Anti-Diabetic and Anti-Inflammatory Effects of Green and Red Kohlrabi Cultivars (Brassica oleracea var. gongylodes)

  • Jung, Hyun Ah (Department of Food Science and Human Nutrition, Chonbuk National University) ;
  • Karki, Subash (Department of Food Science and Nutrition, Pukyong National University) ;
  • Ehom, Na-Yeon (Department of Food Science and Nutrition, Pukyong National University) ;
  • Yoon, Mi-Hee (Department of Food Science and Nutrition, Pukyong National University) ;
  • Kim, Eon Ji (Department of Food Science and Nutrition, Pukyong National University) ;
  • Choi, Jae Sue (Department of Food Science and Nutrition, Pukyong National University)
  • Received : 2014.09.11
  • Accepted : 2014.10.25
  • Published : 2014.12.31


The aim of the present study was to evaluate the anti-diabetic, anti-inflammatory, antioxidant potential, and total phenolic content (TPC) of green and red kohlrabi cultivars. Anti-diabetic and anti-inflammatory activities were evaluated via protein tyrosine phosphatase (PTP1B) and rat lens aldose reductase inhibitory assays and cell-based lipopolysaccharide (LPS)-induced nitric oxide (NO) inhibitory assays in RAW 264.7 murine macrophages. In addition, scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical, and peroxynitrite ($ONOO^-$) were used to evaluate antioxidant potential and TPC was selected to assess phytochemical characteristics. Between the two kohlrabi cultivars, red kohlrabi (RK) had two times more TPC than green kohlrabi (GK) and showed significant antioxidant effects in DPPH, ABTS, and $ONOO^-$ scavenging assays. Likewise, methanol (MeOH) extracts of RK and GK inhibited LPS-induced NO production in a dose dependent manner that was further clarified by suppression of iNOS and COX-2 protein production. The MeOH extracts of RK and GK exhibited potent inhibitory activities against PTP1B with the corresponding $IC_{50}$ values of $207{\pm}3.48$ and $287{\pm}3.22{\mu}g/mL$, respectively. Interestingly, the RK MeOH extract exhibited significantly stronger anti-inflammatory, anti-diabetic, and antioxidant effects than that of GK MeOH extract. As a result, our study establishes that RK extract with a higher TPC might be useful as a potent anti-diabetic, antioxidant, and anti-inflammatory agent.


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