K. Papi Reddy

Synthesis of novel triterpenoid (lupeol) derivatives and their in vivo antihyperglycemic and antidyslipidemic activity.

The triterpenoid, lupeol (1) has been isolated from the leaves extract of Aegle marmelos. Few novel derivatives (2-13) were synthesized from the naturally occurring lupeol (1) and screened for their antihyperglycemic activity (2-11) and antidyslipidemic activity (2-4 and 12-13). The derivative 4 lowered the blood glucose levels by 18.2% and 25.0% at 5h and 24h, respectively, in sucrose challenged streptozotocin induced diabetic rats (STZ-S) model at the dose of 100mg/kg body weight. The compound 4 also significantly lowered 40% (P <0.001) in triglycerides, 30% (P <0.05) in glycerol, 24% (P <0.05) in cholesterol quantity and also improved the HDL-cholesterol by 5% in dyslipidemic hamster model at the dose of 50mg/kg b.wt.

Peganine hydrochloride dihydrate an orally active antileishmanial agent.

Protozoic infections caused by genus Leishmania pose an enormous public health threat in developing countries, compounded by the toxicity and resistance to current therapies. Under the aegis of our ongoing program on drug discovery and development on antileishmanial agents from plants, we carried out bioassay guided fractionation on Peganum harmala seeds which resulted in the isolation of 1 as an antileishmanial agent. 2D-NMR spectral data and single crystal X-ray crystallography data indicated 1 as peganine hydrochloride in dihydrated form. The compound 1 exhibited in-vitro activity against both extracellular promastigotes as well as intracellular amastigotes residing within murine macrophages in Leishmania donovani. Furthermore, 1 also exhibited in-vivo activity, 79.6 (+/-8.07)% against established VL in hamsters at a dose of 100mg/kgb.wt.

In vitro and in vivo anticancer activity of 2-deacetoxytaxinine J and synthesis of novel taxoids and their in vitro anticancer activity

The taxane diterpneoid 2-deacetoxytaxinine J (2-DAT-J) 1 has been isolated from the bark of Himalayan yew, Taxus baccata L. spp. wallichiana in a reasonably good yield (0.1%) and its anticancer activity against breast cancer cell lines (MCF-7 and MDA-MB-231) and normal human kidney epithelial cell line (HEK-293) has been studied. 2-DAT-J (1) showed significant in vitro activity against breast cancer cell line at a concentration of 20 microM and 10 microM in MCF-7 and MDA-MB-231 respectively. Few novel taxoids were derived (7, 8 and 10-13) from the naturally occurring 2-DAT-J (1) and screened for their anticancer activity. The structure-activity relationship studies indicated that the cinnamoyl group on C-5 and acetyl group on C-10 are essential for the anticancer activity. 2-DAT-J (1) was also tested for its in vivo activity on DMBA-induced mammary tumors in virgin female Sprague Dawley rats at a dose of 10mg/kg body weight orally for 30 days and showed significant regression in mammary tumors as compared to vehicle treated group (p<0.05).

NaOAc-Mediated Selective Deprotection of Aromatic Acetates and Its Application in the Synthesis of Natural Products

Abstract We have developed an efficient method to deacetylate the aromatic acetates using NaOAc in excellent yields and demonstrated the application of the procedure in the synthesis of natural products.

BF3-Et2O-Mediated One-Pot Synthesis of Acetylchromans from Polyhydroxyacetophenones and Isoprene/Allyl Alcohol

Abstract A convenient one-pot method has been developed for the synthesis of substituted acetylchromans involving the condensation of polyhydroxyacetophenone with isoprene and long chain allylic alcohol (phytol) in the presence of borontrifluoride etherate (BF3-Et2O).

H2SO4-Promoted Synthesis of (E)-Stilbenes from Substituted Phenylacetones and Substituted Benzaldehydes Through Tandem Aldol–Grob Reaction

Abstract Stilbene derivates (stilbenoids) are present in plants and show a wide range of biological activities and potential therapeutic value. In continuation of our natural product synthesis program, an efficient, simple, and practical method has been developed to regioselectively synthesize (E)-stilbenes using H2SO4 as a catalyst in a short time (30–60 s) at room temperature in good to excellent yields.

An unprecedented biogenetic-type chemical synthesis of 1(15-->11) abeotaxanes from normal taxanes.

A one-pot chemical process using BF(3).Et(2)O for the synthesis of a new class of 1(15-->11) abeotaxanes from normal taxanes has been developed. The chemical structures of rearranged 1(15-->11) abeotaxane were established by extensive 2D NMR spectroscopic data.

Highly Efficient and Selective Deprotection Method for Prenyl, Geranyl, and Phytyl Ethers and Esters Using Borontrifluoride–Etherate

Abstract An efficient, simple, and practical method has been developed for the deprotection of prenyl, geranyl, and phytyl ethers and esters of aromatic and aliphatic compounds using borontrifluoride–etherate (BF3 · OEt2) at room temperature in good to excellent yields for the first time. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT