Luteolin

Luteolin is a flavone. It is one of our more expensive ingredients and is not often included in supplements for this reason.

It is thought to play an important role in thehuman body as an antioxidant, a free radical scavenger, an agent in the prevention of inflammation, a promoter of carbohydrate metabolism, and an immune system modulator.

The characteristics of luteolin are believed to play an important part in the prevention of cancer. Multiple research experiments describe luteolin as a biochemical agent that can dramatically reduce inflammation and the symptoms of septic shock.

Published Clinical Studies

Free radical scavenging, enzyme inhibitory constituents from antidiabetic Ayurvedic medicinal plant Hydnocarpus wightiana Blume

Reddy SV, Tiwari AK, Kumar US, Rao RJ, Rao JM

Natural Products Laboratory, Division of Organic Chemistry-I, Indian Institute of Chemical Technology, Hyderabad, India

Hydnocarpus wightiana is advocated in traditional Indian medicine to possess strong antidiabetic activity. In the course of identifying bioactive fractions from Indian medicinal plants we observed that acetone extract of the seed hulls of H. wightiana possess strong free radicals (DPPH and ABTS) scavenging, alpha-glucosidase and moderate N-acetyl-beta-D-glucosaminidase inhibitory activities. Further fractionation of the extract led to the isolation of hydnocarpin, luteolin and isohydnocarpin in substantial yields. All the compounds showed strong ABTS scavenging property. However, only luteolin could display strong DPPH scavenging activity. Furthermore, all the three compounds also showed varying degrees of alpha-glucosidase and N-acetyl-beta-D-glucosaminidase inhibitory activity, luteolin being the superior. The kinetics of alpha-glucosidase inhibition by these compounds showed that acetone extract inhibits the enzyme in competitive manner however, luteolin and isohydnocarpin showed mixed-type inhibition. This is the first report assigning hydnocarpin and isohydnocarpin free radical scavenging, alpha-glucosidase and N-acetyl-beta-D-glucosaminidase inhibitory properties and luteolin as N-acetyl-beta-D-glucosaminidase inhibitor. This study suggests that presence of amphiphilic antioxidant molecules along with enzyme inhibitory activities in the acetone extract of H. wightiana seed hulls may be responsible for the antidiabetic properties as advocated in traditional medicine.

Protective Effect of Luteolin on Inflammatory Factor-Mediated Insulin Resistance in 3T3-L1 Adipocytes

Li Ding and Xiaoli Chen

Food Science and Nutrition, University of Minnesota, St. Paul, MN

ABSTRACT
Obesity and insulin resistance have been recently linked toa low-grade chronic inflammatory response characterized by increasedmacrophage infiltration, altered cytokine production, and activationof inflammatory signaling pathway in adipose tissue. Pharmacologicalagents and natural products capable of reducing inflammatoryactivity possess anti-diabetic properties. Luteolin, a naturallyoccurring flavonoid, has been demonstrated to inhibit LPS-inducedTNF release and activation of NF-B pathway in macrophages. However,little is known about the role and mechanism of luteolin onanti-insulin resistance and diabetes. In this study, we investigatedthe role of luteolin in the regulation of inflammatory factor-mediatedinsulin resistance in 3T3-L1 adipocytes. Here we show that luteolintreatment for 24 hrs increased insulin-stimulated glucose uptakein a dose-dependent manner in 3T3-L1 adipocytes. Our resultsalso demonstrated that 24 hour treatment of luteolin enhancedinsulin-stimulated PPAR expression in 3T3-L1 adipocytes. Interestingly,time-dependent serine phosphorylation of insulin receptor substrate1 (IRS-1) by TNF was blocked in 3T3-L1 adipocytes with pretreatmentof luteolin for 30 min. Furthermore, luteolin treatment for24 hrs attenuated LPS-stimulated TNF- secretion from both 3T3-L1preadipocytes and adipocytes. When added to 3T3-L1 cells togetherwith LPS during the entire differentiation process, luteolinantagonized the effect of LPS on the induction of IL-6 geneexpression in 3T3-L1 adipocytes. Thus, our data demonstratethat luteolin plays a protective role in inflammation-mediatedadipocyte dysfunction and insulin resistance.