Sukanya Pandeti

Synthesis of new andrographolide derivatives and evaluation of their antidyslipidemic, LDL-oxidation and antioxidant activity

Andrographis paniculata, native to Taiwan, Mainland China and India, is a medicinal herb, which possesses various biological activities including anti-atherosclerosis. Andrographolide (1) has been identified as one of the active constituents against atherosclerosis. In continuation of our drug discovery program we synthesized few novel derivatives of 1 to improve their antidyslipidemic, LDL-oxidation and antioxidant activity. The tosylated derivative 7 has been turned out to be more potent than the parent compound and comparable activity with marketed antidyslipidemic drugs.

Synthesis of novel anticancer iridoid derivatives and their cell cycle arrest and caspase dependent apoptosis.

Nyctanthes arbortristis Linn (Oleaceae) is widely distributed in sub-Himalayan regions and southwards to Godavari, India commonly known as Harsingar and Night Jasmine. In continuation of our drug discovery programme on Indian medicinal plants, we isolated arbortristoside-A (1) and 7-O-trans-cinnamoyl 6β-hydroxyloganin (2) from the seeds of N. Arbortristis, which exhibited moderate in vitro anticancer activity. Chemical transformation of 2 led to significant improvement in the activity in derivative 8 and 15 against HepG2 (human hepatocellular carcinoma), MCF-7 (breast adenocarcinoma) cell lines. The compounds 8 and 15 were also capable of cell cycle arrest and caspase dependent apoptosis in HepG2 cell lines. These iridoid derivatives hold promise for developing safer alternatives to the marketed drugs.

Cytoprotective and Anti‐secretory Effects of Azadiradione Isolated from the Seeds of Azadirachta indica (neem) on Gastric Ulcers in Rat Models

Azadirachta indica is well known medicinal plant mentioned in ancient herbal texts. It has been extensively used in Ayurvedic, Unani and Homoeopathic medicine and has become a luminary of modern medicine. As part of our drug discovery program we isolated azadiradione from the ethanolic extract of seeds of A. indica and evaluated for in‐vivo antiulcer activity in cold restraint induced gastric ulcer model, aspirin induced gastric ulcer model, alcohol induced gastric ulcers model and pyloric ligation induced ulcer model. Azadiradione exhibited potent antiulcer activity through the inhibition of H+ K+‐ATPase (proton pump) activity via its cytoprotective effect and also via its antisecretory effect. This combined effect has valuable potential in the future treatment of peptic ulceration. Copyright

Anti-malarial Activity of New Emodin Derivatives against Plasmodium falciparum Chloroquine Resistant Strain

Emodin (1) is the major bioactive compound of several herb species, which belongs to anthraquinone class of compound. As a part of our drug discovery program, large quantities of emodin (1) was isolated from the roots of Rheum emodi and a library of novel emodin derivatives 2–24 were prepared to evaluate their in-vitro antimalarial activity, among them, compound 17, 18 and 20 showed potent antimalarial activity against chloroquine resistant strain PfK1with the IC50 of 2.28, 2.49 and 2.48 μM respectively with a high safety index.

Arbortristoside-A and 7-O-trans-cinnamoyl-6β-hydroxyloganin isolated from Nyctanthes arbortristis possess anti-ulcerogenic and ulcer-healing properties

Nyctanthes arbortristis Linn (Oleaceae) is widely distributed in sub-Himalayan regions and southwards to Godavari, India commonly known as Harsingar and Night Jasmine. In continuation of our drug discovery program on Indian medicinal plants, we isolated arbortristoside-A (AT) and 7-O-trans-cinnamoyl-6β-hydroxyloganin (6-HL) from the seeds of N. arbortristis. AT and 6-HL exhibited anti ulcer activity in experimentally induced ulcer models including cold restraint stress (CRU), alcohol (AL), pylorus ligation-induced gastric ulcer (PL) models and they also showed ulcer healing effect in chronic acetic acid-induced ulcer model (AC).

Deoxyandrographolide promotes glucose uptake through glucose transporter-4 translocation to plasma membrane in L6 myotubes and exerts antihyperglycemic effect in vivo.

Skeletal muscle is the principal site for postprandial glucose utilization and augmenting the rate of glucose utilization in this tissue may help to control hyperglycemia associated with diabetes mellitus. Here, we explored the effect of Deoxyandrographolide (DeoAn) isolated from the Andrographis paniculata Nees on glucose utilization in skeletal muscle and investigated its antihyperglycemic effect in vivo in streptozotocin-induced diabetic rats and genetically diabetic db/db mice. In L6 myotubes, DeoAn dose-dependently stimulated glucose uptake by enhancing the translocation of glucose transporter 4 (GLUT4) to cell surface, without affecting the total cellular GLUT4 and GLUT1 content. These effects of DeoAn were additive to insulin. Further analysis revealed that DeoAn activated PI-3-K- and AMPK-dependent signaling pathways, account for the augmented glucose transport in L6 myotubes. Furthermore, DeoAn lowered postprandial blood glucose levels in streptozotocin-induced diabetic rats and also suppressed the rises in the fasting blood glucose, serum insulin, triglycerides and LDL-Cholesterol levels of db/db mice. These findings suggest the therapeutic efficacy of the DeoAn for type 2 diabetes mellitus and can be potential phytochemical for its management.

Glucose uptake stimulatory potential and antidiabetic activity of the Arnebin-1 from Arnabia nobelis.

The enhanced disposal of glucose by the peripheral tissue is an important mechanism to regulate hyperglycemia. Here, we investigated the effect of Arnebin-1 from Arnebia nobilis, on glucose disposal in skeletal muscle cells and explored its in vivo antihyperglycemic potential. In L6 myotubes, Arnebin-1 stimulated glucose uptake, mediated through the enhanced translocation of the glucose transporter-4 (GLUT4) to plasma membrane, without changing the amount of GLUT4 or GLUT1. These effects of Arnebin-1 were synergistic with that of insulin. The effect of Arnebin-1 on glucose uptake was abolished in presence of wortmannin, and Arnebin-1 significantly stimulated the phosphorylation of Akt and downstream marker GSK-3β. Moreover, treatment with Arnebin-1 lowered postprandial blood glucose levels in streptozotocin-induced diabetic rats, and improved glucose tolerance and suppressed the rises in the fasting blood glucose, serum insulin, triglycerides, and total cholesterol in db/db mice, associated with enhanced expression of the major marker of the PI-3-Kinase-mediated signaling cascade in skeletal muscle. These findings suggest that Arnebin-1 exert antihyperglycemic activity through stimulating glucose disposal in peripheral tissues via PI-3-Kinase-dependent pathway.

Aegeline inspired synthesis of novel β3-AR agonist improves insulin sensitivity in vitro and in vivo models of insulin resistance

BACKGROUND AND PURPOSE In our drug discovery program of natural product, earlier we have reported Aegeline that is N-acylated-1-amino-2- alcohol, which was isolated from the leaves of Aeglemarmelos showed anti-hyperlipidemic activity for which the QSAR studies predicted the compound to be the β3-AR agonist, but the mechanism of its action was not elucidated. In our present study, we have evaluated the β3-AR activity of novel N-acyl-1-amino-3-arylopropanol synthetic mimics of aegeline and its beneficial effect in insulin resistance. In this study, we have proposed the novel pharmacophore model using reported molecules for antihyperlipidemic activity. The reported pharmacophore features were also compared with the newly developed pharmacophore model for the observed biological activity. EXPERIMENTAL APPROACH Based on 3D pharmacophore modeling of known β3AR agonist, we screened 20 synthetic derivatives of Aegeline from the literature. From these, the top scoring compound 10C was used for further studies. The in-slico result was further validated in HEK293T cells co-trransfected with human β3-AR and CRE-Luciferase reporter plasmid for β3-AR activity.The most active compound was selected and β3-AR activity was further validated in white and brown adipocytes differentiated from human mesenchymal stem cells (hMSCs). Insulin resistance model developed in hMSC derived adipocytes was used to study the insulin sensitizing property. 8 week HFD fed C57BL6 mice was given 50 mg/Kg of the selected compound and metabolic phenotyping was done to evaluate its anti-diabetic effect. RESULTS As predicted by in-silico 3D pharmacophore modeling, the compound 10C was found to be the most active and specific β3-AR agonist with EC50 value of 447 nM. The compound 10C activated β3AR pathway, induced lipolysis, fatty acid oxidation and increased oxygen consumption rate (OCR) in human adipocytes. Compound 10C induced expression of brown adipocytes specific markers and reverted chronic insulin induced insulin resistance in white adipocytes. The compound 10C also improved insulin sensitivity and glucose tolerance in 8 week HFD fed C57BL6 mice. CONCLUSION This study enlightens the use of in vitro insulin resistance model close to human physiology to elucidates the insulin sensitizing activity of the compound 10C and edifies the use of β3AR agonist as therapeutic interventions for insulin resistance and type 2 diabetes.