Chemical composition and selective BuChE inhibitory activity of the essential oils from aromatic plants used to prepare the traditional Ecuadorian beverage horchata lojana

Abstract Ethnobotanical and ethnomedicinal relevance In southern Ecuador, horchata lojana is a popular aromatic and refreshing beverage that is prepared from an aqueous infusion of different mixtures of local medicinal and aromatic plants. The drink is considered a traditional anti-inflammatory agent and brain tonic; due these properties, it has been drunk since Colonial Times. Several pharmacological studies have evaluated the effects of horchata aqueous infusion. However, the aromatic profile and the contribution of the volatile components to the biological activity of the drink have not been investigated so far. For these reasons, we have determined the chemical composition of the essential oils (EOs) distilled from five mixtures of aromatic plants commonly used for the preparation of this traditional drink. Moreover, to support the curative properties of the aromatic plants, the anticholinesterase activity the EOs was examined. Material and methods Different bunches of fresh mixed medicinal and aromatic plants, called tongos, are sold at local markets in the province of Loja for the preparation of different types of horchata. In this research we have purchased plant bunches sold at five popular markets of Loja province. Subsequently, aromatic plants in each bunch were separated from medicinal plants and were then hydrodistilled to give the corresponding EOs. Subsequently, the chemical composition of each EO was determined by GC-MS/GC–FID techniques, whereas the cholinesterase inhibitory activity in vitro was determined against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. Aims of the study i) to contribute to the chemical and pharmacological study of the aroma components of the traditional Ecuadorian drink horchata lojana; ii) to identify botanically the mixtures of aromatic plants used to make the drink; iii) to establish, on the basis of the chemical composition of the EOs, the compounds mainly responsible for the characteristic beverage flavor; iv) to establish the possible existence of an aromatic pattern characteristic of each horchata preparation; v) to test the anticholinesterase activity of the EOs against AChE and BuChE in order to support the traditional consume of the drink as an effective brain tonic. Results A total of 23 botanical families and 32 species of plants used for the preparation of five different variants of the traditional horchata lojana beverage, have been identified. Fourteen aromatic species were determined to be responsible for the characteristic flavor of the drink. All the analyzed EOs belong to the monoterpene type. A total of 88 compounds have been identified in the different EOs, twenty-four of which are common components of the oils. Conclusions According to the main components of the EOs distilled from the five groups of horchata lojana plants, four aromatic profiles have been defined: (i) neral + geranial + carvone, (ii) neral + geraniol + myrcene; (iii) geranial + methyl eugenol + isomenthone + neral + citronellol; (iv) anethol + geraniol + pulegone. Moreover, according to the literature, several aromatic plants and individual EOs components exhibit a wide range of biological activities. This finding as well as the significant BuChE inhibitory activity exhibited in vitro by the EOs give scientific support to the use of identified aromatic plants in the traditional preparation of horchata, that is considered a natural analgesic and anti-inflammatory remedy, and an effective brain tonic.