This work aimed to identify the bioactive compounds present in adult maqui (Aristotelia chilensis) leaves from different stages of development and seasons of the year and compare them with leaves obtained from maqui plants grown in vitro. The qualitative and quantitative analysis of maqui leaf extracts by HPLC-DAD-ESI-MSⁿ showed the presence of different polyphenolic compounds classified into galloyl and caffeoyl quinic acids, ellagitannins and ellagic acid- and flavonoid-derivatives. In general, the total phenolic content of the in vitro samples was higher than that of ex vitro samples, whereas the total flavonoid content was higher in winter basal leaves. Additionally, the analysis by HPLC-MS showed that the extract from spring basal leaves was enriched in quercetin, catechin, kaempferol and 3-caffeoyl quinic acids, while in the in vitro leaves extract, quercetin was not present. As regards lipophilic compounds identified by GC/MS, the samples of in vitro leaves showed a high presence of α-tocopherol and β-sitosterol. In contrast, the samples of adult leaves presented a hight level of linolenic and linoleic acids. These results suggest that maqui leaves could be an excellent source of antioxidants and lipophilic compounds for many industries, such as the nutraceutical and pharmaceutical industries.

Residential heater replacement programs in Chile have been evaluated primarily through fine particulate matter (PM) reduction metrics, without considering chemical speciation of the organic aerosols. This screening-level study characterized and compared particle-bound polycyclic aromatic hydrocarbon (PAH) and nitro-PAH emission factors from a residential firewood and a wood pellet heater, under controlled combustion conditions, and assessed their potential toxic equivalency (BaP-TEQ). Compound quantification used 1-nitropyrene as an index calibration compound; all results are semi-quantitative estimates with a combined analytical uncertainty of approximately 13–32%. Firewood combustion yielded a PAH-dominated emission profile with a total BaP-TEQ EF of 187.8 ng/kg, driven primarily by benzo[a]pyrene (BaP; individual contribution: 183.9 ng/kg). Wood pellet combustion showed a nitro-PAH-dominated profile under the applied semi-quantitative analytical conditions, with concentrations expressed as 1-nitropyrene-equivalent estimates and several compounds identified tentatively by NIST library matching, yielding a total screening-level BaP-TEQ EF of 972.1 ng/kg, approximately five-fold higher than firewood under the applied TEF framework and driven primarily by 6-nitrochrysene (toxic equivalency factor, TEF = 10). This screening-level estimate should not be interpreted as a direct human health risk between the two heating systems. Mean PM emission factors were 1.05 ± 0.55 g/kg for firewood combustion and 0.69 ± 0.15 g/kg for pellet combustion (approximately 1.5-fold difference). These results are reported descriptively given the screening-level nature of the analysis. The shift in particulate chemical profile from PAH-dominated in the firewood system to nitro-PAH-dominated in the pellet system suggests that wood pellets from pine may not be a sustainable approach to address air quality problems in Chile, since reductions in PM emissions alone may not capture relevant differences in the organic toxicological profile between these combustion systems. These findings provide a regional baseline for the chemical speciation of residential biomass emissions in Chile.

Key message Seasonal dynamics shape the antioxidant capacity and volatile composition of Peumus boldus and Cryptocarya alba, suggesting that the potential bioactive inputs for forest therapy may vary throughout the year. Abstract Plants, in their interaction with the environment, synthesize organic compounds that are considered beneficial for human health in the practice of forest therapy. This study describes seasonal changes in the production and activity of volatile organic compounds in two emblematic southern Chilean trees. Phytochemical profiles were obtained by gas chromatography-mass spectrometry, total phenolic content was determined by the Folin–Ciocalteu method, and antioxidant capacity was measured by ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays, in Peumus boldus and Cryptocarya alba leaves obtained from Nonguén National Park (Chile). Climatic data were recorded. The results show that the phytochemical richness of sampled P. boldus trees reached the highest value in autumn, while C. alba showed a slight decrease in summer. The four seasons presented a broad core of constitutive compounds including monoterpenes and monoterpenoids, in both species. ABTS assay showed that antioxidant capacity in P. boldus samples was markedly higher in autumn, while in C. alba, the highest value was reached in winter. DPPH assay showed highest antioxidant capacity in spring in P. boldus samples, and in C. alba it occurred in winter. The highest phenolic accumulation was observed in spring for P. boldus, and in autumn for C. alba. Here we provide an initial characterization of the dynamics of phytochemical variation associated with the seasonal changes occurring in two trees of the southern forest. Further investigation is required to fully understand the emission dynamics in response to seasonal changes, and their potential contribution to human health through the practice of forest therapy.