In Vitro Antimicrobial Activity of Nymphaea pubescens (Pink Water Lily) Leaf Extracts.

This research comparatively investigates the in vitro antimicrobial activity of extracts from Nymphaea pubescens (pink water lily) leaves against pathogenic bacteria. The experimental extracts are aqueous, acetonic, and 95% ethanolic N. pubescens extracts; and the pathogenic bacteria being studied include Aeromonas hydrophila, Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio harveyi, which are commonly found in freshwater fish and brackish aquatic animals. The ethanolic N. pubescens extract achieves the highest bacterial inhibitory effects against V. parahaemolyticus and V. vulnificus. The minimum inhibitory concentrations of the ethanolic extract against A. hydrophila and V. harveyi are 10 mg/mL; and 2.5 mg/mL against V. parahaemolyticus and V. vulnificus. The ethanolic N. pubescens extract is effective against V. parahaemolyticus. The high-performance liquid chromatography results show that, in the phenolic acids group, gallic acid is the most dominant (0.600-3.21% w/w), followed by sinapic acid (0.37-0.83% w/w). In the flavonoids group, catechin is the most dominant (0.02-1.08% w/w), followed by rutin (0.002-0.03% w/w). Essentially, the ethanolic N. pubescens extract can potentially be used as a natural antibiotic agent to treat bacterial infections in fish and aquatic animals.

An In Vitro Study on the Effects of Selected Natural Dietary Fiber from Salad Vegetables for Lowering Intestinal Glucose and Lipid Absorption.

BACKGROUND: Salad vegetables are good sources of dietary fiber and are becoming increasingly popular among consumers. Therefore, these plants have the potential to be developed as functional foods. OBJECTIVE: Using an in vitro model, this study investigated the physical properties and intestinal glucose and lipid absorption capacities of dry dietary fiber from vegetables typically consumed in salads (types of lettuce, including red oak, red coral, green oak, butterhead, and cos). METHOD: Fiber was prepared from each type of lettuce using an enzymatic method and then characterized. Physical properties, including solubility and water-binding, swelling, cation-exchange, and oil-binding capacities, and antihyperglycemic and antihypercholesterolemic effects of fiber were investigated. RESULTS: The hydration capacity of total dietary fiber and insoluble fiber from the majority of sources was significantly different from that of cellulose. Adsorption and diffusion of glucose were directly proportional to incubation time, and the diffusion rate was significantly lower in the treatments containing fiber compared to the cellulose control. Fiber from these vegetables also inhibited amylase and alpha-glucosidase activities. Moreover, fiber from all sources exhibited significantly higher sodium cholate and cholesterol-binding capacity compared to cellulose, and also retarded pancreatic cholesterol esterase activity in a concentration-dependent manner. CONCLUSION: This study demonstrates that natural dietary fiber from salad vegetables can reduce glucose and lipid absorption and breakdown rates, thus preventing increases in postprandial blood glucose and cholesterol levels, which can be beneficial to human health.

Study of prebiotic properties of selected banana species in Thailand.

Prebiotics are functional foods with health-promoting properties that are used in many developed countries. Thailand is one of the countries that produces many plants that should have prebiotic properties. In this study, we investigated the potential prebiotic effects of powders obtained from Saba, Pisang Awak Banana and Silver bluggoe in vitro in accordance with their physical, chemical and microbiological properties. These selected plants were found to demonstrate good water-/oil-binding properties. They contained chlorophyll, beta carotene and lycopene and showed good resistance to stomach and small-intestine enzymes. The selected plants were further used to evaluate prebiotic properties by supplementing as a carbon source in culturing broth for growing probiotic bacteria and pathogenetic bacteria. The increase in the number of probiotic bacteria during fermentation of these selected plants correlated with decreased pH. The growth of four strains of probiotic bacteria seemed to be promoted in MRS broth containing these selected plants, but no significant differences in the number of probiotic bacterial groups were detected in response to difference concentrations of all these selected plants. In addition, we noted that a decrease in the number of all four strains of pathogenic bacteria during fermentation of these selected plants correlated with a decreased pH. Moreover, the antimicrobial activity of selected plant prebiotics supported probiotic substance production to inhibit growth of pathogenic bacteria. In conclusion, we have shown that the addition of selected prebiotic plants, indicating that they should be used as a prebiotic food ingredient, represents a potential alternative to available commercial prebiotics.