Indole Alkaloids of Rauvolfia ligustrina and Their Anxiolytic Effects in Adult Zebrafish.

Rauvolfia species are well known as producers of bioactive monoterpene indole alkaloids, which exhibit a broad spectrum of biological activities. A new vobasine-sarpagan-type bisindole alkaloid (1: ) along with six known monomeric indoles (2, 3/4, 5: , and 6/7: ) were isolated from the ethanol extract of the roots of Rauvolfia ligustrina. The structure of the new compound was elucidated by interpretation of their spectroscopic data (1D and 2D NMR and HRESIMS) and comparison with published data for analog compounds. The cytotoxicity of the isolated compounds was screened in a zebrafish (Danio rerio) model. The possible GABAergic (diazepam as the positive control) and serotoninergic (fluoxetine as the positive control) mechanisms of action in adult zebrafish were also evaluated. No compounds were cytotoxic. Compound 2: and the epimers 3: /4: and 6: /7: showed a mechanism action by GABAA, while compound 1: showed a mechanism action by a serotonin receptor (anxiolytic activity). Molecular docking studies showed that compounds 2: and 5: have a greater affinity by the GABAA receptor when compared with diazepam, whereas 1: showed the best affinity for the 5HT2AR channel when compared to risperidone.

Analysis toxicity by different methods and anxiolytic effect of the aqueous extract Lippia sidoides Cham.

Lippia sidoides Cham. (Verbenaceae) is a species often mentioned in traditional medicine due to the medicinal properties attributed to its leaves, which include antibacterial, antifungal, acaricidal and antioxidant. Several of these actions have been scientifically proven, according to reports in the literature; however, little is known about toxicological aspects of this plant. This work included studies to determine the chemical composition and toxicity tests, using several methods aiming to evaluate the safety for use of the aqueous extract of L. sidoides leaves, in addition, the anxiolytic effect on adult zebrafish was investigated, thus contributing to the pharmacological knowledge and traditional medicine concerning the specie under study. The chemical profile was determined by liquid chromatography coupled to mass spectrometry-HPLC/MS with electrospray ionization. Toxicity was evaluated by zebrafish, Drosophila melanogaster, blood cells, and Artemia salina models. 12 compounds belonging to the flavonoid class were identified. In the toxicity assays, the observed results showed low toxicity of the aqueous extract in all tests performed. In the analysis with zebrafish, the highest doses of the extract were anxiolytic, neuromodulating the GABAa receptor. The obtained results support the safe use of the aqueous extract of L. sidoides leaves for the development of new drugs and for the use by populations in traditional medicine.

Hypoglycemic effect on adult zebrafish (Danio rerio) of the 3ß-6ß-16ß-trihydroxylup-20(29)-ene triterpene isolated from Combretum leprosum leaves in vivo and in silico approach.

Drugs used to manage type 2 diabetes mellitus cause adverse effects. Therefore, the search for new drugs as an alternative for the treatment of diabetes increases. The effect of triterpene 3ß-6ß-16ß-trihydroxylup-20(29)-ene isolated from the leaves of C. leprosum (CLF-1) on sucrose-induced hyperglycemia in adult zebrafish (Danio rerio) was evaluated. Initially, adult zebrafish (n = 6/group) underwent hyperglycemia induction by sucrose at 83.25 mM/L for 7 days by immersion. The hyperglycemic groups were treated with CLF-1 (4, 20, and 40 mg/kg), metformin (200 mg/kg), and acarbose (300 mg/kg) for 4 days. The in silico interaction of CLF-1, metformin, and acarbose with the enzyme maltase-glucoamylase (CtMGAM) was investigated. CLF-1 reduced sucrose-induced hyperglycemia after 4 days of treatment, in addition to having better affinity energy with CtMGAM than metformin and acarbose. Thus, CLF-1 may be a new pharmacological alternative as a hypoglycemic agent for the treatment of diabetes.

Combretum lanceolatum extract reverses anxiety and seizure behavior in adult zebrafish through GABAergic neurotransmission: an in vivo and in silico study.

Combretaceae are reported in the literature for presenting neuroprotective and anxiolytic effects in animal models. Combretum lanceolatum Pohl. has few scientific reports on its pharmacological effects. The aim of this study was to evaluate the anxiolytic and anticonvulsant effects of the ethanol extract from the leaves of C. lanceolatum Pohl. (EtFoCl) and its possible mechanism of GABAergic action in adult zebrafish. EtFoCl was subjected to determination of the total phenol concentration, identification of phytochemical flavonoids by HPLC and in vitro antioxidant activity test, open field test and 96-hour acute toxicity in zebrafish. Anxiolytic doses were tested for pentylenetetrazole-induced seizures in adult zebrafish. To study the mechanisms of action, molecular docking simulations were performed between the main phytochemicals and the GABAA receptor (anxiolytic activity) and carbonic anhydrase II (anticonvulsant). The non-toxic doses that caused motor impairment were assessed in acute and chronic anxiety using the light and dark test. EtFoCl had altered the animals' locomotion, presenting an effect similar to the anxiolytic and anticonvulsant. These effects were prevented with flumazenil (GABAA antagonist). The phytochemicals homoorientin and quercetin-3-O-galactoside coupling in a region close to that of the inhibitor diazepam (GABAA receptor). Regarding the anticonvulsant mechanism, Homoorientina and Isovitexina were identified as the most favorable for the complex form with the carbonic anhydrase enzyme. C. lanceolatum has pharmacological potential for the treatment of acute and chronic anxiety and seizures, which can be partially explained by an interaction with the GABAA receptor.Communicated by Ramaswamy H. Sarma.

Antinociceptive, anti-inflammatory and hypoglycemic activities of the ethanolic Turnera subulata Sm. flower extract in adult zebrafish (Danio rerio).

Turnera subulata Sm. belongs to the family Turneraceae and is found in Brazil. The present study evaluated the antinociceptive, anti-inflammatory, and hypoglycemic potential of T. subulata flower extract (EtFloTsu) in zebrafish (Danio rerio). The total phenol and flavonoid contents of EtFloTsu were determined and identified using the Folin Ciocalteu reagent and aluminum chloride (AlCl3), respectively. The constituents of the extract were identified by HPLC-DAD, and the in vitro antioxidant activity (DPPH) was determined, toxicity in brine shrimp, and acute toxicity of 96 h in adult zebrafish. In addition, adult zebrafish (n = 6/fish) were treated orally with EtFloTsu (4, 20, or 40 mg/kg; vo) and subjected to formalin-induced nociception tests (with its possible mechanism of action with camphor), carrageenan-induced inflammation, and D-glucose-induced hyperglycemia (111 mM). Oxidative stress in the liver and brain tissues was assessed. EtFloTsu showed high levels of phenolic and flavonoid compounds with antioxidant activity. The phytochemicals chlorogenic acid, luteolin-7-o-glucoside, vitexin, and apigenin-7-o-glucoside were also identified in EtFloTsu. The synergism between these constituents was possibly responsible for the antinociceptive (via TRPA1), anti-inflammatory, and hypoglycemic effects of EtFloTsu in adult zebrafish, without causing toxicity in animals. Therefore, T. subulata flowers have therapeutic agents that could treat pain, inflammation, diabetes, and related complications.Communicated by Ramaswamy H. Sarma.

Antinociceptive activity of 3ß-6ß-16ß-trihydroxylup-20 (29)-ene triterpene isolated from Combretum leprosum leaves in adult zebrafish (Danio rerio).

Drugs used to treat pain are associated with adverse effects, increasing the search for new drugs as an alternative treatment for pain. Therefore, we evaluated the antinociceptive behavior and possible neuromodulation mechanisms of triterpene 3ß, 6ß, 16ß-trihydroxylup-20(29)-ene (CLF-1) isolated from Combretum leprosum leaves in zebrafish. Zebrafish (n = 6/group) were pretreated with CLF-1 (0.1 or 0.3 or 1.0 mg/mL; i.p.) and underwent nociception behavior tests. The antinociceptive effect of CFL-1 was tested for modulation by opioid (naloxone), nitrergic (L-NAME), nitric oxide and guanylate cyclase synthesis inhibitor (methylene blue), NMDA (Ketamine), TRPV1 (ruthenium red), TRPA1 (camphor), or ASIC (amiloride) antagonists. The corneal antinociceptive effect of CFL-1 was tested for modulation by TRPV1 (capsazepine). The effect of CFL-1 on zebrafish locomotor behavior was evaluated with the open field test. The acute toxicity study was conducted. CLF-1 reduced nociceptive behavior and corneal in zebrafish without mortalities and without altering the animals' locomotion. Thus, CFL-1 presenting pharmacological potential for the treatment of acute pain and corneal pain, and this effect is modulated by the opioids, nitrergic system, NMDA receptors and TRP and ASIC channels.