Volatile Profiles and DNA Barcodes of Myrtaceae species with Occurrence in the Brazilian Amazon

Myrtaceae family includes many species with taxonomic challenges, making it one of the most complex families to identify. This study used DNA barcoding to find molecular markers for species authentication based on the Myrtaceae family's chemical composition and genetic diversity. Essential oils and genetic material were extracted from the leaves of six different species: Eugenia uniflora, E. patrisii, Myrcia splendens, Psidium guajava, P. guineense, and Psidium sp. The samples were analyzed based on compound classes and grouped into two categories. Group I included samples with high amounts of oxygenated sesquiterpenes (3.69-76.05%) and fatty acid derivatives (0.04-43.59%), such as E. uniflora, Myrcia splendens, and E. patrisii. Group II included samples P. guajava, P. guineense, and Psidium sp., which had a significant content of monoterpene hydrocarbons (0.69-72.35%), oxygenated sesquiterpenes (8.06-68.1%), phenylpropanoids (0.45-22.59%), and sesquiterpene hydrocarbons (0.27-21.84%). The PsbA-trnH gene sequences had a high genetic variability, allowing the species to be distinguished. A phylogenetic analysis showed two main clusters with high Bootstrap values corresponding to the subtribes Eugeniineae, Myrciinae, and Pimentinae. The results suggest a weak correlation between genetic and chemical data in these Myrtaceae species.

Volatile Constituents of Some Myrtaceous Edible and Medicinal Fruits from the Brazilian Amazon

Native and exotic fruits from the Amazon have varied characteristics, with aroma being a decisive factor in their acceptance for medicinal use as a nutraceutical supplement. This work aimed to analyze the chemical constituents of the volatile concentrates of some Myrtaceous fruit species sampled in the Brazilian Amazon. The fruit's pulps were subjected to simultaneous distillation-extraction, and gas chromatography-mass spectrometry was used to analyze their volatile chemical composition. In the volatile concentrate of Eugenia stipitata (Araçá-boi) α-pinene (17.5%), citronellyl butanoate (15.6%), and pogostol (13.5%) were identified as primary constituents; Eugenia uniflora (Ginja) concentrate comprised curzerene (30.5%), germacrone (15.4%), atractylone (13.1%), and (E)-β-ocimene (11.1%); in Myrciaria dubia (Camu-Camu), α-pinene (55.8%), (E)-β-ocimene (13.1%), and α-terpineol (10.0%) were present; in Psidium guajava (Goiaba) were (2E)-hexenal (21.7%), hexanal (15.4%), caryophylla-4(12),8(13)-dien-5-β-ol (10.5%), caryophyllene oxide (9.2%), and pogostol (8.3%); and in Psidium guineense (Araçá), limonene (25.2%), ethyl butanoate (12.1%), epi-β-bisabolol (9.8%), and α-pinene (9.2%) were the main constituents. The analyzed volatile concentrates of these fruit species presented a significant diversity of constituents with a predominance of functional groups, such as monoterpenes, sesquiterpenes, and fatty acid derivatives, originating from the plant's secondary metabolism and playing an important role in their nutritional and medicinal uses.

Exploring the impact of seasonal variations on the chemical composition, antinociceptive, and anti-inflammatory properties of Pogostemon heyneanus Benth. essential oil

Background: Pogostemon heyneanus leaves infusions are relevant in ethnopharmacology for treating colds, coughs, headaches, and asthma. Purpose: The essential oil chemical composition of a Pogostemon heyneanus specimen was monthly monitored from October 2021 to July 2022 to evaluate the climatic influences on its yield and chemical composition and antinociceptive, andanti-inflammatory properties. Methods: The leaves, collected monthly over a 10-month period, were submitted to hydrodistillation. The oils obtained were analyzed by gas chromatography coupled to a mass spectrometer and gas chromatography coupled to flame ionization detector. The P. heyneanus essential oil (PhEO) was tested in vivo to evaluate its peripheral analgesic actions through the abdominal writhing test induced by acetic acid, and peripheral analgesia by tail immersion. Neurogenic and inflammatory pain were evaluated by formalin test, and acute oral toxicity of the oil was also verified. Results: PhEO presented 27 chemical constituents with the highest predominance of patchoulol (43.6%-76.9%), α-bulnesene (0.2%-12.7%), α-guaiene (0.4%-8.9%), seychellene (3.8%-5.1%) and pogostol (0.0%-8.2%). The climatic parameters insolation, humidity, rainfall, and temperature did not influence the essential oil yield or the main chemical constituents, except for pogostol, which presented a strong (r = 0.73) and statistically significant (p < 0.05) correlation with temperature. PhEO did not display toxicity at the maximum 300 mg/kg dosage. The oil showed low peripheral and central analgesic action at 100 mg/kg, while in the neurogenic and inflammatory pain inhibition tests, no actions related to PhEO were observed. In the carrageenan-induced peritonitis test, PhEO did not reduce the migration of leukocytes to the peritoneal cavity compared to the control group. Conclusion: Pogostemon heyneanus is a resistant plant to seasonal influences and a source of patchoulol. Despite ethnopharmacological indications, no in-vivo biological activities such as neurogenic or inflammatory pain were identified in the present work. So, the low influence of the climatic parameters on chemical composition can infer that the low pharmacological activity is also not subject to climatic variations, that is, it does not change due to the climate.

Chemical composition, antinociceptive and anti-inflammatory activities of the curzerene type essential oil of Eugenia uniflora from Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

The Eugenia uniflora leaf infusion is widely used in folk medicine to treat gastroenteritis, fever, hypertension, inflammatory and diuretic diseases.

AIM OF THE STUDY

This work evaluated the acute oral toxic, antinociceptive, and anti-inflammatory activities of the curzerene chemotype of Eugenia uniflora essential oil (EuEO).

MATERIAL AND METHODS

EuEO was obtained by hydrodistillation and analyzed by GC and GC-MS. The antinociceptive action in mice was evaluated for the peripheral and central analgesic activity using abdominal contortion and hot plate tests (50, 100, and 200 mg/kg); xylene-induced ear swelling was carried out for the nociception test, and carrageenan-induced cell migration test. Spontaneous locomotor activity was assessed in the open field test to rule out any nonspecific sedative or muscle relaxant effects of EuEO.

RESULTS

The EuEO displayed a yield of 2.6 ± 0.7%. The major compounds classes were oxygenated sesquiterpenoids (57.3 ± 0.2%), followed by sesquiterpene hydrocarbons (16.4 ± 2.6). The chemical constituents with the highest concentrations were curzerene (33.4 ± 8.5%), caryophyllene oxide (7.6 ± 2.8%), β-elemene (6.5 ± 1.8%), and E-caryophyllene (4.1 ± 0.3%). Oral treatment with EuEO, at doses of 50, 300, and 2000 mg/kg, did not change the behavior patterns or mortality of the animals. EuEO (300 mg/kg) did not cause a reduction in the number of crossings in the open field compared to the vehicle group. The aspartate aminotransferase (AST) level was higher in EuEO-treated groups (50 and 2000 mg/kg) when compared to the control group (p < 0.05). EuEO, at doses of 50, 100, and 200 mg/kg, reduced the number of abdominal writhings by 61.66%, 38.33%, and 33.33%. EuEO did not show increased hot plate test time latency in any of the intervals analyzed. At 200 mg/kg, EuEO decreased paw licking time, with inhibition of 63.43%. In formalin-induced acute pain, EuEO decreased paw licking time at doses of 50, 100, and 200 mg/kg in the first phase, with inhibition of 30.54%, 55.02%, and 80.87%. The groups treated with EuEO at doses of 50, 100, and 200 mg/kg showed ear edema reduction of 50.26%, 55.17%, and 51.31%, respectively. Moreover, EuEO inhibited leukocyte recruitment only at a dose of 200 mg/kg. The inhibitory values of leukocyte recruitment after 4 h of carrageenan application were 4.86%, 4.93%, and 47.25% for 50, 100, and 200 mg/kg of essential oil, respectively.

CONCLUSION

The EuEO, curzerene chemotype, has significant antinociceptive and anti-inflammatory activities and low acute oral toxicity. This work confirms the antinociceptive and anti-inflammatory of this species as the traditional use.

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.

Siparuna guianensis Essential Oil Antitumoral Activity on Ehrlich Model and Its Effect on Oxidative Stress

This work aims to evaluate the chemical composition, in vitro antioxidant capacity, and in vivo antitumoral activity of S. guianensis essential oil against Ehrlich's ascitic carcinoma and the effects on oxidative stress. The animals (Mus musculus) received a daily dose of S. guianensis oil orally (100 mg/kg) for 9 days. The main constituents of essential oil were curzerenone (16.4±1.5 %), drimenol (13.7±0.2 %), and spathulenol (12.4±0.8 %). S. guianensis oil showed antioxidant activity, inhibiting 11.1 % of DPPH radicals (95.7 mgTE/g); and 15.5 % of the β-carotene peroxidation. The group treated with S. guianensis showed a significant reduction in tumor cells (59.76±12.33) compared to the tumor group (96.88±19.15). Essential oil of S. guianensis decreased MDA levels and increased SOD levels in liver tissue. The essential oil of S. guianensis reduced oxidative stress, and showed antitumor and antioxidant activity, being characterized as a new chemical profile in the investigation of pathologies such as cancer.

Seasonal and Circadian Evaluation of the Essential Oil of Dizygostemon riparius (Plantaginaceae), a Wild Flavoring Herb from East Maranhão, Brazil

Dizygostemon riparius (Plantaginaceae) is an aromatic herbal species known as "Melosa", endemic to the Municipality of São Benedito do Rio Preto, East Maranhão state, Brazil. It has a refreshing and pleasant aroma and is used for food flavoring and controlling domestic animal parasites. This work aimed to evaluate the seasonal and circadian influence on the composition and production of essential oils (EOs) from D. riparius. The plant aerial parts were hydrodistilled, and the oils were analyzed by GC and GC/MS. The seasonal study was conducted from August 2019 to July 2020, and the circadian study in dry (November) and rainy (May) periods, at 6 am, 12 am, and 6 pm. The results showed that the medium EOs yield was 2.8 %, and the primary constituents (>2 %) were endo-fenchyl acetate (30.5-42.1 %) and endo-fenchol (31.6-37.4 %), (E)-caryophyllene (2.8-7.6 %), α-fenchene (3.3-6.5 %), p-cymene (0.7-4.5 %), and caryophyllene oxide (1.4-2.7 %). Yield and composition of EOs did not significantly correlate with the climatic parameters, but their seasonal percentages influenced their two main components due to precipitation and solar radiation environmental factors. Quantitative variability in the EOs composition during the dry and rainy seasons was observed in the circadian period. These data may be significant for the plant's economic use.

Seasonality, Composition, and Antioxidant Capacity of Limonene/δ-3-Carene/(E)-Caryophyllene Schinus terebinthifolia Essential Oil Chemotype from the Brazilian Amazon: A Chemometric Approach

Schinus terebinthifolia Raddi is widely used in traditional Brazilian medicine to treat respiratory diseases, as an antiseptic, anti-inflammatory, and hemostatic agent. This study aimed to evaluate the influence of climatic parameters on the yield, antioxidative capacity, and chemical composition of the S. terebinthifolia leaf essential oil. The specimen was collected monthly from October 2021 to September 2022. Leaf essential oils (EOs) were obtained by hydrodistillation, and their chemical compositions were analyzed by gas chromatography/mass spectrometry (GC/MS). Statistical analyses were performed to verify the climatic influences on the yields, chemical composition, and antioxidative capacity. The DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging and inhibition of β-carotene/linoleic acid oxidation assays were performed to assess the antioxidant activity. The leaf essential oil yields ranged from 0.1% (July) to 0.7% (May and September), averaging 0.5 ± 0.2%. There was no significant difference in essential oil production during the dry (0.4 ± 0.2%) and rainy (0.6 ± 0.1%) seasons. The main chemical constituents identified in essential oils were limonene (11.42-56.24%), δ-3-carene (8.70-33.16%) and (E)-caryophyllene (4.10-24.98%). The limonene annual average was 43.57 ± 12.74% and showed no statistical difference during the dry (40.53 ± 13.38%) and rainy (52.68 ± 3.27%) seasons. Likewise, the annual average of δ-3-carene was 22.55 ± 7.11%, displaying no statistical difference between dry (26.35 ± 7.90%) and rainy (31.14 ± 1.63%) seasons. The annual average of (E)-caryophyllene was 11.07 ± 7.15% and this constituent did not show a statistical difference in Tukey's test (p > 0.05) during the dry (12.72 ± 7.56%) and rainy (6.10 ± 1.78%) season. Limonene showed a moderate positive and significant correlation (p < 0.05) with precipitation (r = 0.56) and a weak correlation with temperature (r = -0.40), humidity (r = 0.40), and insolation (r = -0.44). All samples inhibited the oxidation in the β-carotene/linoleic acid system (22.78-44.15%) but displayed no activity in the DPPH method.

Antidepressant Effects of Essential Oils: A Review of the Past Decade (2012-2022) and Molecular Docking Study of Their Major Chemical Components

Depression is a mental disorder that affects more than 300 million people worldwide. The medications available for treatment take a long time to exhibit therapeutic results and present several side effects. Furthermore, there is a decrease in the quality of life of people suffering from this affliction. Essential oils are traditionally used to relieve the symptoms of depression due to the properties of the constituents of these oils to cross the blood-brain barrier acting on depression-related biological receptors associated with reduced toxicity and side effects. In addition, compared to traditional drugs, they have several administration forms. This review provides a comprehensive assessment of studies on plants whose essential oil has exhibit antidepressant activity in the past decade and the mechanism of action of the major components and models tested. An additional in silico study was conducted with the frequent compounds in the composition of these essential oils, providing a molecular approach to the mechanism of action that has been reported in the past decade. This review is valuable for the development of potential antidepressant medications in addition to providing a molecular approach to the antidepressant mechanism of action of the major volatile compounds that have been reported in the past decade.

Chemometrics of the Composition and Antioxidant Capacity of Hyptis crenata Essential Oils from Brazil

Hyptis crenata (Pohl) ex Benth is used in traditional medicine as an analgesic to treat general pain. Six Hyptis crenata samples (Hc-1 to Hc-6) were collected in Pará state, Brazil. The leaf essential oils were obtained by hydrodistillation, and GC-MS and GC-FID were used to analyze their chemical compositions. The antioxidant capacity was measured in vitro using DPPH and carotene/linoleic acid assays. Chemometrics analysis (PCA, HCA, and clustered heat map) were used to identify the sample relationships between those collected in this study and those from the literature (Hc-7 to Hc-16) samples. According to the main chemical constituents identified in the samples described in this work and the literature, the sixteen samples were classified into ten groups. Group I was characterized by 1,8-cineole (31.0%), α-pinene (13.6%), (E)-caryophyllene (7.8%), and β-pinene (7.6%); and Group IV was characterized by 1,8-cineole (17.4-23.5%), α-pinene (15.7-23.5%), β-pinene (10.5-13.4%), and limonene (8.5-9.7%). Both groups are described for the first time. The total antioxidant capacity was expressed in Trolox Equivalent Antioxidant Capacity values (TEAC): TEAC of Hc-5 (551.9 mg.TE/g) and Hc-6 (475.1 mg.TE/g). In the β-carotene/linoleic acid assay, the highest inhibition was from Hc-2 (40.0%), Hc-6 (39.0%), and Hc-3 (29.4%).

Volatile Constituents from Catasetum (Orchidaceae) Species with Occurrence in the Brazilian Amazon

BACKGROUND

Catasetum Rich. ex Kunth is a genus of Neotropical orchids distributed in Central and South American regions. In the Brazilian Amazon, there are more than 60 species of Catasetum. The floral aromas of orchids are little known, particularly of Catasetum species. This work aimed to analyze the chemical constituents of the volatile concentrates of eight Catasetum specimens from the Amazon: C. alatum (1), C. albovirens (2), C. barbatum (1), C. ciliatum (2), C. galeritum (1), and C. gnomus (1).

METHODS

Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyzed and identified the constituents of the volatile concentrates, and principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used in the multivariate statistical analysis.

RESULTS

The Catasetum main constituents in descending order and above 10% were trans-geranylgeraniol, 1,4-dimethoxybenzene, linalool, 2-phenylethyl acetate, geraniol, 7-epi-1,2-dehydro-sesquicineole, 1,8-cineole, benzyl acetate, limonene, methyl salicylate, (E)-β-farnesene, anisyl butyrate, cis-carvone oxide, cadin-4-en-10-ol, indole, α-pinene, and δ-cadinene.

CONCLUSIONS

Multivariate statistical analysis of Catasetum species showed that C. barbatum, C. albovirens, and C. gnomus are distinct from the other studied species, while C. alatum, C. ciliatum, and C. galeritum presented the same primary classes of compounds. These results contribute to a better understanding of the genus Catasetum chemotaxonomy.

Chemical composition and antinociceptive and anti-inflammatory activity of the essential oil of Hyptis crenata Pohl ex Benth. from the Brazilian Amazon

ETHNOPHARMACOLOGICAL RELEVANCE

The leaf tea of Hyptis crenata has its practical use in the Brazilian Amazon for treating gastrointestinal and liver disorders, sweating induction, and as an anti-inflammatory.

AIM OF THE STUDY

Evaluation of the chemical composition, acute oral toxicity, and antinociceptive and anti-inflammatory activities of the H. crenata essential oil.

MATERIAL AND METHODS

The essential oil was hydrodistilled and analyzed by GC and GC-MS. The antinociceptive action in mice was evaluated for the peripheral and central analgesic activity (abdominal contortion and hot plate tests), and the xylene-induced ear swelling was carried out for the nociception test.

RESULTS

Oxygenated monoterpenes (53.0%) and monoterpene hydrocarbons (38.9%) predominated in the H. crenata oil, being 1,8-cineo1e (35.9%), α-pinene (20.8%), camphor (10.0%), and β-pinene (7.3%) their primary constituents. The oral oil administration in the mice did not display changes in behavior patterns or animal mortality at 300 and 2000 mg/kg doses. The control group's biochemical parameters (ALP, AST, ALT) displayed a statistical difference from the treated group, unlike the renal parameters, which showed no variation between the groups. Oil reduced the abdominal contortions at doses of 100 (79.5%) and 300 mg/kg (44.4%), while with endodontacin, the dose was 5 mg/kg (75.2%). In addition, the oil could not decrease the paw licking/biting time at doses of 30, 100, and 300 mg/kg. However, it showed a significant antinociceptive effect on the second phase in the formalin test inhibiting licking time, with a reduction of 50.8% (30 mg/kg), 63.4% (100 mg/kg), 58.0% (300 mg/kg), and morphine (4 mg/kg, 78.3%). The oil administration produced significant inhibition of ear edema at all tested doses, with a better effect produced at 30 mg/kg (64.0% inhibition).

CONCLUSION

The oil of Hyptis crenata, rich in 1,8-cineole, camphor, α-pinene, and β-pinene, totaling 74%, displayed low acute toxicity and significant anti-inflammatory activity, with peripheral and no central antinociceptive action. Thus, these results show an actual perspective on using H. crenata oil in developing a phytotherapeutic product.

Essential Oil Chemotypes and Genetic Variability of Cinnamomum verum Leaf Samples Commercialized and Cultivated in the Amazon

Cinnamomum verum (Lauraceae), also known as "true cinnamon" or "Ceylon cinnamon" has been widely used in traditional folk medicine and cuisine for a long time. The systematics of C. verum presents some difficulties due to genetic variation and morphological similarity between other Cinnamomum species. The present work aimed to find chemical and molecular markers of C. verum samples from the Amazon region of Brazil. The leaf EOs and the genetic material (DNA) were extracted from samples cultivated and commercial samples. The chemical composition of the essential oils from samples of C. verum cultivated (Cve1-Cve5) and commercial (Cve6-c-Cv9-c) was grouped by multivariate statistical analysis of Principal Component Analysis (PCA). The major compounds were rich in benzenoids and phenylpropanoids, such as eugenol (0.7-91.0%), benzyl benzoate (0.28-76.51%), (E)-cinnamyl acetate (0.36-32.1%), and (E)-cinnamaldehyde (1.0-19.73%). DNA barcodes were developed for phylogenetic analysis using the chloroplastic regions of the matK and rbcL genes, and psbA-trnH intergenic spacer. The psbA-trnH sequences provided greater diversity of nucleotides, and matK confirmed the identity of C. verum. The combination of DNA barcode and volatile profile was found to be an important tool for the discrimination of C. verum varieties and to examine the authenticity of industrial sources.

The Volatile Profiles and DNA Barcodes of Lauraceae Species from the Ocotea Complex with Occurrence in the Brazilian Amazon

The Ocotea complex accommodates most of the taxonomic diversity of Neotropical Lauraceae with economic importance and biological potential attributed to their essential oils (EOs) and extracts. However, the botanical taxonomy has had limitations due to the difficulty of identifying and delimiting species and genera. The chemical and molecular markers of Ocotea complex species in Pará state, Brazil, were assessed according to their EO compositions and DNA sequences of matK, trnL-trnF, and ITS regions. The multivariate analysis of EOs constituents has classified them into two main clusters characterized by oils rich in (I) terpenoids and phenylpropanoids and (II) sesquiterpenes. We conducted a phylogenetic analysis of species based on DNA barcode sequences on the Bayesian Inference (PP: 0.70-1,0) and Maximum Likelihood (BS: 72-100 %). The comparison between the volatile profiles and phylogenetic data indicates two main groups for these species collected from the Ocotea complex.

Essential Oil Composition and DNA Barcode and Identification of Aniba species (Lauraceae) Growing in the Amazon Region

Lauraceae species are widely represented in the Amazon, presenting a significant essential oil yield, large chemical variability, various biological applications, and high economic potential. Its taxonomic classification is difficult due to the accentuated morphological uniformity, even among taxa from a different genus. For this reason, the present work aimed to find chemical and molecular markers to discriminate Aniba species collected in the Pará State (Brazil). The chemical composition of the essential oils from Aniba canelilla, A. parviflora, A. rosaeodora, and A. terminalis were grouped by multivariate statistical analysis. The major compounds were rich in benzenoids and terpenoids such as 1-nitro-2-phenylethane (88.34-70.85%), linalool (15.2-75.3%), α-phellandrene (36.0-51.8%), and β-phellandrene (11.6-25.6%). DNA barcodes were developed using the internal transcribed spacer (ITS) nuclear region, and the matK, psbA-trnH, rbcL, and ycf1 plastid regions. The markers psbA-trnH and ITS showed the best discrimination for the species, and the phylogenic analysis in the three- (rbcL + matK + trnH - psbA and rbcL + matK + ITS) and four-locus (rbcL + matK + trnH - psbA + ITS) combination formed clades with groups strongly supported by the Bayesian inference (BI) (PP:1.00) and maximum likelihood (ML) (BS ≥ 97%). Therefore, based on statistical multivariate and phylogenetic analysis, the results showed a significant correlation between volatile chemical classes and genetic characteristics of Aniba species.

Antioxidant and Cytotoxic Activities of Myrtaceae Essential Oils Rich in Terpenoids From Brazil

This work analyzed the chemical compositions and evaluated the antioxidant and cytotoxic activities of essential oils (EO) of Eugenia patrisii (Epat), Eugenia stipitata (Esti), Myrcia splendens (Mspl), Myrcia sylvatica (Msyl), Psidium guajava (Pgua), and Psidium guineense (Pgui-1 and Pgui-2) from the Brazilian Amazon. Sesquiterpenoids were found in high concentrations in the oils of E. patrisii and M. splendens, which were rich in E-caryophyllene (32.0% and 45.8%); E. stipitata and M. sylvatica, which displayed germacrene D (11.8%) and germacrene B (24.5%); and P. guajava that showed epi-β-bisabolol (16.1%) as the main compound. However, P. guineense samples (Pgui-1 and Pgui-2) were rich in monoterpenoids such as limonene (Pgui-1: 30.2%; Pgui-2 30.4%) and α-pinene (Pgui-1: 22.5%; Pgui-2: 17.7%). The samples showed a weak and moderate antioxidant activities in the DPPH assay, displaying inhibition rates from 11.5% to 38.6% (at 10 mg/mL). All samples were cytotoxic against human cancer cells by the MTT method. Epat oil showed higher activity against melanoma (SKMEL-19, IC505.8 µg/mL), gastric (AGP01, IC503.2 µg/mL), and colon (HCT116, IC506.7 µg/mL). Meanwhile, the samples Pgua and Pgui were more active against breast cancer cells (MCF7, IC5012.4 µg/mL and 11.6 µg/mL, respectively).

Monoterpenes and Sesquiterpenes of Essential Oils from Psidium Species and Their Biological Properties

Psidium (Myrtaceae) comprises approximately 266 species, distributed in tropical and subtropical regions of the world. Psidium taxa have great ecological, economic, and medicinal relevance due to their essential oils' chemical diversity and biological potential. This review reports 18 Psidium species growing around the world and the chemical and biological properties of their essential oils. Chemically, 110 oil records are reported with significant variability of volatile constituents, according to their seasonality and collection sites. Monoterpenes and sesquiterpenes with acyclic (C₁₀ and C₁₅), p-menthane, pinane, bisabolane, germacrane, caryophyllane, cadinane, and aromadendrane skeleton-types, were the primary constituents. The essential oils showed various biological activities, including antioxidant, antifungal, antibacterial, phytotoxic, larvicidal, anti-inflammatory, and cytotoxic properties. This review contributes to the Psidium species rational and economic exploration as natural sources to produce new drugs.

Volatile concentrate from the neotropical moss Neckeropsis undulata (Hedw.) Reichardt, existing in the brazilian Amazon

Background

Many natural compounds have been identified and synthesized by the advancement of bryophytes phytochemistry studies. This work aimed to report the composition of Neckeropsis undulata (Hedw.) Reichardt moss volatiles, sampled in the Combú Island, Belém city, Pará state, Brazil. The volatile concentrate of N. undulata was obtained by a simultaneous distillation-extraction micro-system, analyzed by GC and GC-MS, and reported for the first time.

Results

Ten compounds were identified in the volatile concentrate, corresponding to 91.6% of the total, being 1-octen-3-ol (35.7%), α-muurolol (21.4%), naphthalene (11.3%), and n-hexanal (10.0 %) the main constituents. Most of the constituents of the N. undulata volatile concentrate have been previously identified in other mosses, and liverworts spread wide in the world.

Conclusions

1-Octen-3-ol, n-hexanal, 2-ethylhexanol, isoamyl propionate, and octan-3-one are already known metabolic products obtained from enzymatic oxidation of polyunsaturated fatty acids, belonging to the large family of minor oxygenated compounds known as oxylipins. The knowledge of the composition of volatiles from moss N. undulata could contribute to the Neckeraceae species’ chemotaxonomy.

Chemical composition and biological activities of two chemotype-oils from Cinnamomum verum J. Presl growing in North Brazil

Chemical composition and antioxidant and antifungal action of the oils from leaves and wood bark of two chemotypes of Cinnamomum verum J. Presl were evaluated. Plants were sampled in the cities of São Luís and Santa Inês, state of Maranhão, Brazil. GC-MS and GC-FID, DPPH radical scavenging, and in vitro test against the phytopathogenic fungus Colletotrichum musae were used to perform these analyses. Cinnamomum verum is worldwide known as Cinnamon, highlighted for its extensive use in the cooking of diverse cultures of the world, and as a medicinal plant to treat environmental viral diseases. In the leaf oil of São Luís chemotype, eugenol (93.6%) was the main constituent, while in Santa Inês chemotype, it was benzyl benzoate (95.3%). In the bark wood oil of São Luís chemotype, (E)-cinnamaldehyde (89.3%) was the main constituent, while in Santa Inês chemotype, they were benzyl benzoate (23.3%), linalool (14.0%), (E)-caryophyllene (9.1%), caryolan-8-ol (7.2%) and borneol (4.7%). Leaf oils from both chemotypes showed strong to moderate antifungal activity, reaching 100% efficacy in eugenol-containing oils and above 70% in benzyl benzoate oils. In the antioxidant evaluation, the chemotype with a high eugenol content presented an inhibitory concentration higher than 80%, compared to Trolox. The leaf oils of the two C. verum chemotypes showed significant antifungal and antioxidant potential, considering their economic use as a functional and nutraceutical food supplement.

Seasonal and Circadian Rhythm of a 1,8-Cineole Chemotype Essential Oil of Calycolpus goetheanus From Marajó Island, Brazilian Amazon

Chemical composition of essential oils (EOs) of Calycolpus genus have been reported in the literature. However, there is only 1 report about volatile profile from Calycolpus goetheanus. This work aims to evaluate the seasonal and circadian influences on EO composition and yield of C. goetheanus collected in Marajó Island, Brazilian Amazon. For the circadian study, the leaves were collected in January (rainy season) and July (dry season) every 3 hours during a period of 15 hours. The EOs were obtained by hydrodistillation and their chemical compositions analyzed by gas chromatography coupled to mass spectrometry and flame ionization detectors. The major compound identified in all EO samples was 1,8-cineole with amounts ranged from 14.4% (January, 6 am) to 33.0% (July, 3 pm). The highest average of 1,8-cineole was obtained during circadian study of the dry season (25.5% ± 5.8%) and the lowest during the circadian study of the rainy season (15.6% ± 1.5%). The multivariate analysis grouped the samples into 2 different groups: Group I characterized by the lowest amounts of 1,8-cineole (16.0%-18.7%), and Group II characterized by a higher content of 1,8-cineole (24.0%-33.0%). The oil yield and chemical composition did not show relationship with climate parameters (solar radiation, humidity, and temperature). Therefore, there was only quantitative variability in the EOs compositions during the circadian rhythm evaluated on dry and rainy seasons.

Variability in the Chemical Composition of Eugenia biflora Essential Oils from the Brazilian Amazon

Eugenia species are well known for their great economic potential as edible fruits. The leaves of 4 Eugenia biflora specimens (Ebi-1 to Ebi-4) were sampled in the Caratateua Island, Pará state, Brazilian Amazon. Then, the essential oils were hydrodistilled, analyzed by gas chromatography (GC) and GC mass spectroscopy, and their volatile compositions submitted to multivariate analysis (principal component analysis and hierarchical cluster analysis). Ebi-1 and Ebi-2 specimens were classified in the caryophyllene group, with significant content for the sesquiterpenes ( E)-caryophyllene (16.8% and 11.4%) and caryophyllene oxide (28.6% and 20.5%). Ebi-3 specimen was grouped into the cadinane group, characterized by the presence of α-cadinol (14.7%), an oxygenated sesquiterpene. EBI-4 specimen was inserted into the aromadendrane group, with the predominance of the sesquiterpenes globulol (9.8%), germacrene B (7.9%), and γ-elemene (3.1%). Based on the results, a remarkable chemical variability was observed in the oils of Eugenia biflora with occurrence in Pará state, North Brazil. This work is presenting for the first time its caryophyllene, cadinane, and aromadendrane profiles.

Composition, antioxidant capacity and cytotoxic activity of Eugenia uniflora L. chemotype-oils from the Amazon

ETHNOPHARMACOLOGICAL RELEVANCE

Oils and extracts of Eugenia uniflora have been reported as antimicrobial, antifungal, antinociceptive, antiprotozoal, antioxidant and cytotoxic.

AIM OF THE STUDY

The oils of five specimens (E1 to E5) that occur in the Brazilian Amazon were extracted, analyzed for their chemical composition, and submitted to antioxidant and cytotoxic assays.

MATERIAL AND METHODS

Oils were hydrodistilled, analyzed by GC and GC-MS, and submitted to PCA and HCA analyses. The antioxidant activity of the oils was evaluated by the DPPH radical scavenging and the β-carotene/linoleic acid assays. Antiproliferative effects of the oils and curzerene were tested against colon (HCT-116), gastric (AGP-01), and melanoma (SKMEL-19) human cancer cell lines and a normal human fibroblast cell line (MRC-5), using MTT assay.

RESULTS

Oxygenated sesquiterpenes and sesquiterpene hydrocarbons such as curzerene, selina-1,3,7(11)-trien-2-one, selina-1,3,7(11)-trien-2-one epoxide, germacrene B, caryophyllene oxide, and (E)-caryophyllene were predominant in the oils. PCA and HCA analyses classified the oils samples into four chemotypes. TEAC values of chemotype II (E3 oil, 228.3 ± 19.2 mg TE/mL) and chemotype III (E4 oil, 217.0 ± 23.3 mg TE/mL) displayed significant antioxidant activities. The oils E2 and E4 showed cytotoxic activity against all cell lines tested HCT-116 (IC₅₀ E2:16.26 μg/mL; IC₅₀ E4:9.28 μg/mL), AGP-01, (IC₅₀ E2:12.60 μg/mL; IC₅₀ E4:8.73 μg/mL), SKMEL-19 (IC₅₀ E2:12.20 μg/mL; IC₅₀ E4:15.42 μg/mL), and MRC-5 (IC₅₀ E2:10.27 μg/mL; IC₅₀ E4:14.95 μg/mL). Curzerene showed the more significant activity against melanoma cells (SKMEL-19, IC₅₀:5.17 μM), induced apoptosis at 5.0 μM and 10.0 μM compared to DMSO, exhibiting a decrease in the cell migration at 5.0 μM and 10.0 μM, after 30 h of treatment.

CONCLUSION

The curzerene chemotype oil and E. uniflora oils can be indicated as drug candidates for anticancer activity of the lung, colon, stomach, and melanoma, with a real prospect to their subsequent phytotherapeutic development.

Chemical profile of Lippia thymoides, evaluation of the acetylcholinesterase inhibitory activity of its essential oil, and molecular docking and molecular dynamics simulations

The essential oils of the fresh and dry flowers, leaves, branches, and roots of Lippia thymoides were obtained by hydrodistillation and analyzed using gas chromatography (GC) and GC-mass spectrometry (MS). The acetylcholinesterase inhibitory activity of the essential oil of fresh leaves was investigated on silica gel plates. The interactions of the key compounds with acetylcholinesterase were simulated by molecular docking and molecular dynamics studies. In total, 75 compounds were identified, and oxygenated monoterpenes were the dominant components of all the plant parts, ranging from 19.48% to 84.99%. In the roots, the main compounds were saturated and unsaturated fatty acids, having contents varying from 39.5% to 32.17%, respectively. In the evaluation of the anticholinesterase activity, the essential oils (detection limit (DL) = 0.1 ng/spot) were found to be about ten times less active than that of physostigmine (DL = 0.01ng/spot), whereas thymol and thymol acetate presented DL values each of 0.01 ng/spot, equivalent to that of the positive control. Based on the docking and molecular dynamics studies, thymol and thymol acetate interact with the catalytic residues Ser203 and His447 of the active site of acetylcholinesterase. The binding free energies (ΔGbind) for these ligands were -18.49 and -26.88 kcal/mol, demonstrating that the ligands are able to interact with the protein and inhibit their catalytic activity.

Planting and seasonal and circadian evaluation of a thymol-type oil from Lippia thymoides Mart. & Schauer

Background

The oil and extracts of Lippia thymoides have been used for various medicinal and food applications. Entrepreneurs in the Amazon have been considering the economic exploitation of this plant. The present study evaluated the influence of the seasonal and circadian rhythm on the yield and composition of the essential oil of leaves and thin branches of a Lippia thymoides specimen cultivated in Abaetetuba, State of Pará, Brazil. The constituents of the oils were identified by GC and GC–MS and with the application of multivariate analysis: Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA).

Results

The predominance of oxygenated monoterpenes (70.6–91.8%) was observed in oils, followed by monoterpene hydrocarbons (1.2 to 21.6%) and sesquiterpene hydrocarbons (3.9 to 9.1%). Thymol, thymol acetate, γ-terpinene, p-cymene, and (E)-caryophyllene were the first compounds. The mean thymol content was higher in the rainy season (seasonal: 77.0%; circadian: 74.25%) than in the dry period (seasonal: 69.9%; circadian: 64.5%), and it was influenced by climatic variables: rainfall precipitation, solar radiation, temperature, and relative humidity. For the circadian study, PCA and HCA analysis were applied to the constituents of oils from rainy and dry periods. Two groups were formed. A higher thymol content characterized the group 1, followed by (Z)-hexen-3-ol, α-thujene, α-pinene, α-phellandrene and humulene epoxide II, in minor percent. A higher content of p-cymene formed the group 2, γ-terpinene, thymol acetate and (E)-caryophyllene, followed by myrcene, α-terpinene, 1,8-cineole, terpinen-4-ol, methylthymol, and germacrene D, in a low percentage.

Conclusions

The different chemical profiles found in the oils of L. thymoides must be associated with the environmental conditions existing at its collection site. The knowledge of this variation in the oil composition is essential from the ecological and taxonomic point of view, regarding the management and economic use of the species.

Seasonal Study of Methyleugenol Chemotype of Ocimum campechianum Essential Oil and Its Fungicidal and Antioxidant Activities

Ocimum species (Lamiaceae) have aroused great interest to the scientific community with respect to different biological properties attributed to their essential oils. The seasonal variation and antioxidant and fungical activities were carried out for the essential oil of Ocimum campechianum. Its essential oil showed an excellent yield (0.5–5.3%) throughout the season. The essential oils of leaves/stems and inflorescences were analyzed by GC and GC-MS to identify their volatile constituents and associate them with the antioxidant and antifungal activities. Methyleugenol was the main component in the leaves/stems (80.0-87.0%) and inflorescences (75.3–83.5%). The essential oil and the methyleugenol standard showed low antioxidant activity (<40%) against DPPH radical, but high antifungal activity against Fusarium oxysporum and Colletotrichum gossypii phytopatogens as well as the mycelial growth and spore germination of the fungi. The high levels of methyleugenol coupled with good fungicidal activity give great agroindustrial potential to this Ocimum species.

Chemical variability in the essential oil of leaves of Araçá (Psidium guineense Sw.), with occurrence in the Amazon

BACKGROUND

Psidium guineense, known as Araçá, is a Brazilian botanical resource with commercial application perspectives, based on the functional elements of its fruits and due to the use of its leaves as an anti-inflammatory and antibacterial agent. The essential oils of leaves of twelve specimens of Araçá were analyzed by GC and GC-MS to identify their volatile constituents and associate them with the biological activities reputed to the plant.

RESULTS

In a total of 157 identified compounds, limonene, α-pinene, β-caryophyllene, epi-β-bisabolol, caryophyllene oxide, β-bisabolene, α-copaene, myrcene, muurola-4,10(14)-dien-1-β-ol, β-bisabolol, and ar-curcumene were the primary components in descending order up to 5%. Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) displayed three different groups with the following chemical types: limonene/α-pinene, β-bisabolene/epi-β-bisabolol, and β-caryophyllene/caryophyllene oxide. With the previous description of another chemical type rich in spathulenol, it is now understood that at least four different chemotypes for P. guineense should occur.

CONCLUSIONS

In addition to the use of the Araçá fruits, which are rich in minerals and functional elements, it should be borne in mind that the knowledge of the chemical composition of the essential oils of leaves of their different chemical types may contribute to the selection of varieties with more significant biological activity.