Kothakonda Rajendra Prasad

Synthesis and biological evaluation of new piplartine analogues as potent aldose reductase inhibitors (ARIs)

As a continuation of our efforts directed towards the development of anti-diabetic agents from natural sources, piplartine was isolated from Piper chaba, and was found to inhibit recombinant human ALR2 with an IC(50) of 160 μM. To improve the efficacy, a series of analogues have been synthesized by modification of the styryl/aromatic and heterocyclic ring functionalities of this natural product lead. All the derivatives were tested for their ALR2 inhibitory activity, and results indicated that adducts 3c, 3e and 2j prepared by the Michael addition of piplartine with indole derivatives displayed potent ARI activity, while the other compounds displayed varying degrees of inhibition. The active compounds were also capable of preventing sorbitol accumulation in human red blood cells.

Total syntheses of the proposed structure for ieodoglucomides A and B.

The first enantioselective total synthesis of new glycolipopeptides, ieodoglucomides A and B, has been accomplished along with synthetic elaboration to their C14-epimers starting from d-glucose using β-glycosylation and Grubbs olefin cross-metathesis reactions as the key steps. The present synthetic study has indicated the ambiguity in proposed absolute stereochemistry for the natural product.

Synthesis of new chromeno-annulated cis-fused pyrano[4,3-c]isoxazole derivatives via intramolecular nitrone cycloaddition and their cytotoxicity evaluation

New cis-fused chromeno pyrano[4,3-c]isoxazole derivatives have been synthesized by intramolecular [1,3]-cycloaddition of the nitrones generated in situ from hydroxylamine derivatives and 7-O-prenyl derivatives of 8-formyl-2,3-disubstituted chromenones using PEG-400 as a reaction medium under catalyst-free conditions good to excellent yields. The structures were established by spectroscopic data and further confirmed by X-ray diffraction analysis. The results showed that compounds 4b, 4c, 4d, 4e and 4k exhibit very potent antiproliferative activity against MDA-MB-231 breast cancer cells. Compounds 4a, 4c, 4e, 4i and 4k displayed potent inhibitory activity against human MCF-7 breast cancer cell lines. Compounds 4h and 4i exhibited significant anti-proliferative activity against human cervical cancer cell line, HeLa. While 4b, 4d and 4j were active against human lung cancer cell line, A549. In addition, Compound 4j was found to be the most promising against A549 (Lung cancer) with IC50 value of 0.194 μM.

Two new sesquiterpenoids from the rhizomes of Nardostachys jatamansi.

Phytochemical investigation of CHCl3:MeOH (1:1) extract from the rhizomes of Nardostachys jatamansi led to the isolation of two new sesquiterpenoids (5 and 6), along with six known compounds (1–4, 7, and 8). The structures of two new compounds were established using IR, MS, 1D, and 2D NMR techniques. In addition, all the isolates were tested for their cytotoxicities against the A549 (lung cancer), DU-145 (prostate cancer), MCF-7 (breast cancer), and SK-N-SH (neuroblastoma).