International Journal of Biological Macromolecules 76 (2015) 203–208 Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Liposomal thymoquinone effectively combats fluconazole-resistant Candida albicans in a murine model Masood Alam Khan a , Ahmad N. Aljarbou b , Arif Khan a , Hina Younus c,∗ a Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, Buraidah 51452, Saudi Arabia b Department of Pharmaceutics, College of Pharmacy, Qassim University, Buraidah 51452, Saudi Arabia c Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India a r t i c l e i n f o Article history: Received 20 November 2014 Received in revised form 4 February 2015 Accepted 8 February 2015 Available online 20 February 2015 Keywords: Drug delivery Fluconazole-resistant Systemic candidiasis Thymoquinone a b s t r a c t The aim of the present study was to develop a novel liposomal formulation of thymoquinone (TQ) to treat fluconazole-susceptible and -resistant Candida albicans (C. albicans) infections. The liposomal preparation of TQ (Lip-TQ) was used against a fluconazole-susceptible or -resistant isolate of C. albicans. Various doses of fluconazole (0, 5, 10, 20 and 40 mg/kg) or free TQ or Lip-TQ (0, 1, 2 and 5 mg/kg) were used to treat C. albicans infected mice. Mice were observed for 40 days post C. albicans infection, and their kidneys were assessed for the fungal load. Fluconazole showed anti-fungal activity against the drug- susceptible, but not against the -resistant isolate of C. albicans. Free TQ showed its activity against both fluconazole-susceptible or -resistant C. albicans, however, Lip-TQ was found to be the most effective and imparted ∼100% and ∼90% survival of mice infected with fluconazole-susceptible and -resistant isolates of C. albicans, respectively. Mice treated with Lip-TQ showed highly reduced severity of infection in their tissue homogenates. Therefore, Lip-TQ may effectively be used in the treatment of C. albicans infections, including those which are not responding to fluconazole. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Candida albicans is an opportunistic pathogen infecting the skin, mouth, gut and other mucous membranes [1,2]. Immunocompro- mised persons, such as patients undergoing chemotherapy or organ transplantation, or infected with HIV are easy targets of C. albicans [3–6]. Currently there are not many antifungals available and recent trends of emergence of azole-resistant C. albicans are worrisome and threatening [7–10]. Amphotericin B has been a “gold standard” drug for systemic and deep-seated C. albicans infections, however the associated acute hepatic and renal toxicity limits its use in human beings [11–13]. TQ, a major bioactive constituent of Nigella sativa seeds, has been shown to possess anti-oxidant, anti-inflammatory and anti-diabetic properties [14,15]. It protects against drug-induced toxicity and also shows anticancer and antitumor properties [16–19]. TQ has earlier been reported to have a good efficacy in the treatment of allergic lung inflammation, asthma and rheuma- toid arthritis [20,21]. It has also been recently reported to have antiglycating activity and hence this makes it an effective com- pound against diabetic complications [22]. ∗ Corresponding author. Tel.: +91 571 2720 388; fax: +91 571 272 1776. E-mail address: hinayounus@rediffmail.com (H. Younus). Liposomes act as an excellent delivery system for polyene anti- fungal drugs, because they reduce the toxicity and increase their therapeutic index [12,13,23]. Despite many therapeutic applica- tions, yet the use of TQ is limited because of its poor solubility in aqueous medium. In order to increase the solubility and bioavail- ability, TQ seems to be an ideal drug to be used as a liposomal formulation. It has been shown that TQ-loaded carriers inhibited the proliferation of various cancerous cells [24]. The application of TQ has not been explored in the treatment of infectious diseases. In the present study, we determined the action of TQ liposomes in a murine model of systemic candidiasis, which was not responding to fluconazole therapy. 2. Materials and methods 2.1. Materials DPPC (Cat. no. 850355P) and cholesterol (Cat. no. 700100P) were purchased from Avanti Polar Lipids (Alabaster, Alabama, USA). TQ (Cat. no. SC-215986) was purchased from Santa Cruz Biotechnology (Dallas, TX, USA). Fluconazole (Cat. no. 3764) was purchased from Tocris Biosciences (Bristol, UK). Sabouraud dextrose agar (M063) was obtained from HiMedia Company (Mumbai, India). RPMI (Cat. no. R8758) was purchased from Sigma Chemical Company (St. Louis, MO, USA). http://dx.doi.org/10.1016/j.ijbiomac.2015.02.015 0141-8130/© 2015 Elsevier B.V. All rights reserved.