Sesquiterpene Lactones from Calea pinnatifida: Absolute Configuration and Structural Requirements for Antitumor Activity.

This work describes the chromatographic fractionation of the aerial parts of Calea pinnatifida and the structural characterization and determination of the absolute configuration of the isolated compounds as well as their antitumor potential. The HPLC fractionation of the CH2Cl2 phase of the MeOH extract from the leaves of C. pinnatifida led to the isolation of two related sesquiterpene lactones (STLs): calein C (1) and calealactone B (2). Additionally, during the purification process, a derivative of calein C (3) was formed as a product of the Michael addition of MeOH. The structures of Compounds 1-3 were established based on spectroscopic and spectrometric data, while the absolute stereochemistry was established by vibrational circular dichroism. In order to evaluate the effect of the conjugated double bonds on the cytotoxic activity of STLs, Compounds 1-3 were tested against anaplastic (KTC-2) and papillary (TPC-1) thyroid carcinoma cells. Calein C was the most active of the STLs, and displayed activity against both KTC-2 and TPC-1. On the other hand, the calein C derivative (3) was the least cytotoxic of all the compounds tested. These results are promising and suggest the importance of studying sesquiterpene lactones isolated from C. pinnatifida in terms of antitumor activity, especially considering the effects of α,ß-unsaturated carbonyl systems.

Thermoprotective effect of insulin-like growth factor 1 on in vitro matured bovine oocyte exposed to heat shock.

The role of insulin-like growth factor 1 (IGF1) on cellular function and developmental capacity of heat-shocked oocytes has not been completely understood. Therefore, the objective of this study was to determine the effect of IGF1 on apoptosis, mitochondrial activity, cytoskeletal changes, nuclear maturation, and developmental competence of bovine oocytes exposed to heat shock. Cumulus-oocyte complexes were submitted to control (38.5 °C for 22 hours) and heat shock (41 °C for 14 hours followed by 38.5 °C for 8 hours) in the presence of 0 or 100 ng/mL IGF1 during IVM. Heat shock increased the percentage of TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling)-positive oocyte and reduced oocyte mitochondrial activity. However, addition of 100 ng/mL IGF1 minimized these deleterious effects of temperature. Caspase activity was affected neither by heat shock nor IGF1. Exposure of bovine oocytes to 41 °C during the first 14-hour IVM affected cortical actin localization and microtubule organization at the meiotic spindle and reduced the percentage oocytes that reached the metaphase II stage. However, in the presence of IGF1, cortical actin and percentage of metaphase II oocytes were not different between control and heat-shocked oocytes, suggesting a partial beneficial effect of IGF1. There was no effect of IGF1 on microtubule organization. Heat shock also reduced the percentage of oocytes that reached the blastocyst stage, blastocyst cell number, and increased the percentage of TUNEL-positive blastomeres. However, there was no effect of 100 ng/mL IGF1 on oocyte development to the blastocyst stage and blastocyst quality. Therefore, 100 ng/mL IGF1 prevented some heat shock-induced cellular damage in bovine oocytes but had no effect on oocyte developmental competence. In contrast, a low IGF1 concentration (25 ng/mL) had a thermoprotective effect on oocyte developmental competence to the blastocyst stage. In conclusion, IGF1 prevented part of the damage induced by heat shock on oocyte function. This effect was modulated by IGF1 concentration.