Supervisors info:
Θωμαΐδης Νικόλαος, Επίκουρος Καθηγητής, Τμήμα Χημείας, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Summary:
Rosemary is a well-known edible herb from the Lamiaceae mint family with a variety of properties, such as, antioxidant, anti-inflammatory, chemoprotective, and antiproliferative activities. Health promoting activities may be attributed to its phenolic constituents: carnosic acid (CA), carnosol (CS), rosmanol (RS) and 12-O-Methyl carnosic acid (MCA), among others. Since dietary phenolic compounds can only produce biological effects upon intestinal absorption, information about such processes is crucial for the evaluation of their potential impact on human health.
An in vitro simulation of gastrointestinal (GI) digestion was developed to evaluate the effect of gastrointestinal (GI) digestion on the phenolic profile of rosemary extract (RE). After the chemical characterization of GI-RE, evaluation of cytotoxicity activity against Caco-2 cells of RE, purified fraction of GI/RE after solid phase extraction (SPE/GI-RE) and the main rosemary diterpenes took place. According to the cytotoxicity tests of the pure standards, RS exhibited the strongest toxicity.
In the aim of this work was also the study of chemical stability of the main diterpenes in the RE. At the beginning and at the ending of the incubation (6 h), CA, CS, RS and MCA were detected by UHPLC-TOF MS at the apical compartment in the presence and absence of Caco-2 cells. MCA was the more stable rosemary diterpene. On the contrary, CA was degraded mainly to CS and RS, while rosmadial (RD) and rosmanol quinone (RS-Q) were also found. The main degradation product of CS was RS. RD and RS-Q were also detected. Finally RS was degraded to RD and RS-Q. In the presence of cells the data indicated the uptake of the phenolic compounds from the cells.
The intestinal epithelial transport of CA, CS, RS and MCA (either as pure compounds or from RE and SPE/GI-RE) was investigated across Caco-2 cell monolayer in both directions. These compounds were assayed by UHPLC-TOF MS, and their transport parameters were calculated. Phenolic compounds were found to be more effectively absorbed across basolateral membrane when pure standards or diterpenes within the RE and SPE/GI-RE were studied. The data also revealed that plant matrix components and SPE procedure affect the transport of diterpenes across the Caco-2 monolayer. The tested compounds presented low to moderate permeability (Papp) values with RS showing the highest Papp value, followed by CS, MCA and then CA. Finally, efflux ratio values indicate that the main absorption mechanism of the diterpenes via intestine was transcellular transport. Active efflux transport might be involved in MCA transport.
