Protective Roles of Monsonia angustifolia and Its Active Compounds in Experimental Models of Alzheimer's Disease.

Alzheimer's disease (AD), a progressive neurodegenerative disorder, is characterized by the accumulation of neurotoxic ß-amyloid (Aß) peptides, which consequently affects cognitive decline and memory impairment. Current research on AD treatment is actively focusing on the prevention of neurotoxic Aß peptide accumulation. Monsonia angustifolia is reported to be consumed as an indigenous vegetable in Tanzania. In this study, we investigated the effect of the ethanol (EtOH) extract of M. angustifolia dried ground material on Aß production and spatial learning ability as protection against AD. The formation of Aß peptides was significantly reduced in HeLa cells stably transfected with the Swedish mutant form of ß-amyloid precursor protein (APPsw) after treatment with a 60% EtOH extract of M. angustifolia. We next examined the cognitive-improving effects of the EtOH extract in vivo. Tg2576 mice were treated with extract for 6 months and subjected to Morris water maze and novel object recognition tests. The results showed that the 60% EtOH extract of M. angustifolia significantly ameliorated behavioral deficits of the AD transgenic mice and reduced the level of insoluble Aß42 in the cerebral cortex and hippocampus. We further found that the 60% EtOH extract was effective for memory function recovery after shorter treatment (4 months). In addition, we isolated and identified several single compounds, justicidin A, 5-methoxyjusticidin A, chinensinaphthol, retrochinensinaphthol methyl ether, and suchilactone, from M. angustifolia and tested these compounds. Among them, justicidin A potently decreased the formation of Aß in APPsw-transfected cells. These data suggest that the 60% EtOH extract of M. angustifolia has the potential to be developed as a treatment of AD. Furthermore, justicidin A may contribute, at least partially, to the Aß alteration observed with the extract treatment.

Effect of Lycoris chejuensis and Its Active Components on Experimental Models of Alzheimer's Disease.

We found that an extract of Lycoris chejuensis and its three isolated active components, narciclasine, 7-deoxynarciclasine, and 7-deoxy-trans-dihydronarciclasine, each significantly reduced the formation of amyloid-ß peptides in HeLa cells transfected with an amyloid precursor protein carrying the Swedish mutation up to 45 ± 3.6%. The extract down-regulated amyloid precursor protein, especially the mature form by up to 88%, and reduced the ability of secretases to generate toxic amyloid-ß. Double-transgenic mice treated with the extract for 4 months also showed significantly reduced levels of amyloid-ß and plaques while exhibiting improved memory functions in the Morris water maze and novel object recognition tests. In conclusion, the extract and isolated active components of L. chejuensis decreased the production of amyloid-ß by attenuating amyloid precursor protein levels. Furthermore, the extract improved the disrupted memory functions in animals while inhibiting amyloid plaque formation. Thus, this extract, as well as its active components, could prove beneficial in the treatment of Alzheimer's disease.

Neuroprotective effect of modified Chungsimyeolda-tang, a traditional Korean herbal formula, via autophagy induction in models of Parkinson's disease.

AIM OF THE STUDY: Previous studies in our laboratory revealed the neuroprotective effect of modified Yeoldahanso-tang (MYH) in models of Parkinson׳s disease (PD). In this study, we investigated another traditional Korean herbal formula, modified Chungsimyeolda-tang (termed DG), as a potential treatment for PD. Chungsimyeolda-tang has been used in Korea to treat cerebrovascular diseases, such as stroke. Here, we verify the neuroprotective and autophagy-inducing effects of DG to evaluate any potential anti-parkinsonian properties. MATERIALS AND METHODS: 1-Methyl-4-phenylpyridinium (MPP(+)) and rotenone were used to induce cytotoxicity in nerve growth factor (NGF)-differentiated rat pheochromocytoma (PC12) cells. Cell viability was measured using an MTT assay. Induction of autophagy by DG in NGF-differentiated PC12 cells was measured using an immunoblotting assay with an LC3 antibody. The proteasomal inhibitor lactacystin was used to induce ubiquitin-proteasome system (UPS) dysfunction in NGF-differentiated PC12 cells. DG-mediated clearance of aggregated proteins was measured using an immunoblotting assay with a ubiquitin antibody. RESULTS AND CONCLUSIONS: Our findings indicate that DG robustly protects NGF-differentiated PC12 cells against the neurotoxic effects of MPP(+) and rotenone in an in vitro model. Furthermore, DG protects NGF-differentiated PC12 cells against lactacystin-induced cell death. This effect is partially mediated by an increased autophagy associated with the enhanced degradation of aggregated proteins. This study suggests that DG is an attractive candidate drug for inducing autophagy and, therefore, may represent a promising strategy to prevent diseases associated with misfolded/aggregated proteins in various neurodegenerative disorders, including Parkinson׳s disease.

The neuroprotective effect of modified Yeoldahanso-tang via autophagy enhancement in models of Parkinson's disease.

AIM OF STUDY: Modified Yeoldahanso-tang (MYH) is a Korean herbal formula, containing 10 herbs: Pueraria lobata (Willd.) Ohwi, Angelica tenuissima Nakai, Scutellaria baicalensis Georgi, Platycodon grandiflorum (Jacq), Angelicae Dahurica, Cimicifuga heracleifolia Kom, Raphanus sativa L., Polygala tenuifolia (Willd.), Acorus gramineus Soland. and Dimocarpus longan Lour. The constitutive ratio of the ten herbs is at 6:4:2:1:2:2:2:4:6:6 in dry weight. MYH has been used to treat amnesia, hypochondria and dementia in Korea. In this study, we explored the possibility of using MYH in the prevention and treatment of Parkinson's disease (PD). Specifically, we made an effort to demonstrate the neuroprotective effects of MYH using experimental methods similar to those used in a recent study of PD. MATERIALS AND METHODS: 1-Methyl-4-phenylpyridinium (MPP+) (400µM) was used to induce cytotoxicity in NGF (nerve growth factor)-differentiated PC12 cells. Cell viability was measured using a MTT assay. Induction of autophagy by MYH in NGF-differentiated PC12 cells was measured using an immunoblotting assay with LC3 and beclin 1 antibodies. The proteasomal inhibitor lactacystin (10µM) was used to cause UPS dysfunction in NGF-differentiated PC12 cells. Clearance of aggregated proteins by MYH was measured using an immunoblotting assay with an ubiquitin antibody. 1-Methyl-4-phenyl-1,2,3,6-tetrahydrophenylpyridine (MPTP) (20mg/kg, 4 times i.p.) caused substantia nigra injuries in C57BL/6 mice. Dopamine (DA) neurons were identified using a tyrosine hydroxylase-immunohistochemistry (TH-IHC) assay with a rabbit anti-TH antibody. RESULTS: Our findings indicate that MYH provides protection against MPP+-induced injury in NGF-differentiated PC12 cell. And MYH provides neuroprotection against lactacystin-induced NGF-differentiated PC12 cell death, which effect is partially mediated by autophagy enhancement through enhanced degradation of aggregated proteins. Additionally, in a C57BL/6 mice model with MPTP-induced substantia nigra injuries, MYH inhibits both the loss of TH-positive neurons in the substantia nigra pars compacta (SNpc) and the reduction of the optical density of TH-IR fibers in the striatum (ST). CONCLUSIONS: All of our results indicate that MYH treatment has neuroprotective effects that are partially mediated by autophagy enhancement. MYH may be a promising herbal formula for the prevention and treatment of neurodegenerative diseases, especially PD.