Prior or Concomitant Drinking of Vegetable Juice with a Meal Attenuates Postprandial Blood Glucose Elevation in Healthy Young Adults

Controlling postprandial blood glucose levels can prevent and improve lifestyle-related diseases. We aimed to evaluate the effects of a commercially available vegetable juice, which is a convenient alternative to vegetables, on postprandial glucose elevation. In test 1, we confirmed the appropriate timing to consume the vegetable juice (200 mL), and demonstrated that postprandial glucose elevation was attenuated by drinking the vegetable juice with or before the experimental meal. The change in maximum concentration (ΔCmax) of blood glucose was the lowest when the vegetable juice was consumed at 30 min before the meal. In test 2, we confirmed the necessary ingestion volumes of vegetable juice (range: 68.5 - 274 mL) for attenuating the response to 50 g of carbohydrates. After drinking 200 mL of vegetable juice, the ΔCmax and incremental area under the curve values for blood glucose were significantly lower than those for after drinking the same volume of water (p < 0.05). However, a greater volume of vegetable juice did not provide an additive effect. Our results suggest that approximately 200 mL of vegetable juice at 30 min before meals is the most effective method for using vegetable juice to suppress postprandial blood glucose elevation. Stimulation of insulin secretion due to the pre-meal vegetable juice intake may contribute to this effect, although further studies are needed to identify the detailed mechanism for the attenuation.

Fabrication and characterization of spearmint oil loaded nanoemulsions as cytotoxic agents against oral cancer cell

Spearmint oil(SMO), a commonly used essential oil for oral care products, possesses various interesting functions, especially for anticancer property. However, the application of SMO for cancer treatment is limited due to water insoluble. In the present study, nanoemulsions, which have been widely accepted as dosage forms for poorly water-soluble drugs, were selected as candidate carriers for SMO to inhibit oral cancer cell. The nanoemulsions were fabricated using phase inversion temperature method. The factors affecting formation and properties of nanoemulsions including type and amount of surfactants, oil loading and ratio of SMO to virgin coconut oil(VCO) were investigated. Among the surfactants used, the nanoemulsions containing polyoxyethylene castor oil derivatives(Kolliphor ?EL; PCO35, Cremophor ?RH40; PCO40, Eumulgin ?CO60; PCO60) and polyoxyethylene sorbitan fatty acid esters(PSF80) showed 100% creaming after temperature cycling test indicating excellent physical stability while those containing PCO40 demonstrated more transparency and better physical stability. With an increasing amount of PCO40, the droplet size tended to decrease and was in the nano-size range( < 1000 nm) after increasing to more than 5%(w/w). SMOVCO loading also influenced on the droplet size. At 5%(w/w) PCO40, the maximum SMO-VCO loading of 25%(w/w) to attain nanoemulsions was observed. Moreover, the composition of oils had an impact on size of emulsions. The transparent nanoemulsions were only prepared in the range of SMO-VCO from 40:60 to 80:20, suggesting the optimum ratio of SMO tosurfactant and the composition of oils were the critical factors for formation of nanoemulsions. NMR study disclosed that the interaction between PCO40 with both VCO and SMO should be a possible stabilization mechanism. Furthermore, the SMO-VCO nanoemulsions exhibited significant cytotoxic effect against oral carcinoma(KON) cell line using MTT assay. The finding, therefore, revealed the good feasibility of SMO-VCO nanoemulsions as novel carriers for treating of oral cancer.

Effect of antioxidant activity of caffeic acid with cyclodextrins using ground mixture method

In the current study, we prepared a ground mixture(GM) of caffeic acid(CA) with α-cyclodextrin(αCD) and with β-cyclodextrin(βCD), and then comparatively assessed the physicochemical properties and antioxidant capacities of these GMs. Phase solubility diagrams indicated that both CA/αCD and CA/βCD formed a complex at a molar ratio of 1/1. In addition, stability constants suggested that CA was more stable inside the cavity of αCD than inside the cavity of βCD. Results of powder X-ray diffraction(PXRD) indicated that the characteristic diffraction peaks of CA and CD disappeared and a halo pattern was produced by the GMs of CA/αCD and CA/βCD(molar ratios = 1/1). Dissolution testing revealed that both GMs had a higher rate of dissolution than CA alone did. Based on the1 H-1 H NOESY NMR spectra for the GM of CA/αCD, the vinylene group of the CA molecule appeared to be included from the wider to the narrower rim of the αCD ring. Based on spectra for the GM of CA/βCD, the aromatic ring of the CA molecule appeared to be included from the wider to the narrower rim of the βCD ring. This suggests that the structures of the CA inclusion complexes differed between those involving αCD rings and those involving βCD rings. Results of a DPPH radical-scavenging activity test indicated that the GM of CA/αCD had a higher antioxidant capacity than that of the GM of CA/βCD. The differences in the antioxidant capacities of the GMs of CA/αCD and CA/βCD are presumably due to differences in stability constants and structures of the inclusion complexes.