CHROMATOGRAPHIC PURIFICATION OF NATURAL LYCOPENE

The natural lycopene isolation method was developed in three steps. First, carotenoids were extracted from tomato puree with petroleum ether; next, the carotenoid extract was prepurified from all carotenoids except lycopene with solid-phase extraction (SPE) using silica cartridges. Lycopene was then further purified three times with semipreparative high-performance liquid chromatography (HPLC) using a mu Bondapak C-18 column. The purity and recovery of the lycopene were checked after each step with analytical HPLC using a Zorbax ODS column. A solvent mixture of acetonitrile-dichloromethane-methanol (45:10:45) was used in all HPLC evaluations. The shoulder of the lycopene peak was identified with diode array detection. Also, spectral scans for peak purity were made. After extraction, 30 mg of lycopene was recovered from 10 g of tomato puree and the lycopene content amounted to 87% of the total carotenoids. After the SPE, 21 mg of the extracted lycopene remained, the lycopene content being 93% of total carotenoids and that of all-trans-lycopene 80%. The amount of lycopene after the first and third HPLC fractionations declined from 9 to 6 mg, respectively. With the method developed, 6 mg of lycopene was isolated from 10 g of tomato puree. However, the natural lycopene isolated contained about 20% lycopene cis isomers and 3% xanthophylls.