Comparative Analysis of Chemical Constituents by HPLC-ESI-MSn and Antioxidant Activities of Dendrobium huoshanense and Dendrobium officinale.

Dendrobium huoshanense is one of the rare Chinese medicinal herbs with high quality and excellent efficacy. However, its effective chemical basis is still unclear. Of note, D. officinale is the most widely utilized among the Dendrobium species. Therefore, the current study systematically investigated the chemical constituents of methanolic extracts and different polar fractions of aqueous extracts from the two herbs by HPLC-ESI-MSn , and then compared in vitro antioxidant activities of their 5 different polar extracts. Consequently, 61 and 49 compounds were identified from D. huoshanense and D. officinale, respectively, of which, 43 compounds were common to both species. Besides, 17 out of 22 different compounds were identified only in D. huoshanense. Moreover, the peak areas of some shared identical compounds of D. huoshanense were significantly larger than that of D. officinale. In vitro antioxidant evaluation results showed that n-BuOH-soluble fraction of the two herbs exhibited remarkable antioxidant activity. Furthermore, the antioxidant activity of different fractions of D. huoshanense were separately superior to that of D. officinale, which may be attributed to its variable and high contents of flavonoids, bibenzyls and phenanthrenes. These results provide the evidence for the high quality and efficacy of D. huoshanense.