Antitrypanosomal compounds from the leaf essential oil of Strychnos spinosa

info:eu-repo/semantics/nonPublishe

Isolation of quercetin-3-O-sulfate and quantification of major compounds from Psidium guajava L. from Vietnam

peer reviewedThe aim of this study is first to identify the major phenolic compound of a crude ethanol extract of Psidium guajava leaves collected in Vietnam and to develop validated methods for quantification of phenolic and triterpenic components by HPLC-PDA-HRMS. The major phenolic compound was determined as quercetin-3-O-sulfate which is isolated and quantified for the first time in P. guajava. Validated HPLC-DAD quantification methods were developed to quantify the major triterpenic and phenolic derivatives of this extract and found to be accurate in the concentration range of 2–50 μg/mL for phenolic, and 5–100 μg/mL for triterpenic compounds. Four crude ethanol extracts of guava leaves collected at different periods of the year were analyzed using the developed methods and were found to be richer in triterpenic than phenolic derivatives. We also observed that the weather or rainfall influenced the richness in bioactive compounds in guava leaves

Tilia trees: Toxic or valuable resources for pollinators?

To investigate whether Tilia trees are poisonous or valuable resources for bee visitors, we determined the nectar and pollen quantities and composition of the four main Tilia species planted in Western Europe (T. cordata, T. platyphyllos, T. tomentosa, and T. × europaea). We developed a new method to detect nicotine in nectars. We observed insect visitor diversity and abundance. We also assessed bumblebee death when individuals were only fed with Tilia flowers. No traces of mannose or nicotine, incriminated in the Tilia toxicity, have been detected in the nectars of the studied species. Huge numbers of insect visitors, mainly bees and syrphids, visited the trees which offer large numbers of flowers, plenty of sugar rich nectar, and protein-rich pollen. Bumblebees only fed with Tilia flowers did not present any particular mortality. We discuss the different hypotheses of the supposed toxicity and propose future research to solve this debate