 h), different time schedules of treatment were employed: we explored the efficacy of pioglitazone given immediately (1 h) or at delayed time points (24 and 48 h) after noise exposure and the time course and extent of hearing recovery were assessed. We found that pioglitazone was able to protect auditory function at the mid-high frequencies and to limit cell death in the cochlear basal/middle turn, damaged by noise exposure. Immunofluorescence and western blot analysis provided evidence that pioglitazone mediates both anti-inflammatory and anti-oxidant effects by decreasing NF-κB and IL-1β expression in the cochlea and opposing the oxidative damage induced by noise insult. These results suggest that intratympanic pioglitazone can be considered a valid therapeutic strategy for attenuating noise-induced hearing loss and cochlear damage, reducing inflammatory signaling and restoring cochlear redox balance.

Alzheimer's disease and gut microbiota modifications: The long way between preclinical studies and clinical evidence

Recent studies have suggested the role of an infectious component in the pathogenesis of Alzheimer's disease (AD). In light of this, research has focused on some bacteria constituting the intestinal microbial flora which can produce amyloid. Once generated, the latter hypothetically triggers a systemic inflammatory response which compromises complex brain functions, such as learning and memory. Clinical studies have shown that, in cognitively impaired elderly patients with brain amyloidosis, there is lower abundance in the gut of E. rectale and B. fragilis, two bacterial species which have an anti-inflammatory activity, versus a greater amount of pro-inflammatory genera such as Escherichia/Shigella. According to these findings, some clinical studies have demonstrated that supplementation with Lactobacilli- and Bifidobacteria- based probiotics has improved cognitive, sensory and emotional functions in subjects with AD. Moreover, certain herbal products, in particular dietetic polyphenols, have proved capable of restoring dysbiosis and, therefore, their prebiotic role could be effective in counteracting the onset of AD regardless of their activity of free radical scavenging or enhancement of the cell stress response. One of the recent greatest novelties in the field of neurodegenerative diseases is the chance to prevent or slow down AD progression with agents, such as probiotics and prebiotics, acting outside the central nervous system.

Cochlear Homocysteine Metabolism at the Crossroad of Nutrition and Sensorineural Hearing Loss

Hearing loss (HL) is one of the most common causes of disability, affecting 360 million people according to the World Health Organization (WHO). HL is most frequently of sensorineural origin, being caused by the irreversible loss of hair cells and/or spiral ganglion neurons. The etiology of sensorineural HL (SNHL) is multifactorial, with genetic and environmental factors such as noise, ototoxic substances and aging playing a role. The nutritional status is central in aging disability, but the interplay between nutrition and SNHL has only recently gained attention. Dietary supplementation could therefore constitute the first step for the prevention and potential repair of hearing damage before it reaches irreversibility. In this context, different epidemiological studies have shown correlations among the nutritional condition, increased total plasma homocysteine (tHcy) and SNHL. Several human genetic rare diseases are also associated with homocysteine (Hcy) metabolism and SNHL confirming this potential link. Accordingly, rodent experimental models have provided the molecular basis to understand the observed effects. Thus, increased tHcy levels and vitamin deficiencies, such as folic acid (FA), have been linked with SNHL, whereas long-term dietary supplementation with omega-3 fatty acids improved Hcy metabolism, cell survival and hearing acuity. Furthermore, pharmacological supplementations with the anti-oxidant fumaric acid that targets Hcy metabolism also improved SNHL. Overall these results strongly suggest that cochlear Hcy metabolism is a key player in the onset and progression of SNHL, opening the way for the design of prospective nutritional therapies.

Bioactives in Chinese Proprietary Medicine Modulates 5α-Reductase Activity and Gene Expression Associated with Androgenetic Alopecia

Androgenetic alopecia (AGA) is characterized by a progressive and patterned transformation of thick, pigmented terminal scalp hairs into short, hypo-pigmented vellus-like hairs. The use of Minoxidil and Finasteride to treat AGA are often associated with complications in safety and efficacy. However, herbal remedies are deemed to have lesser side effects in many societies. This study aims to identify potential hair growth properties of individual compounds from a Chinese proprietary medicine known as Yangxue Shengfa capsule (YSC), used in China for many years for improving AGA. Six marker compounds, including 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), Chlorogenic acid, Emodin, Ferulic acid, Isoimperatorin, and Paeoniflorin were used for simultaneous HPLC quantification and anti-AGA in-vitro screening. Simultaneous quantification of these components was performed on 75% (v/v) methanol extracts of YSC, using a Welch Ultimate XB-C18 column and gradient elution. Five compounds significantly promoted cell proliferation in cultured immortalized human Dermal Papilla Cells (DPC). Multiple genes associated with the progression of AGA, including IGF-1, DKK-1, and TGF-β1, were found to be regulated by some of these compounds. Interestingly, Ferulic acid and Emodin demonstrated good pharmacological properties against AGA, thereby concluding the potential of these bioactives to be used in the treatment against AGA.

Management of Benign Prostatic Hyperplasia: Could Dietary Polyphenols Be an Alternative to Existing Therapies?

The incidence of benign prostatic hyperplasia (BPH) is gradually on the increase. While conventional drugs such as the α1-adrenergic receptor antagonists and 5α-reductase inhibitors have been found to be useful in the treatment of BPH, the adverse side effects associated with their usage, have led to increased search for alternative means of managing this disease. Furthermore, although surgery has also been suggested to be a sure method, the cost and risks associated with it excludes it as a routine treatment. Dietary polyphenols have gained public interest in recent times due to their roles in the prevention of various diseases that implicate free radicals/reactive oxygen species. However, their roles in the management of BPH have not been explored. Hence, this review on their prospects in the management of BPH and their mechanisms of action. Literature search was carried out in several electronic data bases such as PubMed, Google Scholar, Medline, Agora, and Hinari from1970 to 2017 to identify the current status of knowledge on this concept. The findings from these data bases suggest that while dietary polyphenols may not replace the need for the existing therapies in the management of BPH, they hold promise in BPH management which could be explored by researchers working in this field.

Putative Role of Red Wine Polyphenols against Brain Pathology in Alzheimer's and Parkinson's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common age-related neurodegenerative disorders and hence pose remarkable socio-economical burdens to both families and state. Although AD and PD have different clinical and neuropathological features, they share common molecular mechanisms that appear to be triggered by multi-factorial events, such as protein aggregation, mitochondrial dysfunction, oxidative stress (OS), and neuroinflammation, ultimately leading to neuronal cell death. Currently, there are no established and validated disease-modifying strategies for either AD or PD. Among the various lifestyle factors that may prevent or slow age-related neurodegenerative diseases, epidemiological studies on moderate consumption of red wine, especially as part of a holistic Mediterranean diet, have attracted increasing interest. Red wine is particularly rich in specific polyphenolic compounds that appear to affect the biological processes of AD and PD, such as quercetin, myricetin, catechins, tannins, anthocyanidins, resveratrol, and ferulic acid. Indeed, there is now a consistent body of in vitro and in vivo data on the neuroprotective effects of red wine polyphenols (RWP) showing that they do not merely possess antioxidant properties, but may additionally act upon, in a multi-target manner, the underlying key mechanisms featuring in both AD and PD. Furthermore, it is important that bioavailability issues are addressed in order for neuroprotection to be relevant in a clinical study scenario. This review summarizes the current knowledge about the major classes of RWP and places into perspective their potential to be considered as nutraceuticals to target neuropathology in AD and PD.

Curcumin, Silybin Phytosome(®) and α-R-Lipoic Acid Mitigate Chronic Hepatitis in Rat by Inhibiting Oxidative Stress and Inflammatory Cytokines Production

Chronic hepatitis is recognized as a worldwide health problem that gradually progresses towards cirrhosis and hepatocellular carcinoma. Despite the large number of experiments using animal models for allergic hepatitis, it is still difficult to produce a picture of chronic hepatitis. Therefore, this study was conducted to introduce an animal model approximating to the mechanism of chronicity in human hepatitis. The study also aimed to examine the hepatoprotective effects of curcumin, silybin phytosome(®) and α-R-lipoic acid against thioacetamide (TAA)-induced chronic hepatitis in rat model. TAA was administered intraperitoneally at a dose of 200 mg/kg three times weekly for 4 weeks. At the end of this period, a group of rats was killed to assess the development of chronic hepatitis in comparison with their respective control group. TAA administration was then discontinued, and the remaining animals were subsequently allocated into four groups. Group 1 was left untreated, whereas groups 2-4 were allowed to receive daily oral doses of curcumin, silybin phytosome(®) or α-R-lipoic acid, respectively, for 7 weeks. Increases in hepatic levels of malondialdehyde associated with TAA administration were inhibited in groups receiving supplements. Furthermore, glutathione depletion, collagen deposition, macrophage activation and nuclear factor κappa-B expression as well as tumour necrosis factor-α and interleukin-6 levels were significantly decreased in response to supplements administration. Serological analysis of liver function and liver histopathological examination reinforced the results. The above evidence collectively indicates that the antioxidant and anti-inflammatory activities of curcumin, silybin phytosome(®) and α-R-lipoic acid may confer therapeutic efficacy against chronic hepatitis.

Curcumin Attenuates Iron Accumulation and Oxidative Stress in the Liver and Spleen of Chronic Iron-Overloaded Rats

Objectives

Iron overload is now recognized as a health problem in industrialized countries, as excessive iron is highly toxic for liver and spleen. The potential use of curcumin as an iron chelator has not been clearly identified experimentally in iron overload condition. Here, we evaluate the efficacy of curcumin to alleviate iron overload-induced hepatic and splenic abnormalities and to gain insight into the underlying mechanisms.

Design and Methods

Three groups of male adult rats were treated as follows: control rats, rats treated with iron in a drinking water for 2 months followed by either vehicle or curcumin treatment for 2 more months. Thereafter, we studied the effects of curcumin on iron overload-induced lipid peroxidation and anti-oxidant depletion.

Results

Treatment of iron-overloaded rats with curcumin resulted in marked decreases in iron accumulation within liver and spleen. Iron-overloaded rats had significant increases in malonyldialdehyde (MDA), a marker of lipid peroxidation and nitric oxide (NO) in liver and spleen when compared to control group. The effects of iron overload on lipid peroxidation and NO levels were significantly reduced by the intervention treatment with curcumin (P<0.05). Furthermore, the endogenous anti-oxidant activities/levels in liver and spleen were also significantly decreased in chronic iron overload and administration of curcumin restored the decrease in the hepatic and splenic antioxidant activities/levels.

Conclusion

Our study suggests that curcumin may represent a new horizon in managing iron overload-induced toxicity as well as in pathological diseases characterized by hepatic iron accumulation such as thalassemia, sickle cell anemia, and myelodysplastic syndromes possibly via iron chelation, reduced oxidative stress derived lipid peroxidation and improving the body endogenous antioxidant defense mechanism.

Ferulic Acid: A Hope for Alzheimer's Disease Therapy from Plants

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the deposition of extracellular amyloid-beta peptide (Aβ) and intracellular neurofibrillar tangles, associated with loss of neurons in the brain and consequent learning and memory deficits. Aβ is the major component of the senile plaques and is believed to play a central role in the development and progress of AD both in oligomer and fibril forms. Inhibition of the formation of Aβ fibrils as well as the destabilization of preformed Aβ in the Central Nervous System (CNS) would be an attractive therapeutic target for the treatment of AD. Moreover, a large number of studies indicate that oxidative stress and mitochondrial dysfunction may play an important role in AD and their suppression or reduction via antioxidant use could be a promising preventive or therapeutic intervention for AD patients. Many antioxidant compounds have been demonstrated to protect the brain from Aβ neurotoxicity. Ferulic acid (FA) is an antioxidant naturally present in plant cell walls with anti-inflammatory activities and it is able to act as a free radical scavenger. Here we present the role of FA as inhibitor or disaggregating agent of amyloid structures as well as its effects on biological models.