Using Nature's polyenes as templates: studies of synthetic xanthomonadin analogues and realising their potential as antioxidants

Abstract

Two truncated analogues of polyenyl photoprotective agent xanthomonadin were synthesised using iterative cross coupling and investigated as model photoprotective agents in bacteria.

The cyl Genes Reveal the Biosynthetic and Evolutionary Origins of the Group B Streptococcus Hemolytic Lipid, Granadaene

“…Given the phyletic patterns, we hypothesize that the ancient cyl operon evolved in free-living bacteria, where we conceive possible biological roles that might not be mutually exclusive. First, the ornithine rhamnolipid might be involved in photoprotection and/or membrane stabilization, as with many microbial pigments (Taylor, 1984;Howardwilliams et al, 1989;Rajagopal et al, 1997;Slouf et al, 2012;Madden et al, 2019). Second, it might have evolved as a general defense against competing organisms in which the pigment disrupts their cell membrane.…”

Stereoselective Synthesis of Conjugated Polyenes Based on Tethered Olefin Metathesis and Carbonyl Olefination: Application to the Total Synthesis of (+)-Bretonin B

“…8 The most commonly used methods for the total synthesis of polyene natural products are Pd-catalyzed coupling and cross coupling reactions. 2 These methods have been successfully applied in several cases, e.g., very recently for the synthesis of xanthomonadin analogues, 7 in the construction of the Z,Z,Econfigured triene moiety in fostriecin, 9 and in an iterative approach to a truncated amphotericin B fragment. 10 The stereoselective synthesis of the required coupling partners, such as ω-iodoor ω-bromodienes and vinyl metal compounds, can be a drawback because these often start from unstable haloenals 11 that are then subjected to carbonyl olefination reactions in order to furnish iodo-or bromodienes.…”

“…The stereoselective construction of polyenes is a challenging task in natural product synthesis, , as products and intermediates are often prone to decomposition through photochemical , or oxidative pathways. − In those cases where one or more double bonds are Z -configured, isomerization to all E -isomers, which are in general more stable, arises as an additional problem . The most commonly used methods for the total synthesis of polyene natural products are Pd-catalyzed coupling and cross coupling reactions .…”

Three new species,Xanthomonas hawaiiensissp. nov.,Stenotrophomonas aracearumsp. nov., andStenotrophomonas oahuensissp. nov., isolated from Araceae family

“…The well-known industrial biopolymer and food additive is xanthan gum produced from X. campestris and other Xanthomonas species (Margaritis and Zajic, 1978; Kennedy and Bradshaw, 1984; Gumus et al 2010). Other productions of bioactive secondary metabolites from xanthomonads are pigment xanthomonadin, analogues of which have antioxidant potential, and xanthoferrin, which acts as a bioproduction agent under low iron conditions (Madden et al 2019; Pandey et al 2017). The increasing number of studies on non-pathogenic xanthomonads isolated from rice, banana, citrus, walnut and so on suggest they have the potential of biocontrol and bioprotection against the causal agent of their host plants (Bansal et al 2021; Rana et al 2022; Fernandes et al 2021).…”