First Vesicular Self‐Assembly of an Apocarotenoid Bixin in Aqueous Liquids and Its Antibacterial Activity

Abstract Bixin 1 is the major constituent of the reddish carotenoids present in the seed‐coat of Bixa orellana . The use of the extract of the seed‐coat of Bixa orellana in food, cosmetics and garments is well known. The nano‐sized long 24 C chain molecule has nine conjugated double bonds having extended conjugation with the ‘‐COOH’ and ‘‐COOMe’ groups present at the two ends of the molecule. Herein, we report the first self‐assembly of bixin in several aqueous liquids. The molecule undergoes spontaneous self‐assembly in several liquids yielding vesicular self‐assembly. Characterizations of the self‐assemblies of bixin were carried out by various microscopic techniques, X‐ray diffraction and FTIR studies. The critical vesicular concentrations (CVCs) of the compound carried out in DMSO‐water in three different solvent ratios as 2: 1 (v/v), 1: 1 (v/v) and 1: 4 (v/v) were determined to be 100 μM, 90 μM and 60 μM respectively indicating lower CVC values at higher proportion of water. Utilization of the vesicular self‐assemblies of bixin have been demonstrated in the entrapment and release of fluorophores including the anticancer drugs doxorubicin and curcumin. Self‐assembled bixin and curcumin loaded self‐assembled bixin showed significant antibacterial activity with both Gram positive as well as Gram negative bacteria.