Luteolin suppresses colonic smooth muscle motility via inhibiting L-type calcium channel currents in mice.

As a naturally occurring flavone, luteolin has received much attention due to its antioxidant, anti-inflammatory and anticancer functions. In the present study, we investigated the effect of luteolin on colonic motility and its mechanism using isometric muscle recording and the whole-cell patch-clamp technique in mice. Luteolin dose-dependently inhibited colonic smooth muscles motility and CMMC significantly. BayK8644, an L-type Ca2+ channel agonist, significantly attenuated the luteolin-induced inhibition. Moreover, the calcium currents recorded in colonic smooth muscle cells were dramatically inhibited by luteolin. However, no significant changes were found in the luteolin-induced inhibitory effect in the presence of TEA, a nonselective K+ channel blocker, glibenclamide, an ATP-dependent K+ channel blocker, and apamin, a small-conductance Ca2+-activated K+ channel blocker. Additionally, luteolin did not affect potassium currents. Furthermore, TTX, a Na+ channel blocker, L-NAME, an inhibitor of nitric oxide (NO) synthase, ODQ, an inhibitor of NO-sensitive guanylyl cyclase, and Ani9, a specific ANO1 channels blocker, had no effect on the luteolin-induced suppression. These results suggest that luteolin inhibited colonic smooth muscle motility by inhibiting L-type calcium channels in mice but not through potassium channels, the enteric nervous system (ENS), NO signaling pathways or ANO1 channels of interstitial cells of Cajal (ICCs).

Analysis and determination of diterpenoids in unprocessed and processed Euphorbia lathyris seeds by HPLC-ESI-MS.

Euphorbia lathyris (Caper spurge) is a toxic and potent Chinese materia medica (T/PCMM). This study sought a method for identifying five diterpenoids (Euphorbia factors L1-L3, L7a and L8) with the spectra of UV and mass, quantifying three diterpenoids L1, L2, and L8 in crude extracts of unprocessed and processed E. lathyris seeds by liquid chromatography/electrospray ionization mass spectrometry (LC-ESI-MS). The analysis was achieved on an Agilent Eclipse XDB-C18 column (4.6 mm×150 mm i.d., 5 µm) with an isocratic elution with a mobile phase consisting of water and acetonitrile at a flow rate of 0.25 mL/min at column temperature of 30 °C and UV detection was set at 272 nm. An ESI source was used with a positive ionization mode. The calibration curve was linear in the ranges of 9.9-79 µg/mL for Euphorbia factor L1, 3.8-30.5 µg/mL for Euphorbia factor L2, and 1.0-20.6 µg/mL for Euphorbia factor L8. The average recoveries (n=6) of three diterpenoids were 98.39%, 91.10% and 96.94%, respectively, with RSD of 2.5%, 2.4% and 2.1%, respectively. The contents of the three diterpenoids in processed E. lathyris seeds were 3.435, 1.367 and 0.286 mg/g, respectively, which decreased more sharply than those in unprocessed E. lathyris seeds which were 4.915, 1.944 and 0.425 mg/g, respectively. The method is simple, accurate, reliable and reproducible, and it can be applied to control the quality of unprocessed and processed E. lathyris seeds.