Omar Malagón

The leaf essential oil of Croton chimboracensis, a species native to Ecuador, was investigated using an integrated chemical, biological, and computational approach. Volatile constituents were identified by gas chromatography–mass spectrometry (GC–MS), and their relative proportions were determined by gas chromatography–flame ionization detection (GC–FID) peak-area normalization. Forty-seven compounds were identified, accounting for 95.17% of the total GC–FID peak area. The oil was dominated by hydrocarbon sesquiterpenes (72.75%), with trans-muurola-4(14),5-diene (34.06%), longifolene (15.34%), bicyclogermacrene (7.65%), caryophyllene oxide (5.53%), α-humulene (4.38%), and γ-cadinene (4.02%) as the principal constituents. The essential oil exhibited an assay-dependent radical-scavenging response, with an SC₅₀ value of 15.20 µg/mL in the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay (95% confidence interval CI: 8.97–19.83 µg/mL) and 2983 µg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (95% CI: 2719–3378 µg/mL). The essential oil also inhibited acetylcholinesterase (AChE), with an IC₅₀ value of 43.78 µg/mL (95% confidence interval: 40.68–47.05 µg/mL). Molecular docking and absolute binding free-energy calculations were performed for all 47 identified constituents. These calculations prioritized spirolepechinene, β-phellandrene, β-pinene, alloaromadendrene epoxide, and (2E,4E)-nona-2,4-dien-1-ol as potential AChE-binding constituents, with predicted binding free energies of −20.22 ± 0.93, −16.59 ± 0.87, −16.33 ± 0.91, −15.81 ± 2.53, and −15.29 ± 1.91 kcal/mol, respectively (ΔG ± SEM). These findings identify candidates for subsequent experimental validation and provide molecular hypotheses concerning their possible contributions to the AChE-inhibitory activity of the complete oil. Overall, this study provides an integrated characterization of C. chimboracensis essential oil and establishes a basis for further investigation of its antioxidant and acetylcholinesterase-inhibitory constituents.

Species of the genus Aristolochia are recognized as a rich source of structurally diverse specialized metabolites; however, the volatile chemical composition and biological properties of several Neotropical species remain poorly characterized. In particular, no information is currently available on the essential oil of Aristolochia lingulata Ule ex Pilg., which motivated this chemical, enantioselective, and preliminary biological investigation. The leaf essential oil was analyzed by GC-MS and GC-FID using nonpolar and polar stationary phases, while enantioselective GC-MS was employed to determine the distribution of selected chiral metabolites. Biological activity was evaluated through acetylcholinesterase, butyrylcholinesterase, pancreatic lipase, DPPH, and ABTS assays. A total of 57 constituents were identified and quantified, accounting for 93.5% and 91.3% of the oil on the two stationary phases. Sesquiterpene hydrocarbons and oxygenated sesquiterpenoids predominated, with dauca-5,8-diene, trans-(E)-nerolidol, β-chamigrene, β-cyclocitral, limonene, δ-amorphene, τ-muurolol, and manool among the main constituents. The oil showed moderate acetylcholinesterase inhibition (IC₅₀ = 79.8 ± 0.3 µg/mL), whereas weaker inhibition was observed against butyrylcholinesterase (IC₅₀ = 176.1 ± 3.3 µg/mL) and pancreatic lipase (IC₅₀ = 190.8 ± 9.4 µg/mL). Radical scavenging activity was also weak in the DPPH and ABTS assays (SC₅₀ = 849.7 ± 7.4 and 338.0 ± 3.9 µg/mL, respectively). Overall, this study provides the first characterization of the essential oil of A. lingulata, revealing a distinctive sesquiterpene-rich volatile profile and moderate enzyme-inhibitory activity. These findings expand the phytochemical knowledge of Neotropical Aristolochia species and provide a basis for further investigation of their bioactive constituents, mechanisms of action, and toxicological safety.

Traditionally, Lasiocephalus ovatus Schltdl. (Asteraceae) has been used as an aromatic medicinal plant, particularly in the treatment of kidney-related ailments. However, scientific evidence validating its chemical composition and bioactivity remains limited. According to our literature search, there are no previous studies on the in vitro antibacterial, antioxidant, or anti-inflammatory activities of the essential oil from the aerial parts of Lasiocephalus ovatus; therefore, this study provides the first experimental evidence of these biological activities for this species. An essential oil (EO) was steam-distilled from the aerial parts of L. ovatus, grown at 4410 m above sea level in the paramos of Chimborazo Province (Ecuador), and subsequently analyzed. The distillation yield was 0.21% (w/w) based on dry plant material. Gas chromatography was employed for qualitative (GC-MS) and quantitative (GC-FID) analyses, using two different capillary columns, coated with 5% phenyl methyl polysiloxane (non-polar) and polyethylene glycol (polar) stationary phases. Dual stationary phases were required to provide complementary selectivity, which reinforced the identification and quantification of compounds. The major components of the EO were silphinene (3.4–3.5%), δ-selinene (3.6–3.1%), β-cyclogermacrene (18.7–18.1%), kessane (4.5–4.2%), spathulenol (13.3–13.3%), viridiflorol (3.1–3.0%) and neophytadiene (4.8–4.4%), values referred to the non-polar and polar phase respectively. The enantioselective analysis revealed that (1S,5S)-(−)-α-pinene, (1S,5S)-(+)-β-pinene and (R)-(−)-α-phellandrene were enantiomerically pure, whereas germacrene D was present as a scalemic mixture. The essential oil of L. ovatus exhibited a minimum inhibitory concentration (MIC) of 250 µg/mL against Staphylococcus aureus and 500 µg/mL against Escherichia coli. Its antibacterial activity is likely associated with the presence of bioactive sesquiterpenes such as silphinene, δ-selinene, and spathulenol, which are known for their membrane-disruptive properties. Regarding its antioxidant potential, the observed moderate radical scavenging activity (SC₅₀ = of 375.7 µg/mL) can be attributed to its complex mixture, particularly to oxygenated terpenoids like viridiflorol and spathulenol, which are recognized for their radical-neutralizing capacity. In the anti-inflammatory assay, the EO’s moderate potency (IC₅₀ = 165.29 ± 4.75 μg/mL) is also consistent with the anti-inflammatory profile reported for several of its major constituents, including spathulenol and viridiflorol. While significantly lower than that of aspirin (28.85 ± 7.66 μg/mL), this bioactivity is considerable within the context of a plant extract. Overall, the antibacterial, antioxidant, and anti-inflammatory effects are consistent with the EO’s terpene-rich composition, particularly oxygenated sesquiterpenes, while the enantiomeric distribution of chiral monoterpenes may further modulate bioactivity; consequently, future studies should include enantioselective quantification, broader antioxidant assays (e.g., ABTS, FRAP, ORAC, CUPRAC), cytotoxicity at active concentrations, and mechanistic and in vivo validation.

Essential oils from species of the genus Varronia (Boraginaceae) are recognized for their chemical diversity and biological potential; however, phytochemical information on Varronia crenata Ruiz & Pav. remains scarce, despite its wide distribution in the Andean region. The aim of this study was to provide the first chemical and enantioselective characterization of the essential oil obtained from the leaves of V. crenata growing in Ecuador. Qualitative and quantitative analyses were carried out by GC–MS and GC–FID, respectively, using two columns with stationary phases of contrasting polarity. Compounds were identified by matching linear retention indices and mass spectra to literature references and quantified by external calibration using relative response factors (RRFs) calculated for each compound based on its combustion enthalpy. The most abundant constituents (≥3.0% on average between the two columns) of the essential oil of V. crenata, both in the nonpolar and polar stationary phases, were germacrene D (18.4%), (E)-β-caryophyllene (13.3%), α-copaene (10.4%), tricyclene (9.3%), δ-cadinene (8.9%), and α-pinene (8.3%). The volatile fraction was dominated by sesquiterpenes (60.2%) and monoterpenes (22.1%), while other chemical families were present in minor proportions. The enantioselective analysis was performed on two different columns, coated with stationary phases based on β-cyclodextrins: 2,3-diacetyl-6-tert-butyl-dimethylsilyl-β-cyclodextrin and 2,3-diethyl-6-tert-butyl-dimethylsilyl-β-cyclodextrin. Nine chiral compounds were analyzed; among them, (1R,5R)-(+)-α-pinene, (1R,5R)-(+)-sabinene, and (S)-(+)-β-phellandrene were detected as enantiomerically pure, while the other metabolites presented scalemic mixtures. Overall, the high content of bioactive sesquiterpenes and the observed stereochemical complexity highlight the potential pharmaceutical and agricultural relevance of V. crenata essential oil, while also providing novel chemotaxonomic information for the genus.

This study reports the first chemical characterization of the essential oil of Croton alnifolius. A very low yield of 0.028% ± 0.0012 (w/w) was obtained by steam distillation for 4 h using a Clevenger-type apparatus. The chemical composition of the oil was analyzed by gas chromatography coupled with mass spectrometry (GC–MS) for compound identification and by gas chromatography with a flame ionization detector (GC–FID) for quantification. A total of 49 compounds were identified, representing 94.65% of the total oil composition. The chemical profile was dominated by hydrocarbon sesquiterpenes (53.11%) and hydrocarbon monoterpenes (32.20%). The major constituents included (E)-caryophyllene (17.42%), α-pinene (14.53%), myrcene (9.51%), germacrene D (9.92%), and β-chamigrene (5.48%). The biological activity of the essential oil was also evaluated: it exhibited weak antimicrobial activity against Enterococcus faecium with a Minimum Inhibitory Concentration (MIC) value of 1000 μg/mL, strong antioxidant potential in the ABTS assay (SC₅₀ = 28.43 ± 1.0 μg/mL), and moderate acetylcholinesterase inhibitory activity (61.74 ± 1.02 μg/mL). These results indicate that the unique sesquiterpene rich chemical profile of C. alnifolius contributes to its antioxidant and neuroprotective potential, supporting its relevance as a promising source of bioactive natural products.

Essential oils from the genus Piper are recognized for their chemical diversity and biological potential, yet Piper platylobum has been scarcely investigated. This study aimed to characterize the chemical composition of the leaf essential oil of P. platylobum and evaluate its antimicrobial, antioxidant, and anticholinesterase activities. The oil was obtained by steam distillation and analyzed through gas chromatography–mass spectrometry (GC-MS) and gas chromatography equipped with a flame ionization detector (GC-FID), leading to the identification of 35 compounds that accounted for 91.11% of the volatile fraction. Dillapiole (42.0%) was the principal constituent, followed by α-(E)-bergamotene (5.69%), (E)-caryophyllene (5.01%), and (E)-isocroweacin (3.75%). Biological assays revealed selective antimicrobial activity, with inhibition observed only against Enterococcus faecium (MIC = 1000 µg/mL), while no effect was detected against other bacterial or fungal strains tested. Antioxidant evaluation showed moderate activity in the ABTS assay (SC₅₀ = 335.71 ± 1.43 µg/mL; TEAC = 45.85 ± 1.68 µM Trolox/g EO), but no activity in the DPPH assay. The essential oil also displayed moderate inhibition of acetylcholinesterase (IC₅₀ = 76.86 ± 1.00 µg/mL), suggesting a potential role in neuroprotective applications. This study constitutes the first report on the chemical composition and biological activities of P. platylabum essential oil, highlighting its potential as a novel source of bioactive compounds.

The present research describes the chemical composition and the enantiomeric profile of a spicy green aroma essential oil, distilled from the dry leaves of Baccharis sinuata Kunth (Asteraceae). The distillation yield was as high as 3.0% by weight. The chemical analysis was conducted on two columns, coated with stationary phases of different polarity (5% phenyl—95% methyl polysiloxane, expressed by weight, and 100% polyethylene glycol). Major components (≥2.0% as an average value between the two columns) were as follows: β-pinene (4.9%), limonene (39.0%), (E)-β-caryophyllene (2.0%), bicyclogermacrene (2.7%), γ-cadinene (4.0%), δ-cadinene (7.3%), β-eudesmol (2.0%), α-eudesmol (3.0%), and α-cadinol (2.0%). For the enantioselective analysis, 10 enantiomeric pairs were investigated, using two capillary columns coated with different chiral selectors. As a result, (1R,5R)-(−)-α-thujene, (1S,5S)-(−)-α-pinene, and (1R,2S,6S,7S,8S)-(−)-α-copaene were enantiomerically pure, whereas (R)-(+)-limonene presented a 90.0% enantiomeric excess. All the other analysed chiral compounds were scalemic mixtures. The high distillation yield, its aroma, and the bibliographic bioactivity profile make this essential oil potentially interesting from a commercial point of view. To the best of the authors’ knowledge, this is the first description of an essential oil distilled from leaves of B. sinuata.

The essential oil (EO) obtained from the roots of Valeriana rigida Ruiz & Pav. (Caprifoliaceae), collected in the moorland region of Chimborazo Province, Ecuador, was analyzed for the first time. The chemical profile was qualitatively and quantitatively analyzed using GC-MS and GC-FID, respectively. With both detectors, two stationary phases of different polarities were used. A total of 56 compounds were identified, and the most abundant components (>3% on at least one column) were a mixture of cyclosativene and α-ylangene (4.5–4.4%), α-copaene (9.0–8.8%), decanoic acid (16.0–15.6%), β-chamigrene (3.2–3.1%), δ-cadinene (9.7–9.5%), dodecanoic acid (13.4–12.3%), and 7-epi-α-eudesmol (5.0–4.9%), on a non-polar and polar stationary phase, respectively. Additionally, the enantioselective analysis showed (1S,5S)-(+)-α-pinene, (1R,4S)-(–)-camphene, (1S,5S)-(−)-β-pinene, and (1R,2S,6S,7S,8S)-(–)-α-copaene as enantiomerically pure compounds, whereas germacrene D exhibited both enantiomeric forms. The anti-inflammatory activity of V. rigida EO was comparable to that of aspirin, as indicated by the IC50 values, with no significant differences observed.

The present study is the first report on the chemical and enantiomeric compositions of essential oils from the Ecuadorian species Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. All the volatile fractions presented a sesquiterpene-based chemical profile, typical of other volatile fractions from this genus. Both qualitative (GC-MS) and quantitative (GC-FID) chemical analyses were carried out on two stationary phases of different polarity (non-polar and polar). The main constituents of G. hallii essential oil on the two columns, respectively, were α-pinene (33.6–31.5%), (E)-β-caryophyllene (6.2–6.4%), germacrene D (35.7–38.3%), and bicyclogermacrene (3.8–4.0%). In G. calyculisolvens, the major compounds were α-pinene (11.2–11.0%), p-cymene (4.0–3.7%), α-copaene (3.6–3.7%), (E)-β-caryophyllene (8.1–8.3%), germacrene D (20.8–22.0%), and germacrene D-4-ol (8.4–8.6%). Finally, the main components of G. azuayensis were α-pinene (4.5–4.1%), germacrene D (14.1–12.4%), bicyclogermacrene (2.6–3.0%), tridecanal (6.4–6.2%), and spathulenol (7.8–7.1%). Furthermore, enantioselective analyses were conducted on the three volatile fractions, using two stationary phases based on β-cyclodextrins. As a result, twelve chiral components were investigated, detecting both enantiomerically pure compounds and scalemic mixtures with various enantiomeric excess.

This study presents the first chemical and enantioselective analyses of essential oils (EOs) derived from the leaves of two endemic species, Gynoxys reinaldii Cuatrec. and Gynoxys pulchella (Kunth) Cass., from Loja, Ecuador. The distillation yields, by weight of dry plant material, were 0.04 ± 0.007% for G. reinaldii and 0.03 ± 0.002% for G. pulchella. For both plants, the chemical analyses were conducted by GC-MS (qualitative) and GC-FID (quantitative), on two stationary phases of different polarity (5% phenyl-methylpolysiloxane and polyethylene glycol). The major components of G. reinaldii EO included germacrene D (22.3–22.1%), α-pinene (14.2–14.1%), and (E)-β-caryophyllene (13.6–14.5%). Similarly, G. pulchella EO was characterized by germacrene D (9.5–12.9%), caryophyllene oxide (7.2–6.7%), and n-tricosane (4.9% in both columns). The enantioselective analyses were carried out with two columns, based on 2,3-diacetyl-6-tert-butyldimethylsilyl-β-cyclodextrin and 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin, detecting nine chiral terpenes and terpenoids. In G. reinaldii EO, (1S,5S)-(−)-α-pinene, (1S,5S)-(−)-β-pinene, (1S,5S)-(−)-sabinene, (R)-(−)-α-phellandrene, and (R)-(−)-β-phellandrene were enantiomerically pure, whereas cis-linalool oxide, linalool, terpinene-4-ol, and germacrene D were non-racemic mixtures of enantiomers. In G. pulchella, only (R)-(−)-α-phellandrene was enantiomerically pure. The detection of enantiomerically pure compounds may provide insights into the biosynthetic pathways and potential bioactivities of these EOs.