6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a bioactive ingredient present in wasabi, a popular pungent spice in Japan. Previous studies have revealed the cytoprotective and cancer chemopreventive effects of 6-MSITC. This study aims to clarify the molecular mechanisms by investigating the action of 6-MSITC on the Nrf2/Keap1 system. 6-MSITC up-regulated the expression of NAD(P)H:quinone oxidoreductase 1 (NQO1) by increasing the Nrf2 level. Treatment with 6-MSITC extended the half-life (t(1/2)) of Nrf2 protein from 11.5 to 35.2 min, approximately three times longer. Moreover, 6-MSITC suppressed the ubiquitination of Nrf2 but not Keap1. Alternatively, a modified Keap1 was observed in 6-MSITC-treated cells accompanying reduction of normal Keap1 protein. The results from cellular fractionation and immunocytochemistry assay revealed that Nrf2 was primarily accumulated in nucleus. EMSA and the reporter gene assay further demonstrated that 6-MSITC augmented Nrf2-ARE binding and transcription activity. Silencing Nrf2 using Nrf2 siRNA markedly reduced the Nrf2 level and ARE-driven activity under both baseline and 6-MSITC-induced conditions. Our data revealed that 6-MSITC enhanced Nrf2/ARE-driven NQO1 expression by stabilizing Nrf2 that was accomplished by modifying Keap1 with consequent inhibition of the ubiquitination and proteasomal turnover of Nrf2. The findings provide an insight into the mechanisms underlying 6-MSITC in cytoprotection and cancer chemoprevention.

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Wasabi is a plant of Japanese origin belonging to the Brassicaceae family. Although the wasabi rhizome is a popular condiment in Japan, the leaf is typically discarded. For utilization of the wasabi leaf, we investigated its antiobesity effect on Wistar rats fed a high-fat diet containing wasabi leaf extract (WLE) prepared with 50% ethanol.At the experimental endpoint, WLE had significantly decreased the body weight of rats and upregulated the mRNA expression of the β3-adrenergic receptor (Adrb3) in the interscapular brown adipose tissue (BAT). WLE may have promoted lipid absorption from the dietary fat, as the fecal lipid content was considerably lower in the WLE group. These results suggest that WLE suppressed obesity in rats fed a high-fat diet, which was related to the upregulation of Adrb3 mRNA expression in the interscapular BAT without increased fecal lipid excretion. Thus, wasabi leaves may be used as a functional food material for the suppression of obesity.

Wasabi (Wasabia japonica Matsumura) is a perennial plant, and its rhizome is widely used as a pungent spice. Wasabi rhizome has been reported to have various physiological activities, but the flower has not been studied in depth. The aim of the present study was to isolate compounds from wasabi flowers and clarify their antioxidant and anti-inflammatory activities. Three phenylpropanoids, one alkaloid and seven flavonoids were isolated from wasabi flowers. Among them, 2"-O-trans sinapoyl isovitexin was identified as a novel compound. Five compounds inhibited 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, with IC 50 values of less than 100 μM. Luteolin isolated in this study was found to inhibit nitric oxide production in macrophage-like J774.1 cells, with an IC 50 value of 24.1 ± 4.4 µM. Our results indicate that the phenolic compounds in wasabi flowers are effective ingredients for antioxidant and anti-inflammatory activities. For these reasons, wasabi flowers are expected to be used effectively as a functional food.

To investigate the compounds present in wasabi leaves (Wasabia japonica Matsumura) that inhibit the adipocyte differentiation, activity-guided fractionation was performed on these leaves. 5-Hydroxyferulic acid methyl ester (1: 5-HFA ester), one of the phenylpropanoids, was isolated from wasabi leaves as a compound that inhibits the adipocyte differentiation. Compound 1 suppressed the intracellular lipid accumulation of 3T3-L1 cells without significant cytotoxicity. Gene expression analysis revealed that 1 suppressed the mRNA expression of 2 master regulators of adipocyte differentiation, PPARγ and C/EBPα. Furthermore, 1 downregulated the expression of adipogenesis-related genes, GLUT4, LPL, SREBP-1c, ACC, and FAS. Protein expression analysis revealed that 1 suppressed PPARγ protein expression. Moreover, to investigate the relationship between the structure and activity of inhibiting the adipocyte differentiation, we synthesized 12 kinds of phenylpropanoid analog. Comparison of the activity among 1 and its analogs suggested that the compound containing the substructure that possess a common functional group at the ortho position such as a catechol group exhibits the activity of inhibiting the adipocyte differentiation. Taken together, our findings suggest that 1 from wasabi leaves inhibits adipocyte differentiation via the downregulation of PPARγ.

Wasabi is a member of the Brassicaceae family and produces various isothiocyanates (ITCs). Because 6-methylsulfinylhexyl ITC (6-MSITC) is stable among wasabi ITCs, it has potential as a functional compound. Hair loss can have psychological and social effects on an individual because of its impact on appearance. In this study, we investigated the stimulatory effects of 6-MSITC by culturing on human follicle dermal papilla cells (DPCs). Results showed that 6-MSITC significantly promoted DPC proliferation and upregulated vascular endothelial growth factor (VEGF) mRNA levels compared to control. Furthermore, 6-MSITC significantly upregulated adenosine A2b receptor (ADORA2b) mRNA levels. Previous studies have reported that VEGF was induced through ADORA1 and ADORA2 pathways. We suggest that 6-MSITC stimulates hair growth on DPCs related to the upregulation of ADORA2b mRNA level. Thus, 6-MSITC may be used as a functional compound.

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Testosterone-related steroid hormones are associated with various types of diseases, including prostate cancer and androgenetic alopecia (AGA). The testosterone or dihydroxy testosterone (DHT) circulates through the blood, binds to the androgen receptor (AR) in the cytoplasm, and finally enters the nucleus to activate downstream target genes. We previously found that immortalized dermal papilla cells (DPCs) lost AR expression, which may be explained by the repeated cell passages of DPCs. To compensate for the AR expression, DPCs that express AR exogenously were established. In this study, we performed an RNA-Seq analysis of the AR-expressing and non-AR-expressing DPCs in the presence or absence of DHT to identify the downstream target genes regulated by AR signalling. Furthermore, we treated DPCs with minoxidil sulphate, which has the potential to treat AGA. This is the first comprehensive analysis to identify the downstream genes involved in testosterone signalling in DPCs. Our manuscript provides high-priority data for the discovery of molecular targets for prostate cancer and AGA.