Virtual screening of phytochemicals was performed through molecular docking, simulations, in silico ADMET and drug-likeness prediction to identify the potential hits that can inhibit the effects of SARS-CoV-2. Considering the published literature on medicinal importance, 154 phytochemicals with analogous structure from limonoids and triterpenoids were selected to search potential inhibitors for the five therapeutic protein targets of SARS-CoV-2, i.e., 3CLpro (main protease), PLpro (papain-like protease), SGp-RBD (spike glycoprotein-receptor binding domain), RdRp (RNA dependent RNA polymerase) and ACE2 (angiotensin-converting enzyme 2). The in silico computational results revealed that the phytochemicals such as glycyrrhizic acid, limonin, 7-deacetyl-7-benzoylgedunin, maslinic acid, corosolic acid, obacunone and ursolic acid were found to be effective against the target proteins of SARS-CoV-2. The protein-ligand interaction study revealed that these phytochemicals bind with the amino acid residues at the active site of the target proteins. Therefore, the core structure of these potential hits can be used for further lead optimization to design drugs for SARS-CoV-2. Also, the medicinal plants containing these phytochemicals like licorice, neem, tulsi, citrus and olives can be used to formulate suitable therapeutic approaches in traditional medicines.

Due to several negative issues, market available drugs have been gradually losing their importance in the treatment of cancer. With a view to discover suitable drugs capable of diagnosing as well as inhibiting the growth of cancer cells, we have aspired to develop a group of theranostic metal complexes which will be (i) target specific, (ii) cytoselective, thus rendering the normal cell unaffected, (iii) water-soluble, (iv) cancer cell permeable, and (v) luminescent, being beneficial for healing the cancer eternally. Therefore, to reach our goal, we have prepared novel Ru­(II)- and Ir­(III)-based bimetallic and hetero bimetallic scaffolds using click-derived pyridinyltriazolylmethylquinoxaline ligands followed by metal coordination. Most of the compounds have displayed significant cytoselectivity against colorectal adenocarcinoma (Caco-2) and epithiloid cervical carcinoma (HeLa) cells with respect to normal human embryonic kidney cells (HEK-293) compared to cisplatin [cis-diamminedichloroplatinum­(II)] along with excellent binding efficacy with DNA as well as serum albumin. Complex [(η6-p-cymene)­(η5-Cp*)­RuIIIrIIICl2(K2-N,N-L)]­(PF6)2 [RuIrL] exhibited the best cytoselectivity against all the human cancer cells and was identified as the most significant cancer theranostic agent in terms of potency, selectivity, and fluorescence quantum yield. Investigation of the localization of complex [Ir 2 L] and [RuIrL] in the more aggressive colorectal adenocarcinoma cell HT-29 indicates that mitochondria are the key cellular target for destroying cancer cells. Mitochondrial dysfunction and G2/M phase cell cycle arrest in HT-29 cell were found to be involved in the apoptotic cell death pathway induced by the test complexes [Ir 2 L] and [RuIrL]. These results validate the concept that these types of complexes will be reasonably able to exert great potential for tumor diagnosis as well as therapy in the near future.

Background and aim The year 2020 begins with the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that cause the disease COVID-19, and continue till today. As of March 23, 2021, the outbreak has infected 124,313,054 worldwide with a total death of 2,735,707. The use of traditional medicines as an adjuvant therapy with western drugs can lower the fatality rate due to the COVID-19. Therefore, in silico molecular docking study was performed to search potential phytochemicals and drugs that can block the entry of SARS-CoV-2 into host cells by inhibiting the proteolytic cleavage activity of furin and TMPRSS2. Experimental procedure The protein-protein docking of the host proteases furin and TMPRSS2 was carried out with the virus spike (S) protein to examine the conformational details and residues involved in the complex formation. Subsequently, a library of 163 ligands containing phytochemicals and drugs was virtually screened to propose potential hits that can inhibit the proteolytic cleavage activity of furin and TMPRSS2. Results and conclusion The phytochemicals like limonin, gedunin, eribulin, pedunculagin, limonin glycoside and betunilic acid bind at the active site of both furin and TMPRSS2. Limonin and gedunin found mainly in the citrus fruits and neem showed the highest binding energy at the active site of furin and TMPRSS2, respectively. The polyphenols found in green tea can also be useful in suppressing the furin activity. Among the drugs, the drug nafamostat may be more beneficial than the camostat in suppressing the activity of TMPRSS2.

Due to a number of unpleasant considerations, marketed drugs have steadily lost their importance in the treatment of cancer. In order to find a viable cancer cell diagnostic agent, we therefore focused on metal complexes that displayed target adequacy, permeability to cancer cells, high standard water solubility, cytoselectivity, and luminescent behavior. In this aspect, luminescent 11-{naphthalen-1-yl} dipyrido [3,2-a:2′,3′-c] phenazine based Ru(II)/Ir(III)/Re(I) complexes have been prepared for HCT-116 colorectal cancer stem cell therapy. Our study successfully established the possible cytotoxicity of IrL complex at different doses on HCT-116 colorectal cancer stem cells (CRCSCs). Additionally, an immunochemistry analysis of the complex IrL showed that the molecule was subcellularly localized in the nucleus and other regions of the cytoplasm, where it caused nuclear DNA damage and mitochondrial dysfunction. The level of BAX and Bcl-2 was further quantified by qRT-PCR. The expression of proapoptotic BAX showed increased expression in the complex IrL-treated cell compared to the control, indicating the potential of complex IrL for apoptotic induction. Upon further validation, complex IrL was developed as an inhibitor of autophagy for the eradication of cancer stem cells.

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