Induction of energy metabolism related enzymes in yeast Saccharomyces cerevisiae exposed to ibogaine is adaptation to acute decrease in ATP energy pool

Ibogaine Induces Cardiotoxic Necrosis in Rats-The Role of Redox Processes

Ibogaine is an organic indole alkaloid that is used in alternative medicine to combat addiction. Numerous cases of life-threatening complications and sudden deaths associated with ibogaine use have been reported, and it has been hypothesized that the adverse effects are related to ibogaine's tendency to induce cardiac arrhythmias. Considering that the bioavailability of ibogaine and its primary metabolite noribogaine is two to three times higher in female rats than in male rats, we here investigated the effect of a single oral dose (1 or 20 mg/kg) of ibogaine on cardiac histopathology and oxidative/antioxidant balance. Our results show that ibogaine induced dose-dependent cardiotoxic necrosis 6 and 24 h after treatment and that this necrosis was not a consequence of inflammation. In addition, no consistent dose- and time-dependent changes in antioxidant defense or indicators of oxidative damage were observed. The results of this study may contribute to a better understanding of ibogaine-induced cardiotoxicity, which is one of the main side effects of ibogaine use in humans and is often fatal. Nevertheless, based on this experiment, it is not possible to draw a definitive conclusion regarding the role of redox processes or oxidative stress in the occurrence of cardiotoxic necrosis after ibogaine administration.

Ibogaine Has Sex-Specific Plasma Bioavailability, Histopathological and Redox/Antioxidant Effects in Rat Liver and Kidneys: A Study on Females

Ibogaine induces rapid changes in cellular energetics followed by the elevation of antioxidant activities. As shown earlier in male rats, ibogaine treatment with both 1 and 20 mg/kg b.w. per os led to significant glycogenolytic activity in the liver. In this work, female rats treated with the same doses of ibogaine per os displayed lower liver glycogenolytic activity relative to males, dilatation of the central vein and branches of the portal vein, and increased concentration of thiols 6 h after treatment. These changes were followed by increased catalase activity and lipid peroxidation, and decreased xanthine oxidase activity after 24 h. In kidneys, mild histopathological changes were found in all treated animals, accompanied by a decrease of glutathione reductase (after 6 and 24 h at both doses) and an increase of catalase (6 h) and xanthine oxidase activity (6 and 24 h). Ibogaine did not affect antioxidant enzymes activity in erythrocytes. Bioavailability of ibogaine was two to three times higher in females than males, with similar kinetic profiles. Compared to previous results in males, ibogaine showed sex specific effect at the level of antioxidant cellular system. Effects of ibogaine in rats are sex- and tissue-specific, and also dose- and time-dependent.

Ibogaine-Mediated ROS/Antioxidant Elevation in Isolated Rat Uterus Is β-Adrenergic Receptors and KATP Channels Mediated

Ibogaine effects are mediated by cellular receptors, ATP depletion followed by ROS production and antioxidant enzyme activity elevation in a dose and time dependent manner. Since the role of K_ATP channels and β-adrenoceptors in ROS cellular circuit was established here we explored their role in ibogaine pro-antioxidant effectiveness. Single dose of ibogaine (10 mg/L i.e., 28.8 μmol/L) was applied to isolated rat uterus (spontaneous and Ca²⁺-stimulated) and contractility and antioxidant enzymes activity were monitored during 4 h. Ibogaine increased amplitude and frequency of spontaneous active uteri immediately after addition that was prevented by propranolol (β₁ and β₂ adrenoceptors selective antagonists) and glibenclamide (K_ATP sensitive channels inhibitor; only frequency) pre-treatment. In Ca²⁺-stimulated uteri, ibogaine decreased both amplitude and frequency after 4 h. Pre-treatment with propranolol abolished ibogaine induced amplitude lowering, while glibenclamide had no effect. In both types of active uterus, ibogaine induced a decrease in SOD1 and an increase in CAT activity after 2 h. In Ca²⁺-stimulated uterus, there was also a decrease of SOD2 activity after 2 h. After 4 h, SOD1 activity returned to the baseline level, but GSH-Px activity increased. Pre-treatment with both propranolol and glibenclamide abolished observed changes of antioxidant enzymes activity suggesting that ibogaine pro-antioxidative effectiveness is β-adrenergic receptors and K_ATP channels mediated.

The Effects of Ibogaine on Uterine Smooth Muscle Contractions: Relation to the Activity of Antioxidant Enzymes

Ibogaine is an indole alkaloid originally extracted from the root bark of the African rainforest shrub Tabernanthe iboga. It has been explored as a treatment for substance abuse because it interrupts drug addiction and relieves withdrawal symptoms. However, it has been shown that ibogaine treatment leads to a sharp and transient fall in cellular ATP level followed by an increase of cellular respiration and ROS production. Since contractile tissues are sensitive to changes in the levels of ATP and ROS, here we investigated an ibogaine-mediated link between altered redox homeostasis and uterine contractile activity. We found that low concentrations of ibogaine stimulated contractile activity in spontaneously active uteri, but incremental increase of doses inhibited it. Inhibitory concentrations of ibogaine led to decreased SOD1 and elevated GSH-Px activity, but doses that completely inhibited contractions increased CAT activity. Western blot analyses showed that changes in enzyme activities were not due to elevated enzyme protein concentrations but posttranslational modifications. Changes in antioxidant enzyme activities point to a vast concentration-dependent increase in H₂O₂ level. Knowing that extracellular ATP stimulates isolated uterus contractility, while H₂O₂ has an inhibitory effect, this concentration-dependent stimulation/inhibition could be linked to ibogaine-related alterations in ATP level and redox homeostasis.

The Iboga Alkaloids

Iboga alkaloids are a particular class of indolomonoterpenes most often characterized by an isoquinuclidine nucleus. Their first occurrence was detected in the roots of Tabernanthe iboga, a sacred plant to the people of Gabon, which made it cult object. Ibogaine is the main representative of this class of alkaloids and its psychoactive properties are well documented. It has been proposed as a drug cessation treatment and has a wide range of activities in targeting opioids, cocaine, and alcohol. The purpose of this chapter is to provide a background on this molecule and related compounds and to update knowledge on the most recent advances made. Difficulties linked to the status of ibogaine as a drug in several countries have hampered its development, but 18-methoxycoronaridine is currently under evaluation for the same purposes and for the treatment of leishmaniasis. The chapter is divided into six parts: an introduction aiming at defining what is called an iboga alkaloid, and this is followed by current knowledge on their biosynthesis, which unfortunately remains a "black box" as far as the key construction step is concerned. Many of these alkaloids are still being discovered and the third and fourth parts of the chapter discuss the analytical tools in use for this purpose and give lists of new monomeric and dimeric alkaloids belonging to this class. When necessary, the structures are discussed especially with regard to absolute configuration determinations, which remain a point of weakness in their assignments. Part V gives an account of progress made in the synthesis, partial and total, which the authors believe is key to providing solid solutions to the industrial development of the most promising molecules. The last part of the chapter is devoted to the biological properties of iboga alkaloids, with particular emphasis on ibogaine and 18-methoxycoronaridine.

A capillary zone electrophoresis method for adenine nucleotides analysis in Saccharomyces cerevisiae

Adenosine triphosphate and its metabolites are involved in the cellular metabolism process in Saccharomyces cerevisiae. It is very important to simultaneously determine the relative contents of ATP and its metabolites in yeast. In this study, an effective capillary zone electrophoresis method with high selectivity was established. The calibration curves were linear in the concentration range from 1 to 20mg/L (ATP and cAMP) and 2 to 40mg/L (ADP and AMP) with excellent correlation coefficients (r(2))>0.999. The recovery of ATP, ADP, AMP, and cAMP were 99.4%, 94.7%, 100.3% and 99.6%, respectively. Simple sample preparation and easy detection of ATP and its metabolites make this method suitable for the study of changes in the four adenine nucleotides levels caused by caloric restriction in yeast. It is expected that the current method may contribute to further energy metabolism and related investigations of yeast.

Ex vivo effects of ibogaine on the activity of antioxidative enzymes in human erythrocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Ibogaine is a naturally occurring alkaloid with psychotropic and metabotropic effects, derived from the bark of the root of the West African Tabernanthe iboga plant. The tribes of Kongo basin have been using iboga as a stimulant, for medicinal purposes, and in rite of passage ceremonies, for centuries. Besides, it has been found that this drug has anti-addictive effects.

AIM OF THE STUDY

Previous studies have demonstrated that ibogaine changed the quantity of ATP and energy related enzymes as well as the activity of antioxidant enzymes in cells thus altering redox equilibrium in a time manner. In this work, the mechanism of its action was further studied by measuring the effects of ibogaine in human erythrocytes in vitro on ATP liberation, membrane fluidity and antioxidant enzymes activity.

MATERIALS AND METHODS

Heparinized human blood samples were incubated with ibogaine (10 and 20 μM) at 37°C for 1h. Blood plasma was separated by centrifugation and the levels of ATP and uric acid were measured 10 min after the addition of ibogaine using standard kits. The activity of copper-zinc superoxide dismutase (SOD1), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were measured in erythrocytes after incubation period. The stability of SOD1 activity was further tested through in vitro incubation with H2O2 and scanning of its electrophoretic profiles. Membrane fluidity was determined using an electron paramagnetic resonance spin-labelling method.

RESULTS

Results showed that ibogaine treatment of erythrocytes in vitro increased ATP concentration in the blood plasma without changes in neither erythrocytes membrane fluidity nor uric acid concentration. Ibogaine also increased SOD1 activity in erythrocytes at both doses applied here. Treatment with 20 μM also elevated GR activity after in vitro incubation at 37°C. Electrophoretic profiles revealed that incubation with ibogaine mitigates H2O2 mediated suppression of SOD1 activity.

CONCLUSION

Some of the effects of ibogaine seem to be mediated through its influence on energy metabolism, redox active processes and the effects of discrete fluctuations of individual reactive oxygen species on different levels of enzyme activities. Overall, ibogaine acts as a pro-antioxidant by increasing activity of antioxidative enzymes and as an adaptagene in oxidative distress.