Antioxidant/anti-inflammatory activities and total phenolic content of extracts obtained from plants grown in Vietnam.

BACKGROUND: Medicinal plants have been used to treat various diseases since ancient times. Their specific activities, such as antioxidant, anti-inflammatory and anti-cancer, have been studied intensively. In particular, plants grown in Vietnam have attracted considerable attention among food chemists as ideal sources of natural medicinal chemicals. RESULTS: The methanol extracts from three edible Vietnamese-grown plants, Tram, Voi and Gac, tested with the DPPH assay showed antioxidant activities of 91.7 ± 0.4, 63.4 ± 0.7 and 3.7 ± 0.1% respectively. The malonaldehyde/gas chromatography assay also revealed strong antioxidant activity in Tram and Voi at a level of 25 µg mL(-1) (95.5 ± 0.3 and 78.5 ± 1.4% respectively). These results were confirmed by the thiobarbituric acid assay. The antioxidant activities correlated positively with the level of total phenolics in all plants. Tram exhibited dose response-related lipoxygenase-inhibitory activity, with values of 74.2 ± 3.1% at 5 µg mL(-1) , 62.0 ± 0% at 0.5 µg mL(-1) and 3.0 ± 1.5% at 0.05 µg mL(-1) . Conversely, Voi and Gac showed negative anti-lipoxygenase activity. CONCLUSION: The antioxidant/anti-inflammatory activities and total phenolic contents of the three edible plants grown in Vietnam revealed that they are good sources of supplements for human health.

The effects of high hydrostatic pressure treatment on the flavor and color of grated ginger.

High hydrostatic pressure (HHP) was applied to grated ginger in order to inactivate quality-degrading enzymes in a non-thermal manner. The effects of HHP treatment on the flavor and the color of the grated ginger were investigated just after treatment and during storage. After HHP treatment (400 MPa, 5 min), geraniol dehydrogenase (GeDH) was inactivated to less than 5%, but the activity of polyphenol oxidase (PPO) was reduced only to 37%. Heat treatment (100 °C, 10 min) inactivated GeDH to 43% and PPO to about 10%. In storage, the reduction of geranial, neral, and citronellal to the corresponding alcohols was observed in the untreated and the heat-treated ginger, while it was not in the HHP-treated grated ginger. In the HHP-treated sample, terpene aldehydes almost disappeared without the formation of the corresponding alcohols. Browning was not observed immediately after HHP treatment, while it was complete in the heat-treated sample. The color change during storage appeared to reflect the residual activity of PPO.

Effect of oral rehydration solution on fatigue during outdoor work in a hot environment: a randomized crossover study.

OBJECTIVES: The effects of an oral rehydration solution (ORS) on fatigue were studied in workers engaged in manual work during the summer. METHODS: One hundred and fifty-three workers engaged in loading cargo onto aircraft at Tokyo International Airport who consented to participate in the study were the subjects. The study was carried out on two summer days with fine weather during the daytime shift. The subjects were randomly divided into two groups: with one group restricted to ORS intake and the other group having free-choice of their favorite drink (FAD) in a randomized crossover study. The subjects were asked about the amount of beverage that they consumed and the type of FAD that they chose on the days of the survey. The effects of the ORS and the FAD were compared using a visual analogue scale (VAS) to determine the degree of fatigue experienced immediately after completing work. RESULTS: The average wet bulb globe temperature (WBGT) on the survey days was 30 degrees C. The beverage intake during work was 1,000 ml for most participants and the most commonly chosen types of FAD were tea and coffee. The fatigue VAS was significantly lower on the ORS intake days than on the FAD intake days (50.0 +/- 18.3 vs. 53.9 +/- 16.3). CONCLUSIONS: The results of this study suggest that the intake of ORS during outdoor work in a hot environment would be effective for preventing industrial accidents and heat stroke. It is important to select an appropriate drink to ensure adequate intake of water and electrolytes.

Protective and anticataract effects of the aqueous extract of Cleistocalyx operculatus flower buds on beta-cells of streptozotocin-diabetic rats.

The aim of the present study was to examine whether an aqueous extract of Cleistocalyx operculatus flower buds (COB) had protective and anticataract effects on beta-cells in experimental streptozotocin (STZ)-induced diabetes in rats. After 9 weeks of COB supplementation (500 mg/kg bw), the COB group had a significantly more stable insulin level as compared with the control diabetic group. Increased staining of insulin and preservation of islet cells were apparent in the COB-treated diabetic rats, whereas islet cell degeneration and weak insulin immunohistochemical staining were observed in the control diabetic rats. In addition, COB significantly delayed diabetic cataract formation and caused significant reductions in the glucose, sorbitol, and fructose levels in diabetic rat lenses. Furthermore, as compared to the control diabetic group, the COB group also showed antihyperglycemic effects (reductions in plasma glucose and HbA1c levels).

In vitro evaluation of antibacterial, anticollagenase, and antioxidant activities of hop components (Humulus lupulus) addressing acne vulgaris.

Seven naturally derived components from hop plant (Humulus lupulus L.) extracts were tested for evaluation of biological activities affecting acne vulgaris. Five strains, Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, Kocuria rhizophila and, Staphylococcus pyogenes, were selected as the main acne-causing bacteria. Hop extracts xanthohumol and the lupulones showed strong inhibitory activities against all of the strains. Although hydrogenated derivatives did not show the same level of activity, naturally occurring xanthohumol, humulones, and lupulones all showed moderate to strong anticollagenase inhibitory activities. Antioxidant capacity was also evaluated with seven different methods based on different reactive oxygen species. Xanthohumol showed the highest activity in total oxygen radical absorbance capacity as well as singlet oxygen absorbance capacity.