Antioxidative compounds contained in the leaves of Melissa officinalis L. (lemon balm) were investigated. Six major compounds, protocatechuic acid (or 3,4-dihydroxybenzoic acid, 1), 2-(3',4'-dihydroxyphenyl)-1 ,3-benzodioxole-5-aldehyde (2), caffeic acid (3), rosmarinic acid (4). caffeic acid methyl ester (5), and rosmarinic acid methyl ester (6) were isolated from the extract of the plant and the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity was measured. Among them, compound 2 showed the most potent activity, about ten-fold that of ascorbic acid and of a-tocopherol. The compound had a characteristic I,3-benzodioxole structure and was easily degraded into two molecules of protocatechualdehyde.

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Apple polyphenols (AP) mainly consist of procyanidins (PC), which are composed of (-)-epicatechins and (+)-catechins. In order to investigate the antiageing effects of PC, we measured the lifespan of CAENORHABDITIS ELEGANS worms treated with PC. Treatment with 65 µg/mL PC extended the mean lifespan of wild-type N2 and FEM-1 worms by 12.1 % and 8.4 %, respectively, i.e., to a similar extent as resveratrol. In addition, treatment with 100 µg/mL AP also significantly prolonged the mean lifespan of the same worms by 12.0 % and 5.3 %, respectively, i.e., to a similar extent as PC. In contrast, treatment with (-)-epicatechin did not extend the lifespan of the worms. PC did not modify the growth, food intake, or fecundity of C. elegans. Treatment with PC did not extend the lifespan of MEV-1 worms, which show excessive oxidative stress, indicating that PC had no antioxidant ability in the MEV-1 mutant. Moreover, treatment with PC had no effect on the longevity of SIR-2.1 worms, which lack the activity of SIR-2, a member of the sirtuin family of NAD (+)-dependent protein deacetylases. These results indicated that PC has SIR-2.1-dependent antiageing effects on C. elegans.

New red leaf tea cultivar 'Sunrouge' (Camellia taliensis × Camellia sinensis), for which an application for registration was made in 2009, is an anthocyanin-rich tea. The anthocyanin content of 'Sunrouge' was the highest among 4 tea cultivars, and was 8.4 times higher than that of 'Yabukita'. We purified and isolated 6 anthocyanins from 'Sunrouge' by chromatography, and identified them by LC/MS/MS and NMR analysis. As a result, the four anthocyanins were identified as delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside (2), delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)glucopyranoside (3), cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside (4), and cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)glucopyranoside (5), and the other two were estimated as delphinidin-(Z)-p-coumaroylgalactopyranoside (1), petunidin-(E)-p-coumaroylgalactopyranoside (6). Compound 3 was found in tea for the first time. In general, anthocyanins have various bioactivities, including relieving eyestrain and antioxidative effects, so it is expected that drinking 'Sunrouge' tea brings in similar bioactivities.

Plant polyphenols, RG-tannin, and applephenon had been reported to inhibit cholera toxin (CT) ADP-ribosyltransferase activity and CT-induced fluid accumulation in mouse ileal loops. A high molecular weight fraction of hop bract extract (HBT) also inhibited CT ADP-ribosyltransferase activity. We report here the effect of those polyphenols on the binding and entry of CT into Vero cells. Binding of CT to Vero cells or to ganglioside GM1, a CT receptor, was inhibited in a concentration-dependent manner by HBT and applephenon but not RG-tannin. These observations were confirmed by fluorescence microscopy using Cy3-labeled CT. Following toxin binding to cells, applephenon, HBT, and RG-tannin suppressed its internalization. HBT or applephenon precipitated CT, CTA, and CTB from solution, creating aggregates larger than 250 kDa. In contrast, RG-tannin precipitated CT poorly; it formed complexes with CT, CTA, or CTB, which were demonstrated with sucrose density gradient centrifugation and molecular weight exclusion filters. In agreement, CTA blocked the inhibition of CT internalization by RG-tannin. These data suggest that some plant polyphenols, similar to applephenon and HBT, bind CT, forming large aggregates in solution or, perhaps, on the cell surface and thereby suppress CT binding and internalization. In contrast, RG-tannin binding to CT did not interfere with its binding to Vero cells or GM1, but it did inhibit internalization.Cholera toxin (CT), 1 a heterohexameric AB 5 toxin produced by Vibrio cholerae, is responsible for the life-threatening diarrheal disease. The B subunits bind to cell surface ganglioside GM1 (1, 2), following which the holotoxin is endocytosed by epithelial cells and delivered to the Golgi and endoplasmic reticulum (3, 4), where reduction of a disulfide bond on CTA and proteolysis produce fragments A1 and A2. CTA1, which is enzymatically active, then enters the cytoplasm (5-7), where, in the presence of NAD, it catalyzes the ADP-ribosylation of G␣ s (8 -10), resulting in persistent activation of adenylyl cyclase (11). The subsequent increase in cyclic AMP (12) induces the secretion of fluid and electrolytes into the lumen of the small intestine (13).Natural products, like herbal medications, have long been used to treat diarrheal disease and are useful therapeutic agents. Recently, inhibition of the action of bacterial toxins by plant polyphenols, composed of highly condensed tannins, has been reported (14 -16). These include applephenon, HBT, and RG-tannin, derived from apple, hop bract, and Daio (Rhei rhizoma), respectively. RG-tannin and applephenon suppress CTcatalyzed ADP-ribosylation and CT-induced fluid accumulation in rabbit or mouse ileal loops (14,15). RG-tannin is most likely a procyanidine polymer (mainly 8-mer) containing galloyl groups. Applephenon is composed of chlorogenic acid, catechins, and condensed catechins and procyanidins. Its anti-CT activity was attributed to the highly condensed tannin fraction (14), apple-condensed tannin (ACT), which contains procyanidine polymers...