Effect of Alpha-Ketoglutarate on Neurobehavioral, Neurochemical and Oxidative Changes Caused by Sub-Chronic Cyanide Poisoning in Rats

Neuroprotective flavonoids of the leaf of Antiaris africana Englea against cyanide toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Different parts of Antiaris africana Englea (Moraceae) are used traditionally for the treatment of various diseases, including epilepsy and other nervous system disorders.

AIMS OF THIS STUDY

The current study was designed to evaluate the neuroprotective activity of flavonoids isolated from A. africana against potassium cyanide (KCN)-induced oxidative damage in brain homogenate.

MATERIALS AND METHODS

Dried and ground leaves of A. africana were extracted with methanol and fractioned into n-hexane (HFA), dichloromethane (DFA), ethyl acetate (EFA) and methanol (MFA). Each fraction was assessed for neuroprotective potential by anticholinesterase activity test. The fraction with the best anticholinesterase activity was subjected to various chromatographic techniques through bioassay-guided fractionation to isolate the bioactive compounds. The protective ability of the extract, fractions and compounds against Potassium cyanide (KCN)-induced mitochondrial damage in rat brain homogenate was evaluated. Structures of the isolated compounds were determined using 1D and 2D NMR, mass spectrometry and by comparison with literature data.

RESULTS AND DISCUSSION

The ethyl acetate fraction showed the best anticholinesterase activity with an IC₅₀ of 23.23 ± 1.12 μg/ml. Quercetin and a biflavonoid glucoside identified as 3'-4'-bisquercetin-3β-D-diglucoside from this fraction displayed a remarkable antioxidant activity in the DPPH assay and showed significant (P < 0.05) increase in the activity of dehydrogenase inhibited by KCN in a concentration dependent manner. However, quercetin was more effective in reducing the MDA level and acetylcholinesterase activity that were elevated by KCN.

CONCLUSION

Quercetin and the bisquercetin-diglucoside isolated from the leaves of A. Africana for the first time, are major contributors to the observed neuroprotective property of the plant which supports its folkloric usage in the management of seizures, epilepsy and other neurological disorders.

Efficacy assessment of co-treated alpha-ketoglutarate and N-acetyl cysteine against the subchronic toxicity of cyanide in rats

Cyanide is an important industrial pollutant, major occupational hazard, and a potential chemical warfare agent. Its intentional or accidental exposure to humans is a big clinical problem because of its rapid mode of action. Certain plant origin foods also contain substantial amount of cyanide and cause chronic toxicity. This study explores the protective efficacy of co-treatment of alpha-ketoglutarate (AKG) and an antioxidant N-acetyl cysteine (NAC) against toxicity of subchronically exposed cyanide in rats. We explore the effect of AKG + NAC co-treatment on oxidative stress, inflammation, and histological changes induced due to long-term sublethal cyanide exposure. Cyanide induces oxidative stress by inhibiting metalloenzymes (catalase and superoxide dismutase) causing increase in lipid peroxidation (malondialdehyde) and decrease in reduced glutathione (GSH). It also increases the activity of cyclo-oxygenase enzymes causing oxidative stress-mediated inflammation in the brain. Cyanide exposure also causes degenerative changes in the brain as shown in histology. It also causes pathology in liver and kidney. AKG is known to form cyanohydrins with cyanide reducing the free cyanide levels, and its combination with NAC showed overall improvement in by reducing the oxidative stress and subsequent neuroinflammation. Their combination was also found to improve the histological outcome of vital tissues. AKG, an over-the-counter sport medicine, and the antioxidant NAC per se did not show any detrimental effects in any tested parameter. Hence, oral treatment with AKG and NAC can be beneficial for the treatment of chronic cyanide poisoning.

Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels

In 2016, the EFSA Panel on Contaminants in the Food Chain (CONTAM) published a scientific opinion on the acute health risks related to the presence of cyanogenic glycosides (CNGs) in raw apricot kernels in which an acute reference dose (ARfD) of 20 μg/kg body weight (bw) was established for cyanide (CN). In the present opinion, the CONTAM Panel concluded that this ARfD is applicable for acute effects of CN regardless the dietary source. To account for differences in cyanide bioavailability after ingestion of certain food items, specific factors were used. Estimated mean acute dietary exposures to cyanide from foods containing CNGs did not exceed the ARfD in any age group. At the 95th percentile, the ARfD was exceeded up to about 2.5-fold in some surveys for children and adolescent age groups. The main contributors to exposures were biscuits, juice or nectar and pastries and cakes that could potentially contain CNGs. Taking into account the conservatism in the exposure assessment and in derivation of the ARfD, it is unlikely that this estimated exceedance would result in adverse effects. The limited data from animal and human studies do not allow the derivation of a chronic health-based guidance value (HBGV) for cyanide, and thus, chronic risks could not be assessed.

In vivo studies on hepato-renal impairments in freshwater fish Cyprinus carpio following exposure to sublethal concentrations of sodium cyanide

Reactive oxygen species is an inevitable composite of aerobic systems that could channelize their lethality by imparting oxidative stress under a stressful environment. Cyanide is an important environmental toxicant that could be responsible in the resulting detrimental health issues of aquatic fauna. The present effort investigates the possibilities of hepato-renal damage in freshwater fish Cyprinus carpio following exposure to sublethal concentrations of sodium cyanide (NaCN). Fish were exposed to 0.1 mg/L of NaCN for 10 days (E1) and 20 days (E2) and were further subjected to recovery for 14 days (R) in NaCN-free medium. Liver tissue exhibited a significant decline in activity of catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferase enzymes in exposed fish, unlike in control (C). Subsequent levels of lipid peroxidation elevation at 'E1' and 'E2' suggested oxidative damage to hepatocytes. This was further confirmed through a histopathological evaluation which indicated important findings like lymphocytic infiltration and necrosis in liver and tubular and glomerular degeneration in renal organ. The investigation suggests biochemical and histopathological alterations in fish following exposure to NaCN. Nevertheless, fish upon the recovery period were known to exhibit incomplete recuperation which was indicated by partial restoration tendencies under biochemical and histopathological factions. The study clearly implicated the role of NaCN in emphasizing its toxicity to C. carpio, further suggesting lack of recovery transition at a limited tenure of 14 days. The study might contribute in the course of regulatory surveillance and monitoring of aquatic bodies and may also reflect the possibilities of NaCN contamination during aquaculture practices. Graphical Abstract ᅟ.

Fourier transform infrared (FT-IR) study on cyanide induced biochemical and structural changes in rat sperm

In the recent years, great attention had been focused on cyanide toxicity because of its widespread use in industries and considered to be a ubiquitous pollutant in the environment. Therefore, the current study aimed to evaluate the toxic effect of cyanide on rat sperms at molecular level by using FT-IR technique. For this purpose, rats were randomly divided into four groups and treated with 0.0, 0.64, 1.2 and 3.2 mg kg^-1 body weight (BW) for the period of 90 days. The group treated with lower dose (0.64 mg kg^-1 BW) showed an insignificant change in all the peaks, except the peaks assigned to olefinic 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C-H, CH₂ asymmetric and CH₂ symmetric stretching vibration in the lipids. While, the groups treated with higher doses (1.2 and 3.2 mg kg^-1 BW) showed the significant decrease in the area under the peaks corresponds to different bio-molecules. In addition, spectral second derivative analysis showed the significant alteration in α-helix, turns, β-sheet, aggregated β-sheet and random coil structures in the proteins. In conclusion, the selected higher dosage of cyanide had caused significant decrease in the biochemical composition of rat sperms along with structural changes in the proteins. The FT-IR technique is an excellent tool used for the analysis of oxidative damage in the sperms.

Alpha-ketoglutarate attenuates toxic effects of sodium nitroprusside and hydrogen peroxide in Drosophila melanogaster

The protective effects of dietary alpha-ketoglutarate (AKG) are described that aid fruit flies, Drosophila melanogaster, to resist sodium nitroprusside (SNP) and hydrogen peroxide toxicity. Food supplementation with 10mM AKG alleviated toxic effects of 1mM SNP added to food and improved fly development. Dietary AKG also prevented the increase in levels of oxidative stress markers seen in SNP-reared adult flies. In vitro AKG did not affect the rate of SNP decomposition and did not bind iron and nitrite ions released in this process. Alpha-ketoglutarate also displayed high H2O2-scavenging activity in vitro and efficiently protected adult flies against this compound in combined treatments. Based on the observed antioxidant activity of AKG, it may be suggested that the antioxidant mode of AKG action (apart from its cyanide-binding capability) may be used to prevent the toxic effects of SNP and improve general physiological state of D. melanogaster and other animals and humans.

Subchronic cyanide toxicity on male reproductive system of albino rat

Sexually mature albino rats were orally treated with sodium cyanide, NaCN (0, 0.64, 1.2 and 3.2 mg kg⁻¹BW) for 90 days.