Preparation of carotenoid extracts and nanoemulsions from Lycium barbarum L. and their effects on growth of HT-29 colon cancer cells

H J Hsu; R F Huang; T H Kao; B S Inbaraj; B H Chen

doi:10.1088/1361-6528/aa5e86

Preparation of carotenoid extracts and nanoemulsions from Lycium barbarum L. and their effects on growth of HT-29 colon cancer cells

Nanotechnology. 2017 Mar 7;28(13). doi: 10.1088/1361-6528/aa5e86.

Authors

H J Hsu¹, R F Huang², T H Kao¹, B S Inbaraj¹, B H Chen^{1

2}

Affiliations

¹ Department of Food Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
² Department of Nutritional Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.

PMID: 28266352
DOI: 10.1088/1361-6528/aa5e86

Abstract

Lycium barbarumL., a traditional Chinese herb widely used in Asian countries, has been demonstrated to be protective against chronic diseases such as age-related macular degeneration. The objectives of this study were to determine the carotenoid content inL. barbarumby high-performance liquid chromatography-mass spectrometry, followed by preparation of a carotenoid nanoemulsion to evaluate the mechanism of inhibition on HT-29 colon cancer cells. The highest extraction yield of carotenoids was attained by employing a solvent system of hexane-ethanol-acetone (1:1:1, v/v/v). Nine carotenoids, including neoxanthin (4.47μg g^-1), all-trans-zeaxanthin and itscis-isomers (1666.3μg g^-1), all-trans-β-cryptoxanthin (51.69μg g^-1), all-trans-β-carotene and itscis-isomers (20.11μg g^-1), were separated within 45 min and quantified using a YMC C₃₀column and a gradient mobile phase of methanol-water (9:1, v/v) (A) and methylene chloride (B). A highly stable carotenoid nanoemulsion composed of Capryol^TM90, Transcutol^®HP, Tween 80 and deionized water was prepared with a mean particle size of 15.1 nm. Characterization of zeaxanthin standard, blank nanoemulsion, carotenoid extract and carotenoid nanoemulsion by differential scanning calorimetry curves and Fourier transform infrared spectra revealed a good dispersion of zeaxanthin-dominated carotenoid extract with no significant chemical change after incorporation into nanoemulsion. Thein vitrorelease kinetic study showed a higher release profile at pH 5.2 than at physiological pH 7.4, suggesting a rapid release of carotenoids in the acidic environment (pH 4.5-6.5) characteristic of tumors. Both the carotenoid nanoemulsion and the extract were effective at inhibiting growth of HT-29 colon cancer cells, with an IC₅₀of 4.5 and 4.9μg ml^-1, respectively. Also, both treatments could up-regulate p53 and p21 expression and down-regulate CDK2, CDK1, cyclin A and cyclin B expression and arrest the cell cycle at G₂/M. The study may form a basis for further exploration ofL.barbarumnanoemulsion in cancer treatment.

Keywords: Lycium barbarum L.; carotenoid nanoemulsion; cell cycle; colon cancer cell HT-29.