SARS-CoV-2 pandemic is having devastating consequences worldwide. Although vaccination advances at good pace, effectiveness against emerging variants is unpredictable. The virus has displayed a remarkable resistance to treatments and no drugs have been proved fully effective against COVID-19. Thus, despite the international efforts, there is still an urgent need for new potent and safe antivirals against SARS-CoV-2. Here, we exploited the enormous potential of plant metabolism using the bryophyte Marchantia polymorpha L. and identified a potent SARS-CoV-2 antiviral, following a bioactivity-guided fractionation and mass-spectrometry approach. We found that the chlorophyll derivative Pheophorbide a (PheoA), a porphyrin compound similar to animal Protoporphyrin IX, has an extraordinary antiviral activity against SARS-CoV-2, preventing infection of cultured monkey and human cells, without noticeable cytotoxicity. We also show that PheoA targets the viral particle, interfering with its infectivity in a dose- and time-dependent manner. Besides SARS-CoV-2, PheoA also displayed a broad-spectrum antiviral activity against enveloped RNA viral pathogens such as HCV, West Nile, and other coronaviruses. Our results indicate that PheoA displays a remarkable potency and a satisfactory therapeutic index, which together with its previous use in photoactivable cancer therapy in humans, suggest that it may be considered as a potential candidate for antiviral therapy against SARS-CoV-2.

Titanium complexes with two dioxo bridges between the Cp and the metal can be synthesized by the reaction of [Ti{η 5 -C 5 H 3 -1,3-(SiMe 2 Cl) 2 }Cl 3 ] with different diols. Some of these complexes present a dynamic inversion process affording two diastereomers, A and B, which have been studied by X-ray diffraction and NMR techniques. The X-ray diffraction studies of [Ti{η 5 -C 5 H 3 -1,3-[SiMe 2 (κ 1 -1,2-O 2 C 6 H 4 )] 2 }X] X= Cl (2A), Me (4A), and Bn (5) complexes permit their absolute configuration to be assigned, and an epimerization mechanism has been supported by experimental evidence. Moreover, averaged activation energies (ΔH ⧧ , ΔG ⧧ ) and entropies (ΔS ⧧ ) for both the forward and reverse reactions were calculated from the Eyring−Polanyi equation from the NMR EXSY experiments; these are in agreement with the experimental evidence. Article pubs.acs.org/Organometallics

The new 1,3-disiloxo-bridged dichloro zirconocene [{(η5-C5H3)2-μ,μ-1,3-(Me2SiOSiMe2)2}- ZrCl2] (2) has been synthesized and fully characterized. Complex 2, combined with MAO, polymerizes propene and 1-hexene with high 1,2-regioselectivity, yielding oligomers containing vinylidene end groups produced via a β-hydrogen elimination reaction

Cationic 1,2 and 1,3 doubly constrained geometry di(silylamido)cyclopentadienyl zirconium complexes, whilst being group 4 alkyl‐free 14‐electron d0 species, promote the polymerization of MMA. Different cocatalysts such as B(C6F5)3, Al(C6F5)3 and [CPh3][B(C6F5)4] have been employed to generate the catalytic species in order to collect experimental evidence to propose the polymerization mechanism that these cationic compounds may follow. By systematically studying the role of the active species, this study establishes that the mechanism may be different from the traditional coordination‐addition mechanism proposed for group 4 metal complexes in MMA polymerizations.

The threat of antimicrobial-resistant bacteria is ever increasing and over the past-decades development of novel therapeutic counter measurements have virtually come to a halt. This circumstance calls for interdisciplinary approaches to design, evaluate and validate the mode of action of novel antibacterial compounds. Hereby, carbosilane dendritic systems that exhibit antimicrobial properties have the potential to serve as synthetic and rationally designed molecules for therapeutic use. The bow-tie type topology of BDTL049 was recently investigated against the Gram-positive model organism Bacillus subtilis, revealing strong bactericidal properties. In this study, we follow up on open questions concerning the usability of BDTL049. For this, we synthesized a fluorescent-labeled version of BDTL049 that maintained all antimicrobial features to unravel the interaction of the compound and bacterial membrane. Subsequently, we highlight the bacterial sensitivity against BDTL049 by performing a mutational study of known resistance determinants. Finally, we address the cytotoxicity of the compound in human cells, unexpectedly revealing a high sensitivity of the eukaryotic cells upon BDTL049 exposure. The insights presented here further elaborate on the unique features of BDTL049 as a promising candidate as an antimicrobial agent while not precluding that further rounds of rational designing are needed to decrease cytotoxicity to ultimately pave the way for synthetic antibiotics toward clinical applicability.