Analysis of antioxidant prenylflavonoids in different parts of Macaranga tanarius, the plant origin of Okinawan propolis.

OBJECTIVE: To analyze the antioxidant prenylflavonoids in different parts of Macaranga tanarius (M. tanarius) (Euphorbiaceae) including the leaf, petiole, stem, leaflet, flower and fruit (only in female plant), and to evaluate their antioxidant properties. METHODS: Methanol extracts of each part of M. tanarius were prepared and five prenylflavonoids in them were quantitatively analyzed using HPLC. The fruits from female plant were further separated into seed, pericarp, and glandular trichome. After the quantitative analyses of prenylflavonoids in each part of M. tanarius, antioxidant activity of the extracts was evaluated by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging assay. RESULTS: The leaf of M. tanarius contained two prenylflavonoids as main components in both male and female plants. Both flowers (male and female) contained five kinds of prenylflavonoids. In the petiole, stem and leaflet of both male and female plants, the prenylflavonoids were not detected or their amounts were very low. Five kinds of prenylflavonoids were detected in the seed, pericarp and glandular trichome of female M. tanarius. In particular, the glandular trichome had the highest level of total prenylflavonoids (235 mg/g of fresh plant). DPPH radical scavenging activity of all parts was more than 30%. CONCLUSIONS: We found that different parts of M. tanarius contained antioxidant prenylflavonoids. In particular, not only the glandular trichome but also the leaf contained prenylflavonoids, which indicated that M. tanarius may be developed as a functional plant, because the leaves of this plant can be easily collected.

Antiviral effects of Psidium guajava Linn. (guava) tea on the growth of clinical isolated H1N1 viruses: its role in viral hemagglutination and neuraminidase inhibition.

Rapid evolution of influenza RNA virus has resulted in limitation of vaccine effectiveness, increased emergence of drug-resistant viruses and occurrence of pandemics. A new effective antiviral is therefore needed for control of the highly mutative influenza virus. Teas prepared by the infusion method were tested for their anti-influenza activity against clinical influenza A (H1N1) isolates by a 19-h influenza growth inhibition assay with ST6Gal I-expressing MDCK cells (AX4 cells) using fluorogenic quantification and chromogenic visualization. Guava tea markedly inhibited the growth of A/Narita/1/2009 (amantadine-resistant pandemic 2009 strain) at an IC(50) of 0.05% and the growth of A/Yamaguchi/20/06 (sensitive strain) and A/Kitakyushu/10/06 (oseltamivir-resistant strain) at similar IC(50) values ranging from 0.24% to 0.42% in AX4 cells, being 3.4- to 5.4-fold more potent than green tea (IC(50) values: 0.27% for the 2009 pandemic strain and 0.91% to 1.44% for the seasonal strains). In contrast to both teas, oseltamivir carboxylate (OC) demonstrated high potency against the growth of A/Narita/1/09 (IC(50) of 3.83nM) and A/Yamaguchi/20/06 (IC(50) of 11.57nM) but not against that of A/Kitakyushu/10/06 bearing a His274-to-Tyr substitution (IC(50) of 15.97µM). Immunofluorescence analysis under a confocal microscope indicated that both teas inhibited the most susceptible A/Narita/1/2009 virus at the initial stage of virus infection. This is consistent with results of direct inhibition assays showing that both teas inhibited viral hemagglutination at concentrations comparable to their growth inhibition concentrations but inhibited sialidase activity at about 8-times higher concentrations. Guava tea shows promise to be efficacious for control of epidemic and pandemic influenza viruses including oseltamivir-resistant strains, and its broad target blockage makes it less likely to lead to emergence of viral resistance.

Components of lemon essential oil attenuate dementia induced by scopolamine.

The anti-dementia effects of s-limonene and s-perillyl alcohol were observed using the passive avoidance test (PA) and the open field habituation test (OFH). These lemon essential oils showed strong ability to improve memory impaired by scopolamine; however, s-perillyl alcohol relieved the deficit of associative memory in PA only, and did not improve non-associative memory significantly in OFH. Analysis of neurotransmitter concentration in some brain regions on the test day showed that dopamine concentration of the vehicle/scopolamine group was significantly lower than that of the vehicle/vehicle group, but this phenomenon was reversed when s-limonene or s-perillyl alcohol were administered before the injection of scopolamine. Simultaneously, we found that these two lemon essential oil components could inhibit acetylcholinesterase activity in vitro using the Ellman method.

Effects of direct exposure of green odour components on dopamine release from rat brain striatal slices and PC12 cells.

The effects of odour components on dopamine release from rat brain striatal slices and rat pheochromocytoma (PC12) cells were examined. The striatal slices were directly stimulated with 0.5% odour-including Krebs buffer using a superfusion method. In this experiment, (Z)-3-hexenol, (E)-2-hexenal, n-hexanal, 1,8-cineole or Eucalyptus globulus essential oil was used as an odour component. The concentrations of monoamines released in perfusate were measured by HPLC-ECD. Dopamine release from brain slices was significantly enhanced by perfusion of each odour-including solution. In particular, administration of n-hexanal caused a 9-fold increase in dopamine release. The dopamine release by n-hexanal increased linearly with the concentration of n-hexanal up to 0.5% and was maximal at 0.5%. Since PC12 cells have the ability to release dopamine, the effects of four green odour compounds, (Z)-3-hexenol, (E)-2-hexenal, n-hexanal and n-hexanol, on dopamine release were examined. These odour compounds dose dependently increased dopamine release from PC12 cells, and different patterns of dopamine release were observed with aldehyde or alcohol. Odour compounds thus appear to increase dopamine release from dopamine-releasing cells, with differences between aldehydes and alcohols in pattern of release. Dopamine regulates brain functions such as reward, mood, and attention. Green odours may in turn regulate such brain functions through the stimulation of dopamine release.

Antioxidant prenylated flavonoids from propolis collected in Okinawa, Japan.

Propolis is a resinous substance collected by honeybees from various plant sources. The composition of propolis depends upon the vegetation at the site of collection. We previously isolated four prenylated flavonoids from propolis collected in Okinawa, Japan. In this study, further fractionation of the extracts of Okinawan propolis resulted in the isolation of a new prenylated flavonoid, prokinawan, and four known compounds. The structure of prokinawan was determined by MS and NMR spectroscopic methods. Furthermore, the antioxidant activity using 1,1-diphenyl-2-picryl-hydrazyl radical scavenging and beta-carotene bleaching systems was investigated. The present study proved that the position of the geranyl or prenyl groups on the flavonoid skeleton plays an important role in exhibiting antioxidant activity.

Flavor components of monoterpenes in citrus essential oils enhance the release of monoamines from rat brain slices.

Citrus essential oils have been utilized widely in traditional medicine, and there are various reports of actions such as effects on behavior and effects on pain stimulation response due to exposure. However, there are no reports concerning effects on neurotransmitters after ingestion, and uptake within the brain. We used brain tissue slices to investigate the effect of compounds in lemon essential oil on monoamine release. We investigated R-limonene, gamma-terpinene and citral, major components of lemon essential oil; S-limonene, an isomer of R-limonene and metabolites of these compounds. The effect of each compound on monoamine release from brain tissue slices was found to be dose-dependent. R-Limonene and its S-isomer demonstrated differences with regard to monoamine release from brain tissue. S-Limonene and its metabolites were found to have a stronger effect than the R-isomer. Limonene metabolites taken up in vivo were also found to have a stronger effect on monoamine release than both the R-form and the S-form. In an investigation of dopamine release using stratum slices, terpinene and pinene demonstrated no clear differences in activity attributable to isomers. However, rho-cymene, a gamma-terpinene metabolite, was found to have a stronger effect than gamma-terpinene. These results suggest that the metabolites of these monoterpene compounds contained in citrus essential oils have a stronger effect on monoamine release from brain tissue than the monoterpene compounds themselves.

Difference in plasma metabolite concentration after ingestion of lemon flavonoids and their aglycones in humans.

The concentrations of metabolites in human plasma after ingestion of flavanone glycosides (FG) and their aglycones (FA) in lemon were examined. FG consisting abundantly of eriocitrin were prepared from lemon peel and FA consisting abundantly of eriodictyol were prepared from FG by treatment with beta-glucosidase. Eriodictyol, homoeriodictyol, and hesperetin in plasma up to 4 h after ingestion of FG with water or FA with water by subjects were not detected in plasma of non-enzyme treatment but in plasma after treatment with beta-glucronidase and sulfatase. Metabolites in plasma after ingestion of FG and FA in humans were shown to exist as the glucuro- and/or sulfo-conjugates of eriodictyol, homoeriodictyol, and hesperetin. After ingestion of FA, the concentration of metabolites in plasma exhibited a high maximum peak at 1 h. The AUC (area under the blood concentration time curve) level of metabolites of FA was higher than that of FG. FA were suggested to be absorbed faster and in higher amounts than FG. The AUC of metabolites in subject plasma after ingestion of FG with flavonoid-depleted lemon juice was shown to change to a low level in comparison with that of FG with water. The maximum concentration peak of metabolites in plasma was faster at 0.5 h than FA with water but the AUC level was similar to FA with water, when subjects ingested FA with vodka (40%, ethanol). The absorption hour of FG and FA was shown to be affected by the co-existing solution.

Antioxidative catechol lignans converted from sesamin and sesaminol triglucoside by culturing with Aspergillus.

Sesamin and sesaminol triglucoside in sesame seeds are major lignans that display an abundance of biological activities. Although their antioxidative activity in vitro is weak, they have been reported to suppress oxidative stress in vivo. We investigated the production of new antioxidative lignans from sesame lignans by culturing with the genus Aspergillus to enhance the function of food materials. Media containing sesamin or sesaminol triglucoside increased antioxidative activity for DPPH radical scavenging by culturing with Aspergillus usamii mut. shirousamii RIB2503. The antioxidative lignans in sesamin medium were identified as sesamin 2,6-dicatechol and episesamin 2,6-dicatechol. Those in sesaminol triglucoside medium were identified as sesaminol 6-catechol and episesaminol 6-catechol, which are novel antioxidative lignans. It is suggested that they may exhibit higher antioxidative activity than sesamin and sesaminol triglucoside because they have the catechol functional moiety.

A new prenylated flavonoid from propolis collected in Okinawa, Japan.

The new prenylflavonoid, isonymphaeol-B (1), together with three known compounds, nymphaeol-A (2), nymphaeol-B (3), and nymphaeol-C (4), were isolated from propolis collected in Okinawa, the southern-most prefecture of Japan. The structure of each compound was determined by spectral methods, including mass spectrometry and 2D NMR. Each compound had 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging activity.

New potent antioxidative hydroxyflavanones produced with Aspergillus saitoi from flavanone glycoside in citrus fruit.

Potent antioxidative hydroxyflavanones were produced with Aspergillus saitoi from hesperidin or naringin, which are flavanone glycosides in citrus fruit with weak antioxidative activity. The hydroxyflavanone produced from hesperidin was identified as 8-hydroxyhesperetin (8-HHE), a novel substance, and those from naringin were identified as carthamidin (6-hydroxynaringenin) and isocarthamidin (8-hydroxynaringenin) by FAB-MS, 1H-NMR and 13C-NMR analyses. The antioxidative activity of these hydroxyflavanones was examined by using the free radical-scavenging system of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the methyl linoleate oxidation system. The hydroxyflavanones (8-HHE, carthamidin, and isocarthamidin) exhibited stronger activity than the flavanone glycosides (hesperidin or naringin) and their aglycones (hesperetin or naringenin). The activity of 8-HHE and isocarthamidin was comparable to that of alpha-tocopherol, and that of carthamidin was weaker than that of isocarthamidin. The hydroxyflavanones, which were hydroxylated on A ring of flavanone by Aspergillus saitoi, were obtained as potent antioxidants.

Lemon flavonoid, eriocitrin, suppresses exercise-induced oxidative damage in rat liver.

To examine the preventive effect of the lemon flavonoid, eriocitrin (eriodictyol 7-O-rutinoside), on oxidative stress during acute exercise in vivo, levels of N( epsilon )- (hexanoyl)lysine, HEL; o,o-dityrosine, DT; and nitrotyrosine, NT, as oxidative stress markers, were determined by ELISA in livers of trained rats in addition to thiobarbituric acid-reactive substance (TBARS). Eriocitrin administration prior to exercise significantly suppressed the increases in TBARS caused by lipid peroxidation during acute exercise. The contents of HEL, DT, and NT in rat liver increased dramatically by exercise without eriocitrin administration. However, these increases were significantly suppressed by eriocitrin administration before exercise. Moreover, in this study, to clarify whether eriocitrin influences glutathione metabolite system that is considered to be important for a defense against the damage by oxidative stress, the levels of glutathione in rat liver were determined during exercise. The level of reduced glutathione after exercise was maintained by administration of eriocitrin. The increase in the concentration of oxidized glutathione caused by exercise was significantly suppressed by eriocitrin. This result suggested that eriocitrin might play an important role in the control of the change in glutathione redox status in rat liver during exercise. These findings showed that eriocitrin was effective in the prevention of oxidative damages caused by acute exercise-induced oxidative stress.