In vitro extraction of intra-corneal iron using reverse iontophoresis and vitamin C.

PURPOSE: The aim of this study was to optimize reverse iontophoretic (RI) extraction of ferric/ferrous ions from the cornea. METHODS: Group I consisted of the right eye corneas from 20 normal rabbits. Corneal blood staining was induced in 60 right eyes. The corneal depths from the endothelium to the epithelium layers were divided into three groups by slit-lamp examination: Group II, one-third corneal thickness; Group III, one-half corneal thickness; Group IV, full corneal thickness. RI was performed using vertical diffusion cells. The lower chamber was loaded with glutathione bicarbonate Ringer's buffer (GBR; pH 7.0) or vitamin C (12.5 mg/mL) and GBR (pH 7.0), while the upper chamber was filled with 1 mL GBR. Progress of corneal blood staining removal was evaluated. RESULTS: Application of 1.5 mA to the cornea increased flux by 1.72- and 2.19-fold in Groups III and IV, respectively, but not in Groups I or II, compared to the control. When vitamin C was included, we observed significant flux increases in the controls (1.5-, 2.06-, 2.60-, and 4.59-fold) for Groups I, II, III, and IV, and under RI conditions for Groups III and IV. Following RI, the corneal endothelia appeared similar to corneas from untreated control rabbits, while Draize scores were zero. CONCLUSIONS: These results suggested that extracellular ferric/ferrous ions could be extracted from the cornea in vitro by RI, and that vitamin C reduced Fe(3+) to Fe(2+) in the cornea and altered its permselectivity, thus increasing the RI contribution to iron extraction.

Targeted Bacterial Keratitis Treatment with Polyethylene Glycol-Dithiothreitol- Boric Acid Hydrogel and Gatifloxacin.

OBJECTIVE: To prolong the ocular residence time of gatifloxacin and enhance its efficacy against bacterial keratitis, this study developed a velocity-controlled polyethylene glycol-dithiothreitol- boric acid (PDB) hydrogel loaded with gatifloxacin. MATERIALS AND METHODS: First, the basic properties of the synthesized PDB hydrogel and the gatifloxacin- loaded PDB hydrogel were assessed. Secondly, the in vitro degradation rate of the drugloaded PDB was measured in a simulated body fluid environment with pH 7.4/5.5. The release behavior of the drug-loaded PDB was studied using a dialysis method with PBS solution of pH 7.4/5.5 as the release medium. Finally, a mouse model of bacterial keratitis was established, and tissue morphology was observed using hematoxylin-eosin staining. Additionally, mouse tear fluid was extracted to observe the antibacterial effect of the gatifloxacin-loaded PDB hydrogel. RESULTS: The results showed that the PDB hydrogel had a particle size of 124.9 nm and a zeta potential of -23.3 mV, with good porosity, thermosensitivity, viscosity distribution, rheological properties, and high cell compatibility. The encapsulation of gatifloxacin did not alter the physical properties of the PDB hydrogel and maintained appropriate swelling and stability, with a high drug release rate in acidic conditions. Furthermore, animal experiments demonstrated that the gatifloxacin- loaded PDB hydrogel exhibited superior therapeutic effects compared to gatifloxacin eye drops and displayed strong antibacterial capabilities against bacterial keratitis. CONCLUSION: This study successfully synthesized PDB hydrogel and developed a gatifloxacin drug release system. The hydrogel exhibited good thermosensitivity, pH responsiveness, stability, and excellent biocompatibility, which can enhance drug retention, utilization, and therapeutic effects on the ocular surface.

In Vitro Bioassay-guided Isolation of Radioprotective Fractions from Extracts of Pinus koraiensis Bark.

OBJECTIVE: The aim of this study was to evaluate radioprotective effect of extracts of Pinus koraiensis bark and its fractions on rat splenocytes by using bioassay-guided isolation in order to obtain the best active fraction. MATERIALS AND METHODS: P. koraiensis bark was ground and extracted with water, 40% acetone, 95% ethanol. Bio-guided assay was selected as an evaluation method to further fractionate radioprotective component from P. koraiensis bark extract. Total phenolic and flavonoid contents in fractions were also measured. Rat splenocytes were prepared by using mechanical trituration method. DNA damage was assessed as comet parameters (tail DNA%, tail length, tail moment, olive tail moment). The levels of malondialdehyde (MDA), and activity of superoxide dismutase (SOD), catalase (CAT) in cultured rat splenocytes were also measured. RESULTS: The radioprotective effects decreased from rutin >95% ethanol extracts of Pinus koraiensis bark (95EEP) >40AEP > WEP. The stimulating effects decreased from rutin > n-butanol extract (NBE) > EAE. The results demonstrate that there exists toxic ingredients (PEE and dichloromethane extract), proliferative-promoting, radioprotective component (EAE and NBE) in 95EEP. fraction eluted from n-butanol fractions of 95EEP with 50% methanol solution (NBEPKB-50ME), a fraction of NBE result from bio-guided isolation, demonstrates good radioprotective efficacy on rat splenocytes. NBEPKB-50ME pretreated rat splenocytes demonstrated progressively reduced levels of MDA when compared with γ-ray exposed cells. Different dose of NBEPKB-50ME pretreatment with 8 Gy-irration showed an increase in enzymatic antioxidant. CONCLUSIONS: Proliferative-promoting efficacy, radioprotective effect of different solvents extracts of the bark of P. koraiensis were investigated in this work. NBEPKB-50ME was the best elution in NBE, especially in restoring SOD, CAT activities, content of GSH, decreasing DNA damage. SUMMARY: The radioprotective effects decreased from rutin > 95EEP > 40AEP > WEP. The extract of Petroleum ether, dichloromethane extract (DME) of 95% ethanol extract of P. koraiensis (PEE, DME) show toxic effect on rat splenocytes. The extract of Ethyl acetate, n-butanol extract of 95% ethanol extract of P. koraiensis (EAE, NBE) show proliferative-promoting, radioprotective effect on rat splenocytesSingle-cell gel electrophoresis was used to evaluate the spleen cell DNA damage parameters affected by gamma-radiation and addition of best component NBEPKB-50Me from extract of P. koraiensis barkNBEPKB-50ME pretreatment with 8 Gy-irradiation showed an increase in enzymatic antioxidant capacity. NBEPKB-50ME pretreated (80, 160, 320, 480 mg/ml) rat splenocytes demonstrated progressively reduced levels of MDA when compared with g-ray exposed cells. Abbreviations used: MDA: Malondialdehyde; SOD: Superoxide dismutase; CAT: Catalase; PEE: Petroleum ether Extract; DME: Dichloromethane extract; EAE: Ethyl acetate extract; NBE: n-butanol extract; WAP: Water extracts of Pinus koraiensis bark; 40AEP: 40% acetone extracts of Pinus koraiensis bark; 95EEP: 95% ethanol extracts of Pinus koraiensis bark; TPC: Total phenolic content; TFC: Total flavonoid content; NBEPKB-50ME: Fraction eluted from n-Butanol fractions of 95EEP with 50% methanol solution.

Effects of oleic acid on the corneal permeability of compounds and evaluation of its ocular irritation of rabbit eyes.

OBJECTIVE: To explore the use of oleic acid (OA) in ocular drug delivery. METHODS: Six compounds, namely rhodamine B, sodium-fluorescein, fluorescein isothiocyanate (FITC) dextrans of 4, 10, 20 and 40 kDa were selected as model drugs. The effect of OA on the corneal permeability of drugs was evaluated in vitro, using isolated rabbit corneas by a Franz diffusion cell. The safety of OA was assessed on the basis of corneal hydration level. The ocular irritation of OA was also tested in rabbits in vivo using the Draize eye test. RESULTS: In the presence of OA, at a concentration of 0.02-0.1%, the maximum increase in the apparent permeability coefficient (Papp) was 3.21-, 1.76- and 1.57-fold for rhodamine B, sodium-fluorescein and FITC-dextran of 4 kDa, respectively. However, no significant permeability enhancement of FITC-dextrans of 4, 10, 20 and 40 kDa was found in the presence of OA. It enhanced the corneal penetration of model compounds in a concentration-dependent manner. The Papp values of rhodamine B decreased with increasing concentration of OA, while the Papp values of sodium-fluorescein and FITC-dextrans of 4 kDa increased. The Papp enhanced by 0.1% OA was logarithmically correlated to the molecular weight of model drugs (R(2) = 0.9991). With the 0.02%, 0.05% and 0.1% oleic application, the corneal hydration values were <83%, and Draize scores were <4. CONCLUSION: OA may have potential clinical benefits in improving the ocular drug delivery of both hydrophilic and lipophilic compounds.