NATURAL AROMATIC AND MEDICINAL PLANTS (NAMP) OF NE OF PORTUGAL: RELEVANCE OF GEOCHEMISTRY DATA TO DEFINE THE MEDICAL INTEREST: A PRELIMINARY STUDY

The use of NAMP increasingly as ornamental and medicinal/wellness plants, and its cultivation in a systematic way may possibly have great interest in periods of economic depression in poor regions such as the Nordest of Portugal. The region of Vinhais - Bragança is characterized by the presence of mafic and ultramafic rocks, and the most representative soils are Cambisols and Leptosols. The main purpose of this study was: (a) to evaluate the levels and spatial distribution of some essential elements for living organisms (e.g. Co, Cr, Cu, Fe, Mg, Mn, V and Zn) in the different parts of three selected species of natural vegetation that grows spontaneously; and (b) investigate whether these species can be considered plants with economic interest for to be used in aromatic and medicinal industries taking into account potential risks for human health.

A total of 36 samples (14 Lavandula stoechas L., 10 Thymus mastichina L. and 12 Cistus ladanifer L.) were collected around Bragança municipality and along a 34 km transect from Bragança to Vinhais. The vegetation, were separated into lives, stems, roots and flowers when exists. The parts of plants and the soils were analyzed by ICP/ES & MS after extraction with aqua regia, for 32 chemical elements.

For these study NAMPs, it was found that leaves shows the highest concentrations of these elements which is relavant together with the flowers for aromatic and medicinal industries. The maximun concentrations found in leaves for Lavandula stoechas L. were: (in mg kg^-1) 16, 86, 46, 224 and 1034 for Co, Cr, Cu, V, Zn and Mn respectively and (in %) 0.667 for Fe and 0.704 for Mg. For Thymus mastichina L. maximum contents were: (in mg kg^-1) 16 for Co, 90 for Cr, 76 for Cu, 77 for V, 86.6 for Zn, 501 for Mn and (in %) 2.075 for Fe and 1.067 for Mg. Cistus ladanifer L. the maximun concentrations were globaly lower. Considering international guidelines some of these levels may have great interest for medicinal/wellness uses however for some heavy metals (e.g.Co, Cr and V) these high concentrations are above what is considering excessive or toxic and spatially are related to geological factors (ultrabasic and basic formations). Careful choice of growing site can reduce the heavy metals uptake; however some testes for contaminant will be need before processing in particular when larger amounts of the vegetation are used.