Identification of pheophorbide a as an inhibitor of receptor for advanced glycation end products in Mallotus japonicus.

Accumulation of advanced glycation end products (AGEs) plays an important role in diabetes, immunoinflammation, and cardiovascular and neurodegenerative diseases. Since AGEs mediate their pathological effects through interaction with receptor for AGEs (RAGE), RAGE antagonists would provide a useful therapeutic option for various health disorders. Therefore, in this study, we aimed to identify phytochemicals that would inhibit binding of AGEs to RAGE, which may help develop new drug leads and/or nutraceuticals for AGE-RAGE-related diseases. On screening ethanol extracts obtained from 700 plant materials collected in Myanmar, we found that the ethanol extract from the leaves of Mallotus philippensis inhibited the binding of AGEs to RAGE. We also found that the leaves of M. japonicus, which belongs to the same genera and distributes abundantly in Japan, exhibited the inhibitory activity similar to M. philippensis. Activity-guided fractionation and LC/MS analysis of the ethanol extract of M. japonicus helped identify pheophorbide a (PPBa) as a major component in the active fraction, along with some other pheophorbide derivatives. PPBa exhibited potent inhibitory activity against AGE-RAGE binding, with an IC50 value (0.102 µM) comparable to that of dalteparin (0.084 µM). PPBa may be a valuable natural product for use as a therapeutic agent and/or a nutraceutical against various health complications arising from activation of the AGE-RAGE axis.

Eucommia Leaf Extract Induces BDNF Production in Rat Hypothalamus and Enhances Lipid Metabolism and Aerobic Glycolysis in Rat Liver.

BACKGROUND: Mutations in the brain-derived neurotrophic factor (BDNF) gene and its receptor, tyrosine receptor kinase B (TrkB), have been reported to cause severe obesity in rodents. Our previous study demonstrated that the oral administration of 5% Eucommia leaf extract (ELE) or ELE aroma treatment (ELE aroma) produced anti-obesity effects. OBJECTIVE: In this study, we investigated the effects of ELE on glycolysis and lipid metabolism in male Sprague-Dawley rats, as well as the effects of ELE on BDNF in rat hypothalamus. METHODS AND RESULTS: A significant reduction and a reduction tendency in the respiratory quotient were observed in association with 5% ELE and ELE aroma treatment, respectively. Furthermore, RT-qPCR results showed significant increases in Cpt2, Acad, Complex II, and Complex V mRNA levels in the liver with both treatments. In addition, in rat hypothalamus, significant elevations in BDNF, Akt, PLCγ proteins and CREB phosphorylation were observed in the 5% ELE group and the ELE aroma group. Furthermore, the Ras protein was significantly increased in the ELE aroma group. On the other hand, significant dephosphorylation of ERK1/2 was observed by the western blotting in the 5% ELE group and the ELE aroma group. CONCLUSION: These findings suggest that the ELE treatment enhances the lipid metabolism and increases the aerobic glycolytic pathway, while ELE-induced BDNF may affect such energy regulation. Therefore, ELE has the possibility to control metabolic syndrome.

Pharmacokinetic Study of Compound K in Japanese Subjects After Ingestion of Panax ginseng Fermented by Lactobacillus paracasei A221 Reveals Significant Increase of Absorption into Blood.

Compound K (CK) is a metabolite of a saponin in Panax ginseng, formed from ginsenoside, a triterpenoid glycoside, by human intestinal bacteria. Lactobacillus paracasei A221 isolated from fermented food can hydrolyze (deglycosylate) the main ginsenoside, ginsenoside Rb1, and generate CK. However, the pharmacokinetics of L. paracasei A221 fermented ginseng (FG) and nonfermented ginseng (NFG) have not been investigated so far. The aim of this study was to investigate the pharmacokinetics of CK after oral administration of single doses of FG and NFG in healthy Japanese adults. An open-label, randomized, single-dose, two-period, crossover study was conducted in 12 Japanese healthy volunteers (five men and seven women, aged 40-60 years). All subjects were equally allocated into two groups and administered tablets containing FG or NFG. Until 24 h after the administration, blood samples were sequentially collected, plasma concentrations of CK were measured, and the pharmacokinetic parameters were calculated. We also expected restoration of decreased testosterone level as one of the beneficial effects of FG and measured plasma total testosterone concentrations in male volunteers. The means of Tmax, Cmax, and area under the concentration-time curve (AUC) were significantly different between the two groups. In the FG group, AUC0-12h (ng h/mL) and AUC0-24h (ng h/mL) were, respectively, 58.3- and 17.5-fold higher than those in the NFG group. Moreover, mean testosterone concentration in the FG group significantly increased 24 h after administration. These results showed that the main ginsenoside metabolite of ginseng, CK, produced by L. paracasei A221 has potential utility in health maintenance in healthy middle-aged and old Japanese adults.

Clinical assessment of a supplement of Pycnogenol® and L-arginine in Japanese patients with mild to moderate erectile dysfunction.

A double-blind parallel group comparison design clinical study was conducted in Japanese patients with mild to moderate erectile dysfunction to investigate the efficacy of a supplement containing Pycnogenol® and L-arginine. Subjects were instructed to take a supplement (Pycnogenol® 60 mg/day, L-arginine 690 mg/day and aspartic acid 552 mg/day) or an identical placebo for 8 weeks, and the results were assessed using the five-item erectile domain (IIEF-5) of the International Index of Erectile Function. Additionally, blood biochemistry, urinalysis and salivary testosterone were measured. Eight weeks of supplement intake improved the total score of the IIEF-5. In particular, a marked improvement was observed in 'hardness of erection' and 'satisfaction with sexual intercourse'. A decrease in blood pressure, aspartate transaminase and γ-glutamyl transpeptidase (γ-GTP), and a slight increase in salivary testosterone were observed in the supplement group. No adverse reactions were observed during the study period. In conclusion, Pycnogenol® in combination with L-arginine as a dietary supplement is effective and safe in Japanese patients with mild to moderate erectile dysfunction.

Chronic administration of Eucommia leaf stimulates metabolic function of rats across several organs.

Eucommia bark (Eucommia ulmoides Oliver) has been used as an herbal medicine, and more recently, the plant's leaves have been widely used to prepare tea which may have anti-obesity properties. We used a metabolic syndrome-like rat model, produced by feeding a 35% high-fat diet (HFD), to examine potential anti-obesity and anti-metabolic syndrome effects and mechanisms of chronic administration of Eucommia leaf as an extract or green leaf powder. Eighty rats were studied for 3 months in ten groups. Both forms of Eucommia leaves minimised increases in body weight and visceral fat in a dose-dependent fashion. Increases in plasma levels of TAG and NEFA, and insulin resistance secondary to HFD were lessened by both forms of Eucommia leaf. Concomitantly, an increase in plasma adiponectin levels and suppression of plasma resistin and TNF-α levels were confirmed. Real-time PCR studies showed that both forms of Eucommia leaf enhanced metabolic function across several organs, including diminishing ATP production (white adipose tissue), accelerating ß-oxidation (liver) and increasing the use of ketone bodies/glucose (skeletal muscle), all of which may exert anti-obesity effects under HFD conditions. These findings suggest that chronic administration of either form of Eucommia leaves stimulates the metabolic function in rats across several organs. The anti-obesity and anti-metabolic syndrome activity in this rat model may be maintained through secretion and regulation of adipocytokines that depend on the accumulation of visceral fat to improve insulin resistance or hyperlipaemia.

Endothelium-derived hyperpolarizing factor (EDHF) mediates endothelium-dependent vasodilator effects of aqueous extracts from Eucommia ulmoides Oliv. leaves in rat mesenteric resistance arteries.

The vascular effects of an aqueous extract prepared from the leaves of Eucommia ulmoides Oliv. (ELE), a medicinal herb commonly used in antihypertensive herbal prescriptions in China, were investigated in rat mesenteric resistance arteries. The mesenteric vascular bed was perfused with Krebs solution and the perfusion pressure was measured with a pressure transducer. In preparations with an intact endothelium and precontracted with 7 microM methoxamine, perfusion of ELE (107102 mg/ml for 15 min) caused a concentration-dependent vasodilatation, which was abolished by chemical removal of the endothelium. The ELE-induced vasodilatation was inhibited by neither indomethacin (INDO, a cyclooxygenase inhibitor) nor NG-nitro-L-arginine-methyl ester (L-NAME, a nitric oxide inhibitor). The ELE-induced vasodilatation was significantly inhibited by tetraethylammonium (TEA, a K channel blocker) and 18alpha-glycyrrhetinic acid (18alpha-GA, a gap-junction inhibitor), and abolished by high K-containing Krebs' solution. Atropine (a muscarinic acetylcholine receptor antagonist) significantly inhibited the vasodilatation induced by ELE at high concentrations. These results suggest that the ELE-induced vasodilatation is endothelium-dependent but nitric oxide (NO)- and prostaglandin I2 (PGI2)-independent, and is mainly mediated by the endothelium-derived hyperpolarizing factor (EDHF) in the mesenteric resistance arteries. Furthermore, the ELE-induced EDHF-mediated response involves the activation of K-channels and gap junctions.

Iridoids from the green leaves of Eucommia ulmoides.

The bark of Eucommia ulmoides is a well-known crude drug in oriental medicine, and its leaves have been consumed as a beverage. From the green leaves of this plant, three new iridoids (1-3) were isolated, together with 12 known compounds. Compound 1 is the first iridoid possessing a saturated bond between C-3 and C-4 and having an ether linkage between C-3 and C-2 of the glucose unit. Furthermore, 2 and 3 may be regarded as the first naturally occurring conjugates of an iridoid and an amino acid.