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Proanthocyanidins are abundant in peanut skin, and in this study, the antibacterial effects of a peanut skin extract (PSE) against food-borne bacteria were investigated to find its minimum inhibitory concentration. Food-borne gram-positive bacteria, and in particular Bacillus cereus, was more sensitive to PSE. In particular, the inhibitory activity of epicatechin-(4β → 6)-epicatechin-(2β → O→7, 4β → 8)-catechin (EEC), a proanthocyanidin trimer from peanut skin, against B. cereus was stronger than that of procyanidin A1, a proanthocyanidin dimer. DNA microarray analysis of B. cereus treated with EEC was carried out, with a finding that 597 genes were significantly up-regulated. Analysis of the up-regulated genes suggested that EEC disrupted the normal condition of the cell membrane and wall of B. cereus and alter its usual nutritional metabolism. Moreover, treatment of B. cereus with EEC inhibited glucose uptake, suggesting that EEC affects the cell-surface adsorption.Electronic supplementary materialThe online version of this article (doi:10.1007/s00284-016-1032-x) contains supplementary material, which is available to authorized users.

Mollusks make their shells by biomineralization using Ca 2+ and CO 3 22 from natural environment. In molluscan shells, two types of CaCO 3 crystal which are aragonite and calcite form the species-dependent microstructures. It is believed that shell organic matrices act for control of the crystal types and microstructures. Shell of Pinctada fucata is divided into aragonitic nacreous layer and calcitic prismtic layer. In the recent years, several novel matrix components have been identified in pearl oyster shells by subsequent solubilization of the insoluble matrix, even in the nacreous layer which abounds in the data. In them, we focused our attention on a component, of which the N-terminal amino acid sequence was determined, and attempted cloning genes encoding it. As a result, several clones with typical sequence for the ORF (open reading frame) region were identified and the amino acid sequences were deduced. Further analysis of northern hybridization clarified the tissue specific expressions of the transcripts of the identified genes.

The red skin of peanut ( Arachis hypogaea L. ) contains high levels of polyphenols. Recently, we reported the antiallergic, hypocholesterolemic, and hypoglycemic effects of peanut skin polyphenols １) -３) .These biological effects were determined to be closely related to their stereochemistry. For example, procyanidin A１, a proanthocyanidin dimer were reported to elicit the inhibitory activity of βhexosaminidase release, while(＋) -catechin did not ２) .In addition, epicatechin-(４β →６) -epicatechin (２β →O →７,４β →８)-catechin ( EEC ), a proanthocyanidin trimer, exhibits a more potent cholesterol micelledegrading activity compared to procyanidin A１, while(＋) -catechin did not either ３) .Peanut skin polyphenols have also been documented for their antioxidative effect ４) ， ５) . YU et al . ５) showed that after blanching, loasting, or direct peeling, peanut skin retained its free radical scavenging activities, while the composition of procyanidin dimers, trimers and tetramers was different depending on the processing method. No significant difference was observed between the scavenging activities of dimer, trimer, and tetramer proanthocyanidins using the DPPH(１, １-diphenyl-１-２picrylhydrazyl )radical ６) method, whereas other analytical methods, such as total antioxidant capacity, oxygen radical absorbance capacity (ORAC) , and discoloration of β-carotene were not examined. The antioxidant activity between proanthocyanidin dimers was different. Epicatechin-(４β →８, ２β →O →７) -catechin from peanut skin had lower protective effect on lipid oxidation compared to epicatechin-(４β →８