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Identification of a botanical inhibitor of intestinal diacylglyceride acyltransferase 1 activity via in vitro screening and a parallel, randomized, blinded, placebo-controlled clinical trial.

Velliquette RA, Grann K, Missler SR, Patterson J, Hu C, Gellenbeck KW, Scholten JD, Randolph RK - Nutr Metab (Lond) (2015)

Bottom Line: Phenolic acids (i.e., gallic acid) and polyphenols (i.e., cyanidin) abundantly found in nature appeared to inhibit DGAT1 enzyme activity in vitro.Four polyphenolic rich botanical extracts were identified from in vitro evaluation in both cell-free and cellular model systems: apple peel extract (APE), grape extract (GE), red raspberry leaf extract (RLE) and apricot/nectarine extract (ANE) (IC50 = 1.4, 5.6, and 10.4 and 3.4 μg/mL, respectively).These data suggest that a dietary GE has the potential to attenuate postprandial hypertriglyceridemia in part by the inhibition of intestinal DGAT1 enzyme activity without intolerable side effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Analytical Sciences, Amway R&D, 7575 Fulton St., Building 50-2D, Ada, MI 49355 USA.

ABSTRACT

Background: Diacylglyceride acyltransferase 1 (DGAT1) is the enzyme that adds the final fatty acid on to a diacylglyceride during triglyceride (TG) synthesis. DGAT1 plays a key role in the repackaging of dietary TG into circulating TG rich chylomicrons. A growing amount of research has indicated that an exaggerated postprandial circulating TG level is a risk indicator for cardiovascular and metabolic disorders. The aim of this research was to identify a botanical extract that inhibits intestinal DGAT1 activity and attenuates postprandial hypertriglyceridemia in overweight and obese humans.

Methods: Twenty individual phytochemicals and an internal proprietary botanical extract library were screened with a primary cell-free DGAT1 enzyme assay that contained dioleoyl glycerol and palmitoleoyl Coenzyme A as substrates plus human intestinal microsomes as the DGAT1 enzyme source. Botanical extracts with IC50 values < 100 μg/mL were evaluated in a cellular DGAT1 assay. The cellular DGAT1 assay comprised the analysis of (14)C labeled TG synthesis in cells incubated with (14)C-glycerol and 0.3 mM oleic acid. Lead botanical extracts were then evaluated in a parallel, double-blind, placebo-controlled clinical trial. Ninety healthy, overweight and obese participants were randomized to receive 2 g daily of placebo or individual botanical extracts (the investigational product) for seven days. Serum TG levels were measured before and after consuming a high fat meal (HFM) challenge (0.354 L drink/shake; 77 g fat, 25 g carbohydrate and 9 g protein) as a marker of intestinal DGAT1 enzyme activity.

Results: Phenolic acids (i.e., gallic acid) and polyphenols (i.e., cyanidin) abundantly found in nature appeared to inhibit DGAT1 enzyme activity in vitro. Four polyphenolic rich botanical extracts were identified from in vitro evaluation in both cell-free and cellular model systems: apple peel extract (APE), grape extract (GE), red raspberry leaf extract (RLE) and apricot/nectarine extract (ANE) (IC50 = 1.4, 5.6, and 10.4 and 3.4 μg/mL, respectively). In the seven day clinical trial, compared to placebo, only GE significantly reduced the baseline subtracted change in serum TG AUC following consumption of the HFM (AUC = 281 ± 37 vs. 181 ± 30 mg/dL*h, respectively; P = 0.021). Chromatographic characterization of the GE revealed a large number of closely eluting components containing proanthocyanidins, catechins, anthocyanins and their secondary metabolites that corresponded with the observed DGAT1 enzyme inhibition in the cell-free model.

Conclusion: These data suggest that a dietary GE has the potential to attenuate postprandial hypertriglyceridemia in part by the inhibition of intestinal DGAT1 enzyme activity without intolerable side effects.

Trial registration: This trial was registered with ClinicalTrials.gov NCT02333461.

No MeSH data available.


Related in: MedlinePlus

Percent DGAT1 enzyme inhibition and IC50 values for single phytochemicals in the cell-free assay. Twenty individual phytochemicals were screened through the cell-free DGAT1 enzyme assay. Six of the twenty phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (IC50 ranged from 0.667 to 8.60 μM, compared to A-922500 = 40nM) and all were phenolic acids or polyphenols. Results are the mean of duplicates
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Fig3: Percent DGAT1 enzyme inhibition and IC50 values for single phytochemicals in the cell-free assay. Twenty individual phytochemicals were screened through the cell-free DGAT1 enzyme assay. Six of the twenty phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (IC50 ranged from 0.667 to 8.60 μM, compared to A-922500 = 40nM) and all were phenolic acids or polyphenols. Results are the mean of duplicates

Mentions: We first screened a panel of 20 phytochemicals, mostly polyphenols and phenolic acids (Apigenin, Astilbin, Catechin, Cyanidin Chloride, Dihydrokaempferol, Epigallocatechin Gallate (EGCG), Ellagic Acid, Formononetin, Gallic Acid, Guggulsterone, Kaempferol, Icariin, Luteolin, Naringenin, Paeoniflorin, Punicalagins, Orientin, Sparteine, Taxifolin and trans-Resveratrol) in the cell-free DGAT1 assay to aid in the selection of prospective botanical extracts for screening. Phytochemicals with ≥50 % DGAT1 inhibition at 50 μM were further examined in titration experiments. Six phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (Fig. 3) and all were polyphenols or phenolic acids (data not shown for remaining fourteen phytochemicals). The IC50 values ranged from 0.667 to 8.60 μM compared to 39.9 nM for the synthetic inhibitor A922500.Fig. 3


Identification of a botanical inhibitor of intestinal diacylglyceride acyltransferase 1 activity via in vitro screening and a parallel, randomized, blinded, placebo-controlled clinical trial.

Velliquette RA, Grann K, Missler SR, Patterson J, Hu C, Gellenbeck KW, Scholten JD, Randolph RK - Nutr Metab (Lond) (2015)

Percent DGAT1 enzyme inhibition and IC50 values for single phytochemicals in the cell-free assay. Twenty individual phytochemicals were screened through the cell-free DGAT1 enzyme assay. Six of the twenty phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (IC50 ranged from 0.667 to 8.60 μM, compared to A-922500 = 40nM) and all were phenolic acids or polyphenols. Results are the mean of duplicates
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4526202&req=5

Fig3: Percent DGAT1 enzyme inhibition and IC50 values for single phytochemicals in the cell-free assay. Twenty individual phytochemicals were screened through the cell-free DGAT1 enzyme assay. Six of the twenty phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (IC50 ranged from 0.667 to 8.60 μM, compared to A-922500 = 40nM) and all were phenolic acids or polyphenols. Results are the mean of duplicates
Mentions: We first screened a panel of 20 phytochemicals, mostly polyphenols and phenolic acids (Apigenin, Astilbin, Catechin, Cyanidin Chloride, Dihydrokaempferol, Epigallocatechin Gallate (EGCG), Ellagic Acid, Formononetin, Gallic Acid, Guggulsterone, Kaempferol, Icariin, Luteolin, Naringenin, Paeoniflorin, Punicalagins, Orientin, Sparteine, Taxifolin and trans-Resveratrol) in the cell-free DGAT1 assay to aid in the selection of prospective botanical extracts for screening. Phytochemicals with ≥50 % DGAT1 inhibition at 50 μM were further examined in titration experiments. Six phytochemicals were dose dependent inhibitors of DGAT1 enzyme activity (Fig. 3) and all were polyphenols or phenolic acids (data not shown for remaining fourteen phytochemicals). The IC50 values ranged from 0.667 to 8.60 μM compared to 39.9 nM for the synthetic inhibitor A922500.Fig. 3

Bottom Line: Phenolic acids (i.e., gallic acid) and polyphenols (i.e., cyanidin) abundantly found in nature appeared to inhibit DGAT1 enzyme activity in vitro.Four polyphenolic rich botanical extracts were identified from in vitro evaluation in both cell-free and cellular model systems: apple peel extract (APE), grape extract (GE), red raspberry leaf extract (RLE) and apricot/nectarine extract (ANE) (IC50 = 1.4, 5.6, and 10.4 and 3.4 μg/mL, respectively).These data suggest that a dietary GE has the potential to attenuate postprandial hypertriglyceridemia in part by the inhibition of intestinal DGAT1 enzyme activity without intolerable side effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Analytical Sciences, Amway R&D, 7575 Fulton St., Building 50-2D, Ada, MI 49355 USA.

ABSTRACT

Background: Diacylglyceride acyltransferase 1 (DGAT1) is the enzyme that adds the final fatty acid on to a diacylglyceride during triglyceride (TG) synthesis. DGAT1 plays a key role in the repackaging of dietary TG into circulating TG rich chylomicrons. A growing amount of research has indicated that an exaggerated postprandial circulating TG level is a risk indicator for cardiovascular and metabolic disorders. The aim of this research was to identify a botanical extract that inhibits intestinal DGAT1 activity and attenuates postprandial hypertriglyceridemia in overweight and obese humans.

Methods: Twenty individual phytochemicals and an internal proprietary botanical extract library were screened with a primary cell-free DGAT1 enzyme assay that contained dioleoyl glycerol and palmitoleoyl Coenzyme A as substrates plus human intestinal microsomes as the DGAT1 enzyme source. Botanical extracts with IC50 values < 100 μg/mL were evaluated in a cellular DGAT1 assay. The cellular DGAT1 assay comprised the analysis of (14)C labeled TG synthesis in cells incubated with (14)C-glycerol and 0.3 mM oleic acid. Lead botanical extracts were then evaluated in a parallel, double-blind, placebo-controlled clinical trial. Ninety healthy, overweight and obese participants were randomized to receive 2 g daily of placebo or individual botanical extracts (the investigational product) for seven days. Serum TG levels were measured before and after consuming a high fat meal (HFM) challenge (0.354 L drink/shake; 77 g fat, 25 g carbohydrate and 9 g protein) as a marker of intestinal DGAT1 enzyme activity.

Results: Phenolic acids (i.e., gallic acid) and polyphenols (i.e., cyanidin) abundantly found in nature appeared to inhibit DGAT1 enzyme activity in vitro. Four polyphenolic rich botanical extracts were identified from in vitro evaluation in both cell-free and cellular model systems: apple peel extract (APE), grape extract (GE), red raspberry leaf extract (RLE) and apricot/nectarine extract (ANE) (IC50 = 1.4, 5.6, and 10.4 and 3.4 μg/mL, respectively). In the seven day clinical trial, compared to placebo, only GE significantly reduced the baseline subtracted change in serum TG AUC following consumption of the HFM (AUC = 281 ± 37 vs. 181 ± 30 mg/dL*h, respectively; P = 0.021). Chromatographic characterization of the GE revealed a large number of closely eluting components containing proanthocyanidins, catechins, anthocyanins and their secondary metabolites that corresponded with the observed DGAT1 enzyme inhibition in the cell-free model.

Conclusion: These data suggest that a dietary GE has the potential to attenuate postprandial hypertriglyceridemia in part by the inhibition of intestinal DGAT1 enzyme activity without intolerable side effects.

Trial registration: This trial was registered with ClinicalTrials.gov NCT02333461.

No MeSH data available.


Related in: MedlinePlus