New sesquiterpenes from Daphne laureola (Thymelaceae) roots

The genus Daphne (Thymelaceae family) comprises over 90 species, mainly shrubs, distributed in Europe, North Africa, and Asia, very well known for the presence of toxic diterpenes with the daphnane skeleton such as daphnetoxin;[1] although some species are poisonous others are used for medicinal and cosmetic purposes. Terpenoids, coumarins, flavonoids, and lignans, are among the most significant classes of compounds that were isolated from this genus.[2] Daphne laureola L. (spurge laurel) is a Mediterranean evergreen shrub with glabrous, large, and glossy leaves used traditionally in South Italy as ethnoveterinary remedy,[3] pesticide, repellent,[4] and as potent purgative or emetic poison. In some rural areas of Sicily there is the practice to cover cottage cheese (ricotta) with the plant’s leaves to avoid its theft. Although few preliminary chemical studies were carried out on the plant leaves, reporting the presence mainly of flavonoids[5] and coumarins,[6] the roots were not investigated to date. In this study, D. laureola roots were subjected to static maceration using solvents of increasing polarity, n-hexane, CHCl3, CHCl3-MeOH (9:1), and MeOH. From the chloroform extract three new sesquiterpenes were isolated by means of Biotage® flash chromatography and RP-HPLC, then characterized through 1D and 2D NMR and electronic circular dichroism (ECD) spectroscopies and HRESIMS analyses as guaiane-type sesquiterpenoids with structure similarities to daphneaine G and stelleraterpenoid H. Moreover, some known biflavonoids, lignans, and coumarins were also purified. As future work, the pure isolates will be investigated for their antiangiogenic activity by two in vivo models, chick chorioallantoic membrane and zebrafish embryos. References 1. Stout GH, Balkenhol WG, Poling M, Hickernell GL (1970). Journal of American Chemical Society, 92, 1070-1071. 2. Moshiashvili G, Tabadatze N, Mshvildadze V (2020). Fitoterapia, 143, 104540. 3. Pieroni A, Howard P, Volpato G, Santoro RF (2004). Veterinary Research Communications, 28, 55-80. 4. Viegi L, Vangelisti R (2011). Natural Product Communications, 6, 999-1000. 5. Touati D, Fkih-Tetouani S (1993). Plantes Medicinales et Phytotherapie, 26, 43-48. 6. Juskovic M, Zabar-Popovic A, Matejic J, Mihajilov-Krstev T, Manojlovic N, Vasiljevic P (2017). Oxidation Communications, 40, 1058-1069.