Starch can be exploited as an abundant resource for sustainable production of diverse chemical intermediates such as hydroxymethylfurfural (HMF). We present a simple process of producing HMF from starches using an ionic liquid, 1-octyl-3-methylimidazolium chloride ([OMIM]Cl), and CrCl 2 catalyst. The addition of HCl and CrCl 2 significantly affected the yields of HMF on the whole. CrCl 2 increased the yields of HMF by approximately two-folds on average. The synthesis of HMF was most effective between 60 and 90 min reaction time at both concentrations of 0.3 and 0.5 M HCl. Starch concentration had influence on the productivity of HMF. At 20% starch concentration with 0.3 and 0.5 M HCl, its productivity was greatest (2.8 folds high). Eight starch sources (corn, wheat, rice, potato tuber, sweet potato, tapioca, acorn, and kudzu starch) were tested for the synthesis of HMF. The highest yields of HMF (73.0 AE 3.8 wt%) were obtained in tapioca starch dissolved in 0.5 M HCl.

Hydroxymethylfurfural (HMF) is an important chemical intermediate, but it has not been widely used because of low yields and high production costs. Sucrose is available at lower costs than other sugars and thus could be a biomass-derived abundant source for HMF production. In this study, a catalytic process for efficiently producing HMF from sucrose was scrutinized using 1-methyl-3-octylimidazolium chloride ([MOIM]Cl) as a reaction solvent, and HCl and metal chlorides (CrCl 2 and Zncl 2 ) as a catalyst. The rate of sucrose hydrolysis was relatively much faster in the reactions with HCl than without it. The hydrolysis of sucrose to fructose and glucose was affected by its reaction time. The mixed solvent of 50% [MOIM]Cl and 50% sucrose solution with HCl was more effective in HMF synthesis than single solvent alone. The addition of ZnCl 2 and CrCl 2 increased HMF yields by approximately 1.2-1.8-fold and its higher yield was found in the latter. The highest yield (82.0±3.9 wt%) in HMF production was achieved in the reaction mixture containing 5 g [MOIM]Cl and 5 mL of 20% sucrose solution with 0.5 M HCl plus CrCl 2 at 30 min reaction time. However, 0.3 M HCl was more effective for the HMF productivity than 0.5 M HCl.

A cDNA (SeMIPS1) encoding myo-inositol 1-phosphate synthase (EC 5.5.1.4) (MIPS) has been characterized from sesame (Sesamum indicum L. cv. Dan-Baek) seeds and its functional expression analyzed. The SeMIPS1 protein was highly homologous with those from other plant species (88-94%), while a much lower degree of sequence homology (53-62%) was found with other organisms such as humans, mouse, algae, yeast, Drosophila, bacteria and other prokaryotes. A yeast-based complementation assay in yeast mutants containing a disrupted INO1 gene for yeast MIPS confirmed that the SeMIPS1 gene encodes a functional MIPS. Phylogenetic analysis suggested that the SeM-IPS1 gene diverged as a different subfamily or family member. Southern hybridization revealed several copies of the SeMIPS1 gene present in the sesame genome and northern blotting indicated that expression of the SeMIPS1 gene may be organ specific. Salt stress during sesame seed germination had an adverse influence on transcription of SeMIPS1 and greatly reduced transcript levels as the duration of exposure to a saline environment increased and NaCl concentration increased. Germination initiation of sesame seeds was severely delayed as NaCl level increased. These results suggest that expression of SeMIPS1 is down-regulated by salt stress during sesame seed germination.

In plants ascorbic acid (AsA) is a strong antioxidant or reductant that can be converted to dehydroascorbate (DHA) by oxidation. DHA, a very short-lived chemical, can either be hydrolyzed irreversibly to 2,3-diketogulonic acid or recycled to AsA by dehydroascorbate reductase (DHAR). DHAR cDNA, isolated from sesame hairy roots, was inserted into two plant expression vector systems with the CaMV35S promoter (CaMV35S::DHAR) and a potato tuber-specific promoter, Patatin (Patatin::DHAR). Southern and northern blot hybridization analyses indicated that DHAR cDNA was successfully integrated into the potato genome and actively transcribed. High levels of sesame DHAR transcript and DHAR enzyme activity were determined, by the Patatin promoter, in regenerated potato tubers, but their levels in leaves were very low. In contrast, much higher amounts of transcript were accumulated in the leaves of CaMV35S::DHAR regenerants than in the tubers while the activity of DHAR enzyme was higher in the latter. AsA content in the tubers of Patatin::DHAR transgenic lines was also increased (1.1. to 1.3-fold) cor~pared with that of non-transgenic plants. However, this was not true for the transgenic leaves. In contrast, the CaMV35~ promoter was associated with AsA accumulations in both the tubers (up to 1.6-fold) and the leaves (up to 1.5-fold). Howevel. more detailed analyses indicated that this increased enzyme activity was not always accompanied by an elevation in AsA .c(~ntent from transgenic plants. This suggests that other factors may limit the accumulation of vitamin C via ascorbaterecycling; in transgenic potato plants.

Dehydroascorbate reductase (DHAR) is a biotechnologically or physiologically important reducing enzyme in the ascorbate-glutathione recycling reaction for most higher plants. A DHAR cDNA was isolated from sesame (Sesamum indicum L.) hairy roots, and its structure and biochemical properties were characterized to provide some information about its expressional and biochemical profiles in the hairy root cultures. The cDNA contained a catalytic motif CXXS, which may be indicative of a thiol-dependent redox function. A fusion DHAR expressed in an Escherichia coli expression system was purified with four purification steps until a homogeneous single band signal was seen in an acrylamide gel, and its antibody was prepared for Western blot analyses. The biochemical results showed that the purified recombinant DHAR had an optimal pH of around 6.0, which was different from those (pH 7.8-8.2) of other plant species. The temperature optimal for the DHAR activity was in a relatively wide range of 30-60 degrees C. It was proved by a real-time RT-PCR technique that the transcription activity of the DHAR was about 2-5-fold higher during the first 3 week cultures than during the latter 3 week ones. The highest activity of the sesame DHAR was detected in the 4 week cultures of the hairy roots, after which its activity was rapidly decreased to approximately 80%, suggesting that the most active DHAR occurred in this culture period. Western blot analyses confirmed that the presence of DHAR enzyme was identified in both cultures of the fused E. coli and the sesame hairy roots.