Abstract
This work deals with the question of standardization, repeatability and optimization of medicinal plant extraction in water. Three plants were selected, for which the complementary pharmacological activities are based on different flavonoids, two of which are well documented (hawthorn flowering tops and blackcurrant leaves) with well-known properties, and the third one has been little studied (Chrysanthellum americanum). We established a general extraction protocol in water for these three plants that can be used by each of us, based on infusion that can afford a reproducible daily uptake of bioactive components (phenols, flavonoids, proanthocyanidin oligomers) at drinkable temperature. Granulometry was the most important factor to get the best extraction yields (about 22% for hawthorn, 26% for Chrysanthellum americanum and 28.5% for blackcurrant). Chemical composition of these plants was investigated by colorimetric methods, and also using performant and complementary analytical instrumentations (UHPLC-ESI-MS and FT-ICR MS). Blackcurrant extracts contained much more phenolic compounds (the main UV-detected components detected in UHPLC being flavonols) than the two other plants. Hawthorn extracts contained much more proanthocyanidin oligomers (the main UV-detected components in UHPLC being flavanols, flavonols and flavones) than the two other plants. Chrysanthellum americanum and blackcurrant extracts contained similar amounts of flavonoids, the former one containing essentially hydrocinnamic acid derivatives, flavones, flavanones and aurones as UV-detected components. About 2500 hints were obtained for each plant, among which about 1100 are common to all 3 plants and about 700 are specific to each plant. Quercetin and kaempferol derivatives were identified in blackcurrant leaves extracts, while vitexin-2-O-rhamnoside, hyperoside and isoquercetin were identified in hawthorn flowering tops extracts and flavanomarein and martitimein derivatives, and Oleanolic or Ursolic acid were identified in Chrysanthellum americanum extracts. A significant inhibition of hyaluronidase (≥ 90%) was reported for hawthorn extracts, much higher than that of the other two plant extracts. As for the anti-hypertensive activity, the Chrysanthellum americanum extracts demonstrated higher ACE inhibition than the other two plant extracts. Regarding antioxidant activity, blackcurrant leaf extracts showed the highest antioxidant capacity. Finally, the formation of nanoparticles in the herbal tea infusions (also known as tea creaming), was studied from a kinetic and size-distribution point of view as a function of temperature.