Chemical and biological evaluation of nephrocizin in protecting nerve growth factor-differentiated PC12 cells by 6-hydroxydopamine-induced neurotoxicity

An Overview of Crucial Dietary Substances and Their Modes of Action for Prevention of Neurodegenerative Diseases

Neurodegenerative diseases, namely Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis are becoming one of the main health concerns due to the increasing aging of the world's population. These diseases often share the same biological mechanisms, including neuroinflammation, oxidative stress, and/or protein fibrillation. Recently, there have been many studies published pointing out the possibilities to reduce and postpone the clinical manifestation of these deadly diseases through lifelong consumption of some crucial dietary substances, among which phytochemicals (e.g., polyphenols) and endogenous substances (e.g., acetyl-L-carnitine, coenzyme Q10, n-3 poysaturated fatty acids) showed the most promising results. Another important issue that has been pointed out recently is the availability of these substances to the central nervous system, where they have to be present in high enough concentrations in order to exhibit their neuroprotective properties. As so, such the aim of this review is to summarize the recent findings regarding neuroprotective substances, their mechanisms of action, as well as to point out therapeutic considerations, including their bioavailability and safety for humans.

Bio-effectiveness of the main flavonoids of Achillea millefolium in the pathophysiology of neurodegenerative disorders- a review

The Achillea millefolium L. (Yarrow) is a common herb which is widely being used, worldwide. Achillea is being used for treatment of many disorders since centuries. It is considered safe for supplemental use and flavonoids such as kaempferol, luteolin and apigenin are of main constituents present in Achillea. Most of both antioxidant and anti-inflammatory properties of this herb have been attributed to its flavonoid content. Oxidative and inflammatory processes play important roles in pathogenesis of neurodegenerative diseases. Present review was aimed to review the latest literature evidences regarding application of Achillea and/or its three main flavonoid constituents on epilepsy, Alzheimer's disease, multiple sclerosis, Parkinson's disease and stroke.

The ethyl acetate fraction from Physalis alkekengi inhibits LPS-induced pro-inflammatory mediators in BV2 cells and inflammatory pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis alkekengi is an edible herb whose fruit and calyx are traditionally used to treat a wide range of diseases including inflammation, toothache, and rheumatism. However, the effects of Physalis alkekengi fruit along with its calyx (PAF) on neuroinflammation and inflammatory pain behavior have not been reported yet.

AIM OF THE STUDY

This study evaluated the anti-inflammatory effect of PAF on lipopolysaccharide (LPS)-induced neuroinflammation and several in vivo model of inflammatory pain in mice.

MATERIALS AND METHODS

Here, first we studied the effects of PAF fractions on the production of pro-inflammatory mediators in LPS-treated BV2 microglial cells using enzyme-linked immunosorbent assay. The translocation of nuclear factor-kappa B (NF-κB) and the involvements of Akt and mitogen-activated protein (MAP) kinases in ethyl acetate fraction of PAF (PAF-EA)-mediated anti-inflammatory effect were measured using Western blotting. In in vivo experiments, the efficacy of PAF-EA was evaluated at the doses of 100 and 200mg/kg using several chemical-induced models of inflammatory pain such as acetic acid-induced writhing, formalin-induced paw licking and edema.

RESULTS

We found that compared to other fractions, the PAF-EA more potently inhibited the LPS-induced generation of nitric oxide, tumor necrosis factor-α, interleukin-6 and reactive oxygen species. It also inhibited LPS-induced nuclear translocation of NF-κB. These actions of EA fraction were found to be associated with a disruption of Akt and MAP kinases signaling pathways. The EA fraction also significantly inhibited acetic acid-induced writhing, formalin-induced licking time and edema in mice.

CONCLUSIONS

Our findings support the ethnopharmacological use of P. alkekengi fruit along with its calyx as an anti-inflammatory agent and suggest that the EA fraction of PAF may serve as a potential candidate to treat different neurological disorders and pain associated with inflammation.

Luteolin and Apigenin Attenuate 4-Hydroxy-2-Nonenal-Mediated Cell Death through Modulation of UPR, Nrf2-ARE and MAPK Pathways in PC12 Cells

Luteolin and apigenin are dietary flavones and exhibit a broad spectrum of biological activities including antioxidant, anti-inflammatory, anti-cancer and neuroprotective effects. The lipid peroxidation product 4-hydroxy-2-nonenal (4-HNE) has been implicated as a causative agent in the development of neurodegenerative disorders. This study investigates the cytoprotective effects of luteolin and apigenin against 4-HNE-mediated cytotoxicity in neuronal-like catecholaminergic PC12 cells. Both flavones restored cell viability and repressed caspase-3 and PARP-1 activation in 4-HNE-treated cells. Luteolin also mitigated 4-HNE-mediated LC3 conversion and reactive oxygen species (ROS) production. Luteolin and apigenin up-regulated 4-HNE-mediated unfolded protein response (UPR), leading to an increase in endoplasmic reticulum chaperone GRP78 and decrease in the expression of UPR-targeted pro-apoptotic genes. They also induced the expression of Nrf2-targeted HO-1 and xCT in the absence of 4-HNE, but counteracted their expression in the presence of 4-HNE. Moreover, we found that JNK and p38 MAPK inhibitors significantly antagonized the increase in cell viability induced by luteolin and apigenin. Consistently, enhanced phosphorylation of JNK and p38 MAPK was observed in luteolin- and apigenin-treated cells. In conclusion, this result shows that luteolin and apigenin activate MAPK and Nrf2 signaling, which elicit adaptive cellular stress response pathways, restore 4-HNE-induced ER homeostasis and inhibit cytotoxicity. Luteolin exerts a stronger cytoprotective effect than apigenin possibly due to its higher MAPK, Nrf2 and UPR activation, and ROS scavenging activity.

Flavones: an important scaffold for medicinal chemistry

Flavones have antioxidant, anti-proliferative, anti-tumor, anti-microbial, estrogenic, acetyl cholinesterase, anti-inflammatory activities and are also used in cancer, cardiovascular disease, neurodegenerative disorders, etc. Also, flavonoids are found to have an effect on several mammalian enzymes like protein kinases that regulate multiple cell signaling pathways and alterations in multiple cellular signaling pathways are frequently found in many diseases. Flavones have been an indispensable anchor for the development of new therapeutic agents. The majority of metabolic diseases are speculated to originate from oxidative stress, and it is therefore significant that recent studies have shown the positive effect of flavones on diseases related to oxidative stress. Due to the wide range of biological activities of flavones, their structure-activity relationships have generated interest among medicinal chemists. The outstanding development of flavones derivatives in diverse diseases in very short span of time proves its magnitude for medicinal chemistry research. The present review gives detail about the structural requirement of flavone derivatives for various pharmacological activities. This information may provide an opportunity to scientists of medicinal chemistry discipline to design selective, optimize as well as poly-functional flavone derivatives for the treatment of multi-factorial diseases.

Luteolin modulates 6-hydroxydopamine-induced transcriptional changes of stress response pathways in PC12 cells

The neurotoxin 6-hydroxydopamine (6-OHDA), which causes transcriptional changes associated with oxidative and proteotoxic stress, has been widely used to generate an experimental model of Parkinson's disease. The food-derived compound luteolin has multi-target actions including antioxidant, anti-inflammatory and neurotrophic activities. The aim of this study is to investigate how luteolin affects 6-OHDA-mediated stress response pathways. The results showed that when PC12 cells were pre-treated with luteolin (20 µM) 30 min prior to 6-OHDA (100 µM) exposure, 6-OHDA-induced ROS overproduction, cytotoxicity, caspase-3 activation, and mRNA expression of BIM, TRB3 and GADD34 were significantly attenuated. Moreover, 6-OHDA-mediated cell cycle arrest and transcription of p53 target genes, p21, GADD45α and PUMA, were reduced by luteolin. Luteolin also significantly down-regulated 6-OHDA-mediated unfolded protein response (UPR), leading to decreases in phospho-eIF2α, ATF4, GRP78 and CHOP. In addition, luteolin attenuated 6-OHDA-induced Nrf2-mediated HO-1 and GCLC. Taken together, these results suggest that diminishing intracellular ROS formation and down-regulation of p53, UPR and Nrf2-ARE pathways may be involved in the neuroprotective effect of luteolin.