Main bitter compounds of Gentiana lutea var. aurantiaca roots wild collected in the León Province (Spain)

Gentiana lutea L var. aurantiaca (M. Lainz) Renob. is an endangered plant distributed mainly in the northwest part of Cantabrian Mountains, in the Iberian Peninsula. Its particular characteristics are the color of the flowers, ranging from orange to almost red [1], and also that it grows in soils with pH values between 3.83 and 4.65 [2] from siliceous origin. As for the other G. lutea subspecies, the variety aurantiaca has been used and wild collected for its high contents in bitter compounds (e.g. gentiopicroside, amarogentine, sweroside and swertiamarine). In this study, the content of bitter compounds of G. lutea var. aurantiaca roots, collected in several wild populations in the León province (Cantabrian Mountains) were compared with those of the subsp. lutea, roots collected along the Pyrenees, and subsp. vardjanii Wrab., roots collected in some Trentino areas (Dolomite Alps, Italy). Analyses were carried out by HPLC. Table 1 shows that var. aurantiaca has high contents in bitter compounds, comparable to the vardjanii subspecies, except gentiopicroside, and greater than subsp. lutea, especially when the amarogentine is considered, but lower than those obtained in the subsp. symphyandra (Murb.) Hayek [3], considered as the richest subspecies in amarogentine, although not in terms of root yield when it is cultivated [4]. Moreover Franz et al. [4] remark that the difference of altitudes influence the amarogentine content, but in our study these altitude range are not significant (Table 1). The bitter compounds content of var. aurantiaca makes it proper for its study in terms of cultivation and a comparison between different ecotypes looking for the possibility of outstanding ones.

Tab. 1: Mean values for altitude and main bitter compounds in the roots of different Gentiana lutea L. taxa and from different localities.

Gentiana lutea L.	Altitude	Gentiopicroside	Amarogentine	Sweroside	Swertiamarine
var. aurantiaca	1736 a	7.011b	0.0311 a	0.163 a	0.379 a
subsp. lutea	1625 a	7.151b	0.0130 b	0.142 a	0.281b
subsp. vardjanii	1659 a	8.26 a	0.0281 a	0.108 a	0.337 ab
Different letters for every character indicate a significant difference (p ≤0,05 Duncan test)

Keywords: Gentiana aurantiaca, endangered, Cantabrian Mountains, bitter compounds

References:

[1] Renobales G. Notas acerca del tratamiento de las Gentianaceae para “Flora Ibérica”. 2003; 60 (2): 461 – 469.

[2] González O, Mayo S, Rodríguez A et al. Effect of soil in the growth of Gentiana lutea radical system in north mountain of Léon (Spain). Acta Hort 2012: 281 – 285.

[3] Aiello N, Bontempo R, Vender C. Use of morphological features and amarogentin content for characterization of wild yellow gentian (Gentiana lutea L.) populations in north-east Italy. Acta Botanica Gallica 2013; 160: 33 – 41.

[4] Franz C, Bezzi A, Belliardo F. Variability and breeding of Gentiana lutea L. with respect to bitter substances. In, Atti del Convegno (ed) Genziana e specie amaro-aromatiche, Ricerche ed Applicazioni. University of Camarino Publications, Italy.; 1996: 29 – 34.