SummaryA high-amylose rice with 64.8% amylose content (AC) was developed by transgenic inhibition of two isoforms of starch branching enzyme (SBE), SBEI and SBEIIb, in an indica rice cultivar. The expression of SBEI and SBEIIb was completely inhibited in the transgenic line, whereas the expression of granule-bound starch synthase was normal. Compared with wild-type rice, drastic reductions in both SBEs in the transgenic rice increased apparent AC in flour from 27.2% to 64.8%, resistant starch (RS) content from 0% to 14.6% and total dietary fibre (TDF) from 6.8% to 15.2%. Elevated AC increased the proportion of long unit chains in amylopectin and increased onset gelatinization temperature and resistance to alkaline digestion; however, kernel weight was decreased. A rat feeding trial indicated that consumption of high-amylose rice decreased body weight gain significantly (P < 0.01); increased faecal mass, faecal moisture and short-chain fatty acids; and lowered the faecal pH. An acute oral rice tolerance test revealed that the high-amylose rice had a positive effect on lowering the blood glucose response in diabetic Zucker fatty rats. This novel rice with its high AC, RS and TDF offers potential benefits for its use in foods and in industrial applications.

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Background:Coptidis rhizoma extracts (CREs) have been used widely for their anti-diabetic and anti-microbial activities, and berberine/jatrorrhizine/coptisine/palmatine are the primary bioactive components. Although guidelines have adopted content analyses of these components as a quality control method for CREs, it is difficult to differentiate the CREs from different sources using this method because of the lack of indications for their related pharmacological activities.Purpose: To explore the effect of CREs (CREA/CREB/CREC) with different compositions of major components on the gut microbiota and blood glucose levels in db/db mice.Methods: Degradation of berberine/jatrorrhizine/coptisine/palmatine from CREA/CREB/CREC in rat/mouse intestinal contents and their impact on nine common gastrointestinal bacteria were investigated. In addition, the effects of oral administration of CREA/CREB/CREC for 2 weeks on the gut microbiota and blood glucose levels in db/db mice were monitored via insulin/glucose tolerance test (ITT/GTT), insulin concentration, homeostatic model assessment of insulin resistance and fecal 16S rRNA sequencing.Results and Conclusion: The total amount of berberine/jatrorrhizine/coptisine/palmatine was highest in CREA. Clostridium perfringens was strongly inhibited by all three CREs, with CREA demonstrating the most significant inhibitory effects on minimum inhibitory concentration, time-kill kinetics, and ATP production. In db/db mice, CREA resulted in the most significant decrease in ITT/GTT and depicted different changes in the microbiota from CREB/CREC. Thus, CREs with different compositions of berberine/jatrorrhizine/coptisine/palmatine differed in terms of time-kill kinetics and ATP production assays on C. perfringens. CREA revealed the potent bacterial inhibitory effects and glucose-lowering activity.

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