Chemical constituents and enantiomeric profile of Nectandra reticulata leaf essential oil from Ecuador and its potential archaeobotanical importance

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 obtained from the dry leaves of Gynoxys szyszylowiczii Hieron. was described in this study for the first time. The chemical analysis, conducted on two stationary phases of different polarity, permitted to identify sixty-four compounds, that were quantified with at least one column. The main components, on a non-polar and polar stationary phase respectively, were germacrene D (21.6–19.2%), α-pinene (4.4–4.9%), n-tricosane (4.3% on both columns), (E)-β-caryophyllene (3.3–4.3%), 1-docosene (3.2–2.8%), α-cadinol (2.8–3.1%), and cis-β-guaiene (2.6–3.0%). This investigation was complemented by the enantioselective analysis of some major chiral compounds, carried out on two chiral selectors based on β-cyclodextrines. As a result, (S)-( +)-α-phellandrene, (S)-( +)-β-phellandrene, and (1S,2R,6R,7R,8R)-( +)-α-copaene appeared enantiomerically pure, whereas α-pinene, β-pinene, terpinen-4-ol, and germacrene D were detected as scalemic mixtures. Finally, linalool was practically racemic. The distillation yield, analytically calculated by weight of dry plant material, was 0.03%.

The present study described, for the first time, the chemical and enantiomeric composition of an essential oil, distilled from the cupules of Aiouea montana (Sw.) R. Rohde. On the one hand, chemical analyses were carried out through GC-MS (qualitative) and GC-FID (quantitative), on two stationary phases of different polarity. Major components (≥3.0%) were S-methyl-O-2-phenylethyl carbonothioate (23.1%), α-copaene (20.3%), α-phellandrene (18.7%), (E)-β-caryophyllene (6.1%), and α-pinene (4.5%). On the other hand, enantioselective analyses were conducted, through GC-MS, on two columns with different chiral selectors, based on derivatised β-cyclodextrins. A total of 12 chiral components were analysed, of which (1S,5S)-(−)-α-pinene and (1R,2S,6S,7S,8S)-(−)-α-copaene were found to be enantiomerically pure. All the other chiral components were present as scalemic mixtures. Finally, both chemical and enantiomeric profiles were compared to the ones previously described in the literature for the leaf essential oil of A. montana. In conclusion, cupules of A. montana produced an essential oil with a higher yield in comparison with leaves but with a lower content of S-methyl-O-2-phenylethyl carbonothioate. On the other hand, to some extent, the enantiomeric compositions of these volatile fractions were somewhat different. To the best of the authors’ knowledge, the cupule essential oil of A. montana could be the second main natural source of (−)-α-copaene so far described in the literature.

An Ecuadorian specimen of Ophryosporus peruvianus produced an essential oil with a yield of 0.4% of the weight of the fresh plant material. A total of thirty-two compounds were detected and quantified. The chemical composition showed the predominance of monoterpene hydrocarbons, with sabinene (22.5%), β-pinene (15.1%), limonene (8.3%), β-phellandrene (29.7%), δ-elemene (2.1%), and epi-α-cadinol (2.7%) being the main components, expressed as mean values on two stationary phases of different polarity. This composition was very different from that reported in the literature for the essential oil of a Peruvian specimen, which was dominated by sesquiterpene hydrocarbons. These results indicate the existence of different chemotypes of O. peruvianus. Moreover, an enantioselective analysis of the major chiral constituents was performed, which revealed (R)-(-)-β-phellandrene, (R)-(-)-β-phellandrene and (1R,9R,E)-(-)-β-caryophylleneas enantiomerically pure compounds. On the other hand, β-thujene, β-pinene, β-pinene, sabinene, limonene, and terpinen-4-ol were scalemic mixtures. Finally, a preliminary screening of enzymatic inhibitory activity was performedin vitro, showing modest but interesting inhibition of both butyrylcholinesterase and lipase.

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.

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.

The semi-empirical topological index, previously developed by Heinzen and Yunes, has been applied to predict the chromatographic retention of aliphatic ketones and aldehydes on stationary phases of different polarities (HP-1, HP-50, DB-210 and Innowax). Simple linear regressions between the retention indices and the semi-empirical topological indices (RI = a + bI ET) were established for each stationary phase separately, showing satisfactory statistical parameters. The polarity of the stationary phases, indicated by McReynolds polarity (P R), is reflected in the coefficients of the equations (a and b) obtained for HP-1, HP-50 and DB-210, which linearly vary as the polarity of the stationary phase increases (intercept). Statistical analyses showed that the quantitative structure-chromatographic retention relationship (QSRR) models obtained on stationary phases of low-to-medium polarity (HP-1 and HP-50) have higher stability and predictive ability than those on polar stationary phases (DB-210 and Innowax). Thus, it can be concluded that the semi-empirical topological method, using only one descriptor, yielded better results on low-to-medium polarity stationary phases than methods that used multiple descriptors.

Prediction of the chromatographic retention of saturated alcohols on stationary phases of different polarity applying the novel semi-empirical topological index

Gas chromatographic retention indexes of saturated alcohols on stationary phases of different polarity are related to some of their topological and physicochemical properties by means of multilinear regression analysis. The solutes are linear, branched, and cyclic alcohols with their functional group on a primary, secondary, or tertiary carbon atom. Very close relationships are found, which can be utilized for the prediction of retention indexes of saturated alcohols on stationary phases of any polarity. Other equations obtained with a small number of representative alcohols are also suitable for calculating accurate retention indexes of the 26 tested alcohols.

Linear and reciprocial Kovats retention index-boiling point relationships known from the literature were used to study the Kovats retention index-boiling point dependence of 2-phenyl-2-alkylacetonitriles on stationary phases of different polarity (OV-17, OV-210 and OV-225). The standard chemical potential of the partitioning of one methylene group of an n-alkane for the stationary phase was calculated and compared with available literature data.

Summary In our paper we propose a new method for the determination of heats of vaporization (Anvap(i)) and the Gibbs free energies of vaporization (Ap.p(i)) for individually selected alkylbenzenes, chromatographed on stationary phases of low and medium polarity. The method is based on a new thermodynamic description of the Ko%ts retention index (I(i)) making use of Trouton's rule. In fact, we attribute physical significance to two empirical relationships, well known from the literature. We can describe thermodynamically the magnitude of I(i) using two relations, each of them potentially useful for further determination of Anvap(i) and A~p(i ). A comparison was made of the results obtained with the use of our new approach and of those already existing in the literature attained in a completely different way. The comparison suggests that the calculated AHvap(i) and Al.tp(i) values are thermodynamically acceptable and hence correct, and the data suit into the series of similar values determined on stationary phases of different polarity.

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.

Derivation of solubility parameters of chlorinated dibenzofurans and dibenzo[ p]dioxins from gas chromatographic retention parameters via SOFA

A new HPTLC-image analysis approach for assessing interactions and antioxidant profiles of adrenergic drugs.

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.