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    Enhancement of biocompatibility and carbohydrate absorption control potential of rosmarinic acid through crossinking into microparticles
    (Elsevier, 2019) Şahiner, Mehtap; Blake, Diane A.; Fullerton, Mitchell L.; Sağbaş Suner, Selin; Sunol, Aydın K.; Şahiner, Nurettin
    Rosmarinic acid (RA), a bioflavonoid and antioxidant that exists in plants of the Lamiaceae family, was crosslinked into particles as poly(Rosmarinic Acid) (p(RA)) via an emulsion crosslinking method. The particles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance C-13 NMR spectroscopy, and thermal gravimetric analysis. The zeta potential values of p(RA) particles were determined at different pHs; the isoelectric point was estimated as pH 1.2. The release of monomeric RA from the particles at 37.5 degrees C was found to be similar at different pHs, 1.0, 7.4, and 11.0. The effects of p(RA) on hemolysis and coagulation were found to be minimal. The antioxidant activity of p(RA) particles and RA monomer were almost indistinguishable suggesting that p(RA) particles may be used as an antioxidant. On a per weight basis, p(RA) particles were similar to 66% less cytotoxic to mammalian cells that RA monomer, as assessed using COS-1 cells. In addition, p(RA) was an 8.6-fold stronger inhibitor of alpha-glycosidase than RA; the IC(50)s of the monomer and particles were 0.121 and 0.014 mg/mL, respectively. The strong inhibitory effect of p(RA) on alpha-glycosidase, coupled with its reduced cytotoxicity and antioxidant activity, provide new opportunities for the use of p(RA). (C) 2019 Elsevier B.V. All rights reserved.
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    Fabrication of Biodegradable Poly(naringin) Particles with Antioxidant Activity and Low Toxicity
    (Amer Chemical Soc, 2018) Şahiner, Mehtap; Şahiner, Nurettin; Sağbaş, Selin; Fullerton, Mitchell L.; Blake, Diane A.
    Naringin (NR, 4', 5,7 trihydrocyflavanone-7-O-rhamnoglucoside) is a flavanone found in citrus fruit that is composed of a phenolic compound, naringenin, and a disaccharide, neohesperidose. Poly(NR) [p(NR)] particles in the size range of few micrometers to few hundred nanometers were prepared from highly purified NR and subsequently characterized using UV/visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and zeta potential measurements. The hydrolytic degradation of p(NR) particles at 37.5 degrees C was investigated at pHs 5.4, 7.4, and 9.0. The particles degraded most rapidly at pH 7.4, with >90% degradation after 5 h. The cytotoxicity was assessed by growing COS-1 fibroblasts for 5 days in the presence of increasing concentrations of NR or eluates from the p(NR) particles. Both NR and p(NR) particles were nontoxic for these mammalian fibroblasts; at the highest concentration tested (571 mu g/mL), the percentages of surviving cells after 5 days in culture were 96.7 +/- 0.93 and 91 +/- 11% for NR and p(NR), respectively. The effect of p(NR) on red blood cell hemolysis was also negligible (<2%) at concentrations up to 100 mu g/mL; unpolymerized NR showed slightly higher levels of hemolysis than the p(NR) particles, but values never exceeded 5% at 50 and 100 mu g/mL. Both NR and p(NR) stimulated blood coagulation in a dose-dependent manner; the hemostatic effect was greater for p(NR), which, at 100 mu g/mL, stimulated in vitro blood clotting by similar to 50%. Neither NR nor eluates from p(NR) particles inhibited alpha-glucosidase activity; in fact, both provided a modest (10-30%) stimulation at concentrations from 0.67 to 1.67 mg/mL. p(NR) particles are easily synthesized, break down readily at physiological pH, and have excellent blood and biocompatibility. As such, they will be a useful carrier for drug delivery and as an oral antioxidant supplement.