Fern-9(11)-ene-2α,3ß-diol Action on Insulin Secretion under Hyperglycemic Conditions.

The objective of this study was to investigate the effect and the mechanism of action of fernenediol as an insulin secretagogue. Wistar rats were treated with 0.1, 1, and 10 mg/kg fernenediol before inducing hyperglycemia by oral glucose. The glycaemia, insulin, LDH, calcium, and hepatic glycogen were analyzed. Considering the intestine and pancreas as targets for the triterpene action, the duodenum was used to verify the influence of fernenediol on intestinal glycosidases. Additionally, pancreatic islets were used for studies of 14C-deoxyglucose uptake and the influx of 45Ca2+ in hyperglycemic media with/without fernenediol in the presence/absence of an inhibitor/activator of KATP channels, glibenclamide, diazoxide, nifedipine, calcium chelator (BAPTA-AM), and H-89 and ST, the inhibitors of the PKA and PKC enzymes. Fernenediol significantly reduced glycaemia, potentiated glucose-induced insulin secretion, and stimulated liver glycogen deposition in hyperglycemic rats after an in vivo treatment without changing intestinal disaccharidases activities and showing no influence on intestinal glucose absorption. Also, it stimulated the glucose uptake and calcium influx in pancreatic islets. The involvement of voltage-dependent L-type calcium channels and ATP-dependent potassium channels and the release of calcium from intracellular stores are mandatory for the stimulatory effect of fernenediol on calcium influx. Fernenediol did not change PKA and PKC activities or modify calcium levels. This triterpene is a potent antihyperglycemic agent with a strong insulin secretagogue effect on glycogen accumulation as well. As a whole, this compound presents significant perspectives as a future new drug for the treatment of insulin resistance and/or diabetes.

Acute effect of 3ß-hidroxihop-22(29)ene on insulin secretion is mediated by GLP-1, potassium and calcium channels for the glucose homeostasis.

The effect of 3ß-hidroxihop-22(29)ene (3-BHO) on insulin and glucagon-like peptide 1 (GLP-1) secretion as well as the mechanism of action of the compound in pancreatic islet on glucose homeostasis was investigated. The data from in vivo treatment show that 3-BHO significantly reduces the hyperglycemia by increasing the insulin and GLP-1 secretion, as well as by accumulating hepatic glycogen in hyperglycemic rats. In rat pancreatic ß-cell, 3-BHO stimulates the glucose uptake, insulin vesicles translocation to the plasma membrane and thus the insulin secretion through the involvement of potassium channels (ATP- and Ca(2+)-dependent K(+) channels) and calcium channels (L-type voltage-dependent calcium channels (L-VDCC)). Furthermore, this study also provides evidence for a crosstalk between intracellular high calcium concentration, PKA and PKC in the signal transduction of 3-BHO to stimulate insulin secretion. In conclusion, 3-BHO diminishes glycaemia, stimulates GLP-1 secretion and potentiates insulin secretion and increase hepatic glycogen content. Moreover, this triterpene modulates calcium influx characterizing ATP-K(+), Ca(2+)-K(+) and L-VDCC channels-dependent pathways as well as PKA and PKC activity in pancreatic islets underlying the signaling of 3-BHO for the secretory activity and contribution on glucose homeostasis.

Croton antisyphiliticus Mart. attenuates the inflammatory response to carrageenan-induced pleurisy in mice.

The aim of this study was to investigate the anti-inflammatory effect of the crude hydroalcoholic extract (CHE) from the aerial parts of Croton antisyphiliticus, its fractions and isolated compounds derived from it on the mouse model of pleurisy induced by carrageenan. The aerial parts of C. antisyphiliticus were dried, macerated and extracted with ethanol to obtain the CHE, which was fractionated by liquid-liquid extraction using solvents with increasing polarity to obtain hexane (Hex), ethyl acetate (EA) and aqueous (Aq) fractions. Vitexin and quinic acid were isolated from Aq fraction. Capillary electrophoresis analysis, physical characteristics and spectral data produced by infrared (IR), nuclear magnetic resonance ((1)H and (13)C NMR) and mass spectrometry analyses were used to identify and elucidate the structure of the isolated compounds. The experimental model of pleurisy was induced in mice by a single intrapleural injection of carrageenan (1 %). Leukocytes, exudate concentrations, myeloperoxidase (MPO) and adenosine-deaminase (ADA) activities and nitrate/nitrite (NOx), tumor necrosis factor-α (TNF-α) and interleukin-17 (IL-17) levels were determined in the pleural fluid leakage at 4 h after pleurisy induction. Animals pre-treated with CHE, Hex, EA, Aq, vitexin and quinic acid exhibited decreases in leukocytes, exudate concentrations, MPO and ADA activities and NOx levels (p < 0.05). Also CHE, Hex, EA and vitexin but not quinic acid inhibited TNF-α and IL-17 levels (p < 0.05). C. antisyphiliticus caused anti-inflammatory effect by inhibiting the activated leukocytes, exudate concentrations, NOx, TNF-α, and IL-17 levels. The compounds vitexin and quinic acid may be responsible for this anti-inflammatory action.