In Wuhan, China, severe acute respiratory syndrome caused by coronavirus-2 (SARS-CoV-2) has emerged, causing serious symptoms in patients such as fever, dry cough, and exhaustion. This fatal pandemic spreads over the globe, causing significant infections in humans, mainly in the respiratory tract. COVID-19 is still without a treatment. Until date, researchers have paid close attention to new therapeutic methods, particularly promising antiviral medicines and vaccines. Especially, existing synthetic antivirals have been used against viruses that prevent replication, entry into the cell, and transmission of the virus. These antiviral agents have been the subject the basis of drug discovery studies that directly affect COVID 19. Therefore, we investigated on the potential herbal medicines against various RNA, and DNA viruses, including SARS-CoV-2. Finally, we recommend that natural substances and plants be investigated further, including clinical trials, for the treatment of COVID-19.

The aim of this study was to investigate the antioxidant and enzyme inhibition activities of methanol extracts prepared from Klasea serratuloides (DC) Greuter & Wagenitz subsp. karamanica B. Dogan & A. Duran with Soxhlet, ultrasonic extraction, and maceration methods. 1,1-Diphenyl-2-picryl hydroxyl (DPPH) quenching assay and 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) cation decolorization test were used to evaluate in vitro radical scavenging activity. The total phenolic content was determined with the Folin-Ciocalteu method while the total flavonoid content was evaluated by the aluminum chloride colorimetric method. According to the results, DPPH, ABTS radical scavenging activity and iron chelating activity of methanol of Klasea serratuloides were shown concentrationdependent manner. The extract obtained from maceration was found to be higher than the other extracts. It suggests that the maceration technique was more effective than the other extraction methods for the determination of the phenolic content. The methanol extract of KS using soxhlet (61.17 ± 3.62) and ultrasonic extraction (58.76 ± 1.46) showed higher inhibition than the extract prepared with maceration methods (34.54 ± 0.73) against BChE. All extracts displayed moderate inhibition activity against AChE. As for enzyme inhibition activity, the extract from soxhlet method was found to be more potent tyrosinase, acetylcholinesterase and butyrylcholinesterase inhibitors than the other extracts prepared by ultrasound assisted extraction and maceration methods. The present study suggests that K. serratuloides should be given special attention to conduct further investigation for its phytochemical constituents that attribute to their antioxidant potentials, and enzyme inhibition activities.

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Smyrnium connatum Boiss. and Kotschy is known as “yabani kereviz” in Turkey and its roots are used to treat asthma. Smyrnium species are used by people in different regions as diuretic, depurative and laxative. The aim of this analysis was to test the biological activities of methanol extracts obtained from aerial parts and roots of S. connatum using a Soxhlet extractor, ultrasonic assisted extraction, and maceration procedures. The extracts of S. connatum aerial parts and roots were tested for their acetylcholinesterase, butrylcholinesterase, and tyrosinase inhibitory activities, radical scavenging activity, and iron chelating activities at various concentration using microplate reader. In this study, significant differences were found in acetylcholinesterase, and butrylcholinesterase inhibition and antioxidant determinations between plant extracts prepared using different extraction methods. S. connatum aerial parts generally was detected to be more active in terms of antioxidant activity assay. S. connatum aerial parts and roots showed high inhibition activity against both cholinesterase enzymes. All extracts showed moderate inhibitory activity against tyrosinase. The biological activity of the aerial parts of S. connatum was generally found to be more active than roots of S. connatum. It was assumed that the determination of enzyme inhibitor and antioxidant capacity of the plant had remarkable potentials on the treatment of neurodegenerative diseases.