Mira Jun

6-shogaol-rich extract from ginger up-regulates the antioxidant defense systems in cells and mice.

The rhizome of ginger (Zingiber officinale Roscoe) is known to have several bioactive compounds including gingerols and shogaols which possess beneficial health properties such as anti-inflammatory and chemopreventive effects. Based on recent observations that 6-shogaol may have more potent bioactivity than 6-gingerol, we obtained a 6-shogaol-rich extract from ginger and examined its effects on the nuclear factor E2-related factor2 (Nrf2)/antioxidant response element (ARE) pathway in vitro and in vivo. 6-Shogaol-rich extract was produced by extracting ginger powder with 95% ethanol at 80 °C after drying at 80 °C (GEE8080). GEE8080 contained over 6-fold more 6-shogaol compared to the room temperature extract (GEE80RT). In HepG2 cells, GEE8080 displayed much stronger inductions of ARE-reporter gene activity and Nrf2 expression than GEE80RT. GEE8080 stimulated phosphorylations of mitogen-activated protein kinases (MAPKs) such as ERK, JNK, and p38. Moreover, the GEE8080-induced expressions of Nrf2 and HO-1 were attenuated by treatments of SB202190 (a p38 specific inhibitor) and LY294002 (an Akt specific inhibitor). In a mouse model, the GEE8080 decreased the diethylnitrosamine (DEN)-mediated elevations of serum aspartate transaminase and alanine transaminase as well as the DEN-induced hepatic lipid peroxidation. Inductions of Nrf2 and HO-1 by GEE8080 were also confirmed in the mice. In addition, the administration of GEE8080 to the mice also restored the DEN-reduced activity and protein expression of hepatic antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and catalase. In conclusion, GEE8080, a 6-shogaol-rich ginger extract, may enhance antioxidant defense mechanism through the induction of Nrf2 and HO-1 regulated by p38 MAPK and PI3k/Akt pathway in vitro and in vivo.

Procyanidins from Wild Grape (Vitis amurensis) Seeds Regulate ARE-Mediated Enzyme Expression via Nrf2 Coupled with p38 and PI3K/Akt Pathway in HepG2 Cells

Procyanidins, polymers of flavan-3-ol units, have been reported to exhibit many beneficial health effects such as antioxidant and anti-carcinogenic effects. In this study, we investigated the cancer chemopreventive properties of procyanidins from wild grape (Vitis amurensis) seeds in particular their roles in inducing phase II detoxifying/antioxidant enzymes as well as in modulating the upstream kinases. Ethanolic extract of V. amurensis seeds was fractionated with a series of organic solvents and finally separated into six fractions, F1–F6. Chemical properties of the procyanidins were analyzed by vanillin assay, BuOH-HCl test, and depolymerization with phloroglucinol followed by LC/MS analysis. The F5 had the highest procyanidin content among all the fractions and strongly induced the reporter activity of antioxidant response element as well as the protein expression of nuclear factor E2-related factor (Nrf2) in HepG2 human hepatocarcinoma cells. The procyanidin-rich F5 also strongly induced the expression of the phase II detoxifying and antioxidant enzymes such as NAD(P)H:quinone oxidoreductase1 and hemeoxygenase1. Phosphorylations of the upstream kinases such as MAPKs and PI3K/Akt were significantly increased by treatment with procyanidin fraction. In addition, the procyanidin-mediated Nrf2 expression was partly attenuated by PI3K inhibitor LY294002, and almost completely by p38 inhibitor SB202190, but neither by JNK inhibitor SP600125 nor by MEK1/2 inhibitor U0126. Taken together, the procyanidins from wild grape seeds could be used as a potential natural chemopreventive agent through Nrf2/ARE-mediated phase II detoxifying/antioxidant enzymes induction via p38 and PI3K/Akt pathway.

In vitro BACE1 inhibitory activity of geraniin and corilagin from Geranium thunbergii.

Generation of amyloid β peptide through the proteolytic process of amyloid precursor protein by β-secretase and γ-secretase is a main casual factor of Alzheimers disease, since amyloid β peptide is a major and crucial component of senile plaques in Alzheimers disease brains. In the process of searching for β-secretase inhibitors from natural resources, the EtOAc soluble fraction of Geranium thunbergii exhibited significant β-secretase inhibitory activity. Two compounds, geraniin and corilagin, isolated from the most active EtOAc fraction of G. thunbergii, exhibited predominant inhibition against β-secretase with IC₅₀ values of 4.0 × 10⁻⁶ M and 3.4 × 10⁻⁵ M, respectively. Dixon plot of geraniin and corilagin demonstrated that the β-secretase inhibition was noncompetitive with the substrate, thus clearly suggesting that these compounds might bind either to the β-secretase subsites or to another regulatory domain with Ki values of 2.8 × 10⁻⁶ M and 7.9 × 10⁻⁵ M, respectively. Both compounds exhibited no significant inhibition against α-secretase and other serine proteases including trypsin and chymotrypsin, showing that they were relatively specific and selective inhibitors of β-secretase. These novel findings suggest that geraniin and corilagin from G. thunbergii may be effective therapeutic agents for further drug development in Alzheimers disease.

Inhibitory Effects of Key Compounds Isolated from Corni fructus on BACE1 Activity

Progressive cerebral deposition of Aβ in the brain is a seminal event in the pathogenesis of Alzheimers disease (AD). Aβ is generated from the amyloid precursor protein (APP) by proteolytic processing of β‐secretase (BACE1) and γ‐secretase. Consequently, BACE1, a key enzyme in the production of Aβ, is a prime target for therapeutic intervention in AD. In the course of screening for natural BACE1 inhibitors from Corni fructus, the ethyl acetate (EtOAc) fraction showed significant inhibitory activity against BACE1. By activity guided purification, three compounds of BACE1 inhibitors p‐coumaric acid, gallic acid and ursolic acid were isolated from Corni fructus EtOAc fraction. All isolated compounds suppressed BACE1 in a dose dependent manner. p‐Coumaric acid, in particular, exhibited significant inhibitory activity against BACE1 with 9.0u2009×u200910‐5u2009m and a Ki value of 1.9u2009×u200910‐6u2009m. Also this compound was non‐competitive with a substrate in the Dixon plot, suggesting that it might bind either to the β‐secretase subsite or to another regulatory site. All compounds showed no significant attenuation of TACE (α‐secretase) and other serine proteases such as chymotrypsin and trypsin, demonstrating that they were relatively selective and specific inhibitors of BACE1. These novel findings suggest that Corni fructus contains biologically active components that may be used to attenuate the progression and/or prevention of Alzheimers disease. Copyright

Fatty Acid and Volatile Oil Compositions of Allomyrina dichotoma Larvae

Thirty-two different volatile oils were identified from Allomyrina dichotoma (A. dichotoma) larvae by gas chromatography/mass spectrometry (GC/MS). The major volatile components were 2,2,4-trimethyl-3-carboxyisopropyl pentanoic acid isobutyl ester (5.83%), phenol,2,6-bis(a,a-dimethyl ethyl)-4-(1-methyl-1-phenylethyl) (5.72%), heptacosane (5.49%) and phenol,2,4-bis(1-methyl-1-phenylethyl) (5.47%). The composition of the fatty acids in A. dichotoma larvae was also determined by gas chromatography (GC) and fourteen constituents were identified. Oleic acid (19.13%) was the most abundant fatty acid followed by palmitic acid (12.52%), palmitoleic acid (3.71%) and linoleic acid (2.08%) in 100 g of A. dichotoma larvae on a dry weight basis. The quantity of unsaturated fatty acids (64.00%) were higher than that of saturated ones (36.00%). The predominant fatty acids in A. dichotoma consist of monounsaturated fatty acid (MUFA, 57.70%) such as oleic acid, myristoleic acid and palmitoleic acid, followed by saturated fatty acids (36.00%) and polyunsaturated fatty acids (PUFA, 6.50%). In particular, the presence of essential fatty acids, such as linoleic (5.30%) and linolenic acid (0.40%) give A. dichotoma larvae considerable nutritional and functional value and it may be a useful source for food and/or industrial utilization.

β-Secretase (BACE1) inhibitory property of loganin isolated from Corni fructus

In the course of searching for anti-dementia agents from natural products, loganin isolated from EtOAc fraction of Corni fructus possessed specific inhibitory activity against β-secretase (BACE1) with 9.2u2009×u200910−5u2009M and Ki value of 5.5u2009×u200910−5u2009M. Loganin exhibited less inhibitory activity to α-secretase (TACE) and other serine proteases exhibiting that it was a relatively specific inhibitor of BACE1. These novel findings suggest that loganin may be used to attenuate the progression and/or prevention of Alzheimers disease.

Induction of Nrf2/ARE-mediated cytoprotective genes by red ginseng oil through ASK1-MKK4/7-JNK and p38 MAPK signaling pathways in HepG2 cells.

Background The induction of cellular defensive genes such as phase II detoxifying and antioxidant enzymes is a highly effective strategy for protection against carcinogenesis as well as slowing cancer development. Transcription factor Nrf2 (nuclear factor E2-related factor 2) is responsible for activation of phase II enzymes induced by natural chemopreventive compounds. Methods Red ginseng oil (RGO) was extracted using a supercritical CO2 extraction system and chemical profile of RGO was investigated by GC/MS. Effects of RGO on regulation of the Nrf2/antioxidant response element (ARE) pathway were determined by ARE–luciferase assay, western blotting, and confocal microscopy. Results The predominant components of RGO were 9,12-octadecadienoic acid (31.48%), bicyclo[10.1.0]tridec-1-ene (22.54%), and 22,23-dihydrostigmasterol (16.90%). RGO treatment significantly increased nuclear translocation of Nrf2 as well as ARE reporter gene activity, leading to upregulation of heme oxygenase-1 and NAD(P)H:quinone oxidoreductase 1. Phosphorylation of the upstream kinases such as apoptosis signal-regulating kinase (ASK)1, mitogen-activated protein kinase (MAPK) kinase (MKK)4/7, c-Jun N-terminal kinase (JNK), and p38 MAPK were enhanced by treatment with RGO. In addition, RGO-mediated Nrf2 expression and nuclear translocation was attenuated by JNK inhibitor SP600125 and p38 MAPK inhibitor SB202190. Conclusion RGO could be used as a potential chemopreventive agent, possibly by induction of Nrf2/ARE-mediated phase II enzymes via ASK1–MKK4/7–JNK and p38 MAPK signaling pathways.

Safety of red ginseng oil for single oral administration in Sprague–Dawley rats

The single oral administration of red ginseng oil (5000 mg/kg) to Sprague–Dawley rats induced no changes in behavioral patterns, clinical signs, and body weight, and hepatotoxicity parameters such as aspartate aminotransferase and alanine aminotransferase for 14 d. Therefore, these results suggest that the red ginseng oil is safe and nontoxic acutely.

Fatty Acid Composition and Volatile Constituents of Protaetia brevitarsis Larvae.

A total of 48 different volatile oils were identified form P. brevitarsis larvae by gas chromatography/mass spectrometry (GC/MS). Acids (48.67%) were detected as the major group in P. brevitarsis larvae comprising the largest proportion of the volatile compounds, followed by esters (19.84%), hydrocarbons (18.90%), alcohols (8.37%), miscellaneous (1.71%), aldehydes (1.35%) and terpenes (1.16%). The major volatile constituents were 9-hexadecenoic acid (16.75%), 6-octadecenoic acid (14.88%) and n-hexadecanoic acid (11.06%). The composition of fatty acid was also determined by GC analysis and 16 fatty acids were identified. The predominant fatty acids were oleic acid (C18:1, 64.24%) followed by palmitic acid (C16:0, 15.89%), palmitoleic acid (C16:1, 10.43%) and linoleic acid (C18:2, 4.69%) constituting more than 95% of total fatty acids. The distinguished characteristic of the fatty acid profile of P. brevitarsis larvae was the high proportion of unsaturated fatty acid (80.54% of total fatty acids) versus saturated fatty acids (19.46% of total fatty acids). Furthermore, small but significant amounts of linoleic, linolenic and γ-linolenic acids bestow P. brevitarsis larvae with considerable nutritional value. The novel findings of the present study provide a scientific basis for the comprehensive utilization of the insect as a nutritionally promising food source and a possibility for more effective utilization.

Effects of solvent fractions of Allomyrina dichotoma larvae through the inhibition of in vitro BACE1 and β‐amyloid(25–35)‐induced toxicity in rat pheochromocytoma PC12 cells

Amyloid‐β peptide (Aβ) generation initiated by β‐site amyloid precursor protein cleaving enzyme 1 BACE1 is a critical cause of Alzheimers disease. In the course of our ongoing investigation of natural anti‐dementia resources, the ethyl acetate (EtOAc) fraction exerted strong BACE1‐specific inhibition with the half maximal inhibitory concentration (IC50) value of 9.2 × 10−5u2009μg/mL. Furthermore, Aβ(25–35)‐induced cell death was predominantly prevented by the EtOAc fraction of Allomyrinau2009dichotoma larvae through diminishing of cellular oxidative stress and attenuating apoptosis by inhibiting caspase‐3 activity. Taken together, the present study demonstrated that A.u2009dichotoma larvae possess novel neuroprotective properties not only via the selective and specific inhibition of BACE1 activity but also through the alleviation of Aβ(25–35)‐induced toxicity, which may raise the possibility of therapeutic application of A.u2009dichotoma larvae for preventing and/or treating dementia.