Joyce Kelly R. da Silva

Antinociceptive activity of 1-nitro-2-phenylethane, the main component of Aniba canelilla essential oil

Aniba canelilla (H.B.K.) Mez is a medicinal plant used in the Amazon folk therapeutic as antispasmodic, antidiarreic, carminative, tonic agent and a stimulant of the digestive and central nervous system. Our preliminary studies showed that the plant essential oil has analgesic activity in mice. Now, we are reporting the antinociceptive effect of the compound 1-nitro-2-phenylethane (97.5%), the main component of the essential oil of Aniba canelilla, which was obtained by column chromatographic purification. In the writhing test this compound was dosed at 15, 25 and 50 mg/kg reducing the abdominal writhes in a significant manner; in the hot plate test it was assayed at 50, 100 and 200 mg/kg producing no alterations in the latency time when compared to the control; and in the formalin test the 1-nitro-2-phenylethane was tested at 50 and 25 mg/kg decreasing significantly the second phase of the algic stimulus. The study suggests that the 1-nitro-2-phenylethane has analgesic activity, probably of peripheral origin. The mechanism involved is not completely understood, however, the results suggest that the opioid receptors are involved in the antinociceptive action observed to 1-nitro-phenylethane.

1-Nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, elicits a vago-vagal bradycardiac and depressor reflex in normotensive rats

Previously, it was shown that intravenous (i.v.) treatment with the essential oil of Aniba canelilla (EOAC) elicited a hypotensive response that is due to active vascular relaxation rather than to the withdrawal of sympathetic tone. The present study investigated mechanisms underlying the cardiovascular responses to 1-nitro-2-phenylethane, the main constituent of the EOAC. In pentobarbital-anesthetized normotensive rats, 1-nitro-2-phenylethane (1-10mg/kg, i.v.) elicited dose-dependent hypotensive and bradycardiac effects which were characterized in two periods (phases 1 and 2). The first rapid component (phase 1) evoked by 1-nitro-2-phenylethane (10mg/kg) was fully abolished by bilateral vagotomy, perineural treatment of both cervical vagus nerves with capsaicin (250 microg/ml) and was absent after left ventricle injection. However, pretreatment with capsazepine (1mg/kg, i.v.) or ondansetron (30 microg/kg, i.v.) did not alter phase 1 of the cardiovascular responses to 1-nitro-2-phenylethane (10mg/kg, i.v.). In conscious rats, 1-nitro-2-phenylethane (1-10mg/kg, i.v.) evoked rapid hypotensive and bradycardiac (phase 1) effects that were fully abolished by methylatropine (1mg/kg, i.v.). It is concluded that 1-nitro-2-phenylethane induces a vago-vagal bradycardiac and depressor reflex (phase 1) that apparently results from the stimulation of vagal pulmonary rather than cardiac C-fiber afferents. The transduction mechanism of the 1-nitro-2-phenylethane excitation of C-fiber endings is not fully understood and does not appear to involve activation of either Vanilloid TPRV(1) or 5-HT(3) receptors. The phase 2 hypotensive response to 1-nitro-2-phenylethane seems to result, at least in part, from a direct vasodilatory effect since 1-nitro-2-phenylethane (1-300 microg/ml) induced a concentration-dependent reduction of phenylephrine-induced contraction in rat endothelium-containing aorta preparations.

Chemical constituents and allelopathic and antioxidant activities of Alchorneopsis floribunda Müll. Arg. (Euphorbiaceae)

Chemical investigation of extracts from the stems and leaves of Alchorneopsis floribunda Müll. Arg., collected in the Amazon region, was performed. The main isolated compounds were triterpenes (α-amyrin, β-amyrin, lupeol, betulin, betulinic acid, uvaol, erythrodiol and oleanolic acid) and phenolic acid derivatives from 4-hydroxybenzoic acid (gallic and protocatechuic acids and isocorilagin). In the germination assays, high inhibitory allelopathic effects of the extracts and isocorilagin were observed and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of isocorilagin was higher than those of the standards used (Trolox and butylated hydroxyanisole). This is the first chemical study of the genus Alchorneopsis (Euphorbiaceae).

Antioxidant capacity and biological activity of essential oil and methanol extract of Hyptis crenata Pohl ex Benth

The essential oils of fresh and dried leaves and fine stems of Hyptis crenata furnished the following yields: 1.4% and 0.9%. The main volatile constituents were ±-pinene (22.0%; 19.5%), 1,8-cineole (17.6%; 23.2%), ²-pinene (17.0%; 13.8%), camphor (4.7%; 11.6%), limonene (5.4%; 4.4%) and ³-terpinene (3.5%; 2.4%), totalizing more than 70% in the oils. The DPPH radical scavenging activity (EC50, 16.7 + 0.4 µg/mL) of the methanol extract was comparable to BHT (19.8 ± 0.5 µg/mL) showing a significant antioxidant activity. The oils showed low activities. The amount of total phenolics (TP, 373.0 + 15.9 mg GAE/g) and trolox equivalent (TEAC, 226.8 + 0.5 mg TE/g) confirmed the antioxidant activity of the methanol extract that can be attributed to the presence of polar phenolic compounds. In the brine shrimp bioassay the lethal concentrations (LC50) for the oil and methanol extract were 6.7 + 0.2 µg/mL and 13.0 + 3.7 µg/mL, respectively, providing important evidence of their biological activities.

Cardiovascular effects of 1-nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, in spontaneously hypertensive rats.

This study investigated the cardiovascular responses to the essential oil of Aniba canelilla (EOAC) and its main constituent 1‐nitro‐2‐phenylethane (NP) in spontaneously hypertensive rats (SHRs). In anesthetized SHRs, intravenous (i.v.) bolus injections of EOAC (1–20 mg/kg) or NP (1–10 mg/kg) elicited dose‐dependent hypotensive and bradycardiac effects, which were characterized in two periods (phases 1 and 2). The first rapid component (phase 1) evoked by EOAC and NP both at 10 mg/kg was absent after left ventricle injection, fully abolished by bilateral vagotomy and perineural treatment of both cervical vagus nerves with capsaicin (250 μg/mL) while remained unaltered by i.v. pretreatment with capsazepine (1 mg/kg) or ondansetron (30 μg/kg). In conscious SHRs, NP (5 and 10 mg/kg, i.v.) evoked rapid hypotensive and bradycardiac effects (phase 1) that were fully abolished by methylatropine (1 mg/kg, i.v.) pretreatment. In rat endothelium‐containing mesenteric preparations, increasing concentrations (0.1–1000 μg/mL) of EOAC and NP relaxed the phenylephrine‐induced contraction in a concentration‐dependent manner. It is concluded that NP induces a vago‐vagal bradycardiac and depressor reflex (phase 1) that apparently results from the stimulation of vagal pulmonary rather than cardiac C‐fiber afferents. This effect does not appear to involve activation of either vanilloid TPRV1 or 5‐HT3 receptors located on vagal sensory nerves. The phase 2 hypotensive response to i.v. NP seems to result, at least in part, from its direct vasodilatory effect on the peripheral smooth muscle. All in vivo and in vitro effects of EOAC are mostly attributed to the actions of its main constituent NP.

Essential oil composition of Croton palanostigma Klotzsch from north Brazil

Os oleos essenciais das folhas, ramos finos, galhos, cascas do caule e frutos de Croton palanostigma foram analisados por CG e CG-EM. Os componentes principais determinados no oleo das folhas foram linalol (25,4%), (E)-cariofileno (21,0%), metileugenol (17,2%) e β-elemeno (6,0%); no oleo dos ramos finos foram α-pineno (41,4%), limoneno (29,0%), sabineno (11,5%) e β-pineno (5,7%); no oleo dos galhos foram metileugenol (24,1%), (E)-metilisoeugenol (15,3%), α-pineno (11,2%) e (E)-cariofileno (8,5%); no oleo das cascas do caule foram a-pineno (31,6%), metileugenol (25,6%) e (E)-metilisoeugenol (23,7%); e no oleo dos frutos foram linalol (42,7%), metileugenol (16,3%) e β-elemeno (6,4%). Analise estatistica mostrou que as folhas e os frutos apresentam significante similaridade entre si, assim como os galhos e as cascas do caule. Adicionalmente, o oleo obtido das cascas do caule possui elevada atividade larvicida sobre Artemia salina (CL50, 3,71 ± 0,01 mg mL-1).

Development and validation of a selective HPLC-UV method for thymol determination in skin permeation experiments

Thymol is a natural monoterpene, whose antioxidant and antimicrobial properties suggest a potential use in topical formulations. A simple, precise and selective HPLC method for thymol determination in skin penetration studies was developed and validated in this paper. Separation was achieved with a RP-C18 column, mobile phase comprised of acetonitrile:water (35:65v/v), flow rate of 1.5mL/min, oven temperature at 40°C, injection volume of 30μL and UV detection at 278nm. The validation procedure certified the method was selective for thymol determination even when extracted from skin matrix extracts. It was also linear in a range from 0.5 to 15.0μg/mL, robust, precise and accurate, with recovery rates from the skin layers higher than 90%. Limits of detection and quantification were 0.05 and 0.14μg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing thymol topical formulations.

Detrimental Effect of Phenol Red on the Vitrification of Cat (Felis catus) Ovarian Tissue

The aim of this study was to investigate the effects of different media with or without phenol red or the antioxidant trolox on the successful vitrification of feline ovarian tissue. In a first experiment, ovarian cortical pieces from three cats were vitrified in solutions of Roswell Park Memorial Institute (RPMI)-1640 medium, Minimum Essential Medium, Dulbeccos modified Eagles medium, or Tissue Culture Medium 199 as basic medium, supplemented or not with 50 μM of trolox, all containing 40% ethylene glycol (EG) and 1 M of sucrose. RPMI-1640 (phenol red-free) without trolox was the only medium that preserved the percentage of morphologically normal preantral follicles similar to control (80%). The main difference between RPMI-1640 and the other media was the absence of phenol red and CaCl2. In a second experiment, ovarian cortical pieces from three cats were vitrified in a solution containing RPMI-1640 as basic medium, 40% EG, 1 M of sucrose, supplemented or not with phenol red or CaCl2 alone, or in combination. It was observed that phenol red supplementation led to follicular degeneration. Finally, to evaluate the interaction between phenol red and the cryoprotectant agent (i.e., EG), ovarian tissue was exposed to RPMI-1640 supplemented with phenol red and EG at different concentrations (10%, 20%, or 40%). There was an inverse relationship between EG concentration and free phenol red in the medium after exposure. It is suggested that vitrification of feline ovarian tissue should be performed in a phenol red-free medium. Medium supplementation with 50 μM of trolox was deleterious for follicular morphology.

Acetylcholinesterase inhibitory activity and molecular docking study of 1-nitro-2-phenylethane, the main constituent of Aniba canelilla essential oil.

The odoriferous principle of Aniba canelilla (H.B.K.) Mez is due 1‐nitro‐2‐phenylethane, the main constituent of its essential oil and also responsible for the plants cinnamon scent. This nitroderivative was previously reported by their antioxidant, antinociception, cardiovascular, and vasorelaxant properties, and now it was tested as the inhibitor of acetylcholinesterase using bioautography on TLC plates. The oil and a purified fraction containing 1‐nitro‐2‐phenylethane were analyzed by GC and GC‐MS. The percentage content of 1‐nitro‐2‐phenylethane in the oil and after fractionation was 70.2% and 98.0%, respectively. The results showed that the oil and 1‐nitro‐2‐phenylethane are strong acetylcholinesterase inhibitors with the detection limit of 0.01 ng, equivalent to physostigmine used as the positive control. A molecular docking study was used to determine the position and conformation of the 1‐nitro‐2‐phenylethane inhibitor in the receptor‐binding pocket of the acetylcholinesterase enzyme. The nitrogroup of 1‐nitro‐2‐phenylethane was positioned near of the catalytic serine residue of acetylcholinesterase, forming strong hydrogen bond with its hydroxyl group. Therefore, the electronegative character of 1‐nitro‐2‐phenylethane may explain the interaction that occurs with the catalytic serine residue and its significant inhibitory activity of acetylcholinesterase.

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

BackgroundPsidium 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.ResultsIn 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.ConclusionsIn 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.