# Tris[N-(prop-2-en-1-yl)hydrazinecarbothioamide]-Cobalt(III) Chloride as a Stimulator of the Total Antioxidant Status of Apis mellifera with Acaricidal Activity

## TL;DR

A new cobalt complex boosts honeybee antioxidant levels and kills mites, offering a potential tool for improving bee health.

## Contribution

A novel cobalt(III) complex is shown to enhance antioxidant status in honeybees and act as an acaricide.

## Key findings

- The cobalt complex significantly increased total antioxidant status in honeybee hemolymph and larvae.
- The compound exhibited acaricidal activity against Varroa destructor with an LC50 of 0.2 µmol/L.
- The complex's antioxidant effect was five times stronger than vitamin C in tested conditions.

## Abstract

This study investigates the synthesis and potential applications of the coordination compound cobalt(III) complex tris[N-(prop-2-en-1-yl)hydrazinecarbothioamide]-cobalt(III) chloride ([Co(Tsc)3]Cl3). The complex has been synthesized via the reaction of cobalt(II) chloride hexahydrate with N-(prop-2-en-1-yl)hydrazinecarbothioamide in ethanol. Its antioxidant activity has been evaluated using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, demonstrating a significant effect with an IC50 of 7.3 µmol/L. Toxicity evaluations using Daphnia magna showed a low half maximal inhibitory concentration (LC50) of 56.3 µmol/L. Experimental results have showed that [Co(Tsc)3]Cl3 significantly elevated the total antioxidant status (TAS) of the hemolymph of honeybees and larvae, increasing it by 5 and 8 times, respectively. The IC50 values for antioxidant activity were 2.5 mg/mL in bee hemolymph and 1.3 mg/mL in larval hemolymph, notably lower than control values of 13.6 mg/mL and 10.0 mg/mL. The stimulatory effect of the coordination compound [Co(Tsc)3]Cl3 on TAS was five times higher than that of vitamin C. Additionally, [Co(Tsc)3]Cl3 exhibited acaricidal properties, effectively inhibiting Varroa destructor with an lethal concentration (LC50) of 0.2 µmol/L. These findings indicate that this cobalt complex could serve both a natural antioxidant and an effective acaricide, offering a promising approach to improv bee health and sustainability in apiculture.