curcumin and stevioside

Steviol glycosides possess Bola-form amphiphilic structure, which can solubilize hydrophobic phytochemicals and exert physical modification to the hydrophilic matrix. However, the effect of steviol glycosides on the starch hydrogel is still unclear. Herein, the physicochemical properties, in vitro digestibility, and release behavior of starch hydrogel in the presence of steviol glycosides were investigated. The results showed that the addition of steviol glycosides promoted the gelatinization and gelation of starch, and endowed the starch hydrogel with softer texture, larger volume, and higher water holding capacity. The hydrophobic curcumin was well integrated into hydrogel by steviol glycosides, providing the gel with improved colour brilliance. The introduction of steviol glycosides hardly affected the digestibility of starch gel, but it promoted the release rate of curcumin. Notably, this release behavior was pH dependent, which tended to target the alkaline intestine. This work provided some theoretical supports for the development of sugar-free starchy foods.

Topics: Curcumin; Diterpenes, Kaurane; Glycosides; Hydrogels; Hydrogen-Ion Concentration; Starch; Stevia

Curcuminoids from rhizomes of Curcuma longa possess various biological activities. However, low aqueous solubility and consequent poor bioavailability of curcuminoids are major limitations to their use. In this study, curcuminoids extracted from turmeric powder using stevioside (Ste), rebaudioside A (RebA), or steviol glucosides (SG) were solubilized in water. The optimum extraction condition by Ste, RebA, or SG resulted in 11.3, 9.7, or 6.7mg/ml water soluble curcuminoids. Curcuminoids solubilized in water showed 80% stability at pH from 6.0 to 10.0 after 1week of storage at 25°C. The particle sizes of curcuminoids prepared with Ste, RebA, and SG were 110.8, 95.7, and 32.7nm, respectively. The water soluble turmeric extracts prepared with Ste, RebA, and SG showed the 2,2-diphenyl-1-picrylhydrazyl radical scavenging (SC50) activities of 127.6, 105.4, and 109.8μg/ml, and the inhibition activities (IC50) against NS2B-NS3(pro) from dengue virus type IV of 14.1, 24.0 and 15.3μg/ml, respectively.

Topics: Curcuma; Curcumin; Diterpenes, Kaurane; Glucosides; Plant Extracts

In a search for potential cancer chemopreventive agents from natural resources, stevioside (1), a sweetener, and six related compounds, including two aglycones steviol (6) and isosteviol (7), were screened in an in vitro assay for inhibitory effects on Epstein-Barr virus early antigen activation. Compounds 1, 6 and 7 showed significant activity in this assay and also exhibited strong inhibitory effects in a two-stage carcinogenesis test using mouse skin induced by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). The inhibitory effects of these three compounds were greater than that of glycyrrhizin. Furthermore, these three compounds significantly inhibited mouse skin carcinogenesis initiated by peroxynitrite and promoted by TPA. Their activities were comparable to that of curcumin. These results suggested that 1, as well as 6 and 7, could be valuable as chemopreventive agents for chemical carcinogenesis.

Topics: Animals; Antineoplastic Agents; Carcinogenicity Tests; Chemoprevention; Curcumin; Diterpenes, Kaurane; Glucosides; Glycyrrhizic Acid; Herpesvirus 4, Human; Mice; Skin Neoplasms