Thermochimica Acta 577 (2014) 66–78 Contents lists available at ScienceDirect Thermochimica Acta jo ur nal home p age: www.elsevier.com/locate/tca Cosmeceutical active molecules and ethoxylated alkylphenol (Triton X-100) in hydroalcoholic solutions: Transport properties examination Varun Bhardwaj a , S. Chauhan b , Kundan Sharma b , Poonam Sharma a,∗ a Department of Biotechnology, Bioinformatics and Pharmacy, Jaypee University of Information Technology, Waknaghat, Solan 173234, Himachal Pradesh, India b Department of Chemistry, Himachal Pradesh University, Summer Hill, Shimla 173005, Himachal Pradesh, India a r t i c l e i n f o Article history: Received 12 November 2013 Received in revised form 18 December 2013 Accepted 21 December 2013 Available online 2 January 2014 Keywords: Triton X-100 Antioxidant Interaction Spectroscopy a b s t r a c t This present investigation deals with the effect of antioxidants, viz. butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), on properties of nonionic surfactants, i.e. tert-octylphenol ethoxylate (Triton X-100). Considering the significance of micellar solution as carrier, we examined the transport properties by employing controlled approaches. The positive values of apparent molar volume (  ) and apparent molar adiabatic compression (  ) at all temperatures and concentrations are indicative of the existence of hydrophobic interactions. A slight linear increase in viscosity was observed up to a certain concentration of the surfactant and thereafter, a sharp increase confirms the existence of hydrophobic interactions at higher surfactant concentration. Further, from spectroscopic studies, the order of shifting suggests the existence of intermolecular interaction, especially in the hydrophilic region of surfactant. All the studies were found in support of each other with respect to interaction, and would be utilized in different cosmeceutical formulations. © 2013 Elsevier B.V. All rights reserved. 1. Introduction An antioxidant is a bioactive moiety that originally can be referred to molecules that retard or prevent the utilization of oxy- gen by human tissues and are known to prevent the oxidative system as a whole. In recent years, they have been commonly employed in combination with many drugs and bioactive com- pounds [1,2]. However, when misused they may affect and cause serious harm to human health. To overcome the arising health and microbial resistance problems, antioxidants have emerged as potential indispensable candidates that inhibit oxidation reaction and retard the process of oxidative degradation of pharmaceuti- cal and cosmetic products [3–5]. On the contrary, surfactants are extensively employed as emulsifiers and as physical stabilizing, wetting and suspending agents in many topical pharmaceutical formulations and cosmetic products. Above the critical micelle con- centration (CMC), surfactants are well known to self-associate to form thermodynamically stable and noncovalent aggregates called micelles [6]. The micelles have structural similarity with lipids ∗ Corresponding author. Tel.: +91 1792 239389; fax: +91 1792 245362. E-mail addresses: varunmilton@yahoo.com (V. Bhardwaj), drpoonamsharma@rediffmail.com (P. Sharma). because of their hydrophobic interior and hydrophilic surface. They mimic biomembrane and their structure provides an interest- ing alternative to study the interaction of pharmacological active agents with membrane [7]. Moreover, surfactants are well known for their effects on the permeability characteristics of several biological membranes such as epidermal skin layer [8], and for this reason they can enhance the skin penetration of other com- pounds present in the formulation. Therefore, in recent years they have been employed to enhance the permeation rates of sev- eral drugs/cosmetic products [9]. Nonionic surfactants represent an important class of amphiphiles which find extensive applica- tions in pharmaceutical formulations [10,11]. The effectiveness and the applicability depend on their structural and solution prop- erties. The presence of additives such as co-solute affects the physicochemical properties of a surfactant and provides valuable information with regard to structural change and interactions in the solution [12]. The mechanism by which nonionic surfactants adsorb onto a hydrophobic surface is based on a strong hydrophobic attrac- tion between the solid surface and the surfactant’s hydrophobic tail. In continuation of our interest in bioactive compounds [13,14], we studied the effect of two hydrophobic synthetic antioxidants (as pictured below), viz. butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), in terms of physicochemical interaction and behavior of Triton X-100 (tert-octylphenol ethoxylate). BHA is available in the form of isomeric organic compounds, i.e. 2-tert- butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole, and 0040-6031/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tca.2013.12.014