Influência da sazonalidade na composição química e na atividade antioxidante dos óleos essenciais das folhas de Croton heliotropiifolius e Croton jacobinensis.

Abstract

The species Croton heliotropiifolius (velame) and Croton jacobinensis (marmeleiro-branco) are endemic plants of Northeastern Brazil with proven phytochemical and pharmacological activity. However, studies indicate that seasonality may influence their chemical composition, and consequently their bioactivity.In this perspective, the present research aimed to analyze the influence of seasonality on the chemical composition of the essential oils (EOs) from fresh leaves of both species, evaluating their antioxidant potential throughout the four seasons of the year. Plant material was collected in January (summer), April (autumn), July (winter), and October (spring) of 2024, in the city of Areia, Paraíba (PB), Brazil. The EOs from the fresh leaves of both species were extracted by hydrodistillation and analyzed by gas chromatography coupled with mass spectrometry (GC/MS) for the identification of their constituents. Yields ranged from 0.05% to 0.16% for the essential oil of C. heliotropiifolius (EOCH), and from 0.07% to 0.11% for the essential oil of C. jacobinensis (EOCJ). Statistical analyses showed that periods of lower precipitation and humidity favored oil synthesis, which explains the highest yield observed in spring (0.16%) for EOCH, and suggested that EOCJ presents greater seasonal stability, with less influence of climatic variations on EO production. GC/MS analysis allowed the identification of 27 compounds for EOCH and confirmed 22 compounds for EOCJ. The main compounds found in EOCH were Ecaryophyllene (20.25–33.23%), bicyclogermacrene (1–17.68%), and limonene (6.50– 13.60%), with E-caryophyllene being the major constituent in all samples. For EOCJ, the main constituents were bicyclogermacrene (30.33–47.77%), germacrene D (10.28–18%), and γ-muurolene (0–29.80%), with bicyclogermacrene being the major compound in all seasons. The antioxidant activity of the EOs was evaluated using the ABTS (2,2'-azino-bis(3ethylbenzothiazoline-6-sulfonate)), DPPH (2,2-diphenyl-1-picrylhydrazyl), and TAC (Total Antioxidant Capacity) methods. EOs from both species exhibited antioxidant activity in the three methods tested, with emphasis on the TAC method, which revealed higher activity, with IC₅₀ values comparable or even lower than ascorbic acid (0.658±0.53 mg/mL), EOCH being more active in summer (IC₅₀ = 0.88±0.57 mg/mL) and EOCJ in winter (IC₅₀ = 0.54±0.36 mg/mL). Therefore, it is inferred that both species may represent a promising field in the search for bioactive compounds with antioxidant potential for the prevention of diseases related to oxidative stress.