The aim of this study was to evaluate the composition of aqueous extracts of in vitro shoot cultures and wild plants of Pterospartum tridentatum in order to promote the use of this plant material as a possible source of bioactive compounds. The extraction yield from wild plants compared with in vitro shoot cultures was lower. The total phenolic contents of in vitro shoots were significantly lower compared with those of wild plants. The phenolic profiles of in vitro shoots were very similar to those of wild plants, regardless of the source. However, taxifolin-6- C-glucoside, as well as rutin and isoquercitrin, were not present in extracts of in vitro shoots. An interesting result was the higher molar percentages of rhamnose and uronic acids detected in in vitro shoots compared with the wild plants, which can make the in vitro plant material very useful for obtaining these compounds.

a b s t r a c tPterospartum tridentatum (L.) Willk. decoctions of dried inflorescences are used in Portugal due to their claimed beneficial properties for various health disorders. To disclose the potential contribution of its polysaccharides to health benefits, in this work, hot water extracts from P. tridentatum inflorescences were prepared and fractionated by ethanol precipitation and anion exchange chromatography. The fraction rich in acetylated galactomannans evidenced an increase in nitric oxide (NO) production by macrophages. This activity decreased 60-75% after saponification, confirming that acetylation is an important structural feature for this biological property. In addition, the treatment of pectic polysaccharides with endopolygalacturonase showed that type-I and type-II arabinogalactans, as well as low molecular weight galacturonans and xyloglucans, may also contribute to macrophage NO production. Thus, the polysaccharides present in P. tridentatum dried inflorescences may contribute to the health beneficial properties frequently attributed to the decoctions of this plant.