Original Paper

Journal of Biomedical Science

, Volume 13, Issue 6, pp 763-772

First online:

Fractionation and identification of 9c, 11t, 13t-conjugated linolenic acid as an activator of PPARα in bitter gourd (Momordica charantia L.)

  • Chia-Ying ChuangAffiliated withNutritional Biochemistry Laboratory, Institute of Microbiology and Biochemistry, National Taiwan University
  • , Chin HsuAffiliated withNutritional Biochemistry Laboratory, Institute of Microbiology and Biochemistry, National Taiwan University
  • , Che-Yi ChaoAffiliated withNutritional Biochemistry Laboratory, Institute of Microbiology and Biochemistry, National Taiwan UniversityDepartment of Applied Life Science, Asia University
  • , Yung-Shung WeinAffiliated withDepartment of Chemistry, National Taiwan University
  • , Yueh-Hsiung KuoAffiliated withDepartment of Chemistry, National Taiwan UniversityInstitute of BioAgricultural Science, Academia Sinica
  • , Ching-jang HuangAffiliated withNutritional Biochemistry Laboratory, Institute of Microbiology and Biochemistry, National Taiwan UniversityDepartment of Biochemical Science and Technology, National Taiwan University Email author 

Summary

Bitter gourd (Momordica charantia L.) is a common vegetable in Asia that has been used in traditional medicine for the treatment of Diabetes. PPARs are ligand-dependent transcription factors that belong to the steroid hormone nuclear receptor family and control lipid and glucose homeostasis in the body. We previously reported that the ethyl acetate (EA) extract of bitter gourd activated peroxisome proliferator receptors (PPARs) α and γ. To identify the active compound that activated PPARα, wild bitter gourd EA extract was partitioned between n-hexane and 90% methanol/10% H2O, and the n-hexane soluble fraction was further separated by silica gel column chromatography and finally by preparative HPLC. A transactivation assay employing a clone of CHOK1 cells stably transfected with a (UAS)4-tk-alkaline phosphatase reporter and a chimeric receptor of GAL4-rPPARα LBD was used to track the active component. Based on Mass, NMR, and IR spectroscopy, 9cis, 11trans, 13trans-conjugated linolenic acid (9c, 11t, 13t-CLN) was identified as a PPARα activator in wild bitter gourd. The isolated 9c, 11t, 13t-CLN rich fraction also significantly induced acyl CoA oxidase (ACO) activity in a peroxisome proliferator-responsive murine hepatoma cell line, H4IIEC3, implying that 9c, 11t, 13t-CLN was able to act on a natural PPARα signaling pathway as well. The content of 9c, 11t, 13t-CLN was estimated to be about 7.1 g/kg of our dried wild bitter gourd sample. The concentration of 9c, 11t, 13t-CLN and activation activity in the hydrolyzed EA extract of the seeds was higher than that of the flesh. The potential health benefits of 9c, 11t, 13t-CLN through the PPARα regulated mechanism are worthy to be further characterized in in vivo studies.

Keywords

PPARα 9cis 11trans 13trans-conjugated linolenic acid wild bitter gourd transactivation assay Acyl CoA Oxidase