Abstract

Lepidium peruvianum (maca) (Brassicaceae) is a naturally occurring plant mainly in the high Andes of Peru. In recent years, it has been intensively researched in terms of its influence on various diseases and towards health improvement. Alzheimer’s disease is an incurable disease that most often affects adults over the age of 60. As since 2003 the US Food and Drug Administration (FDA) did not approve any new drug for Alzheimer’s disease (AD) until 2021, there is still a need for new drugs to slow down the progress of the disease. The study focuses on glucosinolates that are present in different cultivars of L. peruvianum tubers and evaluates their inhibitory properties against two cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). By comparing the HPLC-ESI-QTOF-MS/MS fingerprints of different extracts, the phenotypes that were the most rich in glucosinolates were selected. Qualitative analysis of the sulphur-containing metabolites in 50% ethanolic extracts confirmed the presence of ten major components that belonged to the groups of: aliphatic, indolyl, and aromatic glucosinolates, with glucotropaeolin being the leading one, detected at levels between 0–1.57% depending on phenotype, size, processing, and collection site. The PCA analysis showed important variations in glucosinolate content between the samples and different ratios of the detected compounds. The color and size of maca tubers have been shown to have a significant effect on the glucosinolate content. The applied in vitro activity tests confirmed inhibitory properties of extracts and single glucosinolates against AChE and BuChE. The molecular activity of glucosinolates has been explained in relation to both enzymes: AChE and BuChE showing that these metabolites most likely work by blocking the catalytic sites of the enzymes. Based on the obtained results and described mechanism of action, it could be concluded that glucosinolates exhibit inhibitory properties against two cholinesterases present in the synaptic cleft, which indicates that selected phenotypes of L. peruvianum cultivated under well-defined environmental and ecological conditions may present a valuable plant material to be considered for the development of therapeutic products with memory-stimulating properties.

Authors (8)