Rubusoside

Int J Pharm. 2012 Sep 15;434(1-2):453-9.

Reformulation of etoposide with solubility-enhancing rubusoside.[Pubmed: 22698860]

Etoposide (ETO), a widely used anti-cancer drug, is constrained by its low aqueous solubility and by side effects from both the drug and its solubilizing excipients. In this study, a recently discovered natural solubilizer Rubusoside (RUB) was used to achieve the solubilization of ETO.
METHODS AND RESULTS:
Dynamic light scattering and freeze-fracture transmission electron microscopy studies showed that ETO and Rubusoside formed ETO-Rubusoside nanoparticles (～6 nm in diameter). The powder of ETO-Rubusoside nanoparticles was completely reconstitutable in water and remained stable in this solution at 25 and 37°C for at least 24h. Under other physiologic conditions, ETO solution was clear and free of precipitation at 25°C, but underwent various structural transformations. In PBS and simulated intestinal fluid, Rubusoside-solubilized ETO underwent epimerization and equilibrated to cis-ETO. In simulated gastric fluid, Rubusoside-solubilized ETO degraded to 4'-demethylepipodophyllotoxin-beta-d-glucoside and 4'-demethylepipodophyllotoxin. Higher temperatures favored epimerization or degradation. Furthermore, a side-by-side comparison with DMSO-solubilized ETO confirmed that the RUB-solubilized ETO showed no significant differences in cytotoxicity in colon, breast and prostate cancer cell lines.
CONCLUSIONS:
Rubusoside effectively solubilized and stabilized etoposide, which sets the stage for further toxicology, bioavailability, and efficacy investigations.

Chinese Journal of Ethnomedicine & Ethnopharmacy, 2015, 24(24):16-8.

Protective Effects of Rubusoside on the Ultrastructure and Cyt C Translocation Expression of the Palmitic Acid- induced INS- 1 Cells.[Reference: WebLink]

To investigate the protective mechanism of Rubusoside treating on the palmitic acid- induced INS- 1 cells.
METHODS AND RESULTS:
MTT assay was used to detect the cell viability rate of control group,palmitic acid group and different concentrations of Rubusoside group. Transmission electron microscope( TEM) was used to observe the ultrastructur of every group and the immune electron microscopy was used to detect cytochrome C translocationexpression. As evidenced by MTT assay,the cell viability significantly was enhanced by different concentrations Rubusoside pretreatment. TEM revealed degenerative changes in the ultramicroscopic structure of palmitic acid- induced INS- 1 cells whereas various concentrationpretreatment with Rubusoside could significantly attenuated the deterioration of the damage. Immune electron microscopy showed that different concentrations Rubusoside could prevent the cytochrome C releasing from mitochondria to cytoplasm with palmitic acid induced.
CONCLUSIONS:
Rubusoside can improve the survival rate of palmitic acid- induced INS- 1 cells and inhibit the occurrence of apoptosis. It is suggested that the mechanism may be associated with the inhibition of the oxidative stress induced by palmitic acid and prevent the cytochrome C releasing from mitochondrial to cytoplasm,which can activate caspase cascade and a downstream signaling to apopotosis.

Enzyme Microb Technol. 2014 Oct;64-65:38-43.

Production of rubusoside from stevioside by using a thermostable lactase from Thermus thermophilus and solubility enhancement of liquiritin and teniposide.[Pubmed: 25152415]

Solubility is an important factor for achieving the desired plasma level of drug for pharmacological response. About 40% of drugs are not soluble in water in practice and therefore are slowly absorbed, which results in insufficient and uneven bioavailability and GI toxicity. Rubusoside (Ru) is a sweetener component in herbal tea and was discovered to enhance the solubility of a number of pharmaceutically and medicinally important compounds, including anticancer compounds.
METHODS AND RESULTS:
In this study, thirty-one hydrolyzing enzymes were screened for the conversion of stevioside (Ste) to Ru. Recombinant lactase from Thermus thermophiles which was expressed in Escherichia coli converted stevioside to Rubusoside as a main product. Immobilized lactase was prepared and used for the production of Rubusoside; twelve reaction cycles were repeated with 95.4% of Ste hydrolysis and 49 g L(-1) of Ru was produced. The optimum Rubusoside synthesis yield was 86% at 200 g L(-1), 1200 U lactase. The purified 10% Rubusoside solution showed increased water solubility of liquiritin from 0.98 mg mL(-1) to 4.70±0.12 mg mL(-1) and 0 mg mL(-1) to 3.42±0.11 mg mL(-1) in the case of teniposide.

J Agric Food Chem. 2012 Jun 20;60(24):6210-6.

Mass production of rubusoside using a novel stevioside-specific β-glucosidase from Aspergillus aculeatus.[Pubmed: 22530920]

Rubusoside (R) is a natural sweetener and a solubilizing agent with antiangiogenic and antiallergic properties. However, currently, its production is quite expensive, and therefore, we have investigated nine commercially available glycosidases to optimize an economically viable Rubusoside-production method.
METHODS AND RESULTS:
A stevioside (ST)-specific β-glucosidase (SSGase) was selected and purified 7-fold from Aspergillus aculeatus Viscozyme L by a two-step column chromatography procedure. The 79 kDa protein was stable from pH 3.0 to pH 7.0 at 50-60 °C. Hydrolysis of ST by SSGase produced Rubusoside and steviol monoglucosyl ester as determined by (1)H and (13)C nuclear magnetic resonance (NMR). Importantly, SSGase showed higher activity toward ST than other β-linked glucobioses. The optimal conditions for Rubusoside production were 280 mM ST and 16.6 μL of SSGase at pH 5.1 and 63 °C.
CONCLUSIONS:
This is the first discussion detailing the production of Rubusoside by enzymatic hydrolysis of ST and is useful for the food additive and pharmaceutical industries.