Tropical Infectious Disease Research and Education Center (TIDREC), Department of Medical Microbiology, University of Malaya, Kuala Lumpur, Malaysia.
Virol J. 2011 Dec 28;8:560. doi: 10.1186/1743-422X-8-560.
Dengue is a major mosquito-borne disease currently with no effective antiviral or vaccine available. Effort to find antivirals for it has focused on bioflavonoids, a plant-derived polyphenolic compounds with many potential health benefits. In the present study, antiviral activity of four types of bioflavonoid against dengue virus type -2 (DENV-2) in Vero cell was evaluated. Anti-dengue activity of these compounds was determined at different stages of DENV-2 infection and replication cycle. DENV replication was measured by Foci Forming Unit Reduction Assay (FFURA) and quantitative RT-PCR. Selectivity Index value (SI) was determined as the ratio of cytotoxic concentration 50 (CC50) to inhibitory concentration 50 (IC50) for each compound.
The half maximal inhibitory concentration (IC50) of quercetin against dengue virus was 35.7 μg mL-1 when it was used after virus adsorption to the cells. The IC50 decreased to 28.9 μg mL-1 when the cells were treated continuously for 5 h before virus infection and up to 4 days post-infection. The SI values for quercetin were 7.07 and 8.74 μg mL-1, respectively, the highest compared to all bioflavonoids studied. Naringin only exhibited anti-adsorption effects against DENV-2 with IC50 = 168.2 μg mL-1 and its related SI was 1.3. Daidzein showed a weak anti-dengue activity with IC50 = 142.6 μg mL-1 when the DENV-2 infected cells were treated after virus adsorption. The SI value for this compound was 1.03. Hesperetin did not exhibit any antiviral activity against DENV-2. The findings obtained from Foci Forming Unit Reduction Assay (FFURA) were corroborated by findings of the qRT-PCR assays. Quercetin and daidzein (50 μg mL-1) reduced DENV-2 RNA levels by 67% and 25%, respectively. There was no significant inhibition of DENV-2 RNA levels with naringin and hesperetin.
Results from the study suggest that only quercetin demonstrated significant anti-DENV-2 inhibitory activities. Other bioflavonoids, including daidzein, naringin and hesperetin showed minimal to no significant inhibition of DENV-2 virus replication. These findings, together with those previously reported suggest that select group of bioflavonoids including quercetin and fisetin, exhibited significant inhibitory activities against dengue virus. This group of flavonoids, flavonol, could be investigated further to discover the common mechanisms of inhibition of dengue virus replication.
登革热是一种主要的蚊媒疾病，目前尚无有效的抗病毒药物或疫苗。寻找抗病毒药物的努力集中在生物类黄酮上，生物类黄酮是一种具有许多潜在健康益处的植物衍生多酚化合物。在本研究中，评估了四种生物类黄酮对登革热病毒 2 型（DENV-2）在 Vero 细胞中的抗病毒活性。在 DENV-2 感染和复制周期的不同阶段测定这些化合物的抗登革热活性。通过空斑形成单位减少测定法（FFURA）和定量 RT-PCR 测定 DENV 复制。选择指数值（SI）确定为每种化合物的细胞毒性浓度 50（CC50）与抑制浓度 50（IC50）的比值。
当登革热病毒吸附到细胞后使用时，槲皮素对登革热病毒的半最大抑制浓度（IC50）为 35.7μg mL-1。当在病毒感染前连续处理 5 小时并持续至感染后 4 天时，IC50 降低至 28.9μg mL-1。槲皮素的 SI 值分别为 7.07 和 8.74μg mL-1，与所有研究的生物类黄酮相比，SI 值最高。柚皮苷仅对 DENV-2 表现出抗吸附作用，IC50=168.2μg mL-1，相关 SI 为 1.3。当 DENV-2 感染细胞在病毒吸附后进行处理时，大豆苷元表现出较弱的抗登革热活性，IC50=142.6μg mL-1。该化合物的 SI 值为 1.03。橙皮苷对 DENV-2 没有表现出任何抗病毒活性。FFURA 测定的结果与 qRT-PCR 测定的结果一致。槲皮素和大豆苷元（50μg mL-1）使 DENV-2 RNA 水平分别降低了 67%和 25%。柚皮苷和橙皮苷对 DENV-2 RNA 水平没有显著抑制。
研究结果表明，只有槲皮素表现出对 DENV-2 的显著抑制活性。其他生物类黄酮，包括大豆苷元和柚皮苷，对 DENV-2 病毒复制的抑制作用最小或无显著抑制作用。这些发现与之前的报道一起表明，包括槲皮素和非瑟酮在内的特定生物类黄酮组表现出对登革热病毒的显著抑制活性。该组类黄酮，类黄酮醇，可进一步研究以发现抑制登革热病毒复制的共同机制。
