Inhibition of β-amyloid peptide-induced neurotoxicity by kaempferol 3-O-(6″-acetyl)-β-glucopyranoside from butterbur (Petasites japonicus) leaves in B103 cells

Polyherbal and Multimodal Treatments: Kaempferol- and Quercetin-Rich Herbs Alleviate Symptoms of Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder impairing cognition and memory in the elderly. This disorder has a complex etiology, including senile plaque and neurofibrillary tangle formation, neuroinflammation, oxidative stress, and damaged neuroplasticity. Current treatment options are limited, so alternative treatments such as herbal medicine could suppress symptoms while slowing cognitive decline. We followed PRISMA guidelines to identify potential herbal treatments, their associated medicinal phytochemicals, and the potential mechanisms of these treatments. Common herbs, including Ginkgo biloba, Camellia sinensis, Glycyrrhiza uralensis, Cyperus rotundus, and Buplerum falcatum, produced promising pre-clinical results. These herbs are rich in kaempferol and quercetin, flavonoids with a polyphenolic structure that facilitate multiple mechanisms of action. These mechanisms include the inhibition of Aβ plaque formation, a reduction in tau hyperphosphorylation, the suppression of oxidative stress, and the modulation of BDNF and PI3K/AKT pathways. Using pre-clinical findings from quercetin research and the comparatively limited data on kaempferol, we proposed that kaempferol ameliorates the neuroinflammatory state, maintains proper cellular function, and restores pro-neuroplastic signaling. In this review, we discuss the anti-AD mechanisms of quercetin and kaempferol and their limitations, and we suggest a potential alternative treatment for AD. Our findings lead us to conclude that a polyherbal kaempferol- and quercetin-rich cocktail could treat AD-related brain damage.

A review on the ethnobotany, phytochemistry, pharmacology and toxicology of butterbur species (Petasites L.)

ETHNOPHARMACOLOGICAL RELEVANCE

Petasites (butterbur, Asteraceae) species have been used since Ancient times in the traditional medicine of Asian and European countries to treat central nervous system (migraine), respiratory (asthma, allergic rhinitis, bronchitis, spastic cough), cardiovascular (hypertension), gastrointestinal (ulcers) and genitourinary (dysmenorrhea) disorders.

AIM OF THE REVIEW

This study summarized and discussed the traditional uses, phytochemical, pharmacological and toxicological aspects of Petasites genus.

MATERIALS AND METHODS

A systematic search of Petasites in online databases (Scopus, PubMed, ScienceDirect, Google Scholar) was performed, with the aim to find the phytochemical, toxicological and bioactivity studies. The Global Biodiversity Information Facility, Plants of the World Online, World Flora Online and The Plant List databases were used to describe the taxonomy and geographical distribution.

RESULTS

The detailed phytochemistry of the potentially active compounds of Petasites genus (e.g. sesquiterpenes, pyrrolizidine alkaloids, polyphenols and essential oils components) was presented. The bioactivity studies (cell-free, cell-based, animal, and clinical) including the traditional uses of Petasites (e.g. anti-spasmolytic, hypotensive, anti-asthmatic activities) were addressed and followed by discussion of the main pharmacokinetical and toxicological issues related to the administration of butterbur-based formulations.

CONCLUSIONS

This review provides a complete overview of the Petasites geographical distribution, traditional use, phytochemistry, bioactivity, and toxicity. More than 200 different sesquiterpenes (eremophilanes, furanoeremophilanes, bakkenolides), 50 phenolic compounds (phenolic acids, flavonoids, lignans) and volatile compounds (monoterpenes, sesquiterpenes) have been reported within the genus. Considering the phytochemical complexity and the polypharmacological potential, there is a growing research interest to extend the current therapeutical applications of Petasites preparations (anti-migraine, anti-allergic) to other human ailments, such as central nervous system, cardiovascular, malignant or microbial diseases. This research pathway is extremely important, especially in the recent context of the pandemic situation, when there is an imperious need for novel drug candidates.

Allium roseum L. extract inhibits amyloid beta aggregation and toxicity involved in Alzheimer's disease

Allium roseum is an important medicinal and aromatic plant, specific to the North African flora and a rich source of important nutrients and bioactive molecules including flavonoids and organosulfur compounds whose biological activities and pharmacological properties are well known. In the present study, the inhibition of amyloid beta protein toxicity by the ethanolic extract of this plant is investigated for the first time. Preliminary biochemical analyses identified kæmpferol and luteolin-7-o-glucoside as the more abundant phenolic compounds. The effects of A. roseum extract (ARE) on aggregation and aggregate cytotoxicity of amyloid beta-42 (Aβ42), whose brain aggregates are a hallmark of Alzheimer's disease, were investigated by biophysical (ThT assay, Dynamic light scattering and transmission electron microscopy) and cellular assays (cytotoxicity, aggregate immunolocalization, ROS measurement and intracellular Ca2+ imaging). The biophysical data suggest that ARE affects the structure of the Aβ42 peptide, inhibits its polymerization, and interferes with the path of fibrillogenesis. The data with cultured cells shows that ARE reduces Aß42 aggregate toxicity by inhibiting aggregate binding to the cell membrane and by decreasing both oxidative stress and intracellular Ca2+. Accordingly, ARE could act as a neuroprotective factor against Aβ aggregate toxicity in Alzheimer's disease.

Antioxidant compounds of Petasites japonicus and their preventive effects in chronic diseases: a review

Petasites japonicus (P. japonicus) is a plant of the Asteraceae family. Its roots and stems have been used for the treatment or the prophylaxis of migraine and tension headache as a traditional Chinese medicine in Japan and Korea. Sesquiterpenoids, lignans, and flavonoids are components of P. japonicus. Regarding the biological activity of P. japonicus, its anti-allergic effect has been researched extensively using IgE antigen-stimulated degranulation of RBL-2H3 cells or passive cutaneous anaphylaxis reaction in experimental animal models. The study of the antioxidant activity of P. japonicus was initiated approximately 15 years ago using in vitro assays. In addition, its in vivo effect has also been examined in animal models with induced oxidative injury. Moreover, recently, many types of antioxidant compounds have been rapidly and simultaneously identified using the liquid chromatography–mass spectrometry technique. The number of reports on the other functions of this plant, such as its neuroprotective and anti-inflammatory effects, has been increasing. In this review, I summarized the studies of functional foods derived from P. japonicus, which may provide a basis for the development of potential functional foods. Finally, I discuss the future research avenues in this field.

Neuroprotective Effect of ent-Kaur-15-en-17-al-18-oic Acid on Amyloid Beta Peptide-Induced Oxidative Apoptosis in Alzheimer's Disease

ent-Kaur-15-en-17-al-18-oic acid, extracted from the Chinese well known folk herb Leontopodium longifolium, performed a significantly neuroprotective effect on amyloid beta peptide 25-35 (Aβ_25-35)-induced SH-SY5Y cells neurotoxicity in Alzheimer's disease. The results demonstrated that this compound maintained oxidative stress balance, reduced levels of reactive oxygen species (ROS), malondialdehyde (MDA), and improved contents of glutathione (GSH) and superoxide dismutase (SOD) without obvious cytotoxicity. This compound also obviously relieved oxidative stress-induced apoptosis associated with p53 and nuclear factor κB (NF-κB) pathways accompanied by upregulating B-cell lymphoma-2 (bcl-2) and downregulating p53, nuclear factor κB (NF-κB), Bax, Cleaved-caspase 3, and Cytochrome C protein expressions further. Briefly, ent-kaur-15-en-17-al-18-oic acid protected cells from oxidative apoptosis associated with p53 and NF-κB pathways.

Protective effects of the key compounds isolated from Corni fructus against β-amyloid-induced neurotoxicity in PC12 cells

β-Amyloid (Aβ) peptide is the major component of senile plaques and is considered to have a causal role in the development and progression of Alzheimer’s disease (AD). There is compelling evidence supporting the notion that Aβ-induced cytotoxicity is mediated though the generation of ROS. In the present study, we investigated the neuroprotective effects of ursolic acid (UA), p-coumaric acid (p-CA), and gallic acid (GA) isolated from Corni fructus (CF) against Aβ(25-35)-induced toxicity in PC12 cell. Exposure of PC12 cells to 50 μM Aβ(25-35) increased cellular oxidative stress, the number of apoptotic cells and caspase-3 activity and finally caused significant cell death. However, UA, p-CA, and GA not only suppressed the generation of ROS but also attenuated DNA fragmentation and eventually attenuated Aβ-induced apoptosis in a dose-dependent manner. In protecting cells against Aβ neurotoxicity, UA and GA possessed stronger ability against ROS generation than p-CA, while p-CA showed the strongest anti-apoptotic activity. Particularly, p-CA protected cells at the concentration range from 0.5 up to 125 μM without any adverse effect. Taken together, these effects of UA, p-CA, and GA may be partly associated with the neuroprotective effect of CF. Furthermore, our findings might raise a possibility of therapeutic applications of CF for preventing and/or treating neurodegenerative diseases.