Research Institute for Production Development

Torularhodin is the monocyclic C40 carotenoid with the β-ring and a terminal carboxyl group at the acyclic part, with long conjugated double bonds, only synthesized in fungi called red (oleaginous) yeasts, e.g., the genera Rhodotorula and Sporobolomyces. This unique red pigment with strong antioxidant properties is promising for use in food additives, nutritional supplements, and cosmetics. We aimed to produce torularhodin in Escherichia coli through the identification of the biosynthesis genes needed for its heterologous production, while no genes oxidizing torulene to torularhodin had been reported. The Rhodotorula toruloides crtI (CAR1) and crtYB (CAR2) genes, which were chemically synthesized, proved to lead to the complete conversion of phytoene into torulene when they were introduced into an E. coli cell that carried the Pantoea ananatis crtE and Haematococcus pluvialis IDI genes. We found that the Planococcus maritimus genes coding for C30 carotenoid terminal oxidase (crtP/crtNb/cruO) and aldehyde dehydrogenase (aldH/crtNc), through their introduction into the E. coli transformant synthesizing torulene, mediated the efficient oxidations of torulene to torularhodin, and resulted in the production of torularhodin as the dominant carotenoid. This is the first report of torularhodin production in a heterologous host. We also identified the aldH/crtNc gene in R. toruloides.

Background: Glycation, a non-enzymatic reaction between sugars and biomolecules, leads to the formation of advanced glycation end-products (AGEs), which are implicated in the progression of chronic diseases. Connarus ruber (Poepp.) Planch (C. ruber), a traditional medicinal plant used for diabetes, has shown anti-glycation activity. This study aimed to identify the active components in C. ruber extract and elucidate their anti-glycation mechanisms. Methods: Using NMR and LC-MS analyses, we identified epicatechin and procyanidin A2 as major polyphenolic constituents. Collagen glycation assays were performed to evaluate the inhibitory effects of these compounds on fructose- and glyceraldehyde (GA)-induced glycation. Additionally, their cytoprotective effects were assessed using GA-induced cytotoxicity assays in dental pulp stem cells (DPSCs). Results: Both epicatechin and procyanidin A2 inhibited fructose- and GA-induced glycation in a dose-dependent manner, showing greater efficacy than aminoguanidine. Furthermore, these compounds significantly alleviated GA-induced cytotoxicity in DPSCs. Conclusions: These findings suggest that epicatechin and procyanidin A2 are candidate contributors to the anti-glycation and cytoprotective effects of C. ruber. The results support the potential of C. ruber extract as a source of therapeutic agents for glycation-related diseases and for enhancing stem cell viability.

Bluish glass was successfully prepared by mixing oxides and carbon as a reductant into the starting materials, whereas the addition of only α-Fe2O3 into the glass raw materials provided greenish glass. The chemical state of the iron ions in the glass was likely modified from Fe3+ to Fe2+ by the reducing atmosphere caused by carbon during the heating process. Mössbauer spectra and spectrophotometric measurements indicated that the bluish glass contained a high proportion of Fe2+ (67.4%) and mainly absorbed visible light with wavelengths longer than 500 nm.

Marine animals display diverse vibrant colors, but the mechanisms underlying their specific coloration remain to be clarified. Blue coloration is known to be achieved through a bathochromic shift of the orange carotenoid astaxanthin (AXT) by the crustacean protein crustacyanin, but other examples have not yet been well investigated. Here, we identified an ependymin (EPD)-related water-soluble blue carotenoprotein responsible for the specific coloration of the marine blue sponge Haliclona sp. EPD was originally identified in the fish brain as a protein involved in memory consolidation and neuronal regeneration. The purified blue protein, designated as EPD-related blue carotenoprotein-1, was identified as a secreted glycoprotein. We show that it consists of a heterodimer that binds orange AXT and mytiloxanthin and exhibits a bathochromic shift. Our crystal structure analysis of the natively purified EPD-related blue carotenoprotein-1 revealed that these two carotenoids are specifically bound to the heterodimer interface, where the polyene chains are aligned in parallel to each other like in β-crustacyanin, although the two proteins are evolutionary and structurally unrelated. Furthermore, using reconstitution assays, we found that incomplete bathochromic shifts occurred when the protein bound to only AXT or mytiloxanthin. Taken together, we identified an EPD in a basal metazoan as a blue protein that decorates the sponge body by binding specific structurally unrelated carotenoids.

A novel carotenoid with a unique 2,6-cyclo-ψ-end group, named roretziaxanthin (1), was isolated from the sea squirt Halocynthia roretzi as a minor carotenoid along with (3S,3′S)-astaxanthin, alloxanthin, halocynthiaxanthin, mytiloxanthin, mytiloxanthinone, etc. This structure was determined to be 3-hydroxy-1′,16′-didehydro-1′,2′-dihydro-2′,6′-cyclo-β,ψ-carotene-4,4′-dione by UV–VIS, MS, and NMR spectral data. The formation mechanism of roretziaxanthin in the sea squirt was discussed.