Amazon climatic factors driving terpene composition of Iryanthera polyneura Ducke in terra-firme forest: A statistical approach

Iryanthera polyneura (Myristicaceae) is popularly known as cumala-colorada, and can be found in the Amazon rain forest. The present study aimed the evaluation of the chemical composition of the essential oils (EOs) obtained from the leaves of I. polyneura throughout a two-year period in order to correlate chemical findings with seasonality and climatic variation. Leaves from I. polyneura were collected 15 times from three different individuals, identified as 22EO, 80EO and 530EO, between the years of 2009 and 2011. The EOs were obtained and tested by gas-chromatography-mass spectrometry techniques. ANOVA and multivariate analyses were used to assess the relationship between the percentage of terpenes and seasonal/climatic variations. Fifty-nine compounds were detected in the EOs, of which 44 were identified (74.5%). The main components of the EOs were spathulenol (6.42 ± 1.02%), α-cadinol (5.82 ± 0.40%) and τ-muurolol (5.24 ± 0.03%). Higher levels of spathulenol were observed in 22EO during rainy season, while τ-muurolol occurred in high amounts during the dry season, as did α-cadinol in 22EO and 80EO. Correspondence analysis revealed a distinction between two groups of EOs based on seasonality, whereas a canonic correspondence analysis and ANOVA determined how the major compounds were related to both seasonality and climatic factors. Non-metric multidimensional scaling in association with an analysis of similarities showed that the abundance and composition of terpenes in the samples varied moderately among the three Iryanthera individual plants. Present findings have shown that there is variation in the occurrence of the major compounds spathulenol, τ-muurolol and α-cadinol produced by I. polyneura and that the pattern of variation is related to season and climatic changes.