67B-19 |
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C. DING, Dept. of Food Science, Univ. of Wisconsin, Madison, 1605 Linden Dr., Madison, WI 53706, E. Chen, Wisconsin Center for Space Automation & Robotics, Univ. of Wisconsin, Madison, 545 Science Dr., Madison, WI 53711, R. Lindsay, Department of Food Science, 7 Babcock Hall, 1605 Linden Drive, Madison, WI 53706, and W. Zhou, wisconsin center for space automation and robotics, 545 science dr, madison, WI 53705. Ginkgo terpene trilactones (ginkgolide A, B, and bilobalide) are the distinctive compounds uniquely existing in Ginkgo biloba L., with recognized pharmacological properties. Although the chemical and biological properties of the terpene trilactions have been subjected to intensive study both in vivo and vitro, the nature abundance has not been reported. It is important to understand abundance and fluctuation of the terpene trilaction composition with season and geography. The objective of this study is investigating the impact of seasons on the biosynthesis and accumulation of ginkgo terpene trilactones. Leaf samples were collected at monthly intervals (June-November) from six ginkgo trees, then air-dried and ground into a fine powders (300-420) µm. The powdered samples were sequentially extracted with boiling ddH2O and Na2HPO4 solution (0.01M, pH8.0) in water bath (100oC). Obtained extracts then were adjusted to pH 4.5 and partitioned with ethyl acetate. The organic phase containing terpene trilactones was evaporated at 45oC with N2 gas, and the residue was redissolved with 400µl methanol for analysis. HPLC-RI and SSI-LC-MS methods were used for quantification and identification of the terpene trilectones. The results indicated that the biosynthesis and accumulation of ginkgolide A and B were significantly impacted by seasons: the highest concentration was in August, and the lowest was in June. The amount of ginkgolide A or B in August could be ten times higher than that in June. The younger ginkgo trees accumulated higher amount of ginkgolides than older trees, the amount of ginkgolide A or B accumulated in ten years old trees was about four times higher than that in seventy years old trees in August. Accumulation of bilobalide, however, was less impacted by season and age. The data obtained from this study will benefit pharmaceutical and nutraceutical product developments.
Session 67B, Food Chemistry: Antioxidants and bioactive agents
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