Selectivity indices (SI) of the tested extracts.

The leaves of Azadirachta indica L. and Melia azedarach L., belonging to Meliaceae family, have been shown to have medicinal benefits and are extensively employed in traditional folk medicine. Herein, HPLC analysis of the ethyl acetate fraction of the total methanolic extract emphasized the enrichment of both A. indica L., and M. azedarach L. leaves extracts with phenolic and flavonoids composites, respectively. Besides, 4 limonoids and 2 flavonoids were isolated using column chromatography. By assessing the in vitro antiviral activities of both total leaves extracts against Severe Acute Respiratory Syndrome Corona virus 2 (SARS-CoV-2), it was found that A. indica L. and M. azedarach L. have robust anti-SARS-CoV-2 activities at low half-maximal inhibitory concentrations (IC50) of 8.451 and 6.922 μg/mL, respectively. Due to the high safety of A. indica L. and M. azedarach L. extracts with half-maximal cytotoxic concentrations (CC50) of 446.2 and 351.4 μg/ml, respectively, both displayed extraordinary selectivity indices (SI>50). A. indica L. and M. azedarach L. leaves extracts could induce antibacterial activities against both Gram-negative and positive bacterial strains. The minimal inhibitory concentrations of A. indica L. and M. azedarach L. leaves extracts varied from 25 to 100 mg/mL within 30 min contact time towards the tested bacteria. Our findings confirm the broad-spectrum medicinal value of A. indica L. and M. azedarach L. leaves extracts. Finally, additional in vivo investigations are highly recommended to confirm the anti-COVID-19 and antimicrobial activities of both plant extracts.

隶属于楝科的印楝（Azadirachta indica L.）与苦楝（Melia azedarach L.）的叶片，已被证实具有药用功效，且在传统民间医药中得到广泛应用。本研究通过高效液相色谱（HPLC）对总甲醇提取物的乙酸乙酯组分进行分析，结果显示，印楝与苦楝叶片提取物分别富集了酚类与黄酮类成分。此外，本研究通过柱色谱法分离得到4种柠檬苦素类化合物与2种黄酮类化合物。通过体外评估两种叶片总提取物对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的抗病毒活性，研究发现印楝与苦楝均具有较强的抗SARS-CoV-2活性，其半数抑制浓度（IC50）分别低至8.451 μg/mL与6.922 μg/mL。鉴于两种提取物具有较高的安全性，其半数细胞毒性浓度（CC50）分别为446.2 μg/mL与351.4 μg/mL，因此二者均展现出优异的选择性指数（SI>50）。印楝与苦楝叶片提取物对革兰氏阴性及革兰氏阳性菌株均具有抗菌活性；在30分钟的接触时间内，两种提取物对受试细菌的最低抑菌浓度范围为25~100 mg/mL。本研究结果证实了印楝与苦楝叶片提取物具有广谱药用价值。最后，本研究强烈建议开展进一步的体内实验，以验证两种植物提取物的抗COVID-19与抗菌活性。