(E)-9-oxooctadec-10-en-12-ynoic acid from Ixora brachiata Roxb. increases glucose uptake in L6 myotubes by activating the PI3K pathway.

In an attempt to discover new scaffolds for anti-diabetic activity from plants, we screened extracts from Ixora brachiata Roxb. for their effect on glucose uptake in L6 myotubes. The petroleum (PE) extract of the plant showed a significant increase in insulin stimulated glucose uptake by L6 myotubes. The bioactivity guided fractionation of the crude extract yielded a compound (E)-9-oxooctadec-10-en-12-ynoic acid (OEA). The compound induced a dose dependent increase in insulin stimulated glucose uptake in L6 myotubes with an EC50 of 22.96µM. OEA also increased the phosphorylation of IRS-1, Akt and AS160 leading to increased GLUT4 translocation to the plasma membrane indicating that it promotes insulin stimulated glucose uptake in L6 myotubes by activating the PI3K pathway.

NF-κB dependent anti-inflammatory activity of chlorojanerin isolated from Saussurea heteromalla.

Medicinal plants have shown great promise as a source of novel drug compounds for the treatment of inflammatory disorders. In our search for new entities with anti-inflammatory potential, the extracts of the whole plant of Saussurea heteromalla (family-Asteraceae), collected from Himalayas, were evaluated in the high throughput screen for TNF-α and IL-6 inhibitors. The extract blocked TNF-α and IL-6 production in LPS stimulated THP-1 cells (human acute monocyte leukemia cell line) completely at 10 and 30 µg/ml. The plant has been found as a new source of chlorojanerin, a guaianolide type of sesquiterpene lactone. Chlorojanerin was shown to be significantly effective in inhibiting TNF-α and IL-6 production in LPS-stimulated THP-1 cells (IC(50)=2.3±0.2 µM and 1.8±0.7 µM respectively). The compound also blocked TNF-α and IL-6 production from LPS-stimulated human monocytes (IC(50)=1.5±0.4 and 0.7±0.2 µM respectively) and synovial cells from a patient with rheumatoid arthritis (IC(50)<0.03 and 0.5 µM respectively). Transcriptional profiling of the LPS stimulated THP-1 cells revealed that chlorojanerin exerted its anti-inflammatory effect by inhibiting the expression of 8 genes involved in activating the transcription factor - NF-κB. Real time analysis of these genes validated the effect of chlorojanerin on the classical downstream targets of NF-κB. Thus, this study clearly delineated 8 genes which were specifically mitigated due to the effect of chlorojanerin on NF-κB induced signaling at the mRNA level. Further, chlorojanerin at 5 µM also inhibited the binding of NF-κB in a GFP reporter assay system by 55.5% thus validating the microarray gene expression data. This work is a step towards the isolation and characterization of lead anti-inflammatory agents from the extract of Saussurea heteromalla, which can be developed into better therapeutic molecules targeted towards some specific inflammatory diseases.

Plant-derived compounds in clinical trials.

Plants remain an important source of new drugs, new drug leads and new chemical entities. The plant-based drug discovery resulted mainly in the development of anticancer and anti-infectious agents and continues to contribute to the new leads in clinical trials. A total of 91 plant-derived compounds in clinical trials as of September 2007 are described in this review. A summary of the plant-based drugs launched during 2000-2006 is given.