Case study of the Swiss flora for prior phytochemical and biological investigations.

Estimates in the literature as to what extent the world's higher plant species have been studied chemically or for bioactivity are contradictory and range from 0.5% to >12%. In this survey, a model to make credible estimates of the extent of their study is proposed and is exemplified by applying it in a case study of plants native to Switzerland. Using a widely available database (SciFinder Scholar), 454 535 literature references for the 2677 native Swiss plant species were retrieved. It was determined that 55% of these species have been investigated phytochemically and 28% for biological activity. The influence of factors such as commonness, growth form, habitat, medicinal use, and reported toxicity on the extent to which different plant groups have been studied is analyzed. The predictive value of random sampling of subsets of plants is compared to the study of the entire Swiss flora, to show that a credible estimate of the extent of prior studies can be achieved with just 5% of these species.