Fumihiko Yoshizaki

Extensive Screening for Edible Herbal Extracts with Potent Scavenging Activity against Superoxide Anions

To search for edible herbal extracts with potent antioxidant activity, we conducted a large scale screening based on the superoxide scavenging activity. That is, scavenging activity against superoxide anions were extensively screened from ethanol extracts of approximately 1,000 kinds of herbs by applying an electron spin resonance (ESR)-spin trapping method. Among them we chose four edible herbal extracts with prominently potent ability to reduce the signal intensity of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO)–OOH, a spin adduct formed by DMPO and superoxide anion. They are the extracts from Punica granatum (Peel), Syzygium aromaticum (Bud), Mangifera indica (Kernel), and Phyllanthus emblica (Fruit), and are allowed to be used as foodstuffs according to the Japanese legal regulation. The ESR-spin trapping method coupled with steady state kinetic analysis showed that all of the four extracts directly scavenge superoxide anions, and that the superoxide scavenging potential of any of the extracts was comparable to that of L-ascorbic acid. Furthermore, polyphenol determination indicates that the activity is at least in part attributable to polyphenols. These results with such large scale screening might give useful information when choosing a potent antioxidant as a foodstuff.

Extensive screening for herbal extracts with potent antioxidant properties

This paper summarizes our research for herbal extracts with potent antioxidant activity obtained from a large scale screening based on superoxide radical (O2•−) scavenging activity followed by characterization of antioxidant properties. Firstly, scavenging activity against O2•− was extensively screened from ethanol extracts of approximately 1000 kinds of herbs by applying an electron spin resonance (ESR)-spin trapping method, and we chose four edible herbal extracts with prominently potent ability to scavenge O2•−. They are the extracts from Punica granatum (Peel), Syzygium aromaticum (Bud), Mangifera indica (Kernel), and Phyllanthus emblica (Fruit). These extracts were further examined to determine if they also scavenge hydroxyl radical (•OH), by applying the ESR spin-trapping method, and if they have heat resistance as a desirable characteristic feature. Experiments with the Fenton reaction and photolysis of H2O2 induced by UV irradiation demonstrated that all four extracts have potent ability to directly scavenge •OH. Furthermore, the scavenging activities against O2•− and •OH of the extracts of P. granatum (peel), M. indica (kernel) and P. emblica (fruit) proved to be heat-resistant. The results of the review might give useful information when choosing a potent antioxidant as a foodstuff. For instance, the four herbal extracts chosen from extensive screening possess desirable antioxidant properties. In particular, the extracts of the aforementioned three herbs are expected to be suitable for food processing in which thermal devices are used, because of their heat resistance.

A lipase inhibitor monoterpene and monoterpene glycosides from Monarda punctata

An 80% acetone extract of Monarda punctata showed an inhibitory effect on lipase activity in isolated mouse plasma in vitro and carvacrol was obtained as the active constituent. It had an IC₅₀ value of 4.07 mM invitro and suppressed elevations in blood triacylglycerol levels in olive oil-loaded mice. Furthermore, from the whole plant, 22 compounds were isolated. Six monoterpene glycosides, a flavone glucuronide, and other known compounds were identified based on the results of spectroscopic analyses.

Hochu-ekki-to combined with interferon-gamma moderately enhances daily activity of chronic fatigue syndrome mice by increasing NK cell activity, but not neuroprotection.

The purpose of this study was to evaluate the beneficial effect of Hochu-ekki-to (TJ-41) combined with interferon-gamma (IFNγ) on daily activity, immunological and neurological alternation in a mouse model of chronic fatigue syndrome (CFS). CFS was induced by 6 times of repeated injection of Brucella abortus antigen every 2 weeks. Both single TJ-41 and TJ-41 combined with IFNγ increased running activity and thymus weight of CFS mice, while thicker thymic cortex together with elevation of natural killer cell activity was only found in the combined treatment group. No significant improvement was observed in the atrophic brain and decreased expression level of brain-derived neurotrophic factor and Bcl-2 mRNA in hippocampus in both treatment groups. Our results suggest that TJ-41 combined with IFNγ might have a protective effect on the marked reduction in the activity in a model of CFS via normalization of host immune responses, but not neuroprotection.

Lipase inhibitory and LDL anti-oxidative triterpenes from Abies sibirica

A methanol extract of Abies sibirica Ladeb, a Mongolian medicinal plant, had an inhibitory effect on both lipase activity in mouse plasma and LDL anti-oxidative activity, which are preventative factors for arteriosclerosis. The extract was fractionated by silica gel column chromatography and its active constituents were sought. From lipid soluble fractions, 20 terpenoids including seven hitherto unknown triterpenes were isolated. The latter triterpenes had either a γ-lactone ring with a lactol or a derivative thereof. Their chemical structures were determined by spectroscopic methods. The lipase inhibitory activity and LDL anti-oxidative activity of these compounds were evaluated. Some constituents (either lipase inhibitory or LDL anti-oxidative activities) had moderate inhibitory activities.

A Kampo Medicine, Boi-ogi-to, Inhibits Obesity in Ovariectomized Rats.

In women facing menopause, end of menstrual activity is accompanied by lower levels of estrogen and gradual weight gain. Postmenopausal weight gain sounds an alarm for womens health and may lead to hyperlipidemia, a lipid increase and glucose intolerance. These phenomena are connected to lifestyle-related diseases such as hypertension, type II diabetes mellitus, arteriosclerosis and metabolic syndrome, making it essential to prevent weight gain in women. A Kampo medicine, Boi-ogi-to, is traditionally used to treat obese conditions, but the mechanism has not yet been investigated. In this experiment, we tested the antiobesity properties of Boi-ogi-to in ovariectomized rats by measuring changes of serum cytokine levels and adipocytokines in fat cells. After treatment with this extract for 6 weeks (20-week-old rats), we found that there was a significant weight decrease in rats treated with Boi-ogi-to as compared with that in the control group. Serum tumor necrosis factor (TNF)-α levels increased significantly in a dose-dependent manner. Gene expression of adipose tissue in uterus also dose dependently showed a significant increase of TNF-α levels, suggesting that secretion of TNF-α by fat cells might play a role in the ability of Boi-ogi-to to inhibit weight gain. While peroxisome proliferators-activated receptor-γ and adiponectin levels did not show a significant difference as compared with those in the control, levels of mRNA expression showed a tendency to increase dose dependently. Resistin did not show any significant change. These results suggest that Boi-ogi-to might be useful for the prevention of obesity that occurs in women with reduction of estrogen.

Constituents of Rhodiola rosea showing inhibitory effect on lipase activity in mouse plasma and alimentary canal.

As a methanol extract of the rhizome of Rhodiola rosea inhibits the activity of lipase in isolated mouse plasma in vitro and in the mouse gastrointestinal tube in vivo, the active components in this plant were investigated. After fractionation and separation processes, rhodionin and rhodiosin were isolated as active ingredients. Their IC50 values were 0.093 mM and 0.133 mM in vitro, respectively. Both compounds significantly suppressed the elevation of the postprandial blood triglyceride level, e.g., by 45.6 % (150 mg/kg, 60 min after oral administration) and 57.6 % (200 mg/kg, 180 min after oral administration), respectively. Consequently, we anticipate the application of this plant and its constituents to the treatment of lifestyle-related diseases such as hyperlipidemia and exogeneous obesity and to health foods.

New phenolic compounds from Meehania urticifolia

A new phenylethanoid glycoside, rashomoside A (1), a new phenolic glucoside, rashomoside B (2), and a new shikimic acid derivative (3) were isolated from Meehania urticifolia together with 12 known flavones (4–15), three known phenylethanoid glycosides (16–18), and 13 other compounds (19–31). The structure of each of these compounds was elucidated based on the results of spectroscopic analysis.

Diastereomers of lithospermic acid and lithospermic acid B from Monarda fistulosa and Lithospermum erythrorhizon.

Monardic acids A (1) and B (2), which are (7R,8R) diastereomers of lithospermic acid (LA) and lithospermic acid B, respectively, were isolated from Monarda fistulosa. A (7S,8R) isomer (3) of LA was also isolated from this plant, and a (7R,8S) isomer (7) of LA was obtained from Lithospermum erythrorhizon. The absolute configuration of 1 was confirmed by analysis of its hydrolysates, 7-epiblechnic acid and 2R-3-(3,4-dihydroxyphenyl)-2-hydroxypropanoic acid. The configuration in the dihydrobenzofuran moieties of 2, 3, and 7 was extrapolated by using the phenylglycine methyl ester method and a Cotton effect at approximately 250-260 nm in their electronic circular dichroism spectra. Diastereomers (1-3 and 7) displayed moderate hyaluronidase inhibitory and histamine release inhibitory activities.

Cholinesterase-inhibitory diterpenoids and chemical constituents from aerial parts of Caryopteris mongolica

A diterpenoid diglucoside (12,19-di-O-β-d-glucopyranosyl-11-hydroxyabieta-8,11,13-triene-19-one), isoscutellarein 7-O-[β-d-xylopyranosyl-(1→2)]-β-d-glucopyranoside, isoscutellarein 7-O-[α-l-rhamnopyranosyl-(1→2)]-β-d-glucopyranoside, hypolaetin 7-O-[6″-O-(p-E-coumaroyl)]-β-d-glucopyranoside, hypolaetin 7-O-[6″-O-(E-caffeoyl)]-β-d-glucopyranoside, and 15 known compounds were isolated from aerial parts of the Mongolian medicinal plant Caryopteris mongolica. The cholinesterase-inhibitory activities of the constituents were estimated. The abietane diterpenoids (12-O-demethylcryptojaponol and 6α-hydroxydemethylcryptojaponol) showed potent inhibitory activity against acetylcholinesterase from human erythrocytes and electric eel, and against butyrylcholinesterase from horse serum.