@article {49076, title = {Aminoacylase efficiently hydrolyses fatty acid amino acid conjugates of Helicoverpa armigera potentially to increase the pool of glutamine}, journal = {Insect Biochemistry and Molecular Biology }, volume = {165}, year = {2024}, month = {FEB}, type = {Article}, abstract = {

One of the most prevalent bioactive molecules present in the oral secretion (OS) of lepidopteran insects is fatty acid amino acid conjugates (FACs). Insect dietary components have influence on the synthesis and retaining the pool of FACs in the OS. We noted differential and diet-specific accumulation of FACs in the OS of Helicoverpa armigera by using Liquid Chromatography-Quadrupole Time of Flight Mass Spectrometry. Interestingly, we identified FACs hydrolyzing enzyme aminoacylase (HaACY) in the OS of H. armigera through proteomic analysis. Next, we have cloned, expressed, and purified active recombinant HaACY in the bacterial system. Recombinant HaACY hydrolyzes all the six identified FACs in the OS of H. armigera larvae fed on host and non-host plants and releases respective fatty acid and glutamine. In these six FACs, fatty acid moieties vary while amino acid glutamine was common. Glutamine obtained upon hydrolysis of FACs by HaACY might serve as an amino acid pool for insect growth and development. To understand the substrate choices of HaACY, we chemically synthesized, purified, and characterized all the six FACs. Interestingly, rHaACY also shows hydrolysis of synthetic FACs into respective fatty acid and glutamine. Our results underline the importance of diet on accumulation of FACs and role of aminoacylase(s) in regulating the level of FACs and glutamine.

}, keywords = {Aminoacylase, Fatty acid amino acid conjugates, Glutamine, Helicoverpa armigera, Oral secretion}, issn = {0965-1748}, doi = {10.1016/j.ibmb.2024.104070}, author = {Kallure, Gopal S. and Sahoo, Shubhranshu Shekhar and Kale, Rutuja S. and Barvkar, Vitthal T. and Kontham, Ravindar and Giri, Ashok P.} } @article {49837, title = {Achmatowicz rearrangement-enabled unified total syntheses of (+)-passifetilactones A-C}, journal = {RSC Advances}, volume = {15}, year = {2025}, month = {OCT}, pages = {39919-39930}, type = {Article}, abstract = {

In this manuscript, we report the enantio- and diastereoselective total synthesis of three cytotoxic 2-pyrone-derived natural products passifetilactones A-C. Our strategy leverages a unified synthetic approach that originates from simple furan-based building blocks. Key transformations include the Corey-Bakshi-Shibata (CBS) reduction to access chiral furan-derived alcohol, NBS-mediated Achmatowicz rearrangement to construct the alpha-hydroxy-delta-pyrone core, followed by a highly stereoselective, iridium-catalyzed dynamic kinetic intramolecular redox isomerization to access the delta-hydroxy-alpha-pyrone framework. This streamlined route enables efficient access to passifetilactones A, B, and C in 13, 5, and 8 steps, with overall yields of 12\%, 54\%, and 37\%, respectively.

}, doi = {10.1039/d5ra06982c}, author = {Verma, Aman Kumar and Jeddi, Dharmaraju and Kontham, Ravindar} } @article {49604, title = {AgOTf-catalyzed cascade annulation of 5-hexyn-1-ols and aldehydes: enabling the diastereoselective synthesis of [6,6,6]-trioxa-fused ketals and hexahydro-2H-chromenes}, journal = {Chemical Communications}, volume = {61}, year = {2025}, month = {JAN }, pages = {973-976}, type = {Article}, abstract = {

We report the unprecedented diastereoselective synthesis of novel [6,6,6]-trioxa-fused ketals via AgOTf-catalyzed cascade annulation of 5-hexyn-1-ols (with primary or secondary hydroxyl groups) and aldehydes through a [2+2+1+1] pathway. In contrast, 5-hexyn-1-ols with tertiary hydroxyl groups yield hexahydro-2H-chromenes via a [3+1+1+1] pathway.

}, issn = {1359-7345}, doi = {10.1039/d4cc05546b}, author = {Vinodkumar, Ramavath and Nakate, Ashwini K. and Krishna, Gamidi Rama and Kontham, Ravindar} }