Diphenyl Diselenide and Clotrimazole Co-loaded into Eudragit® RS 100 Nanocapsules Formulation Has Superior Antioxidant Potential and Promising Anti-candida Activity

Abstract In the current study, nanocapsules (NC) formulations containing a co-load of clotrimazole (C), a highly prescribed antifungal drug, and diphenyl diselenide [(PhSe)2], an organoselenium compound with a promising scope of pharmacological actions, were prepared. Formulations were characterized as well as the potential toxicity, antioxidant action, and antifungal effect were assessed using in vitro techniques. The NCs were prepared employing Eudragit® RS 100 as polymeric wall and medium chain triglycerides or virgin coconut oil (CO) as core. All NC suspensions had pH around acid range, compound content close to theoretical value (1 mg/mL/drug), average diameter in nanometric range, positive values of zeta potential as well as high encapsulation efficacy and mucoadhesive property. Physicochemical stability was performed over a 30-day period and showed no modification in the aforementioned parameters to all samples. Preliminary screening of toxicological potential performed by the hen's egg test chorioallantoic membrane technique classified the formulations as non-irritant. The DPPH radical assay revealed that nanoencapsulated compounds had superior antioxidant action in comparison to their free forms (concentration range tested 1.0-25.0 µg/mL). Importantly, the formulation composed of CO and containing C and (PhSe)2 showed the highest antioxidant potential and was selected for further investigation regarding antifungal effect against some Candida spp strains. Results of in vitro antifungal assay demonstrated that the C and (PhSe)2 co-encapsulation had a minimum inhibitory concentration (MIC) values around 60. Thus, our study supplies additional data about advantages achieved by encapsulating active compounds.

Protective effects of organoselenium compounds against methylmercury-induced oxidative stress in mouse brain mitochondrial-enriched fractions

We evaluated the potential neuroprotective effect of 1-100 µM of four organoselenium compounds: diphenyl diselenide, 3’3-ditri-fluoromethyldiphenyl diselenide, p-methoxy-diphenyl diselenide, and p-chloro-diphenyl diselenide, against methylmercury-induced mitochondrial dysfunction and oxidative stress in mitochondrial-enriched fractions from adult Swiss mouse brain. Methylmercury (10-100 µM) significantly decreased mitochondrial activity, assessed by MTT reduction assay, in a dose-dependent manner, which occurred in parallel with increased glutathione oxidation, hydroperoxide formation (xylenol orange assay) and lipid peroxidation end-products (thiobarbituric acid reactive substances, TBARS). The co-incubation with diphenyl diselenide (100 µM) completely prevented the disruption of mitochondrial activity as well as the increase in TBARS levels caused by methylmercury. The compound 3’3-ditrifluoromethyldiphenyl diselenide provided a partial but significant protection against methylmercury-induced mitochondrial dysfunction (45.4 ± 5.8 percent inhibition of the methylmercury effect). Diphenyl diselenide showed a higher thiol peroxidase activity compared to the other three compounds. Catalase blocked methylmercury-induced TBARS, pointing to hydrogen peroxide as a vector during methylmercury toxicity in this model. This result also suggests that thiol peroxidase activity of organoselenium compounds accounts for their protective actions against methylmercury-induced oxidative stress. Our results show that diphenyl diselenide and potentially other organoselenium compounds may represent important molecules in the search for an improved therapy against the deleterious effects of methylmercury as well as other mercury compounds.

Oxidative stress response to menadione and cumene hydroperoxide in the opportunistic fungal pathogen Candida glabrata

Candida glabrata is an opportunistic fungal pathogen that can cause severe invasive infections and can evade phagocytic cell clearance. We are interested in understanding the virulence of this fungal pathogen, in particular its oxidative stress response. Here we investigated C. glabrata, Saccharomyces cerevisiae and Candida albicans responses to two different oxidants: menadione and cumene hydroperoxide (CHP). In log-phase, in the presence of menadione, C. glabrata requires Cta1p (catalase), while in a stationary phase (SP), Cta1p is dispensable. In addition, C. glabrata is less resistant to menadione than C. albicans in SP. The S. cerevisiae laboratory reference strain is less resistant to menadione than C. glabrata and C. albicans; however S. cerevisiaeclinical isolates (CIs) are more resistant than the lab reference strain. Furthermore, S. cerevisiae CIs showed an increased catalase activity. Interestingly, in SP C. glabrata and S. cerevisiae are more resistant to CHP than C. albicans and Cta1p plays no apparent role in detoxifying this oxidant.

Pharmacology and toxicology of diphenyl diselenide in several biological models

The pharmacology of synthetic organoselenium compounds indicates that they can be used as antioxidants, enzyme inhibitors, neuroprotectors, anti-tumor and anti-infectious agents, and immunomodulators. In this review, we focus on the effects of diphenyl diselenide (DPDS) in various biological model organisms. DPDS possesses antioxidant activity, confirmed in several in vitro and in vivo systems, and thus has a protective effect against hepatic, renal and gastric injuries, in addition to its neuroprotective activity. The activity of the compound on the central nervous system has been studied since DPDS has lipophilic characteristics, increasing adenylyl cyclase activity and inhibiting glutamate and MK-801 binding to rat synaptic membranes. Systemic administration facilitates the formation of long-term object recognition memory in mice and has a protective effect against brain ischemia and on reserpine-induced orofacial dyskinesia in rats. On the other hand, DPDS may be toxic, mainly because of its interaction with thiol groups. In the yeast Saccharomyces cerevisiae, the molecule acts as a pro-oxidant by depleting free glutathione. Administration to mice during cadmium intoxication has the opposite effect, reducing oxidative stress in various tissues. DPDS is a potent inhibitor of d-aminolevulinate dehydratase and chronic exposure to high doses of this compound has central effects on mouse brain, as well as liver and renal toxicity. Genotoxicity of this compound has been assessed in bacteria, haploid and diploid yeast and in a tumor cell line.

Antioxidant and anti-inflammatory property of Sandhika: a compound herbal drug.

The present study was envisaged to assess the rationality for the use of "Sandhika", a popular Ayurvedic drug in rheumatoid arthritis. This drug, when tested against carrageenan induced paw oedema and cotton pellet granuloma, showed significant anti-inflammatory activity at the dose of 0.25 g/kg body weight. The antioxidant property was assessed by determining cumene hydroperoxide (CHP) induced lipid peroxidation and reduced glutathione content in rat liver homogenate (in vitro). Experiments show the significant protection against lipid peroxidation at the dose of 80 micrograms/ml, measured as reduction in the level of malondialdehyde (MDA) induced by 1.5 mM cumene hydroperoxide (CHP). This effect was accompanied by the maintained reduced glutathione (GSH) content in drug treated rats. Oral treatment of drug up to 2 g/kg body weight for 15 days did not show any rise in serum transaminases (SGOT and SGPT). The results suggest that "Sandhika" which is an indigenous drug for inflammation with no detectable adverse effect, might be acting through scavenging the free radicals.