Maryam Ravaghi; Anna Maria Fadda
Abstract
Introduction: Curcumin is the main ingredient of turmeric spice, derived from rhizome of the Curcuma longa. It is a hydrophobic material with low bioavailability which is rapidly removed from the body due to its instability under physiological conditions and inadequate absorption. Curcumin is a polyphenol ...
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Introduction: Curcumin is the main ingredient of turmeric spice, derived from rhizome of the Curcuma longa. It is a hydrophobic material with low bioavailability which is rapidly removed from the body due to its instability under physiological conditions and inadequate absorption. Curcumin is a polyphenol and one of the most widely explored natural pharmacological agents in nanomedicine due to its high in vitro activity and low systemic bioavailability in vivo. In recent years, many efforts have been made to increase its therapeutic potential for disease prevention and health promotion, by using specific nano-delivery systems. Delivery and accumulation of curcumin in the intestine may represent an attractive strategy to improve its systemic absorption and bioavailability. The incorporation of curcumin in phospholipid vesicles (liposomes) may modulate its accumulation and be released, but do not improve its stability in the gastrointestinal environment due to the phospholipid degradation. An appropriate combination of phospholipid and polymer may provide a suitable strategy to protect the vesicles, resulting in an amelioration of curcumin intestinal deposition and bioavailability. In the present work, the potential use of Eudragit and hyaluronan to complex phospholipids was investigated, thus forming gastroresistant vesicles able to deliver the curcumin to the low intestine.
Materials and Methods: Soy phosphatidylcholine S75 (purity of 70%) and P90G (purity of 94%) were purchased from Lipoid GmbH (Germany). Sodium hyaluronate or hyaluronan with low molecular weight (200–400 kDa) was purchased from DSM Nutritional Products AG Branch Pentapharm (Switzerland). Eudragit S100 and L100 with molecular weight about 125 kDa were provided by Evonik Industries
AG (Germany). Curcumin and other chemicals were analytical grade and procured from Sigma-Aldrich (Italy). This paper was aimed to find a liposome type formulation to immobilize the phospholipid structures, and to protect liposomes and enhance curcumin stability from simulated gastrointestinal conditions. To this purpose, phospholipid (P90G and S75), sodium hyaluronate and Eudragit (S100 and L100) were combined to obtain immobilized liposomes and drug. Liposomes were formed by hydration, combined with sonication using a high intensity ultrasonic disintegrator (Soniprep 150 plus, UK). The average diameter, polydispersity index (PDI) and zeta potential were determined using a Zetasizer nano-ZS (Malvern Instruments, United Kingdom). Entrapment efficiency (EE%) was calculated as the percentage of the drug amount found after dialysis (Spectra/Por® membranes, 12–14 kDa MW cut off, 3 nm pore size, The Netherlands) versus that initially used. Curcumin content was estimated spectrophotometrically at λmax=424 nm by a Perkin Elmer UV/visible spectrophotometer (Lambda 25, USA) after disruption of liposomes. Vesicle formation and morphology were checked by cryogenic electron transmission microscopy, using a Tecnai F20 TEM (FEI Company, The Netherlands). The average diameter, PDI, zeta potential and EE% of the vesicles produced using Eudragit S100 and L100 were measured after 1 month incubation at 4°C to determine their stability. Vesicle behaviour was also measured in fluids at pH 2 and 7 and high ionic strength immediately after dilution, at 2h and 6 h. Data are expressed as mean±standard deviation (n=3 independent samples). Analysis of the data was made using SAS statistical software (version 9.0). Comparison among the means was carried out by Duncan’s multiple range test at p800 nm) and polydispersed (>0.8). In this work, the Eudragit was dispersed in ethanol with the curcumin, leading to a homogeneous, yellow transparent solution, and the curcumin and hyaluronan were dispersed in water. After freeze drying and rehydration with water, the vesicle size and polydispersity decreased, leading to the formation of more suitable systems. Liposomes of Eudragit were spherical or oval, multi-lamellar or large uni-lamellar vesicles with some smaller vesicles inside. These liposomes had high entrapment efficiency (>80%) immediately after production without significant decrease after storage. Liposomes of Eudragit S100 had smaller vesicles (287±31 nm) compared to those of Eudragit L100 (407±33 nm) after preparation Moreover, vesicles containing Eudragit S100 showed better stability during storage. Immobilization of liposomes in polymeric network of hyaluronan-Eudragit increased their stability against the mimicking conditions of gastrointestinal tract such as high ionic strength and pH variation. The present study indicated that the combination of P90G, Eudragit S100 and hyaluronan results in the production of innovative delivery systems with suitable dimensions and adequate stability, capable of protecting the curcumin from the pH variation during the stomach to colon transit, and favoring the local accumulation of the drug. Finally, a more detailed research according to ICH and WHO guidelines should be performed in a more advanced development step.
