Development of rhenacarborane complexes as central nervous system (CNS) drug delivery agents

Anticancer and Antibiotic Rhenium Tri- and Dicarbonyl Complexes: Current Research and Future Perspectives

Organometallic compounds are increasingly recognized as promising anticancer and antibiotic drug candidates. Among the transition metal ions investigated for these purposes, rhenium occupies a special role. Its tri- and dicarbonyl complexes, in particular, attract continuous attention due to their relative ease of preparation, stability and unique photophysical and luminescent properties that allow the combination of diagnostic and therapeutic purposes, thereby permitting, e.g., molecules to be tracked within cells. In this review, we discuss the anticancer and antibiotic properties of rhenium tri- and dicarbonyl complexes described in the last seven years, mainly in terms of their structural variations and in vitro efficacy. Given the abundant literature available, the focus is initially directed on tricarbonyl complexes of rhenium. Dicarbonyl species of the metal ion, which are slowly gaining momentum, are discussed in the second part in terms of future perspective for the possible developments in the field.

Neuroprotective effects of icariin in neonatal hypoxia-ischemic brain damage via its anti-apoptotic property

INTRODUCTION

Neonatal hypoxic-ischemic brain damage (HIBD) is a brain disease that is caused by perinatal asphyxia. Icariin (ICA), which is an active component of Epimedii (a Chinese medicinal herb), has been verified to demonstrate a wide range of therapeutic effects, such as alleviating various kinds of brain injury.

OBJECTIVE

The current study aims to examine the neuroprotective effects of ICA on neonatal HIBD in mice.

MATERIALS AND METHODS

A modified version of the Rice-Vannucci method was performed to establish neonatal HIBD in 7-day-old mouse pups that were pretreated with ICA or vehicle. The infarct volume was measured, and behavioral tests were conducted to assess the protective effects of ICA on the neonatal brain and to evaluate functional recovery after injury. TUNEL staining was used to detect cell apoptosis, and the levels of cleaved caspase-3 and phosphorylated protein kinase B (Akt) were determined by using Western blot.

RESULTS

We showed that pretreatment with ICA could significantly reduce brain damage, improve neurobehavioral outcomes, and suppress apoptotic cell death following HI injury. ICA reversed the HI-induced reduction in phosphorylated Akt and activation of cleaved caspase-3.

CONCLUSION

The results demonstrate that ICA exerts potential neuroprotective effects on neonatal HIBD, which may be mediated by its anti-apoptotic activity.

Recent Advances in Synthetic Methods for Radioiodination

Organic compounds bearing radioisotopes of iodine are widely used for biological research, diagnostic imaging, and radiotherapy. Early reported synthetic methods for the incorporation of radioiodine have generally involved high temperature reactions or strongly oxidizing conditions. To overcome these limitations and to cope with the demand for novel radioiodinated probes, there has been a surge in the development of new synthetic methodology for radioiodination. This synopsis describes the key transformations developed recently.

2,2'-Bipyridine-Modified Tamoxifen: A Versatile Vector for Molybdacarboranes

Investigations on the antitumor activity of metallacarboranes are sparse in the literature and limited to a handful of ruthena- and molybdacarboranes. In this study, the molybdacarborane fragment [3-(CO)2 -closo-3,1,2-MoC2 B9 H11 ] was combined with a vector molecule, inspired by the well-known drug tamoxifen or 4,4'-dihydroxytamoxifen (TAM-diOH). The molybdacarborane derivative [3,3-{4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2'-bipyridine-κ2 N,N'}-3-(CO)2 -closo-3,1,2-MoC2 B9 H11 ] (10), as well as the ligand itself 4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2'-bipyridine (6) showed cytotoxic activities in the low micromolar range against breast adenocarcinoma (MDA-MB-231, MDA-MB-361 and MCF-7), human glioblastoma (LN-229) and human glioma (U-251) cell lines. In addition, compounds 6 and 10 were found to induce senescence and cytodestructive autophagy, lower ROS/RNS levels, but only the molybdacarborane 10 induced a strong increase of nitric oxide (NO) concentration in the MCF-7 cells.

Quinoline-Conjugated Ruthenacarboranes: Toward Hybrid Drugs with a Dual Mode of Action

The role of autophagy in cancer is often complex, ranging from tumor-promoting to -suppressing effects. In this study, two novel hybrid molecules were designed, containing a ruthenacarborane fragment conjugated with a known modulator of autophagy, namely a quinoline derivative. The complex closo-[3-(η6 -p-cymene)-1-(quinolin-8-yl-acetate)-3,1,2-RuC2 B9 H10 ] (4) showed a dual mode of action against the LN229 (human glioblastoma) cell line, where it inhibited tumor-promoting autophagy, and strongly inhibited cell proliferation, de facto blocking cellular division. These results, together with the tendency to spontaneously form nanoparticles in aqueous solution, make complex 4 a very promising drug candidate for further studies in vivo, for the treatment of autophagy-prone glioblastomas.

Pretreatment of Grape Seed Proanthocyanidin Extract Exerts Neuroprotective Effect in Murine Model of Neonatal Hypoxic-ischemic Brain Injury by Its Antiapoptotic Property

Grape seed proanthocyanidin extract (GSPE), an active component extracted from the grape, has been reported to demonstrate antioxidant, anti-inflammatory, anticancer, and antiapoptosis effects. However, little is known about the role of GSPE on neonatal hypoxic-ischemic (HI) brain injury. The aim of this study was to evaluate the neuroprotective effect of GSPE pretreatment on neonatal HI brain injury in mice. A modified Rice-Vannucci method was performed to induce neonatal HI brain injury in the 7-day-old mouse pups pretreated with GSPE or vehicle. The infarct volumes were determined by TTC staining. TUNEL staining was used to detect cells apoptosis, and the expressions of apoptosis-related proteins: bax, bcl2, and cleaved caspase-3 were assayed by Western blot. Behavioral tests were also conducted to assess the functional recovery after injury. We showed that the brain damage and neurobehavioral outcomes improvement was observed in GSPE pretreated group. GSPE was proved to suppress apoptosis through inhibition of bax and cleaved caspase-3 expression. It demonstrates that GSPE could alleviate brain damage maybe through its antiapoptotic activity in a neonatal HI brain injury model, and GSPE has the potential to be a new drug for effective prevention of this disorder.