In-vivo evaluation of the response of Galleria mellonella larvae to novel copper(II) phenanthroline-phenazine complexes

Abstract

Herein we report the in-vivo characterisation and metabolic changes in Galleria mellonella larvae to a series of bis-chelate copper(II) phenanthroline-phenazine cationic complexes of [Cu(phen)] (Cu-Phen), [Cu(DPQ)(Phen)] (Cu-DPQ-Phen) and [Cu(DPPZ)(Phen)] (Cu-DPPZ-Phen) (where phen = 1,10-phenanthroline, DPQ = dipyrido[3,2-ƒ:2',3'-h]quinoxaline and DPPZ = dipyrido[3,2-a:2',3'-c]phenazine). Our aim was to investigate the influence of the systematic extension of the ligated phenazine ligand in the G. mellonella model as a first step towards assessing the in-vivo tolerance and mode of action of the complex series with respect to the well-studied oxidative chemical nuclease, Cu-Phen. The Lethal Dose (LD) values were established over dose ranges of 2 - 30 μg at 4-, 24-, 48- and 72 h by mortality assessment, with Cu-Phen eliciting the highest mortality at 4 h (Cu-Phen, 12.62 μg < Cu-DPQ-Phen, 21.53 μg < Cu-DPPZ-Phen, 26.07 μg). At other timepoints, a similar profile was observed as the phenazine π-backbone within the complex scaffold was extended. Assessment of both cellular response and related gene expression demonstrated that the complexes did not initiate an immune response. However, Label-Free Quantification proteomic data indicated the larval response was associated with upregulation of key proteins such as Glutathione S-transferase, purine synthesis and glycolysis/gluconeogenesis (e.g. fructose-bisphosphate aldolase and glyceraldehyde-3-phosphate). Both Cu-Phen and Cu-DPQ-Phen elicited a similar in-vivo response in contrast to Cu-DPPZ-Phen, which displayed a substantial increase in nitrogen detoxification proteins and proteins with calcium binding sites. Overall, the response of G. mellonella larvae exposure to the complex series is dominated by detoxification and metabolic proteome response mechanisms.

Sublethal and intergenerational effects of fipronil on Binodoxys communis larvae based on transcriptome sequencing

“…In this study, we noted how these genes were increasingly up-regulated at higher fipronil concentrations, indicating that high-dose pesticide stress may demand parasitic wasp larvae a large amount of energy in order to reduce damage to development. Similarly to our findings, previous research has reported that sugar-related metabolic pathways in insects are up-regulated in the presence of insecticide stress (Rochford et al, 2018;Zhang et al, 2021). The neuroactive ligand-receptor interaction pathway transduces different signals such as biogenic amines, neuropeptides, and lipoproteins and regulates insect development and homeostasis (Kwon et al, 2016;Dong et al, 2021).…”

The Antibacterial and Anti-Biofilm Activity of Metal Complexes Incorporating 3,6,9-Trioxaundecanedioate and 1,10-Phenanthroline Ligands in Clinical Isolates of Pseudomonas aeruginosa from Irish Cystic Fibrosis Patients

“…Over the past two decades, transition metal complexes have had a revival of interest as possible alternatives or adjuvants to the current arsenal of antimicrobial agents, and in particular due to the rapid emergence of resistant microorganisms occurring worldwide [ 13 ]. Novel inorganic complexes with 1,10-phenanthroline (phen) ligands have demonstrated promising therapeutic capabilities with diverse biological activity, including anticancer [ 14 , 15 ], antifungal [ 16 , 17 ], antibacterial [ 18 , 19 ] and antiviral [ 20 ] capabilities. In a recent review, we have reported on the research that points to the potential of metal-phenanthroline complexes as alternative therapeutics in this era of antibiotic resistance [ 21 ].…”

In Vivo Activity of Metal Complexes Containing 1,10-Phenanthroline and 3,6,9-Trioxaundecanedioate Ligands against Pseudomonas aeruginosa Infection in Galleria mellonella Larvae

“…Similarly, complexes Mn-tdda-phen and Ag-tdda-phen induced no mortality at 15 µg/larvae (20.39 and 12.5 µM, respectively) while doubling the concentration (40.78 and 24.9 µM, respectively) resulted in 6.66 ± 5.77% death for the former and 23.33 ± 5.77% death for the latter, after exposure for 72 h. Cu-tdda-phen was the most toxic to the larvae, a concentration of 15 µg/larvae (20.15 µM) resulted in a mortality rate of 53.33 ± 5.77% after 72 h and increasing the dose to 30 µg/larvae (40.3 µM) saw complete death of all tested larvae after the same amount of time. It is well known that copper is highly toxic to mammals, and similar studies investigating Cu-phen complexes and their derivatives have also highlighted their lethality towards G. mellonella [ 28 , 35 ]. Although lower concentrations of Cu-tdda-phen did not induce mortality, moderate to severe melanization was observed.…”

“…They have a relatively short life cycle (40–60 days), and can survive at 37 °C which is an important attribute when assessing virulence and treatment of human pathogens [ 30 ]. Therefore, G. mellonella has been extensively utilized to evaluate the pathogenicity of bacterial and fungal pathogens [ 31 , 32 , 33 ], study biofilm formation [ 34 ], measure the in vivo toxicity of novel compounds [ 35 , 36 ], and determine the in vivo efficacy of established [ 37 , 38 ] and novel [ 19 , 39 ] antimicrobial agents. Moreover, studies assessing G. mellonella and mammalian models have reported a correlation in results obtained.…”