Comparing wild and cultivated Arnica montana L. from the Italian Alps to explore the possibility of a sustainable production using local seeds

Mountain arnica (Arnica montana L.) is an herbaceous long-lived plant of nutrient-poor grasslands of European mountains. It is a widely used medicinal plant for the treatment of injuries and accidents, the secondary metabolites that mediate the anti-inflammatory effects of arnica flowerheads being mainly sesquiterpene lactones (SLs, Fig. 1). Habitat fragmentation, abandonment of pasturing and collection for herbal use led to the rapid decline of this species, for this reason, the sustainable production instead of the collection of wild material, should be incentivized. A wild accession of arnica inflorescences versus a commercial from Valsaviore (Italian Alps) were confronted in the germination performances and the phytochemical characterization through High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR) and Gas Chromatography–Mass Spectrometry techniques (GC-MS). Germination percentage (GRP) was high (>75%) both for commercial and wild seeds. 1H NMR spectrum of arnica extracts were very similar and demonstrated a signal richness confirming the presence of sesquiterpene compounds, esters of helenaline and dehydroelenaline. The main compounds identified were 6-O-(2-methylbutyryl)-helenalin (HMB) 6-O-isobutyryl-11α,13-dihydrohelenalin (DHIB), 6-O-(2- methylbutyryl)-helenalin (HIB), 6-O-(2-methylbutyryl)-11α,13-dihydrohelenalin (DHMB) and 6-O- metthacryloylhelenalin (HM). The major compounds in A. montana volatiles composition were germacrene D (found in a quantity of 26 μg/g in wild arnica and 10 μg/g in the cultivated one), α-Bergamotene (18 μg/g in the wild cultivar and 11 μg/g in the cultivated flos), cymene (14 μg/g) limonene (11 μg/g) and α- fellandrene (15 μg/g) in the cultivated arnica and δ-cadinene (13 μg/g) in the wild one. A significantly high percentage of acetic acid methyl ester (38 μg/g) and 2-methyl-methyl ester of propanoic acid (31 μg/g) were found for cultivated arnica and were probably associated with fermentation processes linked to the traditional method of air drying on trellis. In applied botany, the possibility to grow A. montana in marginal territories is of interest for farmers in alpine regions looking for alternative crops in high mountain farming. In our case the wild germplasm was eligible for cultivated cropping both for chemical composition (Fig. 2) and germination performance. The possibility of growing A. montana and a controlled local first transformation are important to incentivize local, good quality and sustainable production (Fig. 3). The growing of seedlings “in loco” could be of great interest both for farmers and for natural conservation purposes.