Antioxidant Activity of Ruthenium Cyclopentadienyl Complexes Bearing Succinimidato and Phthalimidato Ligands

Ligand-Based Radical Reactivity of Metal Thiosemicarbazones Prompts the Identification of Platinum(II)-Based Cytoprotectants

CuATSM, a copper(II) complex of a bis(thiosemicarbazone) of diacetyl, prevents oxidative cell death and acts as a neuroprotectant in vivo, prompting its evaluation to treat amyotrophic lateral sclerosis and other neurodegenerative conditions in the clinic. We recently demonstrated that CuATSM functions as a potent radical-trapping antioxidant (RTA), inhibiting lipid peroxidation and associated ferroptotic cell death by a noncanonical mechanism based on radical addition to the ligand backbone. Herein we report our investigations of the generality of this reactivity, which include studies of corresponding complexes of various other metals, including Co, Ru, Ni, Pd, Pt, and Au. Inhibited autoxidations of styrene and dioxane reveal that most of these complexes exhibit RTA activity, consistent with ligand-based reactivity, but the identity of the metal atom nevertheless plays a role. In particular, analyses of the electronic structures of the complexes of metals within the same group (i.e., the group 10 metals Ni, Pd and Pt) highlight how the metal atom can modulate the ligand-based reactivity by enabling spin delocalization to the other thiosemicarbazone moiety. The RTA activity determined in organic solution largely translates to phospholipid bilayers and mammalian cells, where most complexes inhibited lipid peroxidation and associated ferroptotic cell death. A preliminary structure-activity study revealed Pt complexes with potencies eclipsing those of archetype ferroptosis inhibitors ferrostatin-1 and liproxstatin-1, suggesting that Pt (and to a lesser extent Ni) bis(thiosemicarbazone)s may be better suited to optimization for therapeutic development than those based on Cu.

Carbon monoxide refines ovarian structure changes and attenuates oxidative stress via modulating of heme oxygenase system in a rat model of polycystic ovary syndrome: An experimental study

Background

Carbon monoxide (CO), influences ovarian function, pregnancy, and placental health. Heme oxygenase (HO)-1 and its products, including CO, exhibit protective and anti-inflammatory properties.

Objective

This study investigates the protective effects of CO released by the carbon dioxide-releasing molecule (CORM)-2 against oxidative stress, functional and structural changes of the ovaries, and HO-1 expressions in female rats suffering from polycystic ovary syndrome (PCOS).

Materials and Methods

In this experimental study, 24 Rattus norvegicus var. Albinus female rats (180-200 gr, 8 wk) were randomly divided into 4 groups (n = 6/each): control, CORM-2 (10 mg/kg), PCOS (induced by 4 mg/kg, intramuscular injection and a single dose of estradiol valerate), PCOS + CORM-2. Ovary histological changes were evaluated by crystal violet staining. Malondialdehyde (MDA) level and superoxide dismutase (SOD) activity of ovarian tissue were assessed using enzyme-linked immunosorbent assay. HO-1 expression was evaluated using Western blot.

Results

Corpus luteal formation significantly decreased in the PCOS group and was significantly restored with CORM-2 administration compared to the control group (p < 0.05). The expression of ovarian HO-1 protein was reduced in the PCOS group compared to controls (p < 0.01), and administration of CORM in PCOS rats significantly increased its expression (p < 0.0001). In addition, CORM administration markedly reduced ovarian MDA levels and restored SOD activity (p < 0.0001).

Conclusion

CORM-2 administration to PCOS rats created protective effects by reducing oxidative stress (reducing MDA level and restoring SOD activity) and increasing ovarian HO-1 protein.

Complexes of Ruthenium(II) as Promising Dual-Active Agents against Cancer and Viral Infections

Poor responses to medical care and the failure of pharmacological treatment for many high-frequency diseases, such as cancer and viral infections, have been widely documented. In this context, numerous metal-based substances, including cisplatin, auranofin, various gold metallodrugs, and ruthenium complexes, are under study as possible anticancer and antiviral agents. The two Ru(III) and Ru(II) complexes, namely, BOLD-100 and RAPTA-C, are presently being studied in a clinical trial and preclinical studies evaluation, respectively, as anticancer agents. Interestingly, BOLD-100 has also recently demonstrated antiviral activity against SARS-CoV-2, which is the virus responsible for the COVID-19 pandemic. Over the last years, much effort has been dedicated to discovering new dual anticancer-antiviral agents. Ru-based complexes could be very suitable in this respect. Thus, this review focuses on the most recent studies regarding newly synthesized Ru(II) complexes for use as anticancer and/or antiviral agents.