Interaction of Cationic CTAB Surfactant with Curcumin, an Anticarcinogenic Drug: Spectroscopic Investigation

Abstract

Abstract Curcumin, the most active polyphenolic constituent of turmeric cucuminoids obtained from rhizome Curcuma longa, holds a high place in ayurvedic medicine but its role in conventional disease management is also established. Unfortunately, the compound has poor aqueous solubility, which results in poor bioavailability following high doses by oral administration. In order to enhance its effectiveness and improve bioavailability, surfactant assemblies as the colloidal drug carriers with desired properties have been largely utilized. The interaction of curcumin with cetyltrimethylammonium bromide (CTAB) surfactant has been investigated by absorption spectroscopy as a function of surfactant concentration in pre-micellar and micellar range at acidic pH of 6.4. The pre-micellar and micellar region of pure CTAB surfactant at acidic pH of 6.4 is examined through tensiometry and conductometry techniques. Spectral data shows that in presence of curcumin at lower CCTAB, the change in absorbance and peak form initially was assigned to attraction of positive head group of CTAB towards the β-diketone group of drug. In micellar region including CMC, the type of interaction corresponds to the attachment of C16 chains of CTAB to nonpolar aryl groups of drug and simultaneously displacement of polar head group from β-diketone group of the drug. Finally at post micellar CCTAB, the encapsulation of the curcumin into micelles, predominantly in intact monomeric form is observed with the sharp peak at λmax = 423 nm.