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Effect of oral administration of soy-derived phosphatidic acid on concentrations of phosphatidic acid and lyso-phosphatidic acid molecular species in human plasma
© Purpura et al; licensee BioMed Central Ltd. 2013
- Published: 6 December 2013
- Human Plasma
- Molecular Species
- Resistance Exercise
- Phosphatidic Acid
- Muscle Protein Synthesis
The glycerophospholipid Phosphatidic acid (PA) has been identified as a potential nutritional treatment for gastrointestinal disorders. Dietary food sources rich in PA include cabbage and radish leaves as well as Mallotus japonicas, a Japanese edible herb historically used for the treatment of stomach ulcers. The mammalian target of rapamycin (mTOR) has been shown to regulate rates of muscle protein synthesis and a mechanical stimulus (resistance exercise) has been shown to activate mTOR with PA playing a key role. Supplementation with soy-derived PA significantly increases responses in skeletal muscle hypertrophy, lean body mass, and maximal strength to resistance exercise. PA accounts for less than 0.1% of the total glycerophospholipid concentration of 201 mg/dl in the human plasma. 15 of the more than 600 distinct molecular lipid species quantified in human plasma are PA, 6 are lysophosphatidic acid (LPA). Orally administered PA can be metabolized to LPA and glycerophosphate by pancreatic phospholipases A1 and A2, which hydrolyze the fatty acid at the sn-1 position and the sn-2 position, respectively. Lysophospholipids are absorbed by the mucosal cells of the gastrointestinal tract and are rapidly re-acylated with fatty acids of the body pool resulting in a newly-formed phospholipid-molecule whose fatty acid composition is determined by the physiological and nutritional status and not by its source. This study sought to assess the effect of soy-derived PA supplementation on concentrations LPA and PA molecular species in human plasma.
After a 12 hour overnight fast one subject (20 years of age, bodyweight of 82 kg, and height of 178 cm) was assigned to receive 1.5 grams of soy-derived PA (Mediator, Chemi Nutra, White Bear Lake, MN). Blood draws were taken immediately prior to, and at 30 min, 1, 2, 3, and 7 hours following supplementation. The samples were analyzed by an ultra-performance liquid chromatograph with triple quadrupole mass spectrometry (LC/MS/MS) using 17:1-LPA and 37:4-PA as internal standards to determine the concentration of LPA and PA molecular species in human plasma.
At baseline, 19 PA (highest concentrations: C34:2 (15%), C40:4 (11%), and C36:4 (10%)) and 5 LPA (16:0 (45%), 18:2 (19%), 20:4 (17%), 14:0 (11%) and 18:1 (8%)) molecular species could be quantified with total concentrations of PA of 2.66 nmol/ml, and LPA of 0.11 nmol/ml. Plasma concentrations of PA peaked at 3 hours (+32%) after ingestion and stayed elevated even after 7 hours (+18%). LPA showed a bimodal absorption kinetic with peaks after 1 hour (+500%) and 3 hours (+264%), after almost dropping back to baseline levels after 2 hours. On an individual fatty acid level, most prominent was a 23-fold increase in 20:4-LPA after 1 hour compared to baseline. The increase in 20:4-LPA does not result from the administration of PA, since soy-derived PA does not contain any arachidonic acid (fatty acids distribution of soy-PA: 18:2 (66.1%), 18:1 (12.6%), 16:0 (11.7%), 18:3 (6.1%) and 18:0 (3.4%)). Absorption of soy-derived PA must yield glycerophosphate which is re-acylated with arachidonic acid.
LPA and PA can be molecularly identified and measured. LPA, PA and LPA+PA plasma levels increase 30 min after ingestions, plateau at 1-3 hours and remain above baseline levels after 7 hours. This is the first case study showing that orally administered PA is bioavailable. Future research should repeat this case study with a larger n-size and include the analysis of omega 3 fatty acid-LPA molecular species.
Supported by Chemi Nutra, White Bear Lake, MN.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.