Effective and affordable treatments for patients suffering from coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are needed. We report in vitro efficacy of Artemisia annua extracts as well as artemisinin, artesunate, and artemether against SARS-CoV-2. The latter two are approved active pharmaceutical ingredients of anti-malarial drugs. Proof-of-concept for prophylactic efficacy of the extracts was obtained using a plaque-reduction assay in VeroE6 cells. Subsequent concentration-response studies using a high-throughput antiviral assay, based on immunostaining of SARS-CoV-2 spike glycoprotein, revealed that pretreatment and treatment with extracts, artemisinin, and artesunate inhibited SARS-CoV-2 infection of VeroE6 cells. In treatment assays, artesunate (50% effective concentration (EC50): 7 μg/mL) was more potent than the tested plant extracts (128-260 μg/mL) or artemisinin (151 μg/mL) and artemether (>179 μg/mL), while generally EC50 in pretreatment assays were slightly higher. The selectivity index (SI), calculated based on treatment and cell viability assays, was highest for artemisinin (54), and roughly equal for the extracts (5-10), artesunate (6) and artemether (<7). Similar results were obtained in human hepatoma Huh7.5 cells. Peak plasma concentrations of artesunate exceeding EC50 values can be achieved. Clinical studies are required to further evaluate the utility of these compounds as COVID-19 treatment.

中文翻译：

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青蒿素类药物治疗SARS-CoV-2的体外疗效

需要针对由严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）引起的冠状病毒病2019（COVID-19）的患者提供有效且负担得起的治疗方法。我们报告了青蒿提取物以及青蒿素，青蒿琥酯和蒿甲醚对SARS-CoV-2的体外功效。后两种是经批准的抗疟疾药物的活性药物成分。在VeroE6细胞中使用噬斑减少试验获得提取物预防功效的概念证明。随后使用基于SARS-CoV-2穗状糖蛋白的免疫染色的高通量抗病毒分析进行浓度反应研究，结果表明，提取物，青蒿素和青蒿琥酯的预处理和治疗均抑制了VeroE6细胞的SARS-CoV-2感染。在治疗测定中，青蒿琥酯（50％有效浓度（EC50）：7μg/ mL）比被测植物提取物（128-260μg/ mL）或青蒿素（151μg/ mL）和青蒿素（> 179μg/ mL）更有效，而预处理测定中的EC50通常略高。根据治疗和细胞生存力分析计算得出的选择性指数（SI）对青蒿素（54）最高，对于提取物（5-10），青蒿琥酯（6）和青蒿醚（<7）大致相等。在人肝癌Huh7.5细胞中获得了相似的结果。可以达到超过EC50值的青蒿琥酯血浆峰值浓度。需要进行临床研究以进一步评估这些化合物作为COVID-19治疗的效用。根据治疗和细胞生存力分析计算得出的选择性指数（SI）对青蒿素（54）最高，对于提取物（5-10），青蒿琥酯（6）和蒿甲醚（<7）大致相等。在人肝癌Huh7.5细胞中获得了相似的结果。可以达到超过EC50值的青蒿琥酯血浆峰值浓度。需要进行临床研究以进一步评估这些化合物作为COVID-19治疗的效用。根据治疗和细胞生存力分析计算得出的选择性指数（SI）对青蒿素（54）最高，对于提取物（5-10），青蒿琥酯（6）和青蒿醚（<7）大致相等。在人肝癌Huh7.5细胞中获得了相似的结果。可以达到超过EC50值的青蒿琥酯血浆峰值浓度。需要进行临床研究以进一步评估这些化合物作为COVID-19治疗的效用。