A Simple Method For The Preparation Of Acetoacetate

Ketone Bodies Induce Unique Inhibition of Tumor Cell Proliferation and Enhance the Efficacy of Anti-Cancer Agents

The ketone bodies, sodium and lithium salts of acetoacetate (AcAc) and sodium 3-hydroxybutyrate (3-HB; commonly called beta-hydroxybutyrate) have been found to inhibit the proliferation of cancer cells. Previous studies have suggested that lithium itself may be an inhibiting agent but may be additive or synergistic with the effect of AcAc. We previously found that sodium acetoacetate (NaAcAc) inhibits the growth of human colon cancer cell line SW480. We report here similar results for several other cancer cell lines including ovarian, cervical and breast cancers. We found that NaAcAc does not kill cancer cells but rather blocks their proliferation. Similar inhibition of growth was seen in the effect of lithium ion alone (as LiCl). The effect of LiAcAc appears to be due to the combined effects of acetoacetate and the lithium ion. The ketone bodies, when given together with chemotherapeutic agents, rapamycin, methotrexate and the new peptide anti-cancer agent, PNC-27, substantially lowers their IC50 values for cancer cell, killing suggesting that ketone bodies and ketogenic diets may be powerful adjunct agents in treating human cancers.

In vivo investigation of hyperpolarized [1,3-13C2]acetoacetate as a metabolic probe in normal brain and in glioma

Dysregulation in NAD⁺/NADH levels is associated with increased cell division and elevated levels of reactive oxygen species in rapidly proliferating cancer cells. Conversion of the ketone body acetoacetate (AcAc) to β-hydroxybutyrate (β-HB) by the mitochondrial enzyme β-hydroxybutyrate dehydrogenase (BDH) depends upon NADH availability. The β-HB-to-AcAc ratio is therefore expected to reflect mitochondrial redox. Previous studies reported the potential of hyperpolarized ¹³C-AcAc to monitor mitochondrial redox in cells, perfused organs and in vivo. However, the ability of hyperpolarized ¹³C-AcAc to cross the blood brain barrier (BBB) and its potential to monitor brain metabolism remained unknown. Our goal was to assess the value of hyperpolarized [1,3-¹³C₂]AcAc in healthy and tumor-bearing mice in vivo. Following hyperpolarized [1,3-¹³C₂]AcAc injection, production of [1,3-¹³C₂]β-HB was detected in normal and tumor-bearing mice. Significantly higher levels of [1-¹³C]AcAc and lower [1-¹³C]β-HB-to-[1-¹³C]AcAc ratios were observed in tumor-bearing mice. These results were consistent with decreased BDH activity in tumors and associated with increased total cellular NAD⁺/NADH. Our study confirmed that AcAc crosses the BBB and can be used for monitoring metabolism in the brain. It highlights the potential of AcAc for future clinical translation and its potential utility for monitoring metabolic changes associated with glioma, and other neurological disorders.

Direct assessment of renal mitochondrial redox state using hyperpolarized 13 C-acetoacetate

PURPOSE

The purpose of this study was to investigate the hyperpolarized ketone body 13 C-acetoacetate (AcAc) and its conversion to 13 C-β-hydroxybutyrate (βOHB) in vivo, catalyzed by β-hydroxybutyrate dehydrogenase (BDH), as a novel direct marker of mitochondrial redox state.

METHODS

[1,3-13 C2 ]AcAc was synthesized by hydrolysis of the ethyl ester, and hyperpolarized via dissolution DNP. Cold storage under basic conditions resulted in sufficient chemical stability for use in hyperpolarized (HP) MRI studies. Polarizations and relaxation times of HP [1,3-13 C2 ]AcAc were measured in a clinical 3T MRI scanner, and 8 rats were scanned by dynamic HP 13 C MR spectroscopy of a slab through the kidneys. Four rats were scanned after acute treatment with high dose metformin (125 mg/kg, intravenous), which is known to modulate mitochondrial redox via inhibition of mitochondrial complex I. An additional metformin-treated rat was scanned by abdominal 2D CSI (8 mm × 8 mm).

RESULTS

Polarizations of 7 ± 1% and 7 ± 3%, and T1 relaxation times of 58 ± 5 s and 52 ± 3 s, were attained at the C1 and C3 positions, respectively. Rapid conversion of HP AcAc to βOHB was detected in rat kidney in vivo, via the C1 label. The product HP βOHB was resolved from closely resonating acetate. Conversion to βOHB was also detected via 2D CSI, in both kidney as well as liver regions. Metformin treatment resulted in a significant increase (40%, P = 0.01) of conversion of HP AcAc to βOHB.

CONCLUSION

Rapid conversion of HP AcAc to βOHB was observed in rat kidney in vivo and is a promising new non-invasive marker of mitochondrial redox state. Magn Reson Med 79:1862-1869, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Rat acetoacetic acid decarboxylase inhibition by acetone

Although in mammals, acetone formation from acetoacetic acid is normally regarded as a non-enzymatic (spontaneous) process, the existence of an acetoacetic acid decarboxylase activity was postulated recently. The results imply that this enzymatic activity can be relatively important at the physiological concentrations of ketone bodies found in the rat and that acetone acts as a competitive inhibitor of this enzyme.