Cyanide Removal by ZnTiO3/TiO2/H2O2/UVB System: A Theoretical-Experimental Approach.

Cyanide is a highly toxic substance present in wastewater from various industries. This study investigates the removal of cyanide species (CS) from aqueous solutions using the ZnTiO3/TiO2/H2O2/UVB system. ZnTiO3/TiO2 nanoparticles synthesized by the sol-gel method were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The adsorption capacity of nanoparticles was tested by varying the pH of the solution, adsorbent concentration, and contact time. The adsorption of CS on ZnTiO3 and TiO2 surfaces was verified by Density Functional Theory (DFT) calculations. Photocatalytic experiments were achieved under UVB irradiation (λ = 310 nm). The response surface methodology (RSM) was used to optimize the CS removal efficiency. The detoxification effect was evaluated by acute toxicity tests with brine shrimp. The theoretical results show that the adsorption of CS is energetically more favorable on the ZnTiO3 surface than on the TiO2 surface. The experimental results show that the system consisting of ZnTiO3/TiO2 (200 mg L-1), H2O2 (0.1%), and UVB light removes 99% of CS from aqueous solutions after 60 min and reduces the mortality of nauplii in 90% after 90 min. This system was reused in five consecutive cycles with a total loss of efficiency of 30%.

Therapeutic Applications of Essential Oils from Native and Cultivated Ecuadorian Plants: Cutaneous Candidiasis and Dermal Anti-Inflammatory Activity.

Essential oils are a complex mixture of aromatic substances whose pharmacological actions, including antimicrobial, antioxidant, anticancer, and anti-inflammatory activities, have been widely reported. This study aimed to evaluate the anti-Candida and dermal anti-inflammatory activity of essential oils from native and cultivated Ecuadorian plants. Essential oils from Bursera graveolens, Dacryodes peruviana, Mespilodaphne quixos, and Melaleuca armillaris were isolated by hydrodistillation and were characterized physically and chemically. Its tolerance was analyzed by in vitro and in vivo studies. The antifungal activity was studied against Candida albicans, Candida glabrata, and Candida parapsilosis, whereas the anti-inflammatory effect was evaluated by a mouse ear edema model. The main compounds were limonene, α-phellandrene, (E)-methyl cinnamate, and 1,8-cineole, respectively. All essential oils showed high tolerability for skin application, antifungal activity against the three Candida strains, and anti-inflammatory efficacy by decreasing edema and overexpression of pro-inflammatory cytokines. Dacryodes peruviana essential oil showed the highest antifungal activity. On the other hand, Dacryodes peruviana and Melaleuca armillaris showed the greatest anti-inflammatory potential, decreasing edema by 53.3% and 65.25%, respectively, and inhibiting the overexpression of TNF-α, IL-8, IL-17A, and IL-23. The results suggest that these essential oils could be used as alternative therapies in the treatment of both cutaneous candidiasis and dermal inflammation.

A Study of the Essential Oil Isolated from Ageratina dendroides (Spreng.) R.M. King & H. Rob.: Chemical Composition, Enantiomeric Distribution, and Antimicrobial, Antioxidant, and Anticholinesterase Activities.

Ageratina dendroides is an aromatic species native to Ecuador. In this study, the chemical composition, enantiomeric distribution, and antifungal, antibacterial, antioxidant, and anticholinesterase activities of the essential oil isolated from aerial parts of Ageratina dendroides were determined. The quantitative chemical composition was determined using gas chromatography equipped with a flame ionization detector. The qualitative chemical composition was determined using gas chromatography coupled with mass spectrometry. The enantiomeric distribution was determined using an enantioselective chromatographic column. A broth microdilution method was used to determine the antibacterial activity. This antibacterial activity was tested against three Gram-negative bacilli bacteria and three Gram-positive cocci bacteria. The antifungal activity was tested against two fungi, a fungus, and a yeast. The antioxidant activity was determined using the ABTS (2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) method and DPPH (2,2-diphenyl-1-picrylhydrazyl) method. The anticholinesterase activity was analyzed using the spectrophotometric method. Sixty-eight volatile compounds were identified in the essential oil. These compounds represent 99.49% of the total composition. In terms of the number of compounds and their relative abundance, the most representative group was sesquiterpene hydrocarbons, with thirty-four compounds and an abundance of 49.22%. The main constituents were found to be andro encecalinol (14.41 ± 1.26%), germacrene D (8.86 ± 1.06%), amorpha-4,9-dien-14-al (7.68 ± 0.70%), ß-sesquiphellandrene (7.01 ± 1.49%), α-muurolol (5.89 ± 0.93%), and 7-epi-α-selinene (5.68 ± 0.53%). Five pairs of enantiomers were identified in the essential oil of Ageratina dendroides. The essential oil did not report antimicrobial activity at the maximum concentration tested (MIC > 4000 µg/mL) against any of the microorganisms tested. The antioxidant activity of the essential oil was strong in the ABTS method, with an SC50 of 33.2 ± 1.4 µg/mL. Additionally, the Ageratina dendroides essential oil reported moderate anticholinesterase activity, with an IC50 of 297.8 ± 1.03 µg/mL.

Faujasite-Type Zeolite Obtained from Ecuadorian Clay as a Support of ZnTiO3/TiO2 NPs for Cyanide Removal in Aqueous Solutions.

In this study, zeolites prepared by the hydrothermal method from Ecuadorian clay were combined with the precursor clay and with the semiconductor ZnTiO3/TiO2 prepared by the sol-gel method to adsorb and photodegrade cyanide species from aqueous solutions. These compounds were characterized by X-ray powder diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive X-rays, point of zero charge, and specific surface area. The adsorption characteristics of the compounds were measured using batch adsorption experiments as a function of pH, initial concentration, temperature, and contact time. The Langmuir isotherm model and the pseudo-second-order model fit the adsorption process better. The equilibrium state in the reaction systems at pH = 7 was reached around 130 and 60 min in the adsorption and photodegradation experiments, respectively. The maximum cyanide adsorption value (73.37 mg g-1) was obtained with the ZC compound (zeolite + clay), and the maximum cyanide photodegradation capacity (90.7%) under UV light was obtained with the TC compound (ZnTiO3/TiO2 + clay). Finally, the reuse of the compounds in five consecutive treatment cycles was determined. The results reflect that the compounds synthesized and adapted to the extruded form could potentially be used for the removal of cyanide from wastewater.

Porous Geopolymer/ZnTiO3/TiO2 Composite for Adsorption and Photocatalytic Degradation of Methylene Blue Dye.

In this study, GP (geopolymer) and GTA (geopolymer/ZnTiO3/TiO2) geopolymeric materials were prepared from metakaolin (MK) and characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive X-rays (EDX), specific surface area (SSA), and point of zero charge (PZC). The adsorption capacity and photocatalytic activity of the compounds prepared in the form of pellets was determined by degradation of the methylene blue (MB) dye in batch reactors, at pH = 7.0 ± 0.2 and room temperature (20 °C). The results indicate that both compounds are highly efficient at adsorbing MB, with an average efficiency value of 98.5%. The Langmuir isotherm model and the pseudo second order kinetic model provided the best fits to the experimental data for both compounds. In the MB photodegradation experiments under UVB irradiation, GTA reached an efficiency of 93%, being higher than that achieved by GP (4%). Therefore, the incorporation of ZnTiO3/TiO2 in the geopolymeric matrix allowed GTA to achieve higher overall efficiency, by combining adsorption and photocatalysis, compared to the GP compound. The results indicate that the synthesized compounds could be used for up to five consecutive cycles for the removal of MB from wastewater through adsorption and/or photocatalysis processes.

Chemical Composition, Enantiomeric Distribution and Biological Activity of Essential Oil from Morella pubescens (Humb. & Bonpl. ex Willd.) Wilbur.

The species Morella pubescens, commonly known as wax laurel, is a tree belonging to the Myricaceae family that can be found from Costa Rica to Bolivia. In this study, the chemical composition, enantiomeric distribution, and biological activity of essential oil isolated from the leaves of this species was determined. Hydrodistillation was used to isolate the essential oil (EO). Gas chromatography coupled with mass spectrometry was used to determine the qualitative composition, gas chromatography equipped with a flame ionization detector was used to determine quantitative composition, and gas chromatography on an enantioselective column was used to determine enantiomeric distribution. The broth microdilution method was employed to assess the antibacterial capacity of the essential oil against seven opportunistic microorganisms, including three Gram-positive cocci bacteria, a Gram-positive bacilli bacterium and three Gram-negative bacilli bacteria. 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radical cation and 2,2-diphenyl-1-picrylhydryl free radical were used as reagents to determine the antioxidant activity of essential oil. The spectrophotometric method was used to analyze the acetylcholinesterase inhibitory effect of the essential oil. The extraction method afforded a low yield of around 0.076 ± 0.008% (v/w). Fifty-eight chemical compounds, which represent 97.9% of the total composition, were identified in the essential oil. Sesquiterpene hydrocarbons were the most representative group with 24 compounds (67.8%). The principal constituents were (E)-caryophyllene (27.5 ± 1.3%), limonene (11.8 ± 0.6%), δ-selinene (9.1 ± 0.2%), ß-selinene (8.0 ± 0.2%), selina-3,7(11)-diene (5.3 ± 0.2%) and germacrene B (5.0 ± 0.5%). Three pairs of enantiomers were identified in the essential oil of Morella pubescens. Essential oil presented strong activity against the bacterium Enterococcus faecium (ATCC 27270) with an MIC of 250 µg/mL. The antioxidant activity of essential oil was very strong in the ABTS method with an SC50 of 46.4 ± 1.0 µg/mL and was strong in the DPPH method with an SC50 of 237.1 ± 1.8 µg/mL. Additionally, the essential oil reported strong anticholinesterase activity with an IC50 of 133.5 ± 1.06 µg/mL.

Study of the Chemical Composition and Biological Activity of the Essential Oil from Congona (Peperomia inaequalifolia Ruiz and Pav.).

The species Peperomia inaequalifolia, commonly known as congona, is a succulent herbaceous plant belonging to the Piperaceae family, which is used for different purposes in traditional medicine. In this study, the chemical composition, enantiomeric distribution, and biological activity of essential oil isolated from the leaves of this species was determined. Hydrodistillation was used to isolate the essential oil. Gas chromatography coupled to mass spectrometry was used to determine the qualitative composition, a gas chromatograph equipped with a flame ionization detector was used to determine quantitative composition, and gas chromatography on an enantioselective column was used to determine enantiomeric distribution. Antibacterial activity was determined using the broth microdilution method, for which we used three Gram-positive cocci bacteria, a Gram-positive bacilli bacterium, and three Gram-negative bacilli bacteria. 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cations and 2,2-diphenyl-1-picrylhydryl (DPPH) radicals were used as reagents for determining the antioxidant activity of the essential oil. The spectrophotometric method was used to analyze the acetylcholinesterase inhibitory effect of the essential oil. The yield of leaves in essential oil was 0.16 ± 0.01% (v/w). Forty-three chemical compounds were identified in the essential oil, which represent 97.46% of the total composition. Sesquiterpene hydrocarbons were the most representative group, with 24 compounds (21.63%). The principal constituents were found to be elemicin (27.44 ± 1.35%), bisabolol <α-> (17.76 ± 1.38), myristicin (15.45 ± 0.86), methyl eugenol (6.22 ± 0.24), viridiflorene (6.81 ± 0.10), and safrole (6.68 ± 0.23). Three pairs of enantiomers were identified in the essential oil of Peperomia inaequalifolia. Essential oil presented a minimum inhibitory concentration (MIC) of 4000 µg/mL against Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli. The antioxidant activity of the essential oil was strong according to the DPPH and ABTS methods, with a half radical scavenging capacity (SC50) of 293.76 ± 3.12 µg/mL and 226.86 ± 0.05 µg/mL, respectively. Additionally, the essential oil reported moderate anticholinesterase activity, with an IC50 of 43.93 ± 1.05 µg/mL.

Chemical Profiling, Anticholinesterase, Antioxidant, and Antibacterial Potential of the Essential Oil from Myrcianthes discolor (Kunth) McVaugh, an Aromatic Tree from Southern Ecuador.

Myrcianthes discolor, an aromatic native tree from southern Ecuador, was collected to determine the chemical composition and the biological activity of its essential oil (EO). The EO was obtained by steam-distillation and analyzed by gas chromatography coupled to a mass and a FID detector (GC-MS and GC-FID) and a non-polar DB5-MS column. Enantioselective GC-MS analysis was performed in a chiral capillary column. The antimicrobial, antioxidant, and anticholinesterase potency of the EO was carried out by the broth microdilution method, radical scavenging assays using 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and by measuring the inhibition of the acetylcholinesterase (AChE) enzyme. A total of 58 chemical compounds were identified, corresponding to 94.80% of the EO composition. Sesquiterpenes hydrocarbons represented more than 75% of the composition. The main compounds detected were E-caryophyllene with 29.40 ± 0.21%, bicyclogermacrene with 7.45 ± 0.16%, ß-elemene with 6.93 ± 0.499%, α-cubebene with 6.06 ± 0.053%, α-humulene with 3.96 ± 0.023%, and δ-cadinene with 3.02 ± 0.002%. The enantiomeric analysis revealed the occurrence of two pairs of pure enantiomers, (-)-ß-pinene and (-)-α-phellandrene. The EO exerted a strong inhibitory effect against AChE with an IC50 value of 6.68 ± 1.07 µg/mL and a moderate antiradical effect with a SC50 value of 144.93 ± 0.17 µg/mL for the ABTS radical and a weak or null effect for DPPH (3599.6 ± 0.32 µg/mL). In addition, a strong antibacterial effect against Enterococcus faecium was observed with a MIC of 62.5 µg/mL and Enterococcus faecalis with a MIC of 125 µg/mL. To the best of our knowledge, this is the first report of the chemical composition and biological profile of the EO of M. discolor, and its strong inhibitory effect over AChE and against two Gram-positive pathogenic bacteria, which encourage us to propose further studies to validate its pharmacological potential.

Study of Essential Oil Isolated from Achiote (Bixa orellana) Leaves: Chemical Composition, Enantiomeric Distribution and Antimicrobial, Antioxidant and Anticholinesterase Activities.

Bixa orellana is a native and cultivated species of Ecuador commonly known as achiote (annatto), this species is very versatile with a wide variety of uses and applications of its leaves, fruits and seeds. In this study, the chemical composition, enantiomeric distribution and biological activity of essential oil isolated from the leaves of Bixa orellana were determined. Hydrodistillation was used to isolate the essential oil. Gas chromatography coupled with mass spectrometry was used to determine the qualitative composition, a gas chromatograph equipped with a flame ionization detector was used to determine quantitative composition and gas chromatography on an enantioselective column was used to determine enantiomeric distribution. Antibacterial activity was determined using the broth microdilution method, for which we used three Gram-positive cocci bacteria, a Gram-positive bacilli bacterium and three Gram-negative bacilli bacteria. 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic (ABTS) acid radical cation and 2,2-diphenyl-1-picrylhydryl (DPPH) free radical were used as reagents for determining the antioxidant activity of the essential oil. The spectrophotometric method was used to analyze acetylcholinesterase inhibitory effect of the essential oil. The yield of leaves in essential oil was 0.13 ± 0.01% (v/w). A total of 56 chemical compounds, which represent 99.25% of the total composition, were identified in the essential oil. Sesquiterpene hydrocarbons were the most representative group in number of compounds and relative abundance with 31 compounds and 69.06%, respectively. The principal constituents were found to germacrene D (17.87 ± 1.20%), bicyclogermacrene (14.27 ± 0.97%), caryophyllene < (E)- > (8.56 ± 1.24%) and pinene <α-> (6.34 ± 0.13%). Six pairs of enantiomers were identified in the essential oil of Bixa orellana. The essential oil presented strong activity against the Enterococcus faecium (ATCC 27270) with an MIC of 250 µg/mL and weak activity against Enterococcus faecalis (ATCC 19433) and Staphylococcus aureus (ATCC 25923) with an MIC of 1000 µg/mL. The antioxidant activity of the essential oil was strong according to ABTS methods with a SC50 of 61.49 ± 0.04 µg/mL and was moderate in DPPH with a SC50 of 224.24 ± 6,4 µg/mL. Additionally, the essential oil reported moderate anticholinesterase activity with an IC50 of 39.45 ± 1.06 µg/mL.

Chemical Composition and Biological Activity of Essential Oil from Leaves and Fruits of Limoncillo (Siparuna muricata (Ruiz & Pav.) A. DC.).

Siparuna muricata is an aromatic native shrub or tree from Ecuador known as "limoncillo" or "limón de la sierra" due to its citrus odor. In this study, the chemical composition and biological activity of essential oil from the leaves and fruits of this species was determined. The essential oil was isolated by subjected to hydrodistillation. The chemical composition was determined by gas chromatography equipped with a flame ionization detector and gas chromatography coupled to mass spectrometry. The enantiomeric distribution was determined by gas chromatography using an enantioselective column. The antimicrobial activity against three Gram-positive bacteria, two Gram-negative bacteria and two fungi was determined by the broth microdilution method. The antioxidant activity was analyzed using the 2,2-diphenyl-1-picrylhydryl free radical and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radical cation scavenging activity of essential oil. The acetylcholinesterase inhibitory effect of the essential oil was measured using a spectrophotometric method. The yield was 1.2 ± 0.1 mL/kg for leaves and 1.8 ± 0.2 mL/kg for fruits. A total of 51 compounds were identified in the leaves of the essential oil and 41 in the fruits. In both cases, the chemical compositions were dominated by the group of monoterpene hydrocarbons compounds. The main compound was α-pinene with 23.22 ± 1.03% in essential oil of the leaves and limonene with 24.92 ± 1.20% in the fruits. In both essential oils, five pairs of enantiomers with different enantiomeric excesses were identified. The essential oil of limoncillo leaves presented a strong activity against the fungus Aspergillus niger (ATTC 10231) and Gram-positive bacterium Enterococcus faecium (ATCC 27270) with a MIC of 250 µg/mL and 500 µg/mL, respectively. The essential oil from fruits and leaves of Siparuna muricata presented a moderate antioxidant activity with the ABTS method with a SC50 of 775.3 ± 1.3 µg/mL and 963.3 ± 1.6 µg/mL, respectively. Additionally, the leaves essential oil reported an IC50 value of 52.98 ± 1.04 µg/mL and the fruits essential oil an IC50 value of 98.84 ± 1.04 µg/mL, which can be considered a very strong anticholinesterase activity.

Characterization and In Vivo Anti-Inflammatory Efficacy of Copal (Dacryodes peruviana (Loes.) H.J. Lam) Essential Oil.

Essential oils are natural aromatic substances that contain complex mixtures of many volatile compounds frequently used in pharmaceutical and cosmetic industries. Dacryodes peruviana (Loes.) H.J. Lam is a native species from Ecuador whose anti-inflammatory activity has not been previously reported, thus the aim of this study was to evaluate the anti-inflammatory activity of D. peruviana essential oil. To that end, essential oil from D. peruviana fruits was isolated by hydrodistillation and characterized physically and chemically. The tolerance of the essential oil was analyzed by cytotoxicity studies using human keratinocytes. The anti-inflammatory activity was evaluated by an arachidonic acid-induced edema model in mouse ear. The predominant compounds in D. peruviana essential oil were α-phellandrene, limonene, and α-pinene, with the three compounds reaching approximately 83% of the total composition. Tolerance studies showed high biocompatibility of this essential oil with human keratinocytes. In vivo studies demonstrated a moisturizing effect and an alleviation of several events occurred during the inflammatory process after topical treatment with D. peruviana essential oil such as decline in skin edema; reduction in leukocytic infiltrate; and decrease in inflammatory cytokines TNFα, IL-8, IL-17A, and IL-23. Therefore, this essential oil could be an attractive treatment for skin inflammation.

Chemical and Biological Activity Profiling of Hedyosmum strigosum Todzia Essential Oil, an Aromatic Native Shrub from Southern Ecuador

The present study aimed to determine the chemical composition, enantiomeric distribution and the biological profile of Hedyosmum strigosum essential oil (EO). The antioxidant properties and anticholinesterase effect were measured by spectroscopic methods and antimicrobial potency assessed against 8 bacteria and two fungi. H. strigosum is a native shrub, particularly found in Ecuador and Colombia at 2000 to 3500 m a.s.l. Chemical composition was determined by GC-MS and GC-FID. A total of 44 compounds were detected, representing more than 92% of the EO composition. The main compounds were thymol (24.35, 22.48%), α-phellandrene (12.15, 13.93%), thymol acetate (6.59, 9.39%) and linalool (8.73, 5.82%), accounting for more than 51% of the EO. The enantioselective analysis revealed the presence of 5 pure enantiomers and 3 more as a racemic mixture. The EO exerted a strong antioxidant capacity, determined by ABTS assay, with a SC50 of 25.53 µg/mL and a strong and specific antimicrobial effect against Campylobacter jejuni with a MIC value of 125 µg/mL. A moderate acetylcholinesterase inhibitory effect was also observed with an IC50 value of 137.6 µg/mL. To the best of our knowledge this is the first report of the chemical composition and biological profile of H. strigosum EO.

La3+'s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study.

Density functional theory (DFT) is a widely used method for studying matter at the quantum level. In this study, the surface (101) of TiO2 (anatase phase) was considered to develop DFT calculations and explain the effect of lanthanum ion (La3+) on the electronic properties, adsorption capacity, and photocatalytic activity of this semiconductor. Due to the presence of the La3+ ion, the bandgap energy value of La/TiO2 (2.98 eV) was lower than that obtained for TiO2 (3.21 eV). TDOS analysis demonstrated the presence of hybrid levels in La/TiO2 composed mainly of O2p and La5d orbitals. The chemical nature of the La-O bond was estimated from PDOS analysis, Bader charge analysis, and ELF function, resulting in a polar covalent type, due to the combination of covalent and ionic bonds. In general, the adsorption of the methylene blue (MB) molecule on the surface (101) of La/TiO2 was energetically more favorable than on the surface (101) of TiO2. The thermodynamic stability of doping TiO2 with lanthanum was deduced from the negative heat-segmentation values obtained. The evidence from this theoretical study supports the experimental results reported in the literature and suggests that the semiconductor La/TiO2 is a potential catalyst for applications that require sunlight.

Chemical Composition, Enantiomeric Distribution and Anticholinesterase and Antioxidant Activity of the Essential Oil of Diplosthephium juniperinum.

The aim of this study was to extract and identify the chemical compounds of Diplosthephium juniperinum essential oil (EO) from Ecuador and to assess its anticholinesterase and antioxidant properties. The EO chemical composition was determined by GC−MS. A total of 74 constituents of EO were identified, representing 97.27% in DB-5ms and 96.06% in HP-INNOWax of the total EO. The major constituents (>4.50%) identified were: α-pinene (21.52, 22.04%), geranyl acetate (10.54, 7.78%), silphiper-fol-5-ene (8.67, 7.38%), α-copaene (8.26, 8.18%), 7-epi-silphiperfol-5-ene (4.93, 5.95%), and germacrene D (4.91, 6.00%). Enantioselective analysis of the volatile fraction of D. juniperinum showed: (+)-α-pinene as a pure enantiomer and 5 pairs of enantiomeric compounds. Among them, (−)-ß-Pinene and (−)-Germacrene D presented a high enantiomeric excess of 93.23 and 84.62%, respectively, while (−)-α-Thujene, (−)-Sabinene and (S)-4-Terpineol with a lower enantiomeric excess of 56.34, 47.84 and 43.11%, respectively. A moderate inhibitory effect was observed for Acetylcholinesterase (AChE) and Butyrylcholinesterase (BuChE) enzymes with IC50 values of 67.20 ± 7.10 and 89.00 ± 9.90 µg/mL, respectively. A lower antioxidant potential was observed for the EO measured through DPPH and ABTS radical scavenging assays with SC50 values of 127.03 and >1000 µg/mL, respectively. To the best of our knowledge, this is the first report of the chemical composition, enantiomeric distribution and, anticholinesterase and antioxidant potential of the EO of D. juniperinum. As future perspective, further in-vivo studies could be conducted to confirm the anticholinesterase potential of the EO.

Enantiomeric Composition, Antioxidant Capacity and Anticholinesterase Activity of Essential Oil from Leaves of Chirimoya (Annona cherimola Mill.).

Annona cherimola Mill. is a native species of Ecuador cultivated worldwide for the flavor and properties of its fruit. In this study, hydrodistillation was used to isolate essential oil (EO) of fresh Annona cherimola leaves collected in Ecuadorian Sierra. The EO chemical composition was determined using a non-polar and a polar chromatographic column and enantiomeric distribution with an enantioselective column. The qualitative analysis was carried out by gas chromatography coupled to a mass spectrometer and quantitative analysis using gas chromatography equipped with a flame ionization detector. The antibacterial potency was assessed against seven Gram-negative bacteria and one Gram-positive bacterium. ABTS and DPPH assays were used to evaluate the radical scavenging properties of the EO. Spectrophotometric method was used to measure acetylcholinesterase inhibitory activity. GC-MS analysis allowed us to identify more than 99% of the EO chemical composition. Out of the fifty-three compounds identified, the main were germacrene D (28.77 ± 3.80%), sabinene (3, 9.05 ± 1.69%), ß-pinene (4, 7.93 ± 0.685), (E)-caryophyllene (10.52 ± 1.64%) and bicyclogermacrene (11.12 ± 1.39%). Enantioselective analysis showed the existence of four pairs of enantiomers, the (-)-ß-Pinene (1S, 5S) was found pure (100%). Chirimoya essential oil exhibited a strong antioxidant activity and a very strong anticholinesterase potential with an IC50 value of 41.51 ± 1.02 µg/mL. Additionally, EO presented a moderate activity against Campylobacter jejuni and Klebsiella pneumoniae with a MIC value of 500 µg/mL.

Acaricidal Efficacy of Plants from Ecuador, Ambrosia peruviana (Asteraceae) and Lepechinia mutica (Lamiaceae) against Larvae and Engorged Adult Females of the Common Cattle Tick, Rhipicephalus microplus.

Control measures against common cattle tick Rhipicephalus microplus are of the upmost importance because of considerable, deleterious impact on a farm's economy. Due to resistance phenomena to synthetic acaricides being a constraint in affected farms, the search for plant derivatives as acaricides has increased dramatically in recent years. In this work, essential oils obtained from two Ecuadorian plants, Ambrosia peruviana and Lepechinia mutica (EOAp, EOLm), traditionally used as insecticides in indigenous communities, were studied on larvae and engorged females at the parasitic stages of R. microplus. Larvae and females were treated with five (0.0625, 0.125, 0.25, 0.50 and 1%) and six concentrations (0.125, 0.25, 0.50, 1, 2 and 4%), respectively, of each EOsAp/Lm. A 98-99% larval mortality was achieved with 0.5% of both EOsAp/Lm. EOAp inhibited oviposition and egg hatching up to 82% and 80%, respectively, and had an overall efficacy of 93.12%. Efficacy of EOLm was 72.84%, due to the low influence of EOLm on reproductive parameters. By steam distillation and GC-MS analysis, γ-Curcumene was identified as the main constituent (52.02%) in the EOAp and Shyobunol (10.80%) in EOLm. The results suggest that major components of both essential oils should be further studied as promissory acaricides against R. microplus.

Chemical Constituents of the Essential Oil from Ecuadorian Endemic Species Croton ferrugineus and Its Antimicrobial, Antioxidant and α-Glucosidase Inhibitory Activity.

Croton ferrugineus Kunth is an endemic species of Ecuador used in traditional medicine both for wound healing and as an antiseptic. In this study, fresh Croton ferrugineus leaves were collected and subjected to hydrodistillation for extraction of the essential oil. The chemical composition of the essential oil was determined by gas chromatography equipped with a flame ionization detector and gas chromatography coupled to a mass spectrometer using a non-polar and a polar chromatographic column. The antibacterial activity was assayed against three Gram-positive bacteria, one Gram-negative bacterium and one dermatophyte fungus. The radical scavenging properties of the essential oil was evaluated by means of DPPH and ABTS assays. The chemical analysis allowed us to identify thirty-five compounds representing more than 99.95% of the total composition. Aliphatic sesquiterpene hydrocarbon trans-caryophyllene was the main constituent with 20.47 ± 1.25%. Other main compounds were myrcene (11.47 ± 1.56%), ß-phellandrene (10.55 ± 0.02%), germacrene D (7.60 ± 0.60%), and α-humulene (5.49 ± 0.38%). The essential oil from Croton ferrugineus presented moderate activity against Candida albicans (ATCC 10231) with an MIC of 1000 µg/mL, a scavenging capacity SC50 of 901 ± 20 µg/mL with the ABTS method, and very strong antiglucosidase activity with an IC50 of 146 ± 20 µg/mL.

Variability of the Chemical Composition and Bioactivity between the Essential Oils Isolated from Male and Female Specimens of Hedyosmum racemosum (Ruiz & Pav.) G. Don.

Hedyosmum racemosum (Ruiz & Pav.) G. is a native species of Ecuador used in traditional medicine for treatment of rheumatism, bronchitis, cold, cough, asthma, bone pain, and stomach pain. In this study, fresh H. racemosum leaves of male and female specimens were collected and subjected to hydrodistillation for the extraction of the essential oil. The chemical composition of male and female essential oil was determined by gas chromatography-gas chromatography equipped with a flame ionization detector and coupled to a mass spectrometer using a non-polar and a polar chromatographic column. The antibacterial activity was assayed against five Gram-positive and two Gram-negative bacteria, and two dermatophytes fungi. The scavenging radical properties of the essential oil were evaluated by DPPH and ABTS assays. The chemical analysis allowed us to identify forty-three compounds that represent more than 98% of the total composition. In the non-polar and polar column, α-phellandrene was the principal constituent in male (28.24 and 25.90%) and female (26.47 and 23.90%) essential oil. Other main compounds were methyl chavicol, germacrene D, methyl eugenol, and α-pinene. Female essential oil presented a strong activity against Klebsiella pneumoniae (ATCC 9997) with an minimum inhibitory concentration (MIC) of 500 µg/mL and a scavenging capacity SC50 of 800 µg/mL.

Variability of the Chemical Composition of the Essential Oil from the Amazonian Ishpingo Species (Ocotea quixos).

Ocotea quixos (Lam.) Kosterm. is an aromatic tree native to Ecuador, whose leaves are used to prepare aromatic beverages to which different health benefits are attributed. In this study, Ocotea quixos leaves were collected in the Amazon region in different environmental conditions and subjected to hydrodistillation to isolate the essential oil. The collection variables used were type of soil, amount of shade, and height; in addition, the presence of twig and leaf age and moisture were used as variables. Chemical composition was analyzed by means of gas chromatography equipped with a flame ionization detector and gas chromatography coupled to mass spectrometry. A wide variety of chemical compositions were detected in the samples. In total, forty-seven compounds were identified, which represented between 97.17% and 99.89% of the total composition. The constituents were mainly grouped into aliphatic sesquiterpene hydrocarbons (33.03-55.89%), other compounds (8.94-47.83%), and oxygenated monoterpenes (1.97-39.66%). The main constituents were found to be (E)-cinnamyl acetate (5.96-41.65%), (E)-methyl cinnamate (0.38-37.91%), and trans-caryophyllene (8.77-37.02%). The statistical analysis suggested the existence of two essential oil chemotypes and a direct correlation between environmental conditions and chemical composition of the essential oils.

Study of Volatile Secondary Metabolites Present in Piper carpunya Leaves and in the Traditional Ecuadorian Beverage Guaviduca.

Piper carpunya Ruiz & Pav. is an aromatic shrub native to Ecuador, the leaves of which are used to prepare the traditional beverage Guaviduca. Different health benefits are attributed to the guaviduca beverage, which is consumed as a traditional and folk medicine. In this study, fresh P. carpunya leaves were collected in the winter and summer and subjected to hydrodistillation for the extraction of the essential oil. The guaviduca beverage was prepared by infusion in water and the volatile compounds were isolated by liquid-liquid extraction. Chemical composition and enantioselective analyses were performed by gas chromatography. The antibacterial activity was assayed against Gram-positive and Gram-negative bacteria. The scavenging radical properties of the essential oil was evaluated by 2,2-diphenyl-1-picrylhydryl (DPPH) and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. The acetylcholinesterase inhibitory activity was measured using the spectrophotometric method. The chemical analysis allowed us to identify more than 98% of the compounds in all samples. The main constituent of the essential oil was 1,8-cineole (25.20 ± 1.31%) in P. carpunya collected in winter and (17.45 ± 2.33%) in P. carpunya collected in summer, while in the beverage, there was 14 mg/L. Safrole was identified in the essential oil (PCW 21.91 ± 2.79%; PCS 13.18 ± 1.72%) as well as in the beverage (2.43 ± 0.12 mg/L). Enantioselective analysis was used to investigate the enantiomeric ratio and excess of four chiral components. The essential oil presented a strong activity against Klebsiella pneumoniae with a MIC of 500 µg/mL and a very strong anticholinesterase activity with an IC50 of 36.42 ± 1.15 µg/mL.