Acaricidal and insecticidal activity of essential oils obtained from the aerial parts of three Mexican Bursera species.

In search of new sustainable biopesticides, we determined the phytochemical profiles, acaricidal and insecticidal properties of EOs distilled from the aerial parts of three Mexican Bursera species. Results were obtained by GC-MS analysis and three different bioassays, indicating that the EO of Bursera glabrifolia exhibited high relative abundancies of α-pinene, ß-myrcene, and α-phellandrene, as well as promising pesticidal activity against Spodoptera littoralis larvae (LD50,90 = 32.4, 107.2 µg/larva), and Musca domestica (LD50,90 = 23.2, 103.2, and 13.5, 77.4 µg/female or male adult, respectively) and Tetranychus urticae adults (LD50,90 = 7.4, 30.3 µg/cm2). The Bursera lancifolia and Bursera linanoe samples contained mainly D-limonene or linalyl acetate and linalool, respectively, and showed generally less potent pesticidal properties (S. littoralis larva, LD50,90 = 45.4, 154.4 and 52.2, 158.7 µg/larva, respectively; female M. domestica adult, LD50,90 = 69.2, 210.9 and 45.1, 243.8 µg/female adult, respectively; T. urticae adults, LD50,90 = 20.7, 90.5 and 17.5, 71.4 µg/cm2, respectively). However, the EO of B. linanoe exhibited an especially pronounced activity against male M. domestica adults (LD50,90 = 10.6, 77.2 µg/male adult). Our findings prove the pesticidal potential of Mexican Bursera species in the context of integrated pest management (IPM) and highlight the importance of conducting further research to elucidate both the active principles and possibly existing synergistic effects.

Inhibitory effects of methanolic extracts from the stem barks of ten Mexican Bursera Jacq. ex L. species on the activity of α-amylase and acetylcholinesterase from Tenebrio molitor.

Methanolic stem bark extracts from ten Mexican Bursera Jacq. ex L. species were evaluated in vitro with regard to their inhibitory activity against two Tenebrio molitor-derived enzymes. Seven extracts (B. bicolor, B. copallifera, B. fagaroides, B. grandifolia, B. lancifolia, B. linanoe, and B. longipes) reduced α-amylase activity by 55.37% to 96.25%, with three samples proving to be particularly potent α-amylase inhibitors (B. grandifolia, B. lancifolia, and B. linanoe; IC50 = 162, 132, and 186 µg/mL, respectively). In contrast, no extract inhibited acetylcholinesterase activity by more than 39.94%. Quantitative HPLC analysis did not reveal any clear correlation between the species-specific flavonoid or phenolic acid profiles and the respective extracts' enzyme inhibitory activity. The findings reported herein do not only contribute to improving the current state of knowledge regarding the enzyme inhibitory potential of the Bursera genus, but could also lead to the development of new sustainable bioinsecticides.

Effect of Azadirachta indica A. Juss (Meliaceae) on the serotonin rhythm of Spodoptera frugiperda (Lepidoptera: Noctuidae).

Circadian rhythms are an adaptive response of organisms to the environment that enables them to measure time. Circadian rhythms are some of the most studied biological rhythms. Serotonin (5HT) has been proposed as their modulator of circadian rhythms, playing a pivotal role in their establishment. However, 5HT concentrations are altered in insect organisms when they feed on some plant extracts. Insects show a variety of rhythms. The larval stage of the lepidopteran Spodoptera frugiperda is a pest of economically important crops. As a response, plants have developed secondary metabolites, such as azadirachtin, obtained from Azadirachta indica. We assessed the circadian rhythm of 5HT in the brain and digestive tube of larvae of S. frugiperda; furthermore, the effect of A. indica extract on the oscillations was evaluated. 5HT modulates the rhythms of locomotor activity, and if extracts of A. indica alter the concentration of 5HT, it can indirectly alter the rhythms of locomotor activity, as well as peristaltic movements of the intestine. Larvae were exposed to a 12 h:12 h light-dark (LD) photoperiod, and half of them remained for 72 h under constant darkness (DD). Tissue samples were obtained at six different times during a single 24 h period, and the amount of 5HT was quantified by high-performance liquid chromatography (HPLC). Data were statistically compared by a one-way ANOVA followed by a Tukey post hoc test and subjected to Cosinor analysis for assessment of 24 h rhythmicity. The results showed that the A. indica methanolic extract had an effect on the 5HT concentration of the brain and digestive tube of the larvae. In the brain, the 5HT increase in larvae fed with the extract could alter memory, learning, sleep, and locomotor activity processes. Whereas in the intestine, the 5HT decrease in the larvae fed with the extract could decrease peristalsis movements and, therefore, indirectly influence the antifeedant effect.

Cytotoxic activity and triterpenes content of nine Mexican species of Bursera.

The genus Bursera (Burseraceae) is considered an interesting source of antitumour compounds. This study aimed to evaluate the cytotoxic activity of the dichloromethane-soluble extracts from the bark of nine Mexican Bursera species. The chemical components of the extracts were determined by NMR and mass spectroscopy, whereas its cytotoxicity was tested using the sulphorhodamine (SRB) method on seven cell lines. Triterpenes and fatty acids were the most abundant components found in the extracts. A quantification by HPTLC - densitometry, showed that the species B. copallifera had the highest content of amyrins (287 µg/mg extract) followed by B. submoniliformis (159.5 µg/mg) and B. bicolor (156.5 µg/mg). Regarding cytotoxicicity, the species B. bicolor caused the highest growth inhibition (>90%) in colon (HCT-15) and lung (SK-LU1) lines; while B. fagaroides, B. grandifolia, B. morelensis, B. bicolor and B. linanoe were active in the SK-LU1cell line.

Pharmacological evaluation of the anxiolytic-like effects of Lippia graveolens and bioactive compounds.

CONTEXT: Lippia species (Verbenaceae) are widely used in Latin America and Africa as folk medicine for their tranquilizing properties. OBJECTIVE: To evaluate the anxiolytic-like effects and safety of Lippia graveolens Kunth. by exploring its aqueous and organic leaf extracts and identifying the responsible chemical constituents. MATERIAL AND METHODS: Aqueous and organic extracts (hexane, ethyl acetate and methanol) were pharmacologically evaluated at several doses. Chemical constituents were identified using MS, NMR and GC-MS analysis. The isolated compounds (3 mg/kg, i.p.), extracts (1, 3, 10 and 30 mg/kg, i.p.), and the reference drug diazepam (0.1 mg/kg, i.p.) were assessed in CD-1 mice using experimental behavioural models: open-field, cylinder, hole-board, plus-maze and sodium pentobarbital-induced hypnosis, as well as their acute toxicity (LD50). RESULTS: After administration of the extracts and bioactive compounds, a significant anxiolytic-like response from 1 mg/kg, i.p. was observed, resembling the effect of diazepam. Major presence of thymol (33.40%) was observed in the hexane extract; whereas for the first time in this species a p-cymene + thymol mixture (9.78%), naringenin (0.18%) and cirsimaritin (1.16%) were obtained as bioactive constituents of the ethyl acetate crude extract. Acute toxicity was calculated to be LD50 = 1000 mg/kg for the crude hexane extract, lower in comparison to the other extracts analyzed (LD50 > 2000 mg/kg). DISCUSSION AND CONCLUSION: Our results suggest that L. graveolens exerts anxiolytic-like activity involving many kinds of constituents, mainly of the terpenoid and flavonoid nature. These results reinforce the potential use of this species in the therapy of anxiety.

Anxiolytic and sedative-like effects of flavonoids from Tilia Americana var. Mexicana: GABAergic and serotonergic participation / Efecto ansiolítico y sedante de flavonoides de Tilia Americana var. Mexicana: participación GABAérgica y serotonérgica

Abstract: INTRODUCTION: The inflorescences of Tilia americana var. mexicana are used as an infusion in Mexican traditional medicine due to their tranquilizing effects; however, pharmacological and phytochemical studies of the leaves are lacking. OBJECTIVE: In this research, the anxiolytic and sedative-like efficacy of the Tilia americana var. mexicana leaves was compared to that obtained with its inflorescences and flavonoids therein identified, as well as the possible mechanism of action. METHODS: The sorted and dried inflorescences and leaves were macerated subsequently in hexane, ethyl acetate and methanol. The methanol extracts were qualitative- and quantitative-analyzed by HPLC, using commercial flavonoids standards selected on the basis of their previously reported presence in Tilia species. The pharmacological activity was evaluated in CD-1 mice in the tests: open-field, elevated plus-maze, hole-board, and the sodium pentobarbital-induced sleep potentiation test. In regard to the mechanism of action, participation of benzodiazepine and 5-HT1A serotonin receptors was tested with the respective antagonists: flumazenil and WAY100635. RESULTS: The presence of quercetin, rutin and isoquercitrin was confirmed in the extracts of the inflorescences and leaves. The anxiolytic-like effects were the same between the two organs, which were inhibited in the presence of flumazenil and WAY100635. DISCUSSION AND CONCLUSION: Our results provide evidence that the extracts of the leaves of T. americana var. mexicana are as efficacious as the inflorescences to produce anxiolytic and sedative-like effects, where flavonoids like quercetin, rutin and isoquercitrin are partially responsible for these activities by the involvement of GABA/BDZ and 5HT1A serotonergic receptors.

Resumen: INTRODUCCIÓN: En la medicina tradicional mexicana, la infusión de inflorescencias de Tilia americana var. mexicana es utilizada por sus efectos tranquilizantes; sin embargo, los estudios farmacológicos y fitoquímicos de sus hojas son deficientes. OBJETIVO: En esta investigación, la eficacia ansiolítico-sedante de las hojas de T. americana var. mexicana se comparó con la obtenida con las inflorescencias y los flavonoides previamente identificados; se analizó además el posible mecanismo de acción. MÉTODOS: Inflorescencias y hojas separadas y secas se maceraron sucesivamente en hexano, acetato de etilo y metanol. Los extractos metanólicos se analizaron cualitativa y cuantitativamente por HPLC usando estándares comerciales de flavonoides previamente reportados en especies de Tilia. La actividad farmacológica se evaluó en ratones CD-1 en las pruebas de campo abierto, cruz elevada, tablero con orificios y la prueba de potenciación de hipnosis inducida por pentobarbital sódico. Respecto al mecanismo de acción, la participación de los receptores de benzodiazepinas y 5-HT1A de serotonina se examinó utilizando los antagonistas flumazenil y WAY100635, respectivamente. RESULTADOS: La presencia de quercetina, rutina e isoquercitrina se confirmó en los extractos de inflorescencias y hojas, donde se confirmó el efecto como ansiolítico, el cual fue inhibido en la presencia de flumazenil y WAY100635. DISCUSIÓN Y CONCLUSIÓN: Nuestros resultados dan evidencia de que las hojas de T. americana var. mexicana son tan eficaces como las inflorescencias para producir efectos ansiolítico-sedantes, donde los flavonoides quercetina, rutina e isoquercitrina son responsables parciales y se involucra la participación de los receptores GABA/BDZ y 5HT1A de serotonina.

Chemical composition and anti-inflammatory activity of the volatile fractions from the bark of eight Mexican Bursera species.

The volatile fractions from the bark of eight species of Mexican Bursera were obtained using steam distillation and were subjected to tandem GC-MS analysis for identification of the main constituents. The most abundant components of steam volatiles were monoterpenoids from which alpha-terpineol, terpinen-4-ol, alpha-thujene, linalool and limonene were most frequently isolated. A series of sesquiterpenes and long-chain hydrocarbons were isolated and identified from the barks of some of the studied species . Some volatiles were assayed for anti-inflammatory activity using the TPA-induced ear edema bioassay in mice. The volatile fraction from Bursera lancifolia was about half as active as indomethacin.