Biochemical Aspects of Putative Aminotransferase Responsible for Converting Vanillin to Vanillylamine in the Capsaicinoid Biosynthesis Pathway in Capsicum Plants.

The biosynthesis pathway of capsaicinoids includes the conversion of vanillin to vanillylamine, where putative aminotransferase (pAMT) is thought to be the enzyme responsible in Capsicum plants. The objectives of this study were to prove that pAMT is the enzyme responsible for this conversion in plants and to clarify its catalytic properties using biochemical methods. Both an extract of habanero placenta and recombinant pAMT (rpAMT) constructed by using an Escherichia coli expression system were able to convert vanillin to vanillylamine in the presence of γ-aminobutyric acid as an amino donor and pyridoxal phosphate as a coenzyme. Conversion from vanillin to vanillylamine by the placenta extract was significantly attenuated by adding an anti-pAMT antibody to the reaction system. The amino donor specificity and affinity for vanillin of rpAMT were similar to those of the placenta extract. We thus confirmed that pAMT is the enzyme responsible for the conversion of vanillin to vanillylamine in capsaicinoid synthesis in Capsicum fruits. Therefore, we propose that pAMT should henceforth be named vanillin aminotransferase (VAMT).

An evolutionary view of vanillylamine synthase pAMT, a key enzyme of capsaicinoid biosynthesis pathway in chili pepper.

Pungent capsaicinoid is synthesized only in chili pepper (Capsicum spp.). The production of vanillylamine from vanillin is a unique reaction in the capsaicinoid biosynthesis pathway. Although putative aminotransferase (pAMT) has been isolated as the vanillylamine synthase gene, it is unclear how Capsicum acquired pAMT. Here, we present a phylogenetic overview of pAMT and its homologs. The Capsicum genome contained 5 homologs, including pAMT, CaGABA-T1, CaGABA-T3, and two pseudogenes. Phylogenetic analysis indicated that pAMT is a member of the Solanaceae cytoplasmic GABA-Ts. Comparative genome analysis found that multiple copies of GABA-T exist in a specific Solanaceae genomic region, and the cytoplasmic GABA-Ts other than pAMT are located in the region. The cytoplasmic GABA-T was phylogenetically close to pseudo-GABA-T harboring a plastid transit peptide (pseudo-GABA-T3). This suggested that Solanaceae cytoplasmic GABA-Ts occurred via duplication of a chloroplastic GABA-T ancestor and subsequent loss of the plastid transit signal. The cytoplasmic GABA-T may have been translocated from the specific Solanaceae genomic region during Capsicum divergence, resulting in the current pAMT locus. A recombinant protein assay demonstrated that pAMT had higher vanillylamine synthase activity than those of other plant GABA-Ts. pAMT was expressed exclusively in the placental septum of mature green fruit, whereas tomato orthologs SlGABA-T2/4 exhibit a ubiquitous expression pattern in plants. These findings suggested that both the increased catalytic efficiency and transcriptional changes in pAMT may have contributed to establish vanillylamine synthesis in the capsaicinoid biosynthesis pathway. This study provides insights into the establishment of pungency in the evolution of chili peppers.

A single amino acid substitution alters the vanillylamine synthesis activity of Capsicum pAMT.

Some Capsicum synthesize a unique pungent alkaloid called capsaicin in their fruits. In the synthetic pathway of capsaicin, vanillylamine is produced from vanillin in a reaction catalyzed by a putative aminotransferase (pAMT). Therefore, the capsaicinoids content in the fruits is thought to partially depend on the characteristics of pAMT. Comparing Yume-matsuri (yume), C. annuum variety, and red habanero (RH), C. chinense variety, the vanillylamine synthesis activity of the placental extract was higher in yume than in RH. When each recombinant pAMT (rpAMT) was generated using the Escherichia coli expression system and their activities were compared, yume rpAMT synthesized 14-fold more vanillylamine than RH rpAMT. The amino acid sequence of yume and RH pAMT deduced from the cDNAs revealed that only 7 of 459 residues differed. When a single amino acid residue-substituted rpAMT was generated in which the 56th amino acid was swapped with one other, the amount of vanillylamine synthesis of yume and RH rpAMTs was inverted. Furthermore, it was suggested that the 56th amino acid contributed to the affinity for the coenzyme pyridoxal phosphate. Differences in the vanillylamine synthesis activity of pAMT may also lead to differences in the amount of capsaicin synthesis that accumulates in the fruit. Since capsaicin is a compound with commercial value, this finding may provide new insights into the creation of a variety that can synthesize more capsaicin.

Suppression of Neuroinflammation by Coffee Component Pyrocatechol via Inhibition of NF-κB in Microglia.

According to numerous studies, it has been epidemiologically suggested that habitual coffee intake seems to prevent the onset of neurodegenerative diseases. In this study, we hypothesized that coffee consumption suppresses neuroinflammation, which is closely related to the development of neurodegenerative diseases. Using microglial BV-2 cells, we first found that the inflammatory responses induced by lipopolysaccharide (LPS) stimulation was diminished by both coffee and decaffeinated coffee through the inhibition of an inflammation-related transcription factor, nuclear factor-κB (NF-κB). Pyrocatechol, a component of roasted coffee produced by the thermal decomposition of chlorogenic acid, also exhibited anti-inflammatory activity by inhibiting the LPS-induced activation of NF-κB. Finally, in an inflammation model using mice injected with LPS into the cerebrum, we observed that intake of pyrocatechol as well as coffee decoctions drastically suppressed the accumulation of microglia and the expression of interleukin-6 (IL-6), tumor necrosis factor α (TNFα), CCL2, and CXCL1 in the inflammatory brain. These observations strongly encourage us to hypothesize that the anti-inflammatory activity of pyrocatechol as well as coffee decoction would be useful for the suppression of neurodegeneration and the prevention of the onsets of Alzheimer's (AD) and Perkinson's diseases (PD).

Spermine Suppresses Adipocyte Differentiation and Exerts Anti-Obesity Effects In Vitro and In Vivo.

Endogenous polyamines such as putrescine (Put), spermidine (Spd), and spermine (Spm) affect adipocyte differentiation. In this study, we investigated the effect of exogenously supplemented polyamines on mouse adipocyte differentiation and anti-obesity actions in vitro and in vivo. The preadipocyte cell line, 3T3-L1, was cultured with Put, Spd, or Spm, and lipid accumulation in the cells was measured by Oil Red O staining. Lipid accumulation was significantly suppressed by Spm. Suppression of CCAAT/enhancer binding protein α mRNA by Spm suggested that the decreased lipid accumulation was due to delaying the cell differentiation. The body weight and fat of obese mice induced with a high-fat diet were reduced by oral ingestion of Spm. In conclusion, oral supplementation of Spm has the ability to prevent obesity through inhibition of adipocyte differentiation.

Vanillin reduction in the biosynthetic pathway of capsiate, a non-pungent component of Capsicum fruits, is catalyzed by cinnamyl alcohol dehydrogenase.

Capsicum fruits synthesize capsaicin from vanillylamine, which is produced from vanillin in a reaction catalyzed by a putative aminotransferase (pAMT). Capsiate, a non-pungent compound that is structurally similar to capsaicin, is synthesized from vanillyl alcohol rather than vanillylamine. Vanillyl alcohol is possibly generated by the enzymatic reduction of vanillin, but the enzyme responsible for this reaction is unknown. In the present study, we revealed that the vanillin reductase in the capsiate biosynthetic pathway is cinnamyl alcohol dehydrogenase (CAD), which is an enzyme involved in lignin synthesis. The reduction of vanillin to vanillyl alcohol was greater in the mature red fruit placental extract than in the immature green fruit placental extract. This reduction was suppressed by both N-(O-hydroxyphenyl) sulfinamoyltertiobutyl acetate, a specific inhibitor of CAD, and ethylenediaminetetraacetic acid, a metalloenzyme inhibitor. The CaCAD1 transcript levels in the placenta were higher in the red fruits than in the green fruits. A recombinant CaCAD1 protein obtained using an Escherichia coli expression system reduced vanillin to vanillyl alcohol. This reaction was suppressed by the CAD inhibitors. These results strongly suggest that CAD is the enzyme that catalyzes the reduction of vanillin to vanillyl alcohol during capsiate biosynthesis. Syntenic analyses indicated that genes encoding CAD and capsaicin synthase (Pun1) involved in capsiate biosynthesis were acquired before the pAMT gene during the evolution of the family Solanaceae. This raises the possibility that in the genus Capsicum, the capsiate biosynthetic pathway emerged before the pAMT-encoding gene was acquired as the final trigger for capsaicin biosynthesis.

Osteoclast Differentiation Is Suppressed by Increased O-GlcNAcylation Due to Thiamet G Treatment.

Osteoclasts are the only bone-resorbing cells in organisms and understanding their differentiation mechanism is crucial for the treatment of osteoporosis. In the present study, we investigated the effect of Thiamet G, an O-GlcNAcase specific inhibitor, on osteoclastogenic differentiation. Thiamet G treatment increased global O-GlcNAcylation in murine RAW264 cells and suppressed receptor activator of nuclear factor-κB ligand (RANKL)-dependent formation in tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells, thereby suppressing the upregulation of osteoclast specific genes. Meanwhile, knockdown of O-linked N-acetylglucosamine (O-GlcNAc) transferase promoted the formation TRAP-positive multinuclear cells. Thiamet G treatment also suppressed RANKL and macrophage colony-stimulating factor (M-CSF) dependent osteoclast formation and bone-resorbing activity in mouse primary bone marrow cells and human peripheral blood mononuclear cells. These results indicate that the promotion of O-GlcNAc modification specifically suppresses osteoclast formation and its activity and suggest that chemicals affecting O-GlcNAc modification might potentially be useful in the prevention or treatment of osteoporosis in future.

Biological Properties of the Aggregated Form of Chitosan Magnetic Nanoparticle.

BACKGROUND/AIM: Chitosan-coated iron oxide nanoparticles (Chi-NP) have gained attention because of their biocompatibility, biodegradability, low toxicity and targetability under magnetic field. In this study, we investigated various biological properties of Chi-NP. MATERIALS AND METHODS: Chi-NP was prepared by mixing magnetic NP with chitosan FL-80. Particle size was determined by scanning and transmission electron microscopes, cell viability by MTT assay, cell cycle distribution by cell sorter, synergism with anticancer drugs by combination index, PGE2 production in human gingival fibroblast was assayed by ELISA. RESULTS: The synthetic process of Chi-NP from FL-80 and magnetic NP increased the affinity to cells, up to the level attained by nanofibers. Upon contact with the culture medium, Chi-NP instantly formed aggregates and interfered with intracellular uptake. Aggregated Chi-NP did not show cytotoxicity, synergism with anticancer drugs, induce apoptosis (accumulation of subG1 cell population), protect the cells from X-ray-induced damage, nor affected both basal and IL-1ß-induced PGE2 production. CONCLUSION: Chi-NP is biologically inert and shows high affinity to cells, further confirming its superiority as a scaffold for drug delivery.

Augmentation of Neurotoxicity of Anticancer Drugs by X-Ray Irradiation.

BACKGROUND: In order to investigate the combination effect of anticancer drugs and X-ray irradiation on neurotoxic side-effects (neurotoxicity), a method that provides homogeneously X-ray-irradiated cells was newly established. MATERIALS AND METHODS: PC12 cell suspension was irradiated by X-ray (0.5 Gy) in serum-supplemented medium, immediately inoculated into 96-microwell plates and incubated overnight. The medium was replaced with fresh serum-depleted medium containing 50 ng/ml nerve growth factor to induce differentiation toward nerve-like cells with characteristic neurites according to the overlay method without changing the medium. The differentiated cells were treated by anticancer drugs as well as antioxidants, oxaliplatin or bortezomib, and the viable cell number was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. RESULTS: Antioxidants and anticancer drugs were cytotoxic to differentiating PC12 cells. Combination of anticancer drugs and X-ray irradiation slightly reduced cell viability. CONCLUSION: The present 'population irradiation method' may be useful for the investigation of the combination effect of X-ray irradiation and any pharmaceutical drug.

Pyrocatechol, a component of coffee, suppresses LPS-induced inflammatory responses by inhibiting NF-κB and activating Nrf2.

Coffee is a complex mixture of many bioactive compounds possessing anti-inflammatory properties. However, the mechanisms by which coffee exerts anti-inflammatory effects remains unclear and the active ingredients have not yet been identified. In this study, we found that coffee extract at more than 2.5%(v/v) significantly inhibited LPS-induced inflammatory responses in RAW264.7 cells and that anti-inflammatory activity of coffee required the roasting process. Interestingly, we identified pyrocatechol, a degradation product derived from chlorogenic acid during roasting, as the active ingredient exhibiting anti-inflammatory activity in coffee. HPLC analysis showed that 124 µM pyrocatechol was included in 100% (v/v) roasted coffee. A treatment with 5%(v/v) coffee extract and more than 2.5 µM pyrocatechol inhibited the LPS-induced activation of NF-κB and also significantly activated Nrf2, which acts as a negative regulator in LPS-induced inflammation. Furthermore, intake of 60% (v/v) coffee extract and 74.4 µM pyrocatechol, which is the concentration equal to contained in 60% (v/v) coffee, markedly inhibited the LPS-induced inflammatory responses in mice. Collectively, these results demonstrated that pyrocatechol, which was formed by the roasting of coffee green beans, is one of the ingredients contributing to the anti-inflammatory activity of coffee.

Evaluation of Solubility Characteristics of a Hybrid Complex of Components of Soy.

The purpose of this study was to evaluate the solubilities and physicochemical properties of solid dispersions of daidzein (DDZ) and genistein (GST) (the major isoflavones in soybeans) in γ-cyclodextrin (γCD). Dispersions were prepared in distilled water using a three-dimensional ball mill (3DGMw). Phase solubility diagrams confirmed that DDZ/γCD and GST/γCD formed AL type inclusion complexes with a molar ratio of 1:1. A new peak due to inclusion complexes was observed in the results of powder X-ray diffraction (3DGMw(DDZ/γCD = 1:1) and 3DGMw(GST/γCD = 1:1)). Dissolution tests using distilled water found that solubilities of 3DGMw(DDZ/γCD = 1:1) and 3DGMw(GST/γCD = 1:1) were approximately 37- and 51-fold higher, respectively, than the solubilities of pure DDZ and GST. These observations are expected to expand the usefulness of cogrinding of DDZ or GST with γCD using a three-dimensional ball mill.

Positional differences of intronic transposons in pAMT affect the pungency level in chili pepper through altered splicing efficiency.

Capsaicinoids are unique compounds that give chili pepper fruits their pungent taste. Capsaicinoid levels vary widely among pungent cultivars, which range from low pungency to extremely pungent. However, the molecular mechanisms underlying this quantitative variation have not been elucidated. Our previous study identified various loss-of-function alleles of the pAMT gene which led to low pungency. The mutations in these alleles are commonly defined by Tcc transposon insertion and its footprint. In this study, we identified two leaky pamt alleles (pamtL1 and pamtL2 ) with different levels of putative aminotransferase (pAMT) activity. Notably, both alleles had a Tcc transposon insertion in intron 3, but the locations of the insertions within the intron were different. Genetic analysis revealed that pamtL1 , pamtL2 and a loss-of-function pamt allele reduced capsaicinoid levels to about 50%, 10% and less than 1%, respectively. pamtL1 and pamtL2 encoded functional pAMT proteins, but they exhibited lower transcript levels than the functional type. RNA sequencing analysis showed that intronic transposons disrupted splicing in intron 3, which resulted in simultaneous expression of functional pAMT mRNA and non-functional splice variants containing partial sequences of Tcc. The non-functional splice variants were more dominant in pamtL2 than in pamtL1 . This suggested that the difference in position of the intronic transposons could alter splicing efficiency, leading to different pAMT activities and reducing capsaicinoid content to different levels. Our results provide a striking example of allelic variations caused by intronic transposons; these variations contribute to quantitative differences in secondary metabolite contents.

Short communication: Milk basic protein promotes proliferation and inhibits differentiation of mouse chondrogenic ATDC5 cells.

It has been reported that the intake of milk basic protein (MBP) increases bone density by promoting bone formation and suppressing bone resorption. However, few studies have been done on MBP in cartilage, the tissue adjacent to bone. We therefore investigated the effect of MBP on a chondrocyte cell line, ATDC5. In a proliferative assay using the WST-1 method, the addition of 10, 100, and 1,000 µg/mL of MBP to ATDC5 cells significantly increased the cell number by about 1.2-, 1.5-, and 1.7-fold, respectively, compared with the control cells. The cell cycle analysis using flow-cytometry revealed that the proportion of S- and G2/M-phase cells was increased but that of G0/G1 phase was decreased in a dose-dependent manner with MBP addition. We measured the alkaline phosphatase activity of MBP-treated ATDC5 cells to examine the differentiation stage of the cells. Alkaline phosphatase activity was suppressed in a dose-dependent manner with MBP addition and was especially drastic at higher doses of MBP (100 and 1,000 µg/mL). The Alizarin Red S staining intensity, the indicator for calcification of cells, was lower in the MBP-treated (100 µg/mL) cells than in nontreated control cells. In the reverse-transcription PCR experiment, the mRNA level of SRY-box containing gene 9 (Sox9) and type II collagen (Col2) was significantly increased in the MBP-treated cells compared with the control cells. A significant decrease of the mRNA level of runt-related transcription factor 2 (Runx2) and type X collagen (Col10) was also observed in the MBP-treated cells. These results suggested that MBP promoted the proliferation of chondrocytes by suppressing their differentiation toward calcification.

Assessment of the Physical Properties of Inclusion Complexes of Forchlorfenuron and γ-Cyclodextrin Derivatives and Their Promotion of Plant Growth.

The current study prepared solid dispersions of forchlorfenuron (CPPU) and γ-cyclodextrin (γCD) or CPPU and 2-hydroxypropyl-γ-cyclodextrin (HPγCD) via cogrinding and coprecipitation to assess their physicochemical properties and their effect on plant growth. According to phase solubility diagrams, both CPPU/γCD and CPPU/HPγCD formed an inclusion complex at a molar ratio of 1/1. According to differential scanning calorimetry and powder X-ray diffraction, a ground mixture (GM) of CPPU and γCD (molar ratio = 1/1), a GM of CPPU and HPγCD (molar ratio = 1/1), and a coprecipitate (CP) of CPPU and γCD (molar ratio = 1/1) formed an inclusion complex. According to 1H-1H nuclear Overhauser effect spectroscopy NMR spectroscopy of the GMs and CP, the aromatic rings of the CPPU molecule are presumably included in CD from the wider to the narrower rim of its ring. Cultivation of broccoli sprouts with the GMs and CP resulted in no differences in the length of sprouts in comparison to a commercial preparation (Fulmet).

The Biological Efficacy of Natural Products against Acute and Chronic Inflammatory Diseases in the Oral Region.

The oral inflammatory diseases are divided into two types: acute and chronic inflammatory diseases. In this review, we summarize the biological efficacy of herbal medicine, natural products, and their active ingredients against acute and chronic inflammatory diseases in the oral region, especially stomatitis and periodontitis. We review the effects of herbal medicines and a biscoclaurin alkaloid preparation, cepharamthin, as a therapy against stomatitis, an acute inflammatory disease. We also summarize the effects of herbal medicines and natural products against periodontitis, a chronic inflammatory disease, and one of its clinical conditions, alveolar bone resorption. Recent studies show that several herbal medicines such as kakkonto and ninjinto reduce LPS-induced PGE 2 production by human gingival fibroblasts. Among herbs constituting these herbal medicines, shokyo (Zingiberis Rhizoma) and kankyo (Zingiberis Processum Rhizoma) strongly reduce PGE 2 production. Moreover, anti-osteoclast activity has been observed in some natural products with anti-inflammatory effects used against rheumatoid arthritis such as carotenoids, flavonoids, limonoids, and polyphenols. These herbal medicines and natural products could be useful for treating oral inflammatory diseases.

Roasted Coffee Reduces ß-Amyloid Production by Increasing Proteasomal ß-Secretase Degradation in Human Neuroblastoma SH-SY5Y Cells.

SCOPE: Epidemiological studies have shown that coffee consumption may be associated with a lower risk of developing several neurological disorders, including Alzheimer's disease (AD). Caffeine is a prominent candidate component underlying the preventive effects of coffee; however, the contribution of other constituents is unclear. To clarify this issue, the effect of roasting coffee beans on ß-secretase (BACE1) expression in human neuroblastoma SH-SY5Y cells is investigated. METHODS AND RESULTS: Coffee (2%) reduces Aß accumulation in culture medium to 80% of control levels after 24 h. Accordingly, BACE1 expression is decreased to 70% of control levels at 12 h. Experiments using cycloheximide and MG132, a proteasome inhibitor, reveal that coffee enhanced BACE1 degradation through activation of proteasomal activity. Furthermore, coffee activates cAMP-dependent protein kinase, and consequently, phosphorylation of a serine residue of proteasome 26S subunit, non-ATPase 11 (PSMD11). Pyrocatechol, a strong antioxidant known as catechol or 1,2-dihydroxybenzene, produced from chlorogenic acid during roasting, also reduces BACE1 expression by activation of proteasomal activity. Furthermore, pyrocatechol reduces Aß production in SH-SY5Y cells. CONCLUSION: The data suggest that the roasting process may be crucial for the protective effects of coffee consumption in AD.

Supplemented Chondroitin Sulfate and Hyaluronic Acid Suppress Mineralization of the Chondrogenic Cell Line, ATDC5, via Direct Inhibition of Alkaline Phosphatase.

Chondroitin sulfate (CS) is a sulfated polysaccharide produced by chondrocytes. Alkaline phosphatase (ALP) is an important enzyme involved in the mineralization of chondrocytes. In recent years, it has been reported that CS regulates the differentiation of various cells. In this study, we investigated the effect of supplemented CS on ALP activity and mineralization of the chondrogenic cell line, ATDC5. In addition, hyaluronic acid (HA), a non-sulfated and acidic polysaccharide, was used in comparison to CS. CS and HA significantly suppressed ALP activity without affecting ATDC5 cell proliferation. In addition, although the inhibition of ALP activity was observed at every time point, Alp mRNA expression level was not affected by CS. The suppressive effect of CS on ALP activity was abrogated by pre-treatment with chondroitinase ABC (CSase). CS and L-homoarginine (hArg), an inhibitor of ALP, significantly suppressed mineralization in ATDC5 cells. In conclusion, supplemented CS directly inhibits ALP to prevent the progression of chondrocytes from differentiation to mineralization.

Glucosamine Suppresses Osteoclast Differentiation through the Modulation of Glycosylation Including O-GlcNAcylation.

Osteoclasts represent the only bone resorbing cells in an organism. In this study, we investigated the effect of glucosamine (GlcN), a nutrient used to prevent joint pain and bone loss, on the osteoclastogenesis of murine macrophage-like RAW264 cells. GlcN supplementation suppressed the upregulation of osteoclast-specific genes (tartrate-resistant acid phosphatase (TRAP), cathepsin K, matrix metallopeptidase 9, and nuclear factor of activated T cell c1 (NFATc1)), receptor activator of nuclear factor-κB ligand (RANKL)-dependent upregulation of TRAP enzyme activity, and the formation of TRAP-positive multinuclear cells more effectively than N-acetylglucosamine (GlcNAc), which we have previously shown to inhibit osteoclast differentiation. To clarify the mechanism by which GlcN suppresses osteoclastogenesis, we further investigated the effect of GlcN on O-GlcNAcylation by Western blotting and on other types of glycosylation by lectin blotting. We found that, upon addition of GlcN, the O-GlcNAcylation of cellular proteins was increased whereas α2,6-linked sialic acid modification was decreased. Therefore, these glycan modifications in cellular proteins may contribute to the suppression of osteoclastogenesis.

Coffee extract inhibits adipogenesis in 3T3-L1 preadipocyes by interrupting insulin signaling through the downregulation of IRS1.

Although epidemiological data have indicated that a strong negative association exists between coffee consumption and the prevalence of obesity-associated diseases, the molecular mechanisms by which coffee intake prevents obesity-associated diseases has not yet been elucidated. In this study, we found that coffee intake significantly suppressed high-fat diet (HFD)-induced metabolic alternations such as increases in body weight and the accumulation of adipose tissue, and up-regulation of glucose, free fatty acid, total cholesterol and insulin levels in the blood. We also found that coffee extract significantly inhibited adipogenesis in 3T3-L1 preadipocytes. In the early phase of adipogenesis, 3T3-L1 cells treated with coffee extract displayed the retardation of cell cycle entry into the G2/M phase called as mitotic clonal expansion (MCE). Coffee extract also inhibited the activation of CCAAT/enhancer-binding protein ß (C/EBPß) by preventing its phosphorylation by ERK. Furthermore, the coffee extract suppressed the adipogenesis-related events such as MCE and C/EBPß activation through the down-regulation of insulin receptor substrate 1 (IRS1). The stability of the IRS1 protein was markedly decreased by the treatment with coffee extract due to proteasomal degradation. These results have revealed an anti-adipogenic function for coffee intake and identified IRS1 as a novel target for coffee extract in adipogenesis.

Roasting Enhances the Anti-Cataract Effect of Coffee Beans: Ameliorating Selenite-Induced Cataracts in Rats.

PURPOSE: Coffee is a widely consumed beverage. While recent studies have linked its intake to a reduced risk of cataracts, caffeine is believed to be the key factor for its effect. To know how roasting beans affects the effect of coffee on cataract formation, we investigated the impact roasting using a selenite-induced cataract rat model. MATERIALS AND METHODS: Sprague Dawley rats were given a single injection of sodium selenite, which induced formation of nuclear cataracts by day 6, with or without coffee intake (100% coffee, 0.2 mL/day) for following 3 days. RESULTS: The concentrations of glutathione (GSH) and ascorbic acid (AsA) in selenite-induced cataract lenses declined to half that of controls. However, 3 days of coffee intake ameliorated the reduction of GSH and AsA so that concentrations remained at 70-80% that of controls. Roasting enhanced the preventive effect of coffee by further reducing cataract formation and ameliorating selenite-induced reduction of antioxidants. High-performance liquid chromatography analysis revealed degradation of chlorogenic acid and generation of pyrocatechol during the coffee roasting process. We discovered that pyrocatechol, at doses equivalent to that found in dark-roasted coffee, was equally effective as caffeine at reducing cataract formation and ameliorating the reduction of antioxidants. CONCLUSION: Our results indicate that pyrocatechol, generated during the roasting process, acts as an antioxidant together with caffeine to prevent cataract formation.