Historical chemical annotations of Cinchona bark collections are comparable to results from current-day high‑pressure liquid chromatography technologies

Nataly Allasi Canales, Tobias Nikolaj Gress Hansen, Claus Cornett, Kim Walker, Felix Driver, Alexandre Antonelli, Carla Maldonado, Mark Nesbitt, Christopher J. Barnes, Nina Rønsted. Journal of Ethnopharmacology. 2020. https://doi.org/10.1016/j.jep.2019.112375

In short - Here, we demonstrated the consistency between historical chemical annotations of Cinchona bark (quinas) collections and results obtained through modern HPLC techniques. Our study highlights the value of historical records in understanding the chemical composition and medicinal properties of natural products. Integrating Indigenous Andean knowledge with contemporary scientific methods offers significant potential for advancing pharmaceutical research and harnessing the therapeutic potential of traditional remedies.

Piece of Cinchona cordifolia (now Cinchona pusbescens Valh) bark with chemical annotations of the four major quinine alkaloids provided by Howards and Sons, collected 1856, Kew Economic Botany Collection specimen #52799. Photo: EBC-RBGK.

Knowledge gap - The genus Cinchona (Rubiaceae) has a long history of use in traditional medicine and as a source of quinine, a potent antimalarial compound. However, there is limited knowledge about the historical chemical diversity of antimalarial alkaloids within and between Cinchona species. Historical collections of Cinchona bark stored at the Royal Botanic Gardens, Kew, UK, and other museums hold great uncovering potential into the alkaloid chemistry of the Cinchona genus and the historical search for the most effective barks. Here, we validated the accuracy of these historical records by comparing them with the results obtained through modern HPLC techniques.

Results - We validated the accuracy of the historical chemical records, by John Eliot Howard et al. performed >150 years ago, comparing them with our results obtained through modern HPLC techniques. We found that our results are comparable to the historical ones. Additionally, the quantity of two of the major alkaloids, quinine and cinchonine, and the total content of the four alkaloids obtained were significantly similar between the historical and current day analysis using linear regression.

Conclusions - Our findings 1. show alkaloids are stable through time and natural history collections are a reliable source to advance pharmaceutical research. And 2. emphasise the importance of recognizing the value of Indigenous practices and knowledge systems. By combining Indigenous wisdom with contemporary scientific methods, researchers can enhance drug discovery and development processes, identify new bioactive compounds, and optimize the utilization of natural resources.