Abstract

Ugni molinae Turcz. (commonly known as murtilla) is a native shrub that grows in the south-central regions of Chile. Famous by his edible and aromatic red fruits, its leaves are also important in Chilean folk medicine because of their analgesic, anti-inflammatory and antibacterial properties. Due to the increasing commercial value of Ugni molinae in the national market, in 1996 the National Institute of Agronomical Research (INIA, Carillanca) started a domestication plan for the improvement of its fruits by collecting 100 accessions from different regions of Chile and, by molecular characterization, they were able to find 45 different murtilla genotypes. Usually, once murtilla fruits are collected, the leaves are pruned and discarded in spite of the mentioned medicinal properties. Therefore, with the purpose of raising the value of the crops (since both fruits and leaves could be exploited at the same time), the leaves of 10 genotypes (G1 to G10) selected because they have the best relative fruit quality, were given by INIA to detect chemical differences between them, which can be used as a first approximation to determine chemomarkers suitable for quality control of the medicinal leaves. To accomplish this, NMR metabolomic analysis and multivariate data analysis were performed. The leaves (20 mg) were extracted by ultrasonication with 1:1 CD3OD:KH2PO4 buffer in D2O (MD6) and 600 MHz 1H-NMR spectras were measured and bucketed using AMIX software. Then, 250 buckets of 0.04 ppm were obtained and statistically analyzed using SIMCA software. To resolve difficulties in the identification of some signals, 2D-NMR of G10 was measured. By principal component analysis (PCA), six groups were discriminated (G4/G10, G5, G2, G6/G8, G9, G1/G3/G7). The analysis of the loading plots allowed us to explain the differences by the content of primary and secondary metabolites like saponins (oleanane and ursane glycosides), flavonols (like myricetin, myricitrin, galloyl hyperin), phenolic acids (quinic and gallic acid) and sugars (mainly fructose, glucose and sucrose). The differences found in the chemical composition between the genotypes could explain the differences in the pharmacological assays perform in our laboratory, but this relationship is yet to be identified. Finally, the search for an improved and standardized culture with medical purpose is an important aspect in natural product research and it should be taken into account to achieve chemical and pharmacological standardization.