Although several plant-derived drug groups (vinca alkaloids, taxanes, podophyllotoxin derivatives and camptothecins) continue to be widely used in cancer therapy, the anticancer potential of the Plant Kingdom remains largely unexplored. In this work, we have carried out a random screening for selective anticancer activity of 57 extracts from 45 plants collected in Grazalema Natural Park, an area in the South of Spain of high plant diversity and endemism. Using lung cancer cells (A549) and lung non-malignant cells (MRC-5), we found that several extracts were more cytotoxic and selective against the cancer cell line than the standard anticancer agent cisplatin. Five active extracts were further tested in cancer and normal cell lines from other tissues, including three skin cell lines with increasing degree of malignancy. An extract from the leaves of Daphne laureola L. (Thymelaeaceae) showed a striking potency and selectivity on lung cancer cells and leukemia cells; the IC₅₀ values against these cancer cells were approximately 10000-fold lower than against the normal cells. Daphnane-type diterpene orthoesters may be responsible for this highly selective anticancer activity.

Daphne wolongensis described on the basis of a few known individuals was investigated in the wild, in Baoxing Valey, Sechuan. Its status of valid species was verified morphologically and genetically. Three newly found populations were compared to the closely related species Daphne retusa, D. tangutica, D. longilobata, D. acutiloba, D. sureil, to clones available in cultivation and selected cultivars. The high bootstrap values indicate a good level of genetic differentiation between each of the studied species. The hypothesis whether D. wolongensis is a hybridogenous species was rejected, it is a well-defined independent species. Based on morphological and genetic data, it seems likely that another species, D. limprichtii can be a mountain form of D. tangutica. Variability of populations in Wolong gives a good opportunity to select genotypes with a higher or better performance of combination of traits. From 51samples collected in Wolong it was possible to select the top ten different types as genetic resources for breeding. Daphne wolongensis, in the visited sites of Wolong area, occupies less than 1 km2. Together with isolated finds, the number of found individuals is less than 500 and the area is not larger than 10 km2, thus it falls to the IUCN category of “Critically Endangered” plants.