Pathogenesis of Huntington's Disease: An Emphasis on Molecular Pathways and Prevention by Natural Remedies

BACKGROUND

Huntington's disease is an inherited autosomal dominant trait neuro-degenerative disorder caused by changes (mutations) of a gene called huntingtin (htt) that is located on the short arm (p) of chromosome 4, CAG expansion mutation. It is characterized by unusual movements, cognitive and psychiatric disorders.

OBJECTIVE

This review was undertaken to apprehend biological pathways of Huntington's disease (HD) pathogenesis and its management by nature-derived products. Natural products can be lucrative for the management of HD as it shows protection against HD in pre-clinical trials. Advanced research is still required to assess the therapeutic effectiveness of the known organic products and their isolated compounds in HD experimental models.

SUMMARY

Degeneration of neurons in Huntington's disease is distinguished by progressive loss of motor coordination and muscle function. This is due to the expansion of CAG trinucleotide in the first exon of the htt gene responsible for neuronal death and neuronal network degeneration in the brain. It is believed that the factors such as molecular genetics, oxidative stress, excitotoxicity, mitochondrial dysfunction, neuroglia dysfunction, protein aggregation, and altered UPS leads to HD. The defensive effect of the natural product provides therapeutic efficacy against HD. Recent reports on natural drugs have enlightened the protective role against HD via antioxidant, anti-inflammatory, antiapoptotic, and neurofunctional regulation.

Antibacterial and fungicidal effect of ethanol extracts from Juniperus sabina, Chamaecyparis lawsoniana, Pseudotsuga menziesii and Cephalotaxus harringtonia

We determined a high antibacterial effect of ethanol extracts of four species of gymnosperms (Juniperus sabina, Chamaecyparis lawsoniana, Pseudotsuga menziesii and Cephalotaxus harringtonia) against 23 strains of bacteria of families Enterobacteriaceae (Escherichia coli, Enterococcus faecalis, Salmonella typhimurium, S. adobraco, Proteus vulgaris, P. mirabilis, Serratia marcescens, Klebsiella pneumoniae), Staphylococcaceae (Staphylococcus aureus, S. epidermidis), Yersiniaceae (Yersinia enterocolitica), Bacillaceae (Bacillus subtilis, B. cereus), Listeriaceae (Listeria ivanovi, L. іnnocua, L. monocytogenes), Corynebacteriaceae (Corynebacterium xerosis), Campylobacteraceae (Campylobacter jejuni), Nocardiaceae (Rhodococcus equi), Pseudomonadaceae (Pseudomonas аeruginosa) and one strain of fungi of the Saccharomycetaceae family (Candida albicans). The experiment in vitro revealed zone of inhibition of growth of colonies, measuring over 8 mm, produced by ethanol extracts from J. sabina against seven species of bacteria (S. aureus, B. subtilis, B. cereus, L. іnnocua, C. xerosis, Rh. equi and P. аeruginosa), Ch. lawsoniana – against five species (E. coli, B. subtilis, L. іnnocua and Rh. equi), P. menziesii –two species (Rh. equi and P. mirabilis), C. harringtonia – ten species of microorganisms (E. coli, S. aureus, S. epidermidis, L. ivanovi, L. monocytogenes, C. xerosis, C. jejuni, P. vulgaris, S. marcescens and C. albicans). As a result of the research, the most promising plants for further in vivo study of antibacterial activity were C. harringtonia and J. sabina.

Ginkgo biloba flavonoid glycosides in antimicrobial perspective with reference to extraction method

The present study aims to investigate the effect of extraction method on the recovery of flavonoid glycosides, antimicrobials and antioxidants from Ginkgo leaves collected from six different locations in Uttarakhand, Indian Himalaya. Four extraction methods, namely maceration, reflux, shaker and soxhlet were considered, where reflux extracts showed higher antimicrobial antioxidant activity and higher content of flavonoid glycosides. The reference standards of Ginkgo flavonoid glycosides (quercetin, kaempferol and isorhamnetin) and crude extracts were tested for their antimicrobial activity against gram positive and gram negative bacteria and fungi following disc diffusion method and minimum inhibitory concentration (MIC). All the test microorganisms were observed to be inhibited significantly by Ginkgo flavonoids in plate based assays. Correlation coefficients exhibited the extent of contribution of flavonoid glycosides in antimicrobial activity and confirmed the reflux method as a potential method for extraction. Moreover, antioxidant activity as measured by DPPH assay was also found to be higher in reflux method. Significant variation (p < 0.05) in the flavonoid glycosides among the locations was also observed and sample collected from GB6 location was found to be the best for quercetin and isorhamnetin, while GB5 for kaempferol. Significant correlation (r < 0.05, r < 0.001) was obtained while developing the relationship between total flavonoid glycosides and antimicrobials. The present study, thus suggests the reflux method of extraction to be the best for maximum recovery of flavonoid glycosides with higher antioxidant and antimicrobial activities from Ginkgo extract.

Ginkgetin aglycone ameliorates LPS-induced acute kidney injury by activating SIRT1 via inhibiting the NF-κB signaling pathway

Background

Ginkgetin aglycone (GA), a novel Ginkgo biloba extract (GBE) by acid hydrolysis and recrystallization, is characterized by higher liposolubility and antioxidation than classical GBEs. There is no study depicting the functional role of GA in acute kidney injury (AKI). Here, we firstly reported the protective effect of GA on lipopolysaccharide (LPS)-induced AKI and its underlying mechanism.

Methods

ELISA analysis was applied to measure plasma level of TNF-α and IL-6, and NF-κB activity in kidney homogenate. Renal function analysis was performed by detecting serum concentration of Kim-1 and urine level of BUN. Cell apoptosis in kidney tissues was detected by TUNEL assay and caspase-3 activity assay. qRT-PCR was conducted to determine mRNA expression of TNF-α, IL-6 and IκBα. Western blot was carried out to confirm expression of p-IκBα, SIRT1, and iNOS.

Results

GA administration protected mice from LPS-induced AKI by attenuating inflammatory response, renal injury, as well as tubular apoptosis both in vivo. GA suppressed inflammatory response induced by LPS in HK-2 cells. Moreover, GA upregulated SIRT1 expression and blocked the NF-κB signaling pathway in LPS-induced AKT in vivo and vitro. Furthermore, suppression of SIRT1 abated the inhibitory effect of GA on LPS-induced inflammatory response and renal injury.

Conclusions

GA prevented LPS-induced AKI by activating SIRT1 via inhibiting the NF-κB signaling pathway, providing new insights into the function and molecular mechanism of GA in AKI. Therefore, GA may be a promising therapeutic agent for the treatment of septic AKI.

Variation in Flavonoid Composition and Radical-Scavenging Activity inGinkgo bilobaL. due to the Growth Location and Time of Harvest

The aim of our research is to investigate the qualitative and quantitative composition and antioxidant activity of flavonoids in leaf samples ofGinkgo bilobaL.(G. biloba)growing in Lithuania and also to provide practical recommendations for the pharmaceutical industry to determine the optimum harvesting time and growth location ofG. bilobaleaves. The obtained results indicate that the growth location and time of sample collection have a significant influence (p≤0.05) on the content of active compounds. July and August are the best months to harvestG. bilobaleaves for industry. To ensure the rational collection ofG. bilobaraw material, the location of plantations is recommended in the western and southwestern phytoregions. The obtained results also indicate that the flavonoid content inG. bilobaleaf has a significantly positive correlation (r=0.952,p≤0.001) with antioxidant activity. The aqueous acetonic extracts from green leaves scavenge radicals to a greater degree than those from yellowGinkgoleaves. The results of this investigation provide information regarding the most suitable Lithuanian growing location to produceG. bilobawith an optimized content of health-promoting compounds.

Optimization of a CUPRAC-Based HPLC Postcolumn Assay and Its Applications for Ginkgo biloba L. Extracts

The aim of the present work was to improve and validate the HPLC-CUPRAC postcolumn method for the evaluation of active antioxidant markers from the acetonic extracts of Ginkgo biloba leaves. Improvement of the HPLC online assay was performed by evaluating the suitable loop temperature, the reaction loop length, and the impact of flow rate. Separation of the analytes was performed by the HPLC method on an ACE C18 analytical column using a gradient elution program. The separated antioxidant markers in the extracts reacted with copper(II)-neocuproine (Cu(II)-Nc) reagent in the postcolumn reaction coil. The reagent was reduced by antioxidants to the copper(I)-neocuproine (Cu(I)-Nc) chelate with a maximum absorption at 450 nm. Validation experiments confirmed sufficient precision, sensitivity, and effectiveness of the corresponding method, which could be used for further evaluations of active antioxidant compounds in similar plant materials.

Antioxidant activity and protecting health effects of common medicinal plants

Medicinal plants are traditionally used in folk medicine as natural healing remedies with therapeutic effects such as prevention of cardiovascular diseases, inflammation disorders, or reducing the risk of cancer. In addition, pharmacological industry utilizes medicinal plants due to the presence of active chemical substances as agents for drug synthesis. They are valuable also for food and cosmetic industry as additives, due to their preservative effects because of the presence of antioxidants and antimicrobial constituents. To commonly used medicinal plants with antioxidant activity known worldwide belong plants from several families, especially Lamiaceae (rosemary, sage, oregano, marjoram, basil, thyme, mints, balm), Apiaceae (cumin, fennel, caraway), and Zingiberaceae (turmeric, ginger). The antioxidant properties of medicinal plants depend on the plant, its variety, environmental conditions, climatic and seasonal variations, geographical regions of growth, degree of ripeness, growing practices, and many other factors such as postharvest treatment and processing. In addition, composition and concentration of present antioxidants, such as phenolic compounds, are related to antioxidant effect. For appropriate determination of antioxidant capacity, the extraction technique, its conditions, solvent used, and particular assay methodology are important.