Chemical diversity of essential oils from the Brazilian medicinal plant Lychnophora pinaster Mart from different environments

Lychnophora pinaster Mart. (arnica-mineira) is an endangered popular Brazilian medicinal species with occurrence restricted to the State of Minas Gerais, Brazil. The species inhabits areas with different soil and climate conditions, which may affect the chemical composition of essential oils. The plant is frequently cited for its anti-rheumatic, anti-inflammatory, analgesic and other biological activities. Previous works in a restricted area report a predominance of phenylpropanoids compounds in its essential oil composition. Due to the potential economic use as a phytomedicine and the limited geographic coverage of previous studies, this research aimed to analyze the essential oil of populations from different regions and the influence of the soil on the essential oil chemical composition. Six populations of two regions were analyzed: Diamantina (DIMa), Olhos D'Agua (OD) and Grao Mogol (GM), from the North, and Caete/Rio Acima (CTRA), Nova Lima/Serra da Calcada (NLSC) and Serra da Moeda (SM), from the Metropolitan Region of Belo Horizonte. Soil analyses revealed differences between the soils. Diamantina (DIMa) and Serra da Moeda (SM) presented the highest essential oil yield among populations (0.12 %), while the smallest was observed for NLSC, with 0.04 %. There was no difference in yield between regions. Principal component analysis demonstrated the diversity of chemical profiles between populations. For the northern region, the major substances were alpha-pinene (12 %) for GM; 14-acetoxy a hu mulene, (21.9 %) for DIMa and 14-hydroxy-4,5-dehydro-caryophyllene and squamulose (9.13 % and 8.30 %, respectively) for OD. For the metropolitan region of Belo Horizonte, the substances with higher levels were sesquiterpene 1 (35.16 %) and sesquiterpene 7 (8.13 %) for MS; 1,7-diepi-a-cedrenal (6.46 %), (Z)-nerolidol (12.60 %), sesquiterpene 2 (14.62 %) in CTRA. Olhos D'Agua (OD) registered as the major an unidentified compound (38.46 %). Diamantina, Olhos D'Agua and Nova Lima/Serra da Calcada showed chemical similarity, although they belong to different regions of the state, distant by 273 km. Grao Mogol (GM), Serra da Moeda (SM) and Caete/Rio Acima (CTRA) did not show chemical similarity to each other or to the others. The populations differed for the chemical composition and soil characteristics. The multivariate analysis indicated that certain compounds and nutrients of the soil were simultaneously relevant for population differentiation. The chemical diversity found in L. pinaster essential oils of different regions with predominance of sesquiterpenes may affect the biological activities.