Exploration of possible biosynthetic origin of 1/8/9-orthoester moiety in phragmalins

Research progress of meliaceous limonoids from 2011 to 2021

“…460 Natural phragmalin-type 1/8/9-orthoesters (major existence) were transformed from phragmalins with esteried substituent at the C-1 and hydroxyl groups at C-8 and C-9. 461 Tabulalin, as a ne precursor with free 1/8/9-hydroxy groups,…”

“…Among them, 3-O-isovalerylswietenolide and 3-O-isobutyrylswietenolide showed excellent antifeedant activity with DC 50 values of 0.19 and 0.009 mg L À1 , respectively, compared with the natural limonoid swietenolide (80.6 mg L À1 ) against fourth-instar Spodoptera frugiperda larvae. 254,465 By similar modication strategies, analogs of granatumin L were synthesized and evaluated for human immunodeciency virus 1 (HIV-1) and inuenza A virus (IAV); a number of derivatives were found to be more potent than granatumin L. 461 Epoxyazadiradione, as a ring-intact limonoid derived from Neem oil with modest antiplasmodial activity, has multiple key structural moieties including a,b-unsaturated ketone, 7-acetoxy, 17-ketocarbonyl, and furan residues. In 2017, Babu and coworkers' ndings demonstrated that the epoxyazadiradione scaffold can be modied to enhance antiplasmodial and cytotoxic activities.…”

“…460 Natural phragmalin-type 1/8/9-orthoesters (major existence) were transformed from phragmalins with esterified substituent at the C-1 and hydroxyl groups at C-8 and C-9. 461 Tabulalin, as a fine precursor with free 1/8/9-hydroxy groups, may be converted into 1/8/9-orthoesters by acetylation and protonation. Furthermore, the reversible conversion and transesterification mechanism of 8/9/11-and 8/9/30-orthoesters have been reported under acid-catalyzed conditions.…”

“…Among them, 3- O -isovalerylswietenolide and 3- O -isobutyrylswietenolide showed excellent antifeedant activity with DC 50 values of 0.19 and 0.009 mg L −1 , respectively, compared with the natural limonoid swietenolide (80.6 mg L −1 ) against fourth-instar Spodoptera frugiperda larvae. 254,465 By similar modification strategies, analogs of granatumin L were synthesized and evaluated for human immunodeficiency virus 1 (HIV-1) and influenza A virus (IAV); a number of derivatives were found to be more potent than granatumin L. 461…”