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BACKGROUND: The major component of lemongrass by weight is dietary fibre (DF), but no literature has been reported on its DF components and fermentation products when ingested. OBJECTIVE: This study analysed DF components of lemongrass, investigated the potential of the major product from total DF (TDF) fermentation to inhibit α-amylase and HMG-CoA reductase, key enzymes of diabetes mellitus and hypercholesterolemia, respectively, and determined the serum glucose- and cholesterol-lowering potential of TDF in an animal model. METHODS: Lemongrass DF components were analysed, TDF was fermented in vitro; the major fermentation product was isolated for enzyme inhibitory assays; and postprandial blood glucose- and cholesterol-lowering potential of TDF was determined in Sprague-Dawley rats. RESULTS: TDF in lemongrass was 65.7 g/100g and soluble DF, 2.8 g/100 g. Significant amount of propionate (10.9 mM/g TDF) was produced after TDF fermentation; propionate inhibited 20.4% α-amylase activity, and 13.1 % HMG-CoA reductase activity in vitro. TDF further exhibited antihyperglycemic and cholesterol-lowering potential in an animal model. CONCLUSIONS: DF from lemongrass was shown to reduce hyperglycemia and hypercholesterolemia in an animal model, through mild inhibition of α-amylase and HMG-CoA reductase. Thus, lemongrass DF may have a significant role in mitigating the risk of type 2 diabetes mellitus and hypercholesterolemia.

† Background and aims In recent years, Cyperus rotundus has become a problem weed in lowland rice (Oryza sativa) grown in rotation with vegetables in the Philippines. As the growth of C. rotundus is commonly suppressed by prolonged flooding, the ability of the weed to grow vigorously in flooded as well as upland conditions suggests that adapted ecotypes occur in these rotations. Studies were conducted to elucidate the mechanisms that permit C. rotundus to tolerate flooded soil conditions. † Methods Upland and lowland ecotypes of C. rotundus were compared in terms of growth habit, carbohydrate reserves and metabolism, and activities of enzymes involved in alcoholic fermentation ‐ alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC). † Key Results The lowland ecotype has much larger tubers than the upland ecotype. Prior to germination, the amylase activity and total non-structural carbohydrate content in the form of soluble sugars were greater in the tubers of lowland plants than in those of upland C. rotundus. At 24 h after germination in hypoxic conditions, PDC and ADH activities in the lowland plants increased, before decreasing at 48 h following germination. In contrast, ADH and PDC activities in the upland plants increased from 24 to 48 h after germination. † Conclusions Tolerance of lowland C. rotundus of flooding may be attributed to large carbohydrate content and amylase activity, and the ability to maintain high levels of soluble sugars in the tubers during germination and early growth. This is coupled with the modulation of ADH and PDC activities during germination, possibly to control the use of carbohydrate reserves and sustain substrate supply in order to avoid starvation and death of seedlings with prolonged flooding.