Determination of carotenoids in the Chinese medical herb Jiao-Gu-Lan (Gynostemma pentaphyllum MAKINO) by liquid chromatography

The amount and variety of carotenoids in Jiao-Gu-Lan (Gynostemma pentaphyllum MAKINO), a traditional Chinese medicinal herb which is currently sold in Taiwan and China as herbal tea, were determined by HPLC. Dried Jiao-Gu-Lan samples were ground into fine materials, and the carotenoids were extracted, saponified and subjected to HPLC analysis. A gradient mobile phase of methanol/isopropanol (99/1, v/v) (A) and methylene chloride (B) was used: 100% A and 0% B initially, maintained for 15 min, decreased to 70% A in 45 min, maintained for 15 min, and returned to 100% A in 65 min. A total of 25 carotenoids were resolved within 54 min by using a C-30 column with flow rate at 1.0 mL min(-1) and detection at 450 nm. For all the six cultivars of Jiao-Gu-Lan samples, all-trans-lutein was present in largest amount (72-376 mug g(-1)), followed by cis isomers of lutein (0-72 mug g(-1)), neochrome (13-65 mug g-1), neoxanthin (0-41 mug g-(1)), all-trans-alpha-carotene (0-27 mug g(-1)), auroxanthin (7-23 mug g(-1)), violaxanthin (3-22 mug g(-1)), luteoxanthin (4-19 mug g(-1)), all-trans-p-carotene (0-7.6 mug g(-1)), beta-cryptoxanthin (0-6.7 mug g(-1)), and cis isomers of beta-carotene (0-1.9 mug g(-1)), on a dry weight basis.