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.

Euphorbia dioeca Kunth as a novel source for alpha-glucosidase inhibitors / Euphorbia dioeca Kunth como una nueva fuente de inhibidores de alfa-glucosidasa

Euphorbia dioeca Kunth belongs to the Wanderer’s herb complex that is traditionally used for skin diseases and recently as antidiabetic. The methanol and aqueous extracts were evaluated for their in vitro alpha-glucosidase inhibitory activity and an oral starch tolerance test. These extracts showed an IC50 of 0.55 and 0.85 mg/mL, respectively. In diabetic Long Evans rats, the methanol and aqueous extracts reduced significantly the postprandial hyperglycemia peak in 15.2 percent and 12.8 percent, respectively. The alpha-glucosidase inhibitory activity is related with the presence of glycosides, phenolic compounds and flavonoids. Additionally, the safety parameters of both extracts were assessed by means of an acute toxicity test, being classified as innocuous. The traditional use of E. dioeca to control type 2 diabetes was confirmed, being an important source of alfa-glucosidase inhibitors.

Euphorbia dioeca Kunth, pertenece al complejo de plantas medicinales denominado Hierba de la Golondrina; el cual se utiliza para diversos padecimientos, destacando su uso como antidiabético. En dicho marco, se evaluó tanto la actividad inhibitoria de alfa-glucosidasa in vitro, como su desempeño en una prueba de tolerancia a una carga de almidón postprandial. Los extractos inhibieron la actividad de la alfa-glucosidasa con una CI50 de 0.55 y 0.85 mg/mL, respectivamente. Los extractos metanólico y acuoso disminuyeron significativamente el pico hiperglucémico postprandial en un 15.2 por ciento y un 12.8 por ciento, respectivamente, cuando se evaluó en ratas diabéticas. La actividad inhibitoria de alfa-glucosidasa, reflejada en ambas pruebas, está relacionada con la presencia de glicósidos, compuestos fenólicos y flavonoides. De manera adicional, ambos extractos fueron evaluados en una prueba de toxicidad aguda, siendo clasificados como inocuos. Se corroboró el uso tradicional de E. dioeca para el control de la diabetes tipo 2, siendo una importante fuente de compuestos inhibidores de alfa-glucosidasa.

Regulation of acidic ribosomal protein expression and phosphorylation in maize.

Acidic ribosomal proteins (ARPs) are highly conserved phosphoproteins in eukaryotic organisms. They participate in translation regulation by interacting with eEF-2 elongation factors in the peptide elongation process. During maize germination, protein synthesis is tightly regulated by different mechanisms that are not yet clearly understood. The objective of this research is to characterize the expression patterns of the two maize ARPs (P1 and P2) and their phosphorylated status in germinating maize embryonic axes. Expression of P1 and P2 mRNA transcripts was analyzed by Northern blots with specific cDNA probes. Results indicated that both transcripts are among the mRNA stored pool of the quiescent axes and each displays a distinctive expression pattern during germination. P1 and P2 synthesis initiates very early in germination, as demonstrated by [(35)S]methionine pulse-labeling experiments. This synthesis was not insulin/IGF-stimulated as the synthesis of the bulk of ribosomal proteins that was responsive to this stimulus. P1 and P2 proteins were purified from ribosomes of maize embryonic axes and their physicochemical characteristics determined. A cytoplasmic pool of dephosphorylated P1 and P2 proteins was found in axes of quiescent and germinated stages that freely assembled into the ribosomes. IEF analysis of ARPs revealed one P1 (P1-1) and two P2 (P2-1 and P2-2) forms in the ribosomes of 24 h germinated axes. Kinetic studies of ARP phosphorylation during germination revealed a specific order of phospho-ARP appearance, suggesting that this process is under regulation within this period. It is concluded that P1 and P2 phosphorylation rather than ARP expression or assembly into ribosomes is the main step that regulates ARP function in axes during maize germination.