Toxicological evaluation of 5-methoxy-2-aminoindane (MEAI): Binge mitigating agent in development

5-Methoxy-2-aminoindane Reverses Diet-Induced Obesity and Improves Metabolic Parameters in Mice: A Potential New Class of Antiobesity Therapeutics

The escalating prevalence of obesity and its related disorders represents a daunting global health challenge. Unfortunately, current pharmacological interventions for obesity remain limited and are often associated with debilitating side effects. Against this backdrop, the psychoactive aminoindane derivative 5-methoxy-2-aminoindane (MEAI) has gained considerable attention for its ability to induce a pleasurable, alcohol-like sensation while curbing alcohol consumption. Given the potential impact of MEAI on food addiction and energy homeostasis, we examined its metabolic efficacy on appetite regulation, obesity, and related comorbidities under acute and chronic settings, utilizing a mouse model of diet-induced obesity (DIO). Our results demonstrated that MEAI treatment significantly reduced DIO-induced overweight and adiposity by preserving lean mass and decreasing fat mass. Additionally, MEAI treatment exhibited positive effects on glycemic control by attenuating DIO-induced hyperglycemia, glucose intolerance, and hyperinsulinemia. Furthermore, MEAI reduced DIO-induced hepatic steatosis by decreasing hepatic lipid accumulation and lowering liver triglyceride and cholesterol levels, primarily by inhibiting de novo lipid synthesis. Metabolic phenotyping revealed that MEAI increased energy expenditure and fat utilization while maintaining food consumption similar to that of the vehicle-treated group. Lastly, MEAI normalized voluntary locomotion actions without any overstimulatory effects. These findings provide compelling evidence for the antiobesity effects of MEAI treatment and call for further preclinical testing. In conclusion, our study highlights the potential of MEAI as a novel therapeutic approach for treating obesity and its associated metabolic disorders, offering hope for the development of new treatment options for this global health challenge.

The metabolic fate of two new psychoactive substances - 2-aminoindane and N-methyl-2-aminoindane - studied in vitro and in vivo to support drug testing

The aim of this study was to characterize the in vitro and in vivo metabolism of 2-aminoindane (2,3-dihydro-1H-inden-2-amine, 2-AI), and N-methyl-2-aminoindane (N-methyl-2,3-dihydro-1H-inden-2-amine, NM-2-AI) after incubations using pooled human liver microsomes (pHLMs), pooled human liver S9 fraction (pS9), and rat urine after oral administration. After analysis using liquid chromatography coupled to high-resolution mass spectrometry, pHLM incubations revealed that 2-AI was left unmetabolized, while NM-2-AI formed a hydroxylamine and diastereomers of a metabolite formed after hydroxylation in beta position. Incubations using pS9 led to the formation of an acetyl conjugation in the case of 2-AI and merely a hydroxylamine for NM-2-AI. Investigations on rat urine showed that 2-AI was hydroxylated also forming diasteromers as described for NM-2-AI or acetylated similar to incubations using pS9. All hydroxylated metabolites of NM-2-AI except the hydroxylamine were found in rat urine as additional sulfates. Assuming similar patterns in humans, urine screening procedures might be focused on the parent compounds but should also include their metabolites. An activity screening using human recombinant N-acetyl transferase (NAT) isoforms 1 and 2 revealed that 2-AI was acetylated exclusively by NAT2, which is polymorphically expressed.

2-Aminoindan and its ring-substituted derivatives interact with plasma membrane monoamine transporters and α2-adrenergic receptors

RATIONALE

Over the last decade, many new psychostimulant analogues have appeared on the recreational drug market and most are derivatives of amphetamine or cathinone. Another class of designer drugs is derived from the 2-aminoindan structural template. Several members of this class, including the parent compound 2-aminoindan (2-AI), have been sold as designer drugs. Another aminoindan derivative, 5-methoxy-2-aminoindan (5-MeO-AI or MEAI), is the active ingredient in a product marketed online as an alcohol substitute.

METHODS

Here, we tested 2-AI and its ring-substituted derivatives 5-MeO-AI, 5-methoxy-6-methyl-2-aminoindan (MMAI), and 5,6-methylenedioxy-2-aminoindan (MDAI) for their abilities to interact with plasma membrane monoamine transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT). We also compared the binding affinities of the aminoindans at 29 receptor and transporter binding sites.

RESULTS

2-AI was a selective substrate for NET and DAT. Ring substitution increased potency at SERT while reducing potency at DAT and NET. MDAI was moderately selective for SERT and NET, with tenfold weaker effects on DAT. 5-MeO-AI exhibited some selectivity for SERT, having sixfold lower potency at NET and 20-fold lower potency at DAT. MMAI was highly selective for SERT, with 100-fold lower potency at NET and DAT. The aminoindans had relatively high affinity for α₂-adrenoceptor subtypes. 2-AI had particularly high affinity for α_2C receptors (K_i = 41 nM) and slightly lower affinity for the α_2A (K_i = 134 nM) and α_2B (K_i = 211 nM) subtypes. 5-MeO-AI and MMAI also had moderate affinity for the 5-HT_2B receptor.

CONCLUSIONS

2-AI is predicted to have (+)-amphetamine-like effects and abuse potential whereas the ring-substituted derivatives may produce 3,4-methylenedioxymethamphetamine (MDMA)-like effects but with less abuse liability.

Pharmacokinetic and pharmacodynamic evaluation of 5-methoxy-2-aminoindane (MEAI): A new binge-mitigating agent

5-Methoxy-2-aminoindane (MEAI) is a novel psychoactive aminoindane derivative, exerting euphoric, alcohol-like tipsy experience and reduced desire to consume alcoholic beverages. Our previous toxicological evaluation of MEAI in rats, clearly indicated MEAI's potential to be further evaluated as a promising binge mitigating agent due to its favorable safety profile. In the light of these observations, we have determined MEAI's pharmacokinetic (PK) profile in rats and evaluated in-vitro its pharmacodynamics (PD) profile. Following oral and intravenous administration of MEAI, two metabolites were identified, namely, N-acetyl-MEAI and 5-hydroxy-N-acetyl-AI, arising from N-acetylation and oxidative demethylation. The PK-parameters of MEAI and N-acetyl-MEAI were derived from single i.v. bolus (10 mg/kg) and single oral doses (10 and 90 mg/kg) of MEAI to rats. MEAI displayed extensive total clearance (2.8 L/h/kg) and a very short plasma and brain half-life (0.5-0.7 h). At 10 mg/kg, MEAI displayed low oral bioavailability (25%) and a plasma to brain ratio in the range of 3-5.5, with brain MEAI peak levels attained rapidly. Non-linear pharmacokinetic behavior was observed in the 90 mg/kg oral group, in which the bioavailability increased by 500%. The non-linear behavior was also evident by the significant increase in plasma half-life of MEAI and its metabolite, N-acetyl-MEAI. N-acetyl-MEAI levels in plasma and brain were about ten times lower than the parent compound, indicative of its minor contribution to MEAI's pharmacological effect. MEAI displayed weak to moderate ligand binding inhibition at the 5-HT2B receptor, while the remaining neurochemical targets were unaffected. Further studies, in non-rodent species are required, in-order to assess MEAI's PK and PD profile adequately.