Bioextracts of Cistus ladanifer L. growing in São Domingos mine as source of valuable compounds

Abstract

Cistus ladanifer L. is an autochthones species with great potential for phytostabilisation of mining areas from Iberian Pyrite Belt (IBP) as well as medicinal and odoriferous/fragrance interest. In order to valorise C. ladanifer in the rehabilitation process of these areas, the aims of this study were to: i) compare the organic composition of bioextracts obtained from shoots of C. ladanifer growing in contaminated and non-contaminated areas; ii) quantify some valuable organic compounds of these bioextracts; and iii) evaluate the influence of the concentration of the potentially hazardous elements (PHE's) in the shoots on the quality of the bioextracts. Composite samples of soils and C. ladanifer shoots were collected in São Domingos mining area (IPB, SE of Portugal) and in a reference area with non-contaminated soils and similar climatic conditions (Corte do Pinto). Total concentrations of PHE's (Al, As, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined, after acid digestion, in these soils and shoots. Bioextracts were obtained from plant shoots using n-hexane in an accelerated solvent extractor. Organic compounds were identified by gas chromatography–mass spectrometry and some valuable organic compounds (α-pinene, camphene, camphor, fenchone and verbenone) were quantified. Multielemental concentration of the plant residues after obtaining the bioextracts was carried out. São Domingos soils can be considered contaminated with As, Cr, Cu and Pb. The highest concentrations of As, Co, Cu, Fe, Pb and Zn were determined in São Domingos shoots, while the contrary was observed for Ni. The main organic compounds in the bioextracts were benzenepropanoic acid and viridiflorol. Independently of the population, similar profile was observed having slight variability in the amounts (%) of some organic compounds (e.g. benzenepropanoic acid, verbenone, bornyl acetate, borneol). The highest concentration of α-pinene was obtained in São Domingos bioextracts while the other determined valuable compounds presented similar concentrations. Concentrations of PHE's in the shoots were not correlated with organic composition of the bioextracts. No elements transfer occurred during the compounds extraction.The bioextracts obtained from C. ladanifer growing in São Domingos mining area had valuable compounds and did not pose any human health risk. Phytostabilisation of contaminated soils with this species can provide economic return by the exploration of several valuable compounds.