Phytochemical Composition and Antioxidant, Anti-Acetylcholinesterase, and Anti-α-Glucosidase Activity of Thymus carnosus Extracts: A Three-Year Study on the Impact of Annual Variation and Geographic Location

Abstract

Thymus carnosus Boiss. is a near-threatened species, and, as for many species, its potential for medicinal purposes may be lost if measures towards plant protection are not taken. A way of preserving these species is to increase knowledge about their medicinal properties and economic potential. Thus, with the objective of studying the potentiality of introducing T. carnosus as a crop, the stability of the phytochemical profile of T. carnosus was studied during a period of three years by comparing the phytochemical profile of extracts obtained from plants harvested in two different edaphoclimatic locations, as well as by comparing the respective bioactivities, namely, antioxidant, antidiabetic, antiaging, and neuroprotective activities. It was reported, for the first time, the effect of annual variation and geographic location in the phytochemical composition of aqueous decoction and hydroethanolic extracts of T. carnosus. In addition, the presence of two salvianolic acid B/E isomers in T. carnosus extracts is here described for the first time. Despite the variations in phytochemical composition, according to harvesting location or year, T. carnosus extracts maintain high antioxidant activity, assessed by their capacity to scavenge ABTS•+, •OH , NO•, O2•− radicals, as well as to prevent β-carotene bleaching. All extracts presented significant potential to inhibit acetylcholinesterase (AChE), tyrosinase, and α-glucosidase, denoting neuroprotective, anti-aging, and anti-diabetic potential. In conclusion, the vegetative stage and location of harvest are key factors to obtain the maximum potential of this species, namely, a phytochemical profile with health benefit bioactivities.

Linking Variability in Phytochemical Composition with Safety Profile of Thymus carnosus Boiss. Extracts: Effect of Major Compounds and Evaluation of Markers of Oxidative Stress and Cell Death

“…These results correlate with the phytochemical composition reported by Martins-Gomes et al, 2023 [3], where L1-2020-HE had the highest phenolic and terpenoid concentrations, while L2-2018-HE had the lowest phytochemical concentration [3]. The ADextracts-induced anti-proliferative activity resulted in IC 50 values ranging between 517.80 and 718.60 µg/mL, i.e., higher IC 50 values than those of HE, hypothetically due to a lower content of phenolic compounds and the absence of terpenoids (compared with HE).…”

“…On the other hand, an orthogonal partial least squares-discriminant analysis (OPLS-DA) model allowed for the identification of eriodictyol, luteolin, and quercetin derivatives as the main contributors to acetylcholinesterase and α-glucosidase inhibitions. Despite the higher contribution of flavonoid derivatives, T. carnosus extracts presented a higher content in phenolic acids, such as salvianolic acids and RA [3].…”

“…The inter-annual stability of such activities provoked new interest on the use of this species in the human diet. It was shown that, despite the variation induced by the harvest year and location, all extracts retained significant neuroprotective activity (evaluated through the inhibition of acetylcholinesterase (between ~32% and 61%) and tyrosinase (between ~11% and 43%)) and antidiabetic activity (α-glucosidase inhibition between ~12% and 27%) [3]. Despite presenting the highest variation within the extracts analyzed, tyrosinase inhibition did not present a significant correlation with any individual component of the extracts.…”

“…We have recently reported the potential of this species as a novel functional food and as a source of nutraceuticals. Both aqueous decoction (AD) and hydroethanolic (HE) extracts were identified as promising antitumoral, antidiabetic, neuroprotective, and antioxidant agents [1][2][3].…”

“…Martins-Gomes et al, 2023 [3], described for the first time the variation in the phytochemical composition of Thymus carnosus extracts as being dependent on year and harvest location. In addition, Martins-Gomeset al, 2023 [3], reported a correlation between the variation in the phytochemical profile of extracts and the antioxidant, neuroprotective, and antidiabetic activities. The inter-annual stability of such activities provoked new interest on the use of this species in the human diet.…”