Seasonal Variation in Essential Oil Composition and Antioxidant Capacity of Aniba canelilla (Lauraceae): A Reliable Source of 1-Nitro-2-phenylethane

Aniba canelilla (Kunth) Mez essential oil has many biological activities due to its main compound 1-nitro-2-phenylethane (1N2F), followed by methyleugenol, a carcinogenic agent. This study analyzed the influence of seasonality on yields, antioxidant capacity, and 1N2F content of A. canelilla leaf and twig essential oils. Essential oils (EOs) were extracted with hydrodistillation and analyzed with gas chromatography coupled to mass spectrometry and a flame ionization detector. Antioxidant capacity was measured using the free radical scavenging method (DPPH). Chemometric analyses were carried out to verify the influence of climatic factors on the production and composition of EOs. 1-Nitro-2-phenylethane was the major constituent in A. canelilla EOs throughout the seasonal period (68.0–89.9%); methyleugenol was not detected. Essential oil yields and the 1N2F average did not show a statistically significant difference between the dry and rainy seasons in leaves and twigs. Moderate and significant correlations between major compounds and climate factor were observed. The twig oils (36.0 ± 5.9%) a showed greater antioxidant capacity than the leaf oils (20.4 ± 5.0%). The PCA and HCA analyses showed no statistical differences between the oil samples from the dry and rainy seasons. The absence of methyleugenolin in all months of study, described for the first time, makes this specimen a reliable source of 1N2F.


Introduction
The Lauraceae comprises around 50 genera and 2500 to 3000 species distributed in tropical and subtropical regions; mainly, taxa are aromatic trees and shrubs rich in essential oils [1,2].Lauraceae is native and non-endemic in Brazil, with 27 genera and 466 species of trees, shrubs, and lianas, known as climbers [3].
The Lauraceae has economic potential in several industrial sectors, such as food, wood, pharmaceuticals, and perfumery.Regarding its ethnobotany, its taxa are used to treat several pathologies [4,5].Among the genera of this family, Aniba species have many scientific studies highlighting their pharmacological potential, emphasizing A. rosaeodora Ducke, A. parviflora (Meisn.)Mez, and A. canelilla (Kunth) Mez [6,7].
Aniba canelilla (Kunth) Mez is an aromatic species popularly known as "precious bark", "false cinnamon", "canelão", and "precious leaf".It is native and endemic to Brazil and found in the north, central-west, and southeast regions of the country.It is widely used in popular medicine to treat inflammation, intestinal pain, respiratory diseases, microbial, and parasitic infections [3,8].Furthermore, A. canelilla essential oil is a natural antioxidant for food preservation and disease control, presenting high potential for use in cosmetics and pharmaceutical products [8].
In the aromatic and medicinal plants market, essential oils (EOs) are widely sought after due to their applications in perfumery, beverages, food, and cooking.EOs can be present in different parts of plants, such as leaves, seeds, stems, bark, and roots [9].Moreover, they are used in traditional medicine as antimicrobial agents, as they are biologically active compounds with important health effects [10,11].
Nitro-substituted compounds have demonstrated broad biological activities and their pharmacological potential has been reviewed [15].Furthermore, the presence of the hydrophobic phenyl group makes 1N2F lipophilic and affects its membrane and blood-brain barrier transport ability [16,17].
On the other hand, there are reports in the literature indicating the presence of methyleugenol in the A. canelilla essential oil, which is considered a carcinogen and mutagen with a solid link to safrole [18,19].Due to the biological activities of this species and its possible industrial and pharmacological applications, the objective of this study was to evaluate its antioxidant potential and the influence of climatic factors on the yields and 1-nitro-2-phenylethane contents of the essential oil of A. canelilla.

Essential Oil Yields vs. Environmental Conditions
The climatic parameters (precipitation, temperature, and insolation) were monitored from August 2021 to July 2022 to evaluate the influence of seasonality on the composition and yields of A. canelilla essential oil.The average precipitation values ranged from 116.6 mm (July) to 527.4 mm (March), the average temperature from 25.9 • C (January) to 27.6 • C (October), and the values of insolation from 105.4 h (March) to 256.1 h (August).Based on rainfall data, the months of March to May comprise the rainy season with an average rainfall of 472.5 ± 60.2 mm, and the months of August to February, in addition to June to July, comprise the dry season with an average rainfall of 237.2 ± 67.8 mm (see Figure 1).In the seasonal study of Lippia alba (Mill.)N.E.Br.ex Britton & P. Wilson (Verbenaceae), the dry season also comprised the months of August to February and the rainy period from March to May [20].
The A. canelilla specimen was collected in the city of Belém, located in northern Brazil, which has a predominantly hot and humid climate.The climate of the Amazon region has only two delimited seasons, the rainy and the dry.Despite this, the seasons can change according to the atmospheric phenomena in the region [21].
In this seasonal study, the oil yields of A. canelilla leaves ranged from 1.1% (February) to 1.7% (July), and of the twigs ranged from 0.4% (June) to 1.2% (September).The essential oil yields of A. canelilla leaves (1.1-1.7%;1.3 ± 0.2) were higher than the twigs (0.4-1.2%; 0.8 ± 0.2) in all months of this study, except in September, where they were the same (1.2%).Furthermore, the average yield of leaves (1.3 ± 0.2) and twigs (0.8 ± 0.2) showed a statistical difference (p < 0.05) in the Tukey test.The A. canelilla specimen was collected in the city of Belém, located in northern Brazil, which has a predominantly hot and humid climate.The climate of the Amazon region has only two delimited seasons, the rainy and the dry.Despite this, the seasons can change according to the atmospheric phenomena in the region [21].
A specimen of A. canelilla collected in Belém, Pará, Brazil, presented an oil yield of 1.5% for leaves and 1.0% for twigs [6].Another specimen collected in Amazonas also showed higher oil yields in the leaves (1.3%) than in the twigs (1.2%) [22].
The essential oil yields of leaves (L) and twigs (T) did not show a statistically significant difference between the dry (L: 1.3 ± 0.2; T: 0.8 ± 0.2) and rainy (L: 1.3 ± 0.3; T: 0.8 ± 0.2) seasons.In this sense, the influence of seasonality on the EOs of a specimen of Psidium acutangulum DC. (Myrtaceae) collected in the city of Belém, Pará, Brazil, has been reported; the oil yields also showed no statistical differences between the dry (0.7 ± 0.3%) and rainy (0.9 ± 0.2%) periods [23].Regarding climatic factors vs. essential oil yields, the Pearson correlation coefficient (r) analysis showed that there was no significant correlation between the yields of A. canelilla leaves and twigs, respectively, with regard to temperature (r = 0.01 and r = −0.11),insolation (r = 0.30 and r = −0.20),or precipitation (r = −0.17;r = 0.10), as shown in Table 1.A specimen of A. canelilla collected in Belém, Pará, Brazil, presented an oil yield of 1.5% for leaves and 1.0% for twigs [6].Another specimen collected in Amazonas also showed higher oil yields in the leaves (1.3%) than in the twigs (1.2%) [22].
The essential oil yields of leaves (L) and twigs (T) did not show a statistically significant difference between the dry (L: 1.3 ± 0.2; T: 0.8 ± 0.2) and rainy (L: 1.3 ± 0.3; T: 0.8 ± 0.2) seasons.In this sense, the influence of seasonality on the EOs of a specimen of Psidium acutangulum DC. (Myrtaceae) collected in the city of Belém, Pará, Brazil, has been reported; the oil yields also showed no statistical differences between the dry (0.7 ± 0.3%) and rainy (0.9 ± 0.2%) periods [23].Regarding climatic factors vs. essential oil yields, the Pearson correlation coefficient (r) analysis showed that there was no significant correlation between the yields of A. canelilla leaves and twigs, respectively, with regard to temperature (r = 0.01 and r = −0.11),insolation (r = 0.30 and r = −0.20),or precipitation (r = −0.17;r = 0.10), as shown in Table 1.Yields and composition of secondary metabolites can be affected from plant formation to final isolation [24].For example, the EO present in the leaves of Nectandra grandiflora Nees (Lauraceae), collected in the Rio Grande do Sul (Brazil), showed seasonal variability, with the highest yield in spring (0.75 ± 0.06%) and the lowest yield in the winter (0.39 ± 0.02%) [25].Moreover, Ocotea porosa (Nees & Mart.) had an oil content of 0.82%, while Ocotea quixos (Lam) Kosterm had an EO content equivalent to 1.6% [25].
The 1N2F (L: 71.2%; T: 68.2%) [14] and (L: 88.3%; T: 70.9%) [6] was previously identified in high amounts in A. canelilla EOs.Both studies found that the levels of 1N2F in the leaves were higher than in the twigs, which vary from the results of this study.
Based on the analysis of the Pearson correlation coefficient (r) shown in Table 1, there was a moderate and significant positive correlation (p < 0.05) between precipitation and the 1N2F contents in the leaves (r = 0.61) and twigs (r = 0.60), and a moderate negative correlation between 1N2F and temperature (r = −0.59) in the leaves.The twigs had a weak negative correlation between 1N2F content and temperature (r = −0.47)and insolation (r = −0.37).
Based on the analysis of the Pearson correlation coefficient (r) shown in Table 1, there was a moderate and significant positive correlation (p < 0.05) between precipitation and the 1N2F contents in the leaves (r = 0.61) and twigs (r = 0.60), and a moderate negative correlation between 1N2F and temperature (r = −0.59) in the leaves.The twigs had a weak According to the statistically significant compounds classes, monoterpene hydrocarbons showed a moderate positive correlation with temperature (r = 0.69) and a strong positive correlation with insolation (r = 0.71) in the twigs.Oxygenated monoterpenoids showed a strong positive correlation with temperature (r = 0.78) in the leaves and a moderate negative correlation with precipitation in the leaves (r = −0.60)and twigs (r = −0.63).Sesquiterpene hydrocarbons showed a strong positive correlation with temperature (r = 0.70) and a strong negative correlation with precipitation (r = −0.70) in the leaves.Furthermore, oxygenated sesquiterpenoids showed a strong negative correlation with the average temperature (r = −0.70) in the twigs, and benzenoids showed a moderate negative correlation with temperature (r = −0.58)and a moderate positive correlation with precipitation in the leaves (r = 0.58) and twigs (r = 0.61).
Moreover, the highest amounts of 1N2F were obtained in March (F: 85.2%; T: 89.9%), a month with the highest precipitation (527.4 mm) and lowest sunshine (105.4 h), according to Figure 3.
The only seasonal study of A. canelilla reported in the literature indicated the presence of methyleugenol in its essential oil, which was used in foods as a flavoring agent.However, nowadays, methyleugenol is considered a carcinogen and mutagen with a strong link to safrol [18,19].
1N2F and methyleugenol contents varied with the season in a specimen from Carajás, southeast of Pará State [19].During the rainy season, 1N2F showed higher amounts (95.3%) than methyleugenol (17.7%).Therefore, in the dry season, methyleugenol presented higher concentrations (45.8%) than 1N2F (39.0%).Comparing these results with the sample of A. canelilla collected in the city of Belém, state of Pará, the specimen of this article can be considered a natural and secure source of 1N2F.
Molecules 2023, 28, 7573 9 of 18 correlation with the average temperature (r = −0.70) in the twigs, and benzenoids showed a moderate negative correlation with temperature (r = −0.58)and a moderate positive correlation with precipitation in the leaves (r = 0.58) and twigs (r = 0.61).
Moreover, the highest amounts of 1N2F were obtained in March (F: 85.2%; T: 89.9%), a month with the highest precipitation (527.4 mm) and lowest sunshine (105.4 h), according to Figure 3.The only seasonal study of A. canelilla reported in the literature indicated the presence of methyleugenol in its essential oil, which was used in foods as a flavoring agent.However, nowadays, methyleugenol is considered a carcinogen and mutagen with a strong link to safrol [18,19].
1N2F and methyleugenol contents varied with the season in a specimen from Carajás, southeast of Pará State [19].During the rainy season, 1N2F showed higher amounts (95.3%) than methyleugenol (17.7%).Therefore, in the dry season, methyleugenol presented higher concentrations (45.8%) than 1N2F (39.0%).Comparing these results with the sample of A. canelilla collected in the city of Belém, state of Pará, the specimen of this article can be considered a natural and secure source of 1N2F.Furthermore, the specimen in this study was evaluated with an in vivo experiment, where 1N2F increased antioxidant capacity and glutathione (GSH) concentrations, and reduced lipid peroxidation (both peritoneal and plasma).The essential oil decreased leukocyte migration induced by carrageenan, confirming its potential to treat inflammatory diseases and oxidative stress [28].
The volatile constituents of EOs are produced by secretory cells that minimize the risk of autotoxicity and allow the presence of high concentrations of secondary metabolites in places where their defense function may be vital [24].Furthermore, several factors can lead to variations in the composition of secondary metabolites.Among these factors, seasonality stands out, a term used to designate variations that occur due to different times of the year [29].

Antioxidant Capacity vs. Environmental Conditions DPPH Radical Scavenging
The A. canelilla oils, obtained from a twelve-month collection process of leaves and twigs samples, showed a DPPH radical scavenging capacity with an average of 20.4 ± 5.0% for the leaf oils and 36.0 ± 5.9% for the twigs, as shown in Table A2 and Figure 4.The reaction kinetics were considered slow, with an average of 120 min.The highest percentage of inhibition of the DPPH radical was observed for the twig oils collected in September (42.0 ± 1.3%), March (40.6 ± 1.0%), August and October (40.2 ± 1.3%), February (39.8 ± 1.5), and April (37.2 ± 0.4).The total antioxidant capacity was expressed in values equivalent to the standard Trolox.TEAC (mg.TE/g) of the leaf oils showed an average of 114.4 ± 27.7, which is about ten times as low as Trolox; however, the TEAC for the twig oils showed an average of 203.0 ± 33.3, which is five times as low as Trolox.TEAC of the leaves and twigs were statistically different in the Tukey test (p < 0.05).
September (42.0 ± 1.3%), March (40.6 ± 1.0%), August and October (40.2 ± 1.3%), February (39.8 ± 1.5), and April (37.2 ± 0.4).The total antioxidant capacity was expressed in values equivalent to the standard Trolox.TEAC (mg.TE/g) of the leaf oils showed an average of 114.4 ± 27.7, which is about ten times as low as Trolox; however, the TEAC for the twig oils showed an average of 203.0 ± 33.3, which is five times as low as Trolox.TEAC of the leaves and twigs were statistically different in the Tukey test (p < 0.05).
Molecules 2023, 28, x FOR PEER REVIEW 10 of 18 A study of Aniba canelilla essential oils (110 to 1400 µg mL −1 ), obtained from Amazonas and Pará state (northern Brazil) and using Trolox as the standard, demonstrated a DPPH inhibition of 32.4 to 93.0%.For the methanolic extract (2 to 10 µg mL −1 ), the values ranged from 29.8 to 92.6%.They also reported the antioxidant capacity of 1N2F (200 to 1000 µg mL −1 ) and Trolox (2 to 10 µg mL −1 ); the values ranged from 11.5 to 63.2% and 21.5 to 96.7%, respectively [22].In addition, the ethanolic extract of A. canelilla bark obtained from Pará state displayed optimum antioxidant activity (IC50 1.80 ± 0.16).The same study demonstrated equivalence between the extract of A. canelilla and Lascorbic acid.Its antioxidant potential was attributed to the presence of phenolic compounds, capable of interrupting the chain reactions caused by free radicals due to its ability to donate hydrogen atoms [31].
A study of Aniba canelilla essential oils (110 to 1400 µg mL −1 ), obtained from Amazonas and Pará state (northern Brazil) and using Trolox as the standard, demonstrated a DPPH inhibition of 32.4 to 93.0%.For the methanolic extract (2 to 10 µg mL −1 ), the values ranged from 29.8 to 92.6%.They also reported the antioxidant capacity of 1N2F (200 to 1000 µg mL −1 ) and Trolox (2 to 10 µg mL −1 ); the values ranged from 11.5 to 63.2% and 21.5 to 96.7%, respectively [22].In addition, the ethanolic extract of A. canelilla bark obtained from Pará state displayed optimum antioxidant activity (IC 50 1.80 ± 0.16).The same study demonstrated equivalence between the extract of A. canelilla and L-ascorbic acid.Its antioxidant potential was attributed to the presence of phenolic compounds, capable of interrupting the chain reactions caused by free radicals due to its ability to donate hydrogen atoms [31].
For the HCA of A. canelilla twigs, it was also possible to analyze the formation of three distinct groups.Group I includes the months of August and October.Group II presents the months of September, February, and January.Furthermore, group III comprises the months of March, April, May, and June (see Figure 7).
(r = 1.24), linalool (r = 1.28),E-caryophyllene (r = 1.80), and caryophyllene oxide (r = 1.09).The second component (PC2) explained 32.11% of variability and showed negative correlations with 1N2F (r = −0.32),E-caryophyllene (r = −0.13),and caryophyllene oxide (r = −2.50),and positive correlations with α-pinene (r = 1.07), linalool (r = 1.88), and βlongipinene (r = 3.07).The third component (PC3) explained 17.29% of the data, presenting negative correlations with linalool (r = −0.37)and E-caryophyllene (r = −1.99),and positive correlations with α-pinene (r = 2.44), β-longipinene (r = 0.10), and caryophyllene oxide (r = 1.00).In relation to the HCA, the PCA analysis confirmed the formation of three distinct groups.For the HCA of A. canelilla twigs, it was also possible to analyze the formation of three distinct groups.Group I includes the months of August and October.Group II presents the months of September, February, and January.Furthermore, group III comprises the months of March, April, May, and June (see Figure 7).PCA and HCA analysis of Aniba canelilla leaves and twigs did not differentiate oil samples during the dry and rainy seasons.A previous study on the seasonality of essential oils from Psidium friedrichsthalianum leaves from Brazil did not show a separation of samples in the dry and rainy seasons [32].Some species present variation in the concentrations of their constituents, but cannot be separated in chemometric analyses due to their metabolism not correlating with biotic, abiotic factors, and climatic parameters, which can interfere with metabolic pathways [33].However, correlations were observed between climatic parameters and oil constituents and their compound classes, as mentioned previously (see Table 1).PCA and HCA analysis of Aniba canelilla leaves and twigs did not differentiate oil samples during the dry and rainy seasons.A previous study on the seasonality of essential oils from Psidium friedrichsthalianum leaves from Brazil did not show a separation of samples in the dry and rainy seasons [32].Some species present variation in the concentrations of their constituents, but cannot be separated in chemometric analyses due to their metabolism not correlating with biotic, abiotic factors, and climatic parameters, which can interfere with metabolic pathways [33].However, correlations were observed between climatic parameters and oil constituents and their compound classes, as mentioned previously (see Table 1).

Plant Material and Climatic Data
The leaves and twigs of A. canelilla were collected from a specimen from the city of Belém, Pará state, Brazil (coordinates: 1°27′20.3″S/48°26′18.1″W).For this seasonal study, leaves (200 g) and twigs (120 g) were sampled on the 10th day of each month at 10 a.m. from August 2021 to July 2022.The specimen was collected in accordance with the Brazilian legislation relating to the protection of biodiversity (Sisgen A704928).
The climatic parameters (insolation, temperature, and rainfall) of the mentioned area were obtained monthly from the website of the National Institute of Meteorology (INMET, http://www.inmet.gov.br/portal/,accessed on 31 August 2022, from the Brazilian Government [34]).

Extraction and Oil Composition
The leaves and twigs were dried in a refrigerated room, ground, and subjected to hydrodistillation (in duplicate) using a Clevenger-type apparatus (3 h) according to the methodology described by Figueiredo et al. [35].
The chemical compositions of the obtained essential oils were analyzed with gas chromatography-flame ionization detector (GC-FID, Shimadzu Corporation, Tokyo, Japan) and gas chromatography-mass spectrometry (GC/MS, Shimadzu Corporation, Tokyo, Japan) simultaneously [35].

Plant Material and Climatic Data
The leaves and twigs of A. canelilla were collected from a specimen from the city of Belém, Pará state, Brazil (coordinates: 1 • 27 20.3S/48 • 26 18.1 W).For this seasonal study, leaves (200 g) and twigs (120 g) were sampled on the 10th day of each month at 10 a.m. from August 2021 to July 2022.The specimen was collected in accordance with the Brazilian legislation relating to the protection of biodiversity (Sisgen A704928).
The climatic parameters (insolation, temperature, and rainfall) of the mentioned area were obtained monthly from the website of the National Institute of Meteorology (INMET, http://www.inmet.gov.br/portal/,accessed on 31 August 2022, from the Brazilian Government [34]).

Extraction and Oil Composition
The leaves and twigs were dried in a refrigerated room, ground, and subjected to hydrodistillation (in duplicate) using a Clevenger-type apparatus (3 h) according to the methodology described by Figueiredo et al. [35].
The chemical compositions of the obtained essential oils were analyzed with gas chromatography-flame ionization detector (GC-FID, Shimadzu Corporation, Tokyo, Japan) and gas chromatography-mass spectrometry (GC/MS, Shimadzu Corporation, Tokyo, Japan) simultaneously [35].
The individual components were identified by comparing their retention indices and mass spectra (molecular mass and fragmentation pattern) with the libraries of the GCMS-Solution system [26,27].The retention index was calculated for all volatile components using a homologous series of C 8 -C 40 n-alkanes (Sigma-Aldrich, Milwaukee, WI, USA) according to the linear equation of van Den Dool and Kratz [36].GC-FID and GC-MS analyses were performed in duplicate.

Statistical Analysis
Statistical analysis was performed according to Santos et al. [23].Statistical significance was assessed using the Tukey test (p < 0.05).GraphPad Prism software, version 8.0, was used to calculate Pearson's correlation coefficients (r).Principal component analysis (PCA) was applied to verify the inter-relationship in the oil components (>2%).Hierarchical cluster analysis (HCA), considering Euclidean distance and complete linkage, was used to verify the similarity of oil samples based on the distribution of constituents selected in the previous PCA analysis.

Conclusions
The leaves showed higher essential oil yields than the twigs during this study.However, the yields showed no statistical difference between dry and rainy periods, indicating that the essential oil from the specimen can be extracted throughout the year.
The major constituent identified throughout the seasonal period in the essential oils from the leaves and twigs of Aniba canelilla was 1N2F.The results suggest that separating the leaves from the twigs is unnecessary, considering that 1N2F is present in all parts of the plant.
Methyleugenol was not identified in any of the study months-a fact described for the first time-which makes the specimen a reliable source of 1N2F.Furthermore, the oils from the twigs showed greater antioxidant capacity than those from the leaves.Therefore, this work contributes to the knowledge of the pharmacological potential of the species and encourages possible phytotherapeutic applications with the essential oils from the leaves and twigs of A. canelilla.

Figure 1 .
Figure 1.Relationship between climatic parameters and essential oil yields of leaves and twigs of Aniba canelilla in this seasonal study.

Figure 1 .
Figure 1.Relationship between climatic parameters and essential oil yields of leaves and twigs of Aniba canelilla in this seasonal study.

Figure 2 .
Figure 2. Chemical structures of the main compounds identified in the essential oils of A. canelilla leaves and twigs.

Figure 2 .
Figure 2. Chemical structures of the main compounds identified in the essential oils of A. canelilla leaves and twigs.

Figure 4 .
Figure 4. DPPH radical scavenging of the monthly oils of Aniba canelilla.(A) Inhibition of leaf oils; (B) TEAC of leaf oils; (C) inhibition of twig oils; (D) TEAC of twig oils.Values with the same letters in same graphic do not differ statistically in the Tukey test (p > 0.05).

Molecules 2023 , 18 Figure 5 .
Figure 5. HCA analysis of the main compounds of essential oils from A. canelilla leaves.

Figure 5 .
Figure 5. HCA analysis of the main compounds of essential oils from A. canelilla leaves.

Figure 6 . 18 Figure 6 .
Figure 6.PCA analysis of the main compounds of essential oils from A. canelilla leaves.

Figure 7 .
Figure 7. HCA analysis of the main compounds of essential oils from A. canelilla twigs.

Figure 7 .
Figure 7. HCA analysis of the main compounds of essential oils from A. canelilla twigs.

Figure 8 .
Figure 8. PCA analysis of the main compounds of essential oils from A. canelilla twigs.

Figure 8 .
Figure 8. PCA analysis of the main compounds of essential oils from A. canelilla twigs.
250 µg/mL and the same reaction mixture.The DPPH inhibition percentage calculated the radical scavenging activity of each sample according to the following equation, inhibition = 100 [(A − B)/A], where A and B are the blank and sample absorbance values in the end reaction.The results were expressed in milligrams of Trolox equivalents (mgTE/g) per gram of each sample.The total antioxidant activity was expressed as milligrams of Trolox, calculated utilizing the following equation, TE(mg/)g = [(A − B)/(A − C)] × [25/1000] × [250.29/1000]× [1000/10] × D, where A, B, and C are the blank, sample, and Trolox absorbance values in the end reaction, respectively, and D is the dilution factor.All experiments were triplicated.

Table A1 .
Chemical constituents of Aniba canelilla essential oils in this seasonal study.