In recognition of nature’s potential – and the need to replace drugs that have become ineffective by emerging resistance – several large-scale plant screenings were performed in the 1960s and 1970s. During this time, The American Cancer Institute (NCI) sponsored an extensive program screening about 35 000 plant species for anticancer activity which led to the discovery of taxol (paclitaxel) from the Pacific Yew tree, Taxus brecifoli. Later, another anticancer agent, docetaxel, was isolated from the European Yew, Taxus baccata. Today, the taxanes are one of the most powerful classes of compounds among all chemotherapeutic drugs, exhibiting a wide range of activity and are of special benefit in fighting metastatic breast, ovarian and lung cancer.
Other natural compounds, in particular the vinca alkaloids from the periwinkle plant, Vinca rosea, are well known cytostatics. The introduction of high-throughput synthesis and combinatorial chemistry in recent years has led to a decline in the screening of natural products by the pharmaceutical industry, which is now considered as a premature decision. In a call for ‘back to the future’ the advantage of using ‘crude’ botanical extracts has been emphasized as opposed to the standard approach which has been to isolate, synthesize and administer the single chemical compound thought to be responsible for the effect of the extract. The different components in a botanical may have synergistic activities and the presence of multiple compounds in an extract can buffer the toxic effects of a single constituent. The present study aimed to discover such a botanical extract, which we believe has been obtained by the extract of Inula helenium.