Forgotten Edible alpine plants in the canton of Valais

Tradition possesses plenty of forgotten wild edible plants and may help researchers in the quest for new food varieties. Swiss alpine cantons, especially the canton of Valais, have still had a viable tradition. However, societal changes and extensive urbanization have caused this knowledge to be confined to lateral valleys. This contribution aimed to document wild edible plants which were collected in the canton of Valais. 38 informants originating from four different valleys of the canton (Val d’Entremont, Val d’Illiez, Val d’Hérens, and Val d’Anniviers) were interviewed with semi-directive interviews.
98 edible plant species, which belong to 38 families, were identified. Plants were classified in eight categories based on the way they were traditionally used including salads, cooked vegetables, spices, alcoholic drinks, teas, syrups, jams, and raw snacks. The categories with the highest number of citations were teas (18%), followed by cooked vegetables (16%), jams (16%), and raw snacks (16%). Taraxacum officinale, Sambucus nigra, Chenopodium bonus-henricus, and Urtica dioica were the most cited plants and most commonly used in the different valleys. Knowledge on edible plants is found from its origins in agriculture and activities as shepherds. Books written in the XIXth and early XXth centuries have documented these uses and have allowed identification of around 40 food plants, which had already fallen in oblivion (e.g. Bunium bulbocastanum).
Two traditional edible plants (Phyteuma orbiculare and Cirsium spinosissimum) were submitted to a thorough phytochemical investigation. Each plant was successively extracted with dichloromethane and methanol. Extracts were subjected to HPLC-MS DAD analyses and pure constituents were isolated by preparative and semi-preparative methods (Diaion HP-20, liquid-liquid extraction, Sephadex LH-20, open column on silica gel, preparative and semi-preparative columns on C18). The molecular structures of the isolated compounds were elucidated by chemical and spectroscopic methods. In addition, substances relevant for nutrition (e.g. vitamins, fatty acids, minerals, and major polyphenols) were quantified.
The first species investigated was the round-headed rampion (Phyteuma orbiculare L., Campanulaceae). The sweet flowers of the plant were consumed by shepherds as raw snacks, whereas nutty-tasting leaves (rosettes) were eaten as a salad. No phytochemical studies or biological data had been published for the entire genus Phyteuma.
23 substances including different polyphenols, fatty acids, and triterpenes were identified from dried aerial parts. Phytochemical investigations also revealed the presence of two novel saponins, phyteumosides A and B. The aglycon of phyteumoside A possessed an unprecedented skeleton that could be rationalized as an incompletely cyclized onoceroid triterpene, whereas that of phyteumoside B was a new 17-polypodene skeleton. Identification of these two substances was achieved by compilation of chemical and enzymatic hydrolyses, followed MS/MS, GC-MS, NMR and X-rays analyses. In addition to these two new substances, a new dimeric phenylpropanoid glycosylate derivative (tangshenoside VII) could be isolated and elucidated.
Concerning the quantification of substances relevant for nutrition, Phyteuma orbiculare contained interesting amounts of ascorbic acid, beta-carotene, polyphenols, polyinsaturated fatty acids, calcium, magnesium and potassium
This food plant, which possesses interesting nutritive properties and favorable breeding predispositions, could be an interesting candidate for further agronomic development. However, species of the same genus have a larger biomass and it was interesting to compare their phytochemical profile. HPLC-MS DAD analyses revealed similar metabolite profiles for P. spicatum, P. ovatum, and P. orbiculare but showed differences for P. hemisphaericum.
The second plant to be investigated was a thistle, Cirsium spinosissimum (Asteraceae). Surrounding leaves and the pappus hairs were removed before consumption, and the receptacle was eaten in early summer time. Taste of the receptacle is similar to that of an artichoke, and its consistency is tender.
A total of 20 substances including polyphenols, a monoterpene lactone, fatty acids and a spermine derivative were identified. Major polyphenols were linarin and pectolinarin and have been previously isolated from other Cirsium species.
This plant contains vitamins and polyunsaturated fatty acids in low amounts, and an interesting level of potassium. Cirsium spinosissimum is not really convenient for further cultivation due to its spiny morphology.
Other alpine edible plants selected during this work could be interesting with regard to their chemical composition, and for future breeding. They should be the main focus of further investigations. The establishment of alpine plants as new food crops would represent a diversification of the activities in mountain agriculture.