The rhizomes of the Zingiberaceae family are a vegetable widely used in many Asian countries, and their medicinal functions have been broadly discussed and accepted in many traditional recipes. In this study, 18 species of five genus of Zingiberaceae plants from Taiwan area were collected and analyzed for their functional properties. Methanolic extracts of the plants were analyzed for their total phenol compounds, alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) scavenging activity, and reducing power. Antimicrobial activity of these samples was also determined. The results showed that the total phenol compounds of the Alpinia genus averaged 17, 30 mg/g for Curcumas, and the highest, 36.5 mg/g for Vanoverberghia sasakiana. Antioxidant performances were best observed in Vanoverberghia and Hedychium, both 89%, and DPPH scavenging activity followed similar trends. Particularly, Zingiber oligophyllum, considered as a traditional medicinal plant used in Taiwan exhibited low DPPH scavenging activity and reducing power. Most Zingiberaceae plant extracts exhibited antimicrobial activity against all tested food microorganisms. Hedychium and Vanoverberghia, did not show antimicrobial activities on Escherichia coli and Vibrio parahaemolyticus. This study is a positive demonstration of the utility of screening Taiwan's endemic Zingiberaceous plants for their food and medicinal uses.

Oxidative stress can result in insulin resistance, a primary cause of type-2 diabetes. Methylglyoxal (MG), a highly reactive dicarbonyl metabolite generated during glucose metabolism, has also been confirmed to cause pancreatic injury and induce inflammation, thereby resulting in insulin resistance. Recently, resveratrol has been reported to exert antioxidant properties, protecting cells from the generation of reactive oxygen species (ROS). The aim of this study was to evaluate resveratrol activation of nuclear factor erythroid 2-related factor 2 (Nrf2) to attenuate MG-induced insulin resistance in Hep G2 cells. Therefore, the molecular signaling events affecting resveratrol-mediated heme oxygenase-1 (HO-1) and glyoxalase expression levels were further investigated in this study. Our findings indicated that resveratrol activated the extracellular signal-regulated kinase (ERK) pathway but not the p38 or c-Jun N-terminal kinase (JNK) pathways, subsequently leading to Nrf2 nuclear translocation and elevation of HO-1 and glyoxalase expression levels. Moreover, resveratrol significantly elevated glucose uptake and protected against MG-induced insulin resistance in Hep G2 cells. In contrast, depletion of Nrf2 by small interfering RNA (si-RNA) resulted in the abrogation of HO-1 and glyoxalase expression in the MG-treated resveratrol group in Hep G2 cells. Administration of an appropriate chemopreventive agent, such as resveratrol, may be an alternative strategy for protecting against MG-induced diabetes.

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Antroquinonol (AQ) and 4-acetylantroquinonol B (4-AAQB), isolated from the mycelium of Antrodia cinnamomea, have a similar chemical backbone to coenzyme Q (CoQ). Based on the postulation that biosynthesis of both AQ and 4-AAQB in A. cinnamomea starts from the polyketide pathway, we cultivated this fungus in a culture medium containing [U-C]oleic acid, and then we analyzed the crude extracts of the mycelium using UHPLC-MS. We found that AQ and 4-AAQB follow similar biosynthetic sequences as CoQ. Obvious [C] fragments on the ring backbone were detected in the mass spectrum for [C]AQ, [C]4-AAQB, and their [C] intermediates found in this study. The orsellinic acid, formed from acetyl-CoA and malonyl-CoA via the polyketide pathway, was found to be a novel benzoquinone ring precursor for AQ and 4-AAQB. The identification of endogenously synthesized farnesylated intermediates allows us to postulate the routes of AQ and 4-AAQB biosynthesis in A. cinnamomea.