Metallo-antiviral aspirants: Answer to the upcoming virusoutbreak

Metallodrugs: Synthesis, mechanism of action and nanoencapsulation for targeted chemotherapy

As a multifactorial and heterogeneous disease, cancer has a high mortality rate, and the search for more effective treatments is an enormous challenge. Metal coordination compounds open a range of possibilities that conventional organic and biological molecules can no longer fulfil due to increasing drug resistance. Metallodrugs still have tremendous potential to help overcome drug resistance and find new cures in medicine, considering that at least 25 metallic elements participate in healthy functioning of the human body. Transition metal ions, such as copper, zinc and iron, are incorporated into catalytic proteins, the so-called metalloenzymes, which participate in various chemical reactions necessary for life. The interaction of metal complexes in different pathways with the structural richness of deoxyribonucleic acid encouraged to seek to understand the mechanisms of action and overcome the obstacles encountered for a promising future of these drugs. The success of platinum-based metallodrugs is one of the great inspirations for the search of new metallodrugs, although the approval of these molecules has been slow in recent years due to the risk of systemic toxicity and insufficient understanding of their mechanisms. To overcome the clinical limitations encountered in some metallodrugs, nanoencapsulation has been proposed as a new approach to improve therapeutic index in chemotherapy. The remarkable selectivity of nanoencapsulated metallodrugs and their enhanced capacity to bypass various biological barriers allow site-specific targeting. In this review, we present the advances in the development and use of the most relevant metallodrugs, and new delivery approaches, in the fight against cancer.

Coordination chemistry suggests that independently observed benefits of metformin and Zn2+ against COVID-19 are not independent

Independent trials indicate that either oral Zn2+ or metformin can separately improve COVID-19 outcomes by approximately 40%. Coordination chemistry predicts a mechanistic relationship and therapeutic synergy. Zn2+ deficit is a known risk factor for both COVID-19 and non-infectious inflammation. Most dietary Zn2+ is not absorbed. Metformin is a naked ligand that presumably increases intestinal Zn2+ bioavailability and active absorption by cation transporters known to transport metformin. Intracellular Zn2+ provides a natural buffer of many protease reactions; the variable "set point" is determined by Zn2+ regulation or availability. A Zn2+-interactive protease network is suggested here. The two viral cysteine proteases are therapeutic targets against COVID-19. Viral and many host proteases are submaximally inhibited by exchangeable cell Zn2+. Inhibition of cysteine proteases can improve COVID-19 outcomes and non-infectious inflammation. Metformin reportedly enhances the natural moderating effect of Zn2+ on bioassayed proteome degradation. Firstly, the dissociable metformin-Zn2+ complex could be actively transported by intestinal cation transporters; thereby creating artificial pathways of absorption and increased body Zn2+ content. Secondly, metformin Zn2+ coordination can create a non-natural protease inhibitor independent of cell Zn2+ content. Moderation of peptidolytic reactions by either or both mechanisms could slow (a) viral multiplication (b) viral invasion and (c) the pathogenic host inflammatory response. These combined actions could allow development of acquired immunity to clear the infection before life-threatening inflammation. Nirmatrelvir (Paxlovid®) opposes COVID-19 by selective inhibition the viral main protease by a Zn2+-independent mechanism. Pending safety evaluation, predictable synergistic benefits of metformin and Zn2+, and perhaps metformin/Zn2+/Paxlovid® co-administration should be investigated.