Seasonal phytochemical variation of Peumus boldus and Cryptocarya alba and its impact in forest therapy.

Volatile compounds produced by trees are one of the responsables of the benefits of forest
therapy. This study describes seasonal changes in the production and activity of volatile organic
compounds in the leaves of two emblematic southern Chilean forest trees that are especially valued
for their aromas and therapeutic properties and their implications for the practice of forest therapies
are discussed. Phytochemical profiles were obtained by gas chromatography-mass spectrometry,
total phenolic content was determined by the Folin–Ciocalteu method, and antioxidant activity was
measured by ABTS (2,2'-azino-bis3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-
picrylhydrazyl) assays, using Peumus boldus and Cryptocarya alba leaves obtained from Nonguén
National Park (Chile). Climatic data, such as temperature, precipitation, and UV radiation, were
recorded. The results show that P. boldus exhibited the highest terpene diversity and greatest ABTS
antioxidant capacity in autumn, while the DPPH antioxidant activity peaked in spring and the total
phenolic synthesis was inversely correlated with precipitation. On the other hand, C. alba reached
the highest antioxidant activities (ABTS and DPPH) in winter, contrasting with a low total phenolic
content during this season and with the higher production of 4-terpineol detected in summer. These
patterns may indicate a seasonal specialization strategy for P. boldus. For C. alba, it may be more of
a “constitutive readiness” strategy. Moreover, this information suggests that the fall and winter
seasons are the best times to reap the maximum therapeutic benefits of forest bathing in forests
where P. boldus and C. alba grow.