Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice
Neelakantan H, Vance V, Wetzel MD, Wang HYL, McHardy SF, Finnerty CC, Hommel JD, Watowich SJ
Biochemical Pharmacology (2018)
Eleven days of subcutaneous 5-Amino-1MQ at 20 mg/kg three times daily produced approximately 5% body weight loss and a roughly 35% reduction in epididymal white adipose tissue mass in diet-induced-obese mice — the pharmacological replication of the Kraus 2014 antisense-knockdown phenotype that anchors every subsequent NNMT-inhibitor claim.
This is the foundational pharmacology paper for 5-amino-1-methylquinolinium (5-Amino-1MQ) as a selective small-molecule inhibitor of nicotinamide N-methyltransferase (NNMT), published in Biochemical Pharmacology (volume 147, pages 141–152, accepted late 2017, indexed 2018) by Neelakantan and colleagues at the University of Texas Medical Branch and the University of Texas at San Antonio. The paper translates the Kraus et al. 2014 Nature antisense-knockdown phenotype into a small-molecule program — testing whether the genetic knockdown's anti-obesity, insulin-sensitizing, and tissue-SAM/NAD+ elevation phenotype can be reproduced by a competitive enzyme inhibitor at clinically tolerated systemic exposure.
The enzyme-kinetic characterization establishes 5-Amino-1MQ as a selective NNMT inhibitor with a biochemical IC50 of approximately 1 μM and a cellular EC50 of 2.3 ± 1.1 μM in adipocytes. Binding kinetics are competitive with the nicotinamide substrate and uncompetitive with the SAM methyl donor — consistent with binding at the nicotinamide-substrate site. Selectivity against structurally related methyltransferases (PNMT, COMT, and other SAM-dependent enzymes) and against the NAD+ salvage-pathway enzymes was characterized in the paper to support the off-target safety case.
The in-vivo efficacy readout used diet-induced-obese C57BL/6 mice maintained on a high-fat diet for 16 weeks, then treated with 5-Amino-1MQ at 20 mg/kg subcutaneously three times daily for 11 days (a total daily exposure of approximately 34 mg/kg/day). Treated animals lost approximately 5.1% body weight from baseline (compared with approximately 1.4% gain in vehicle controls), with epididymal white adipose tissue mass decreased by approximately 35%, adipocyte size reduced by over 30%, adipocyte volume reduced by over 40%, and plasma total cholesterol reduced by approximately 30% — all without changes in food intake. The food-intake-independent mechanism is the same partitioning-altered phenotype that the antisense-knockdown approach reported in the Kraus paper. Intracellular metabolomics in adipocytes confirmed the predicted target-engagement signature: reduced 1-MNA (the NNMT product), elevated NAD+, elevated SAM, and suppressed lipogenesis.
This is the load-bearing primary characterization for the small-molecule pharmacology of 5-Amino-1MQ that the entire 5-Amino-1MQ peptide page and the gray-market biohacker use case rest on. A subsequent paper from the same group extended the model into aged-muscle injury contexts (Neelakantan et al. 2019, Biochem Pharmacol 163:481–492) and a 2022 follow-up combined NNMT inhibition with caloric restriction in DIO mice (Dimet-Wiley et al. Sci Rep 2022).
The paper is preclinical and rodent-only — no human data. The 11-day treatment duration is short relative to the chronic-exposure context that biohacker oral use describes; chronic-toxicology data at multi-month timescales relevant to practitioner use have not been published. The administration route in the efficacy study was subcutaneous rather than oral, and although the paper characterized membrane permeability, an in-vivo oral pharmacokinetic comparison at the doses producing the efficacy readout has not been published — the gray-market use of oral 5-Amino-1MQ in humans rests on the assumption that the molecule's small size and lipophilicity translate to oral bioavailability, not on a characterized oral AUC and Cmax. The sample size was modest (n=9 per group per the paper's primary analysis), adequate for the mouse-level effect-size estimation but small for any precision claim. The mouse model is diet-induced obesity in C57BL/6 — the conventional rodent obesity model with the conventional translational caveats. The SAM-elevation finding mirrors the Kraus 2014 phenotype and carries the same chronic-exposure-uncharacterized methylation-cycle question: sustained elevation of cellular SAM could in principle perturb DNA methylation maintenance and histone-methylation patterns over long timescales, and no published study of any NNMT inhibitor has characterized this potential consequence at multi-month exposure. The cation-versus-iodide-salt molecular-weight distinction (cation ~159 Da, iodide salt ~286 Da) introduces a dose-labeling source of variance for gray-market supply that the original pharmacology paper used the cation-equivalent doses for. Sponsorship and conflicts disclosed in the paper. The translational gap between this mouse pharmacology and the /peptides/5-amino-1mq practitioner-use context is the central caveat the broader peptide-page assembly treats.
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