Phenylpropenoid content in high-altitude cultivated Rhodiola rosea L. provenances according to plant part, harvest season and age

The phenylpropenoid glycosides rosavin, rosarin, rosin summarised as ‘total rosavins’ are quality indicators of Rhodiola rosea L. Here we report the systematic quantification of these glycosides and the aglycon cinnamyl alcohol in various provenances cultivated homogenously at 1580 m altitude. (I) We examined rhizomes versus roots in cultivation year 9 (20 provenances). Extracts (70% ethanol) contained 0.5–4.3 mg/mL (rhizomes) and 0.4–2.5 mg/mL (roots) total rosavins. The rosavin/cinnamyl alcohol ratio (average rhizomes 8.1:1, roots 6.2:1), was more influenced by plant origin than plant part. We additionally analysed salidroside including its aglycon tyrosol. The rosavins/salidroside ratios (including aglycons) of 6.4:1 (rhizome) and 5.5:1 (root) indicated authentic R. rosea independent of plant part and origin. (II) Rhizomes extracts (8 provenances) from various dates during years 6 and 7 contained 0.4–4.8 mg/mL total rosavins corresponding to 0.2–3.0% in the dry drug. Age (decreasing trend) and provenance impact were superposed by seasonal variation with a phenylpropenoid peak in spring. Rosavin/cinnamyl alcohol ratios in North European plants were 3–8:1, for Alpine/Pyrenean plants 9–14:1. (III) Compared to our previous dataset from cultivation in South England, on average, there was no major difference between phenylpropenoid values from cultivation at 65 m and 1580 m apart from moderately more cinnamyl alcohol at higher altitude. As per provenance, absolute values were site dependent but phenylpropenoid glycoside/aglycon ratios consistent. In conclusion, this is the first systematic investigation for a high altitude cultivation of R. rosea demonstrating the major extent plant part, season and age influence absolute phenylpropenoid values. In contrary, relative phenolic compound profiles are mostly origin-determined, independent of cultivation conditions and site, and could be used for authentication in quality control.