ISHS Acta Horticulturae 725: V International Symposium on In Vitro Culture and Horticultural Breeding
APPLICATION OF THE TEMPORARY IMMERSION SYSTEM FOR THE IN VITRO PRODUCTION OF BIOACTIVE COMPOUNDS IN HARPAGOPHYTUM (DEVIL'S CLAW) |
| Authors: | G. Leveille, D. Rai, E. Cahill, E. Caffrey, E. Tennyson, G. Wilson |
| Keywords: | harpagide-iridoid, harpagoside, tuber, tuberisation, glasshouse |
| DOI: | 10.17660/ActaHortic.2006.725.83 |
| Abstract:
Extracts of tubers of Devil's Claw (Harpagophytum procumbens, Pedaliaceae) are widely used for the relief of muscular pain. The anti-inflammatory activity has been attributed to free and glycoside forms of iridoid monoterpenes harpagoside, harpagide, procumbine and harpagogenine. In this study growth and iridoid content of in vitro plants grown by temporary immersion (TIS) harvested after 4 months is compared to 2 year old whole plants grown in a glasshouse (GH) in Ireland. Total iridoids were assayed by a colorimetric method, harpagoside was measured by HPLC and conclusively identified in extracts by tandem mass spectrometry with reference to known standards. In the TIS cultures (200 ml) the immersion time was 1h per day over 4 months. The biomass produced consisted mainly of normal plants with rooted leafy shoots, together with some partially differentiated callus. The total iridoid levels in root, stem and leaf tissues of TIS grown plants were similar to that of glasshouse grown plants. However TIS plants did not produce tubers which are the main organ for storage of iridoids in GH plants. The harpagoside concentration in the leaves of TIS grown plants was significantly greater (6.0 mg/gDW) than in the leaves of glasshouse (GH) grown plants (3.5 mg/gDW), levels in the stem were similar (TIS 3.8 mg/gDW, GH 5 mg/gDW) whereas in the root iridoid levels were 8 mg/gDW (GH), greater than in the TIS plants (2 mg/gDW). Tuber tissue from GH plants contained 15 mg/gDW , similar to reported levels in African plants. These results show that in vitro plants grown by TIS accumulate total iridoids at levels similar to whole plants. TIS plants also contain the bioactive iridoid harpagoside, however the proportion of harpagoside in the iridoid fraction differs between tissues within the same plants and also between TIS and glasshouse grown plants. | |
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