Bioactivity-Guided Identification of Botanical Inhibitors of Ketohexokinase.
OBJECTIVE
In developed countries with westernized diets, the excessive consumption of added sugar in beverages and highly refined and processed foods is associated with increased risk for obesity, diabetes, and cardiovascular diseases. As a major constituent of added sugars, fructose has been shown to cause a variety of adverse metabolic effects, such as impaired insulin sensitivity, hypertriglyceridemia, and oxidative stress. Recent studies have shown that ketohexokinase isoform C is the key enzyme responsible in fructose metabolism that drive's fructose's adverse effects. The objective of this study was to identify botanical ingredients with potential for inhibitory activity against ketohexokinase-C and fructose-induced metabolic effects by using a series of in vitro model systems.


METHODS
Extracts from 406 botanicals and 1200 purified phytochemicals were screened (initial concentration of 50 μg/mL and 50 μM, respectively) for their inhibitory activity using a cell free, recombinant human ketohexokinase-C assay. Dose response evaluations were conducted on botanical extracts and phytochemicals that inhibited ketohexokinase-C by > 30% and > 40%, respectively. Two different extract lots of the top botanical candidates were further evaluated in lysates of HepG2 cells overexpressing ketohexokinase-C for inhibition of fructose-induced ATP depletion. In addition, extracts were evaluated in intact Hep G2 cells for inhibition of fructose-induced elevation of triglyceride and uric acid production.


RESULTS
Among the botanical extracts, phloretin (Malus domestica) extracts were the most potent (IC50: 8.9-9.2 μg/mL) followed by extracts of Angelica archangelica (IC50: 22.6 μg/mL-57.3 μg/mL). Among the purified phytochemicals, methoxy-isobavachalcone (Psoralea corylifolia, IC50 = 0.2 μM) exhibited the highest potency against ketohexokinase isoform C activity followed by osthole (Angelica archangelica, IC50 = 0.7 μM), cratoxyarborenone E (Cratoxylum prunifolium, IC50 = 1.0 μM), and α-/γ-mangostin (Cratoxylum prunifolium, IC50 = 1.5 μM). Extracts of Angelica archangelica, Garcinia mangostana, Petroselinum crispum, and Scutellaria baicalensis exhibited ketohexokinase inhibitory activity and blocked fructose-induced ATP depletion and fructose-induced elevation in triglyerides and uric acid.


CONCLUSIONS
Angelica archangelica, Garcinia mangostana, Petroselinum crispum, and Scutellaria baicalensis were the top four botanical candidiates identified with inhibitory activity against ketohexokinase-C. Future studies are needed to show proof of mechanism and the efficacy of these botanical extracts in humans to blunt the negative metabolic effects of fructose-containing added sugars.
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
MyPhuong T
MT
Le
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Miguel A
MA
Lanaspa
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Christina M
CM
Cicerchi
Amway Research and Development, Ada, Michigan, United States of America.
Jatinder
J
Rana
Amway Research and Development, Ada, Michigan, United States of America.
Jeffrey D
JD
Scholten
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Brandi L
BL
Hunter
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Christopher J
CJ
Rivard
Amway Research and Development, Ada, Michigan, United States of America.
R Keith
RK
Randolph
Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Richard J
RJ
Johnson
D029970:Angelica archangelica / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000737:chemistry*; D005631:Fructokinases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D005632:Fructose / Q000737:chemistry / Q000378:metabolism*; D029762:Garcinia mangostana / Q000737:chemistry; D056945:Hep G2 Cells; D006801:Humans; D015228:Hypertriglyceridemia / Q000188:drug therapy* / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D028528:Petroselinum / Q000737:chemistry; D064209:Phytochemicals / Q000008:administration & dosage / Q000737:chemistry*; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry
D004791:Enzyme Inhibitors; D007328:Insulin; D064209:Phytochemicals; D010936:Plant Extracts; D005632:Fructose; D005631:Fructokinases; C021475:ketohexokinase