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Subjects:
Medicine, Research & Experimental
Essential oils are biosynthesized in the secondary metabolism of plants, and in their chemical composition, they can be identified different classes of compounds with potential antioxidant and biological applications. Over the years in the Amazon, several species of aromatic plants were discovered and used in traditional medicine. The literature has shown that essential oils extracted from amazon species have several biological activities, such as antioxidant, antibacterial, antifungal, cytotoxic, and antiprotozoal activities. These activities are related to the diversified chemical composition found in essential oils that, by synergism, favors its pharmacological action. In light of this vital importance, this study aimed at performing a review of the literature with particular emphasis on the chemical composition and biological activities in studies conducted with species collected in the Amazon, taking into consideration in particular the last 10 years of collection and research
- species of Brazil
- essential oils
- bioactive compounds
- biological activities
1. Introduction
Brazil has the world’s highest plant diversity. It houses more than 46,000 species of plants, algae, and fungi, and most of this biodiversity is found in the Amazon [1,2]. This biome occupies 5 million km2 of the territory, corresponding to 60% of the entire national territory. Such areas include the Brazilian Amazon, which accounts for 51% of all tropical plant species. The Brazilian Amazon forest accounts for approximately 26% of the remaining tropical rainforests on Earth [3,4].
Typifying this exuberance, 12 families that provide essential oil are predominant in the Amazon region (in descending order): Piperaceae, Asteraceae, Myrtaceae, Lamiaceae, Annonaceae, Lauraceae, Euphorbiaceae, Verbenaceae, Scrophulariaceae, Anacardiaceae, Burseraceae, and Rutaceae [5,6].
Essential oils are volatile, with a strong smell and taste derived from the secondary metabolites of the plants. Essential oils can be extracted from the roots, stems, leaves, and flowers by steam distillation, hydrodistillation, and squeezing citrus fruit pericarps. The terminology “oil” is closely related to the physicochemical characteristics of these substances, as they are liquids at room temperature [7,8].
The biological activity of essential oils is due to the diversity of chemical components in these volatile oils. These properties include antibacterial, antifungal, and antioxidant activities [9,10,11,12]. Essential oils can also be used as raw materials for products such as cosmetics and perfumes, or in pharmaceutical industries to obtain structural derivatives (plant products) in addition to horticulture [7,13].
Although essential oils have several potential applications, many aromatic plants in the Amazon ecosystem are under constant environmental pressure, as this region undergoes increasing fires, deforestation, and unsustainable forest exploitation [5].
Although Brazil is still the largest natural angiosperm bank in the world and these aromatic plants have the potential for varied uses, part of this exuberance was lost long before scientific knowledge was gained [3,14]. Therefore, efforts and resources must be invested to acquire a greater awareness of the diversity and value of the plants that remain in the Amazon region.
2. Chemical Composition of the Essential Oils of the Amazon
Table 1 shows the major chemical components found in the essential oils of the species from the Amazon region.
Table 1. Major chemical constituents (≥3.00%) found in the essential oils of the Amazon.
| Species | Family | Extraction Method | Compounds | References |
|---|---|---|---|---|
| Anaxagorea brevipes (leaves) |
Annonaceae | HD | β-eudesmol (13.16%), α-eudesmol (13.05%), γ-eudesmol (7.54%), guaiol (5.12%), caryophyllene oxide (4.18%) and β-bisabolene (4.10%) | [15] |
| Aniba duckei (Synonym: A. rosaeodora) (leaves and thin branches) |
Lauraceae | HD | linalool (89.34%) | [16] |
| A. parviflora (Aerial parts) |
Lauraceae | HD | linalool (45.0%) | [17] |
| A. parviflora (branches) |
Lauraceae | HD | γ-eudesmol (16.80%), (E)-caryophyllene (15.70%), linalool (12.40%), β-phellandrene (6.7%), and bicyclogermacrene (6.00%) | [18] |
| A. parviflora (leaves) |
Lauraceae | HD | β-phellandrene (15.10%), linalool (14.10%) and γ-eudesmol (12.90%). | [18] |
| A. rosaeodora (Aerial parts) |
Lauraceae | HD | linalool (88.60%) | [17] |
| A. rosaeodora (Aerial parts) |
Lauraceae | HD | linalool (93.60%) | [19] |
| Annona exsucca (Dry leaves) |
Annonaceae | HD | (E)-caryophyllene (31.26%), linalool (10.80%), β-elemene (10.30%), germacrene D (10.28%), bicyclogermacrene (9.84%) | [20] |
| Bauhinia ungulata (leaves) |
Fabaceae | HD | (E)-caryophyllene (15.9%), caryophyllene oxide (9.2%) α-humulene (8.1%) and epi-γ-eudesmol (7.5%) | [21] |
| Bocageopsis pleiosperma (Barks) |
Annonaceae | HD | β-bisabolene (38.53%), δ-cadinene (7.55%), β-selinene (6.46%) and α-selinene (5.18%) | [22] |
| B. pleiosperma (leaves) |
Annonaceae | HD | β-bisabolene (55.77%), (E)-α-bergamotene (6.94%) and β-farnesene (E) (6.05%) | [22] |
| B. pleiosperma (twigs) |
Annonaceae | HD | β-bisabolene (34.37%), cryptomerione (9,60%) and (2Z, 6Z)-farnesol (7,20%), | [22] |
| B. multiflora (Leaves) |
Annonaceae | HD | spathulenol (20.30%) and β-bisabolene (11.90%) | [23] |
| B. multiflora (Aerial parts) |
Annonaceae | HD | cis-linalool oxide (33.10%) and 1-epi-cubenol (16.60%). | [24] |
| B. multiflora (fresh leaves) |
Annonaceae | HD | spathulenol (13.00–16.20%), β-bisabolene (13.20–13.80%) and caryophyllene oxide (10.70–12.00%) | [25] |
| Copaifera multijuga (resin) |
Fabaceae | Perforation in the trunk of the species | (E)-caryophyllene (57.29%), caryophyllene oxide (10.34%) and α-humulene (9.11%) | [26] |
| Croton cajucara (leaves) |
Euphorbiaceae | HD | 7-hydroxycalamenene | [27] |
| Duguetia quitarensis (Aerial parts) |
Annonaceae | HD | 4-heptanol (33.80%), α-thujene (18.40%) and (E)-caryophyllene (14.40%) | [24] |
| Endlicheria arenosa (Leaves) |
Lauraceae | HD | bicyclogermacrene (42.20%) and (E)-caryophyllene (10.10%). | [28] |
| E. arenosa (Twigs) |
Lauraceae | HD | limonene (33.20%) and terpinen-4-ol (15.60%) | [28] |
| Ephedranthus amazonicus (Leaves) |
Annonaceae | HD | spathulenol (16.90%) and humulene epoxide II (16.30%) | [23] |
| Eugenia cuspidifolia (Dry leaves) |
Myrtaceae | HD | caryophyllene oxide (57.46%) and α-copaene (3.75%) | [29] |
| E. egensis (Aerial parts) |
Myrtaceae | HD | 5-hydroxy-(Z)-calamenene (35.80%), (E)-caryophyllene (8.90%) and (E)-cadina-1,4-diene (6.30%) | [30] |
| E. flavescens (Aerial parts) |
Myrtaceae | HD | (E)-γ-bisabolene (35.00%) and β-bisabolene (34.70%) | [30] |
| E. patrisii (Aerial parts) |
Myrtaceae | HD | (2E,6E)-Farnesol (34.50%) and (2E,6Z)-Farnesol (23.20%). | [30] |
| E. patrisii (Dry leaves) |
Myrtaceae | HD | May: germacrene D (20.03%), bicyclogermacrene (11.82%) and (E)-caryophyllene (11.04%) September: γ-elemene (25.89%), (E)-caryophyllene (10.76%) and germacrene B (8.11%) |
[31] |
| E. patrisii (Leaves) |
Myrtaceae | HD | (E)-caryophyllene (32.00%) and bicyclogermacrene (10.00%) | [32] |
| E. piauhiensis (dry leaves) |
Myrtaceae | HD | γ-elemene (17.48%), (E)- caryophyllene (16.46%) and bicyclogermacrene (8.11%) | [33] |
| E. polystachya (Aerial parts) |
Myrtaceae | HD | germacrene D (18.40%), ishwarane (15.70%) and 7-epi-α-selinene (7.50%) | [30] |
| E. punicifolia (Dry leaves) |
Myrtaceae | HD | May: β-elemene (25.12%), (E)-caryophyllene (13.11%), bicyclogermacrene (9.88%) and selin-11-en-4α-ol (9.16%) September: (E)-caryophyllene (11.47%), β-pinene (5.86%), bicyclogermacrene (5.86%), and γ-muurolene (5.55%) |
[31] |
| E. stipitata (Leaves) |
Myrtaceae | HD | germacrene D (11.80%) and Z-α-bisabolene (8.38%). | [32] |
| E. uniflora (leaves) |
Myrtaceae | HD | Curzerene (34.40—53.10%) | [34] |
| E. tapacumensis (Dry leaves) |
Myrtaceae | HD | caryophyllene oxide (55.95%) and α-copaene (13.67%) | [29] |
| Fusaea longifolia (Aerial parts) |
Annonaceae | HD | β-selinene (19.30%), cis-β-guaiene (18.30%), (Z)-α-bisabolene (12.00%) and (E)-caryophyllene (7.10%) | [24] |
| Guatteria blepharophylla (Leaves) |
Annonaceae | HD | caryophyllene oxide (55.70%). | [23] |
| G. friesiana (dry leaves) |
Annonaceae | HD | β-eudesmol (51.92 ± 9.15%), γ-eudesmol (18.91 ± 5.41%) and α-eudesmol (12.56 ± 2.80%) | [35] |
| G. megalophylla | Annonaceae | HD | spathulenol (27.76%), γ-muurolene (14.34%), bicyclogermacrene (10.47%) and β-elemene (7.48%) | [36] |
| G. pogonopus (dry leaves) |
Annonaceae | HD | spathulenol (24.80 ± 11.38%), γ-amorphene (14.72 ± 3.37%) and germacrene D (11.75 ± 6.33%). | [35] |
| G. punctata (Aerial parts) |
Annonaceae | HD | germacrene D (19.80%), (E)-nerolidol (9.90%) and (E)-caryophyllene (8.40%). | [24] |
| Hedychium coronarium (Rhizome) |
Zingiberaceae | HD | eucalyptol (33.70%), β-pinene (30.00%) and α-pinene (10.00%) | [37] |
| Ipomea setifera (Dry leaves) |
Convolvulaceae | SD | (E)-caryophyllene (36.70%) and β-elemene (20.49%) | [38] |
| I. asarifolia (Dry leaves) |
Convolvulaceae | SD | phytol derivade (10.67–35.49%) and (E)-caryophyllene (15.93–19.93%) | [38] |
| Iryanthera polyneura (Leaves) |
Myristicaceae | HD | spathulenol (6.42 ± 1.02%), α-cadinol (5.82 ± 0.40%) and τ-muurolol (5.24 ± 0.03%). |
[39] |
| Lippia gracilis (dry leaves) |
Verbenaceae | HD | limonene (56.16%), geraniol (12.09%) and β-myrcene (6.22%). | [33] |
| L. origanoides (aerial parts) | Verbenaceae | HD | Carvacrol (37.12%), p-cymene (11.64%) and thymol (7.83%) | [40] |
| L. origanoides (leaves) |
Verbenaceae | HD | carvacrol (48.31%), p-cymene (9.11%), thymol (8.78%), (E)-caryophyllene (6.74%) and 2,5-dimethoxyacetophenone (6.63%) | [41] |
| L. thymoides (Fresh and Dry Leaves) |
Verbenaceae | HD | thymol (59.29–62.78%), p-cymene (2.97–8.97%), (E)-caryophyllene (5.21–8.84%) and thymyl acetate (4.92–7.22%). | [42] |
| L. thymoides (Freash and Dry leaves) |
Verbenaceae | HD | thymol (58.90–66.33%), thymol acetate (7.49–8.10%), γ-terpinene (7.58–9.36%) and p-cymene (5.30–8.36%). | [43] |
| L. thymoides (Freash and Dry flowers) |
Verbenaceae | HD | thymol (37.86–48.04%), thymol acetate (21.44–33.81), γ-terpinene (0.15–15.06%) and p-cymene (0.07–7.18%) | [43] |
| L. thymoides (Freash and Dry branches) |
Verbenaceae | HD | thymol (63.59–66.20%), thymol acetate (5.07–5.96%) γ-terpinene (3.39–9.36%) and p-cymene (3.27–3.35%) | [43] |
| L. thymoides (Freash and Dry roots) |
Verbenaceae | HD | (11Z)-11-hexadecenoic acid (38–02-40.92%), (9Z)-octadecenoic acid (27.40–28.21%) and thymol (19.34–22.18%) | [43] |
| Mentha piperita (Dry leaves) |
Lamiaceae | HD | linalool (51.80%) and epoxyocimene (19.30%). | [44] |
| Mesosphaerum suaveolens (aerial parts) |
Lamiaceae | HD | eucalyptol (30.15–64.44%), linalool (0.00–12.85%), β-pinene (3.27–9.04%) and sabinene (0.00–8.58%) | [45] |
| Myrcia erythroxylon (Dry leaves) |
Myrtaceae | HD | α-humulene (26.79%), bicyclogermacrene (13.26%) and (E)-caryophyllene (10.55%) | [33] |
| M. splendens (Leaves) |
Myrtaceae | HD | (E)-caryophyllene (45.80%) |
[32] |
| M. splendens (Leaves) |
Myrtaceae | HD | (E)-caryophyllene (36.23%), trans-γ-bisabolene (10.04%), cis-γ-bisabolene (8.33%) and trans-β-farnesene (7.81%) |
[46] |
| M. sylvatica (Leaves) |
Myrtaceae | HD | germacrene B (24.50%) and γ-elemene (12.50%) |
[32] |
| M. sylvatica (Fresh leaves) |
Myrtaceae | HD | 1-epi-cubenol (9.90%), cadalene (7.20%), β-selinene (7.00%), β-calacorene (5.40%), cis-calamenene (4.80%), muskatone (4.40%), δ-cadinene (4.20%), cubenol (4.20%) and ar-curcumene (1.90%) | [10] |
| M. sylvatica (Dried Leaves) |
Myrtaceae | HD | ar-curcumene (7.60%), 1-epi-cubenol (6.90%), β-selinene (6.00%), cadalene (5.80%), β-calacorene (5.50%), cis-calamenene (5.20%), arturmerol (4.90%), δ-cadineno (4.20%), cubenol (4.20%) and muskatone (3.40%). | [10] |
| M. tomentosa (Dry leaves) |
Myrtaceae | HD | May: γ-elemene (12.52%), germacrene D (11.45%) and (E)-caryophyllene (10.22%) September: spathulenol (40.70%), zingiberene (9.58%) and γ-elemene (6.89%) |
[31] |
| Nectandra cuspidata (Leaves) |
Lauraceae | HD | (E)-caryophyllene (26.90%) and bicyclogermacrene (16.00%) | [47] |
| N. puberula (Leaves) |
Lauraceae | HD | apiole (22.20%), (E)-caryophyllene (15.10%) and β-pinene (13.30%). | [47] |
| N. puberula (branches) |
Lauraceae | HD | apiole (28.10%), pogostol (19.80%) and viridiflorol (11.20%) | [47] |
| Ocimum campechianum (leaves and stems) |
Lamiaceae | HD | methyleugenol (80.00– 87.00%) |
[48] |
| O. campechianum (inflorescences) |
Lamiaceae | HD | methyleugenol (75.30–83.50%) | [48] |
| O. canum (dry leaves) |
Lamiaceae | HD | thymol (42.15%), p-cymene (21.17%) and γ-terpinene (19.81%) | [49] |
| Ocotea caniculata (leaves) |
Lauraceae | HD | β-selinene (20.30%), β-caryophyllene (18.90%) and 7-epi-α-selinene (14.30%) | [50] |
| O. caniculata (branches) |
Lauraceae | HD | selin-11-en-4-α-ol (20.60%), β-selinene (12.10%) and 7-epi-α-selinene (9.00%) | [50] |
| O. caudata (leaves) |
Lauraceae | HD | bicyclogermacrene (29.60%), germacrene D (19.90%) and α-pinene (9.80%) | [50] |
| O. caudata (branches) |
Lauraceae | HD | δ-cadinene (13.8%), germacrene D (8.9%), and α-muurulol (7.80%) | [50] |
| O. cujumary (leaves) |
Lauraceae | HD | β-caryophyllene (22.20%), caryophyllene oxide (12.40%) and 2-tridecanone (7.30%) | [50] |
| O. cujumary (branches) |
Lauraceae | HD | selin-11-en-4-α-ol (20.60%), β-selinene (12.10%) and 7-epi-α-selinene (9.00%). | [50] |
| Onychopetalum amazonicum (leaves) |
Annonaceae | HD | (E)-caryophyllene (17.00%), caryophyllene oxide (11.90%) and spathulenol (10.40%) | [51] |
| O. amazonicum (trunk bark) |
Annonaceae | HD | α-epi-cadinol (14.00–24.10%), allo-aromadendrene (21.20%) and α-gurjunene (10.60–14.90%) | [51] |
| Piper aequale (Aerial parts) |
Piperaceae | HD | δ-elemeno (18.92%), β-pineno (15.56%), α-pinene (12.57%), cubebol (7.20%), β-atlantol (5.87%) and bicyclogermacrene (5.51%) | [52] |
| P. aduncum (Aerial parts) |
Piperaceae | HD | dilapiole (64.40%), piperitone (3.30%) and (E)-β-ocimene (3.00%) | [53] |
| P. aduncum (Dry leaves) |
Piperaceae | MAE | dilapiol (91.07%) | [54] |
| P. aduncum (Dry leaves) |
Piperaceae | SD | dilapiole (53.60%), myristicin (24.30%) and (Z)-carpacin (11.90%) | [55] |
| P. aleyreanum (Aerial parts) |
Piperaceae | HD | β-elemene (16.30%), bicyclogermacrene (9.20%), δ-elemene (8.20%), germacrene D (6.90%) and (E)-caryophyllene (6.20%) | [12] |
| P. anonifolium (Aerial parts) |
Piperaceae | HD | selin-11-en-4-ol (20.00%), β-selinene (12.70%), α-selinene (11.90%) and α-pinene (8.80%). | [12] |
| P. augustum (Leaves) |
Piperaceae | HD | (E)-caryophyllene (27.10%), germacrene D (11.20%) and β-elemene (5.80%) | [37] |
| P. brachypetiolatum (Fresh Leaves) |
Piperaceae | HD | (E)-nerolidol (44.23 ± 2.23%) and caryophyllene oxide (10.08 ± 0.74%) | [56] |
| P. callosum (Aerial parts) |
Piperaceae | HD | Safrole (69.20%), methyleugenol (8.60%) and myrcene (6.20%) | [53] |
| P. capitarianum (Leaves, stems, and inflorescences) |
Piperaceae | HD | (E)-caryophyllene (15.30–20.00%), α-humulene (9.10–12.70%), β-myrcene (1.40–10.50%), α-selinene (5.30–7.00%) and β-selinene (4.90–6.30%) | [57] |
| P. demeraranum (dry leaves) |
Piperaceae | HD | β-elemene (33.10%), Limonene (19.30%) and bicyclogermacrene (8.80%) | [58] |
| P. divaricatum (Aerial parts) |
Piperaceae | HD | methyleugenol (69.20%), eugenol (16.20%) and germacreno D (3.50%) | [53] |
| P. duckei (dry leaves) |
Piperaceae | HD | (E)-caryophyllene (27.10%), germacrene D (14.70%) and eucalyptol (5.80%) | [58] |
| P. glandulosissimum (Fresh Leaves) |
Piperaceae | HD | (E)-caryophyllene (19.11 ± 0.40%), α-selinene (8.38 ± 0.17%) and β-selinene (6.38 ± 0.13%) | [56] |
| P. hispidum (Aerial parts) |
Piperaceae | HD | (E)-caryophyllene (10.50%), α-humulene (9.50%), δ-3-carene (9.10%), α-copaene (7.30%), limonene (6.90%), caryophyllene oxide (5.90%) and β-selinene (5.10%). | [12] |
| P. leticianum (Leaves) |
Piperaceae | HD | (E)-caryophyllene (21.80%), germacrene D (9.00%) and β-elemene (5.10%) | [37] |
| P. madeiranum (Fresh Leaves) |
Piperaceae | HD | caryophyllene oxide (16.92 ± 0.21%), selin-11-en-4-a-ol (9.26 ± 0.12%), β-copaene (9.16 ± 0.12%) and β-selinene (8.70 ± 0.11%). | [56] |
| P. marginatum (Aerial parts) |
Piperaceae | HD | p-mentha-1(7),8-diene (39.00%) and 3,4-methylenedioxy propiophenone (19.00%), |
[53] |
| P. marginatum (Aerial parts) |
Piperaceae | HD | (E)-isoosmorhizole (32.20%) and (E)-anethole (26.40%) | [53] |
| P. mollipilosum (Fresh Leaves) |
Piperaceae | HD | β-selinene (32.44 ± 1.14%) and caryophyllene oxide (11.70 ± 0.42%), | [56] |
| Psidium guajava | Myrtaceae | HD | epi-β-bisabolol (16.10%), ar-curcumene (9.80%), β-bisabolene (9.20%), (E)-caryophyllene (5.10%), and caryophyllene oxide (4.50%) | [32] |
| P. guineense Leaves) |
Myrtaceae | HD | limonene (30.20–30.4%) and α-pinene (17.70–22.50%) | [32] |
| P. myrsinites (dry Leaves) |
Myrtaceae | HD | (E)-caryophyllene (26.05%), α-humulene (23.92%) and caryophyllene oxide (10.09%) | [33] |
| Renealmia breviscapa (Fresh rhizomes) |
Zingiberaceae | HD | (E)-caryophyllene (62.38%), α-Humulene (9.56%) and guaiol (9.27%) | [59] |
| R. breviscapa (fresh leaves) |
Zingiberaceae | HD | (E)-caryophyllene (28.25%), cis-3-hexenol (15.05%) and bicyclogermacrene (6.90%) | [59] |
| R. chrysotricha (Fresh rhizomes) |
Zingiberaceae | HD | α-terpineol (26.14%), coronarin E (25.10%) and eucalyptol (15.87%) | [59] |
| R. chrysotricha (Fresh leavess) |
Zingiberaceae | HD | cis-3-hexenol (57.28%), (E)- caryophyllene (6.85%) and caryophyllene oxide (4.92%) | [59] |
| R. nicolaioides (Fresh rhizomes) |
Zingiberaceae | HD | (E)-caryophyllene (22.78%), α-terpineol (14.15%) and (E)-nerolidol (11.06%) | [59] |
| R. nicolaioides (fresh leaves) |
Zingiberaceae | HD | (E)-nerolidol (21.03%), α-terpineol (11.92%) and germacrene D (10.33%) | [59] |
| Siparuna aspera (Leaves) |
Siparunaceae | HD | germacrene D (23.30%), bicyclogermacrene (7.80%) and α-pinene (7.00%). | [37] |
| S. camporum (dry leaves) |
Siparunaceae | HD | γ-patchoulene (28.63%), α-Phellandrene (12.80%) and Guaiadiene-6,9 (9.23%), | [33] |
| S. macrotepala (Leaves) |
Siparunaceae | HD | germacrene D (42.10%), bicyclogermacrene (11.80%) and δ-cadinene (5.00%) | [37] |
| Syzygium cumini (leaves) |
Myrtaceae | HD | α-pinene | [60] |
| Virola calophyla (leaves) |
Myristicaceae | HD | (E)-caryophyllene (55.70%) and caryophyllene oxide (9.80%) | [61] |
| V. multinervia (leaves) |
Myristicaceae | HD | (E)-caryophyllene (54.80%) and bicyclogermacrene (10.00%) | [61] |
| V. pavonis (leaves) |
Myristicaceae | HD | β-selinene (60.50%) and (E)-caryophyllene (12.70%) | [61] |
| V. surinamensis (barks) |
Myristicaceae | HD | Aristolene (28.40 ± 5.03%), α-gurjunene (15.00 ± 3.17%) and valencene (14.10 ± 4.87%). | [62] |
| V. surinamensis (leaves) |
Myristicaceae | HD | α-farnensene (14.50 ± 3.24), β-elemene (9.61 ± 1.02%) and bicyclogermacrene (8.10 ± 2.42%). | [62] |
| Vismia cayennensis (Leaves) |
Hypericaceae | HD | germacrone (25.42%) and curzerene (25.29%) | [63] |
| V. guianensis (Leaves) |
Hypericaceae | HD | α-copaene (29.45%), (E)-nerolidol (24.06%) and (E)-caryophyllene (10.04%) | [63] |
| Xylopia aromatica (leaves) |
Annonaceae | HD | spathulenol (21.50%, trans-pinocarveol (10.20%) and dihidrocarveol (11.60%) | [23] |
HD: Hydrodistillation; SD: steam distillation; MAE: microwave-assisted extraction.
In the documented studies, the essential oils were obtained by hydrodistillation, except in the case of the species Copaifera multijuga (perforation), Piper aduncum (MAE), P. aduncum (SD), Ipomea setifera (SD), and I. asarifolia (SD). Gas chromatography coupled with mass spectrometry (GC-MS) was used to identify the volatile compounds in the essential oils. There was little difference in the chemical composition and chemical profile of the essential oils of the species studied based on the families/genera/species, which may be related to the type of botanical material used from the plant in the extraction of the essential oils.
The chemical profile of essential oils from species of the Annonaceae family showed hydrocarbon and oxygenated sesquiterpenes as the main constituents, where the compounds β-bisabolene (55.77%), caryophyllene oxide (55.70%), and β-eudesmol (51.92%), were respectively dominant in the essential oils of Bocageopsis pleiosperma [22], Guatteria blepharophylla [23], and G. friesiana [35]. However, it was possible to observe other types of chemical classes in the genus Anonnace-ae, such as the oxygenated monoterpene cis-linalool oxide (33.10%) in the essential oil of Bocageopsis multiflora [24] and the alcohol 4-heptanol (33.80%) in the essential oil of Duguetia quitarensis [24].
Oxygenated monoterpenes, hydrocarbon sesquiterpenes, and phenylpropanoids are the major components in the essential oils of the Lauraceae family, where linalool (93.60%) is dominant in the essential oil of Aniba rosaeodora [16], as well as bicyclogermacrene (42.20%) and apiole (28.10%), respectively, in the essential oil of Endlicheria arenosa [28] and Nectandra puberula [47]. Phenylpropanoids and oxygenated monoterpenes are also present in essential oils of the Lamiaceae family, where methyleugenol (80.00–87.00%) [48] and eucalyptol (16–33%) are dominant [64].
Studies carried out by Aranha et al. [29] and Da Silva et al. [30] confirmed the predominance of oxygenated sesquiterpenes and hydrocarbons in species of the genus Eugenia of the Myrtaceae family. Hydrocarbon sesquiterpenes were also observed as the main chemical classes in the essential oils of the genus Myrcia, where (E)-caryophyllene (45.80%) was dominant in the essential oil of M. splendens [32]. Monoterpene hydrocarbons characterize the essential oil profile of some species of the genus Psidium [32].
In species of the Piperaceae family, phenylpropanoids are present in the essential oils of some species of the genus Piper, as shown in the study of Piper aduncum essential oil by Nascimento et al. [54], the main component of which is dilapiol (91.07%). In species of the family Verbenaceae, the presence of oxygenated monoterpenes such as thymol (63.59–66.20%) was documented in Lippia thymoides essential oil [43]. In the species of Zingiberaceae, Siparunaceae, and Myristicaceae, sesquiterpenes are one of the main chemical classes in the chemical profile of the essential oil of some species, especially the compounds (E)-caryophyllene (62.38%) [59], and β-selinene (60.50%) [61].
3. Antioxidant Activity of Essential Oils
Essential oils comprise different organic compounds that have conjugated carbon double bonds, where the functional species are hydroxyl radicals, which can transfer hydrogen, inhibit free radicals, and minimize oxidative stress [65]. Essential oils with antioxidant properties are preferred over synthetic antioxidants because the former are safer for human health and are eco-friendly [66,67].
Aromatic plants are a well-known source of essential oils with antioxidant properties. These properties are exhibited by the raw essential oils and the isolated chemical constituents, both of which are efficient in preventing lipid oxidation [68]. The antioxidant potential of essential oils can be attributed to a single volatile constituent present in the chemical composition or to the synergistic effect among many components [69]. Table 2 summarizes the antioxidant potential of essential oils from Amazonian plants.
Table 2. Essential oils of the Amazon and their antioxidant activities.
| Species (Plants Part) |
Family | Method | Results | References |
|---|---|---|---|---|
| Aniba parviflora (Leaves) |
Lauraceae | DPPH | TEAC = 90.1–287.9 mg TE/mL | [18] |
| A. parviflora (Branches) |
Lauraceae | DPPH | TEAC = 94.1–358.4 mg TE/mL | [18] |
| A. rosaeodora (Aerial parts) |
Lauraceae | ABTS | EC50 = 15.46 µg/mL | [19] |
| Endlicheria arenosa (Leaves) |
Lauraceae | DPPH | TEAC = 334.1 ± 41.6 mg TE/mL | [28] |
| E. arenosa (Twigs) |
Lauraceae | DPPH | TEAC = 252.6 ± 24.4 mg TEmL | [28] |
| Eugenia egensis (Aerial parts) |
Myrtaceae | DPPH | TEAC = 216.5 ± 11.6 mg TE/mL | [30] |
| E. flavescens (Aerial parts) |
Myrtaceae | DPPH | TEAC = 122.6 ± 6.8 mg TE/mL | [30] |
| E. patrisii (Aerial parts) |
Myrtaceae | DPPH | TEAC = 111.2 ± 12.4 mg TE/mL | [30] |
| E. patrisii (Leaves) |
Myrtaceae | DPPH | Inhibition = 28.9 ± 4.8% | [32] |
| E. patrisii (Dry leaves) |
Myrtaceae | DPPH | Inhibition = 99.0 ± 0.099% (Specimen A) Inhibition = 204.0 ± 0.877% (Specimen B) |
[31] |
| ABTS | Inhibition = 31.4 ± 0.1% (Specimen A) Inhibition = 17.9 ± 0.069% (Specimen B) |
|||
| E. punicifolia (Dry leaves) |
Myrtaceae | DPPH | Inhibition = 408.0 ± 0.10% (Specimen A) Inhibition = 285.0 ± 0.028% (Specimen B) |
[31] |
| ABTS | Inhibition = 9.5 ± 0.034% (Specimen A) Inhibition = 37.7 ± 0.035% (Specimen B) |
|||
| E. uniflora (Leaves) |
Myrtaceae | DPPH | Inhibition = 42.6 ± 0.3 to 64.2 ± 0.3% | [34] |
| E. uniflora (Dry leaves) |
Myrtaceae | DPPH | Inhibition = 30.3 ± 3.3 to 40.6 ± 1.9% | [48] |
| β-Carotene | Inhibition = 153.5 ± 16.5 to 228.3 ± 19.2% | |||
| MTT | Inhibition = 10.8 ± 3.4 to 26.3 ± 1.2% | |||
| Hedychium coronarium (Rhizome) |
Zingiberaceae | DPPH | IC50 = 9.04 ± 0.55 mg/mL | [37] |
| ABTS | IC50 = 2.87 ± 0.17 mg/mL | |||
| Lippia thymoides (Fresh Leaves) |
Verbenaceae | DPPH | Inhibition = 89.97 ± 0.31% | [42] |
| L. thymoides (Dry leaves) |
Verbenaceae | DPPH | Inhibition = 63.53 b ± 5.04–73.63 ± 2.09% | [42] |
| Mentha piperita (Dry leaves) |
Lamiaceae | DPPH | AA = 79.9 ± 1.6% | [44] |
| Myrcia splendens (Leaves) |
Myrtaceae | DPPH | Inhibition = 28.4 ± 7.1% | [32] |
| M. sylvatica (Leaves) |
Myrtaceae | DPPH | Inhibition = 18.5 ± 3.5% | [32] |
| M. tomentosa (Dry leaves) |
Myrtaceae | DPPH | Inhibition = 213.0 ± 0.905% (Specimen A) Inhibition = 208.5 ± 0.940% (Specimen B) |
[31] |
| ABTS | Inhibition = 53.6 ± 0.150% (Specimen A) Inhibition = 0.333 ± 0.247% (Specimen B) |
|||
| Ocimum campechianum (leaves and stems and inflorescences) |
Lamiaceae | DPPH | Inhibition = 36.0% (leaves and stems) Inhibition = 41.6% (inflorescences) |
[48] |
| TEAC = 58.5 mgTE/mL (leaves and stems) TEAC = 68.4 mgTE/mL (inflorescences) |
||||
| Piper aequale (Aerial parts) |
Piperaceae | DPPH | TEAC = 280.9 ± 22.2 mg TE/mL | [52] |
| P. aleyreanum (Aerial parts) |
Piperaceae | DPPH | TEAC = 412.2 ± 9.5 mg TE/mL | [12] |
| P. anonifolium (Aerial parts) |
Piperaceae | DPPH | TEAC = 148.6 ± 26.9 mg TE/mL | [12] |
| P. augustum (Leaves) |
Piperaceae | DPPH | IC50 = 6.17 ± 0.33 mg/mL | [37] |
| ABTS | IC50 = 2.16 ± 0.20 mg/mL | |||
| P. brachypetiolatum (Fresh Leaves) |
Piperaceae | DPPH | EC50 = 64.8 ± 3.8 µg/mL | [56] |
| ABTS | EC50 = 159.7 ± 8.3 µg/mL | |||
| P. glandulosissimum (Fresh Leaves) |
Piperaceae | DPPH | EC50 = 104.4 ± 6.4 µg/mL | [56] |
| ABTS | EC50 = 200.9 ± 6.4 µg/mL | |||
| P. hispidum (Aerial parts) |
Piperaceae | DPPH | TEAC = 303.1 ± 49.2 mg TE/mL | [12] |
| P. leticianum (Leaves) |
Piperaceae | DPPH | IC50 = 4.26 ± 0.11 mg/mL | [37] |
| ABTS | IC50 = 2.65 ± 0.25 mg/mL | |||
| P. madeiranum (Fresh Leaves) |
Piperaceae | DPPH | EC50 = 66.8 ± 5.2 µg/mL | [56] |
| ABTS | EC50 = 242.6 ± 6.8 µg/mL | |||
| P. mollipilosum (Fresh Leaves) |
Piperaceae | DPPH | EC50 = 79.0 ± 4.9 µg/mL | [56] |
| ABTS | EC50 = 280.5 ± 6.6 µg/mL | |||
| Psidium guajava (Leaves) |
Myrtaceae | DPPH | Inhibition = 38.6 ± 7.0% | [32] |
| P. guineense | Myrtaceae | DPPH | Inhibition = 11.5 ± 2.0% (Pgui-1) Inhibition = 27.7 ± 2.3% (Pgui-2) |
[32] |
| Siparuna aspera (Leaves) |
Siparunaceae | DPPH | IC50 = 20.70 ± 0.80 mg/mL | [37] |
| ABTS | IC50 = 1.12 ± 0.04 mg/mL | |||
| S. macrotepala (Leaves) |
Siparunaceae | DPPH | IC50 = 29.37 ± 1.15 mg/mL | [37] |
| ABTS | IC50 = 0.80 ± 0.03 mg/mL |
DPPH, 2,2-Diphenyl-1-picrylhydrazyl; ABTS, 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate); EC50 (concentration required to obtain 50% antioxidant effect).
Studies on the antioxidant capacity of essential oils from the Amazon region have shown promising results. da Silva et al. [18] studied the essential oil from both the leaves and branches of Aniba parviflora, which strongly inhibited 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals. The authors indicated that the antioxidant activity may be related to the presence of β-phellandrene, linalool, β-caryophyllene, and γ-eudesmol, which presented antioxidant potential in other documented studies.
The antioxidant potential of some essential oils is equivalent to the inhibition potential of the Trolox standard determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, as observed for the essential oils of leaves and twigs of Endlicheria arenosa [28]. These results may be related to the difference in the chemical composition of the two oils because the chemical profile of the product distilled from the leaves was characterized by the sesquiterpene hydrocarbons bicyclogermacrene (42.2%), germacrene D (12.5%), and β-caryophyllene (10.1%).
Other studies have shown that the inhibition potential of essential oils for the free radicals DPPH and ABTS is higher than that of the Trolox standard, as in the case of the essential oils of Eugenia patrisii, E. punicifolia, and Myrcia tomentosa [31]. Some studies have also reported that a high thymol content may favor higher potential inhibition for essential oils, in which thymol is a major constituent [42]. This is a result of the presence of hydroxyl radicals that facilitate the capture of free radicals and reduce the effects of lipid oxidation [70].
This entry is adapted from the peer-reviewed paper 10.3390/molecules27144373
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