Novel nanomicelle formulation to enhance bioavailability and stability of curcuminoids

Abstract

Objectives: Curcuminoids, comprising curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC), are bioactive phytochemicals with numerous pharmacological effects. Oral biological availability of curcuminoids is low due to the low aqueous solubility and rapid metabolism. This study aimed at fabricating a nanomicellar curcuminoid formula with enhanced pharmacokinetic properties.

Materials and methods: Curcuminoids nanomicelles were prepared and characterized regarding particle properties, stability, release profile and pharmacokinetic parameters.

Results: Encapsulation efficiency of curcuminoids in nanomicelles were 100%. Particle size analysis demonstrated a mean size of around 10 nm that remained stable for 24 months. Dissolution test showed the complete dissolution of encapsulated curcuminoids from nanomicelles within 20 min while the free curcuminoids were poorly dissolved (approximately 7% after 60 min). The results of long-term (24 months) and accelerated (6 months) stability studies showed no changes in the size and content of nanomicelles. The release studies in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) showed no release of curcuminoids for at least 4 hours. In vivo study in BALB/c mice showed improved pharmacokinetic parameters including maximum plasma concentration (C_max) and time to reach the maximum concentration (T_max) with nanomicelles as compared to free curcuminoids and two other commercial products. T_max for all the three curcuminoid components was observed 30 min following oral administration. AUC of nanomicellar curcuminoids was 59.2 times more than free curcuminoids.

Conclusion: These data indicated that nanomicelles could improve solubility, oral bioavailability and also the stability of curcuminoids. Thus, they merit further investigation for enhancing pharmacological effects of curcuminoids.

Keywords: Biological availability; Curcuminoid; Drug stability; Micelle; Pharmacokinetics.

Figure 1

TEM image of nanomicelles. Diluted nanomicelles (20 µl) were deposited onto carbon coated copper grid. After 1 minute, the excess nanomicelles was removed by filter paper (Whatman®) and stained with 10 µl of 1 % sodium phosphotungstate pH 7.0 for 2 min. The samples were photographed with a Phillips CM100 electron microscope (Philips/FEI Corporation, Eindhoven, Holland)

Figure 2

Critical micelle concentration (CMC) as a function of log concentration of nanomicelles. To determine the CMC of nanomicelles in distillated water, the acetone solution containing iodine (15 µl from 16.3 mg/ml) were added to 2 ml of various concentration of nanomicelles suspension (0.125-10 mg/ml) in distilled water. The absorption intensity was plotted against log (concentration). With a sharp increase in absorbance measurement using UV–vis spectra (UV-160A Shimadzu) at λ_max=369 nm, the CMC can be verified

Figure 3

Release profile of curcuminoids according to dissolution test of USP35 (mean±SD, n=3). Dissolution of curcuminoids were determined in 900 ml water containing 1% sodium lauryl sulfate at 37.0 ± 0.5 °C at 100 rpm. Samples were obtained at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 min and were passed through a 0.22 µm filter, diluted with mobile phase, and subjected to HPLC

Figure 4

Long-term (A) and accelerated stability (B) studies of nanomicellar curcuminoid formula according to the ICH guidelines (2003) code Q1A(R2). Nanomicelles were stored in tube containers preserved from light. Samples were taken at 0, 3, 6, 12, 15, 18, 21 and 24 months for long-term [30 °C ± 2 °C, 65 % relative humidity ± 5%] and at 0, 1, 2, 4 and 6 months for accelerated condition [40 °C ± 2 °C, 75% relative humidity ± 5%] studies. Nanomicelles diluted with the HPLC mobile phase were then injected to HPLC column in triplicate

Figure 5

Release profiles of curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) in simulated gastric fluid (SGF) (A) and simulated intestinal fluid (SIF) (B). Data represent the means ± SD (n=3). Nanomicelles were diluted in the above mentioned media (1:10), followed by sampling at 0, 1, 2, 4, 6, 12, 24, 48 and 72 hr time points and curcuminoids concentration were determined using HPLC

Figure 6

Concentration of curcumin, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) in mouse plasma after a single oral administration of: nanomicellar, commercial product 1 (CP1), commercial product 2 (CP2) and free curcuminoids (35 mg/mouse). Data are expressed as mean±SD (n=3). Mice received a single dose (35 mg) of curcuminoids via oral gavage. Blood samples were obtained at 30 min, 1, 2, 4 and 6 h after dosing via heart puncture. Plasma was separated by centrifugations and deproteinated using methanol precipitation and was then injected to the HPLC system

Figure 7

Typical chromatogram of curcuminoids in plasma after dosing (a) Sinacurcumin, (b) CP1, (c) CP2, (d) pure curcuminoids and (e) chromatogram corresponding to standard