In vitro and in vivo characterization of erythrosin B and derivatives against Zika virus

Zika virus(ZIKV)causes significant human diseases without specific therapy.Previously we found erythrosin B,an FDA-approved food additive,inhibited viral NS2B−NS3 interactions,leading to inhibition of ZIKV infection in cell culture.In this study,we performed pharmacokinetic and in vivo studies to demonstrate the efficacy of erythrosin B against ZIKV in 3D mini-brain organoid and mouse models.Our results showed that erythrosin B is very effective in abolishing ZIKV replication in the 3D organoid model.Although pharmacokinetics studies indicated that erythrosin B had a low absorption profile,mice challenged by a lethal dose of ZIKV showed a significantly improved survival rate upon oral administration of erythrosin B,compared to vehicle control.Limited structure−activity relationship studies indicated that most analogs of erythrosin B with modifications on the xanthene ring led to loss or reduction of inhibitory activities towards viral NS2B−NS3 interactions,protease activity and antiviral efficacy.In contrast,introducing chlorine substitutions on the isobenzofuran ring led to slightly increased activities,suggesting that the isobenzofuran ring is well tolerated for modifications.Cytotoxicity studies indicated that all derivatives are nontoxic to human cells.Overall,our studies demonstrated erythrosin B is an effective antiviral against ZIKV both in vitro and in vivo.

Correlation of Vascular Endothelial Growth Factor Production with Photochemical Reaction-induced Retinal Edema

Background： Retinal edema is the major complication of retinal vein occlusion and diabetic retinopathy; it can damage visual function by influencing macular region. This study was to establish a rat retinal edema model and explore the related VEGF expression and observe the responses to anti-VEGF drugs in this model. Methods： A rat retinal edema model was established by inducing photochemical reaction using a 532 nm laser after the intravenous injection of Erythrosin B. Immediately after the laser treatment, models were given intravitreal injections of Ranibizumab or Conbercept to inhibit VEGF expression, and the changes of retinal thickness were measured. Retinal edema was observed using fundus photography （FP）, optical coherence tomography （OCT）, and fluoresce in fundus angiography （FFA） at 0, 1, 2, 4, 7 and 14 days after intervention. The retinal VEGF expression was measured using enzyme-linked immunosorbent assay （ELISA） and western blotting at each time point. The rat retinal edema model was also used to verify the function of anti-VEGF polypeptide ZY1. Results： Both retinal edema and vascular leakage were clearly observed at 1, 2 and 4 days after photochemical induction and the retinal thickness increased notably over the same period. The retinal VEGF expression peaked at day 1 and retina became thickening simultaneously. After the interventions, the VEGF expression of the Ranibizumab and Conbercept groups decreased at each time point compared to the edema group （26.90 ± 3.57 vs. 40.29 ± 6.68, F = 31.269 on day 1 and 22.36 ± 1.12 vs. 29.92 ± 0.93 F = 163.789 on day 2, both P 〈 0.01）; the mean RT （278 ± 4 vs. 288 ± 3, F = 134.190 on day 1 and 274 ± 7 vs. 284 ± 6, F = 64.367 on day 2, both P 〈 0.05） and vascular leakage in these groups also decreased. The same results were observed in the ZY1 group, particularly at day 2 （P 〈 0.05）. Conclusions： This retinal edema model induced by a photochemical reaction is reliable and repeatable. Induced edema increases expression of VEGF. This model can be used to test new drugs.