Jih Min Sung

Starch biosynthesizing enzymes in developing grains of rice cultivar Tainung 67 and its sodium azide-induced rice mutant

The relationships between the rate of starch accumulation and the activities of enzymes involving starch biosynthesis in developing grains of field grown rice (Oryza sativa) cultivar Tainung 67 and its sodium azide-induced mutant SA419 were investigated and compared throughout the grain filling period. The results indicated that the activities of most of the grain enzymes involving sugar‐starch conversion rose and reached their maximum between 7 and 14 days after anthesis (DAA), but declined rapidly after 21 DAA. The changes in the rate of starch accumulation correlated well with the changes in the activities of sucrose synthase (SUS), invertase, hexokinase, AGPglucose pyrophosphorylase, UDPglucose pyrophosphorylase, phosphoglucoisomerase, phosphoglucomutase, soluble starch synthase (SSS), granule bound starch synthase (GBSS), starchbranching enzyme (SBE) and starch debranching enzyme (SDBE), during the grain filling period. The rapid grain-fill and shorter period of grain filling in mutant SA419, as compared with Tainung 67, were associated with its higher activity of starch synthesizing at the early phase of grain growth. The lower amylose content of SA419 grains (8%) in comparison with Tainung 67 grains (20%) was possibly due to their inferiority to synthesize amylose through GBSS and SDBE. # 2003 Elsevier Science B.V. All rights reserved.

Bioavailability of cranberry bean hydroalcoholic extract and its inhibitory effect against starch hydrolysis following in vitro gastrointestinal digestion

This study used a simulated in vitro gastrointestinal digestion procedure to assess the bioavailability of a freeze-dried cranberry bean hydroalcoholic extract (polyphenol content of 28.73mgg-1). The amount of polyphenols in 200mg of cranberry bean extract increased from 5.73 (non-digested original) to 11.39mg following gastric digestion, but decreased to 6.05mg during intestinal digestion. When cranberry bean extract was accompanied with starch for the digestion tests, the added cranberry bean extract exhibited a potent inhibitory effect against glucose release during simulated intestinal digestion, with IC50 values of 472mg cranberry bean extract or 13mg polyphenols. A significant decrease in polyphenols was observed for the sample collected from dialysis phase, with only 11% of non-digested original polyphenols permeating through the dialysis membrane (0.63mg) and preserving an inhibitory effect against α-glucosidase to some extent. Therefore, polyphenol-rich cranberry bean extract may be used to manage postprandial hyperglycemia.

Comparisons of protein, lipid, phenolics, γ-oryzanol, vitamin E, and mineral contents in bran layer of sodium azide-induced red rice mutants.

BACKGROUND The bran part of red rice grain is concentrated with many phytochemicals, including proanthocyanidins, oryzanol and vitamin E, that exert beneficial effects on human health, but it contains low levels of essential minerals such as Fe and Zn. In the present study, the protein, lipid, phytochemicals and mineral contents in bran samples were compared among red rice SA-586 and its NaN₃-induced mutants. RESULTS The plant heights of NaN₃-induced mutants were decreased. The contents of protein, lipid, total phenolics, total flavonoids, total anthocyanins, total proanthocyanidins, total γ-oryzanol, total tocopherols and total tocotrienols also varied among the tested mutants. The brans of mutants M-18, M-56 and M-50 contained more proanthocyanidins, γ-oryzanol, vitamin E than that of SA-586, respectively. M-54 accumulated more Fe content (588.7 mg kg⁻¹ bran dry weight) than SA-586 (100.1 mg kg⁻¹ bran dry weight). CONCLUSIONS The brans of M-18, M-50 and M-56 are good sources of proanthocyanidins, vitamin E and γ-oryzanol, respectively, while the bran of M-54 is rich in Fe. Thus these mutants could be used to produce high-value phytochemicals or Fe byproducts from bran during rice grain milling or as genetic resources for rice improvement programs.

γ-Oryzanol, tocol and mineral compositions in different grain fractions of giant embryo rice mutants.

BACKGROUND Rice embryo is concentrated with lipid, protein and some bioactive chemicals. Two rice mutants IR64-GE and TNG71-GE (M7 generation) were characterised by an enlarged embryo compared with their wild types. In the present study, distributions of protein, lipid, total phenolics, γ-oryzanol, tocols and some essential minerals in these two giant embryo mutants and their respective normal embryo wild types IR64 and TNG71 were compared. RESULTS The embryo dry weights of giant embryo mutants IR64-GE and TNG71-GE were 0.92 and 1.32 mg per seed respectively. These values were higher than those of their respective normal embryo genotypes (0.50 and 0.62 mg per seed). Large variations in protein, lipid, phenolic, γ-oryzanol, tocol and minerals levels were found between mutant and wild-type pairs. The brown rice of TNG71-GE had higher total γ-oryzanol (average of 24% increase) and total tocol (average of 75% increase) levels than TNG71, IR64 and IR64-GE. CONCLUSION The embryo and bran parts of giant embryo mutant TNG71-GE were found to be good sources of vitamin E and γ-oryzanol. Therefore it could be used to produce high-value by-products from milled embryo and bran parts and as a genetic resource for rice improvement programmes. TNG71-GE can also be used as a nutrient-fortified rice cultivar.

Karyological, morphological and phytochemical characteristics of medicinal plants Sophora flavescens Aiton grown from seeds collected at different localities

BackgroundDried roots of Sophora flavescens Aiton contain many phytochemicals that exhibit beneficial effects on human health. This study examined and compared the karyological, morphological and phytochemical characteristics of three S. flavescens populations collected from the Danda, Hualien and Yuli of Taiwan and a population collected from Gansu, China.ResultsKaryotypes of the four populations were similar, with a diploid number of 2n = 18. The Hualien population produced more roots but with less matrine and oxymatrine contents in its root tissue than others. However, only the root of Danda population had a measurable level of naringenin. The dried root of Yuli population had greater ferric reducing antioxidant power and trolox equivalent antioxidant capacity than that of the other populations.ConclusionsThus, the collected S. flavescens populations, particularly the population collected from Danda, have the potential to be used in breeding programs.