Inhibitory effects of choleretic hydroxyacetophenones on ileal bile acid transport in rats

Extraction and characterization of phenolic compounds with antioxidant and antimicrobial activities from pickled radish

The pickled radish can be kept at room temperature for years without spoilage. 2,6-dihydroxyacetophenone (DHAP), 4-hydroxybenzaldehyde (HBA), and 4-hydroxyphenethyl alcohol (4-HPEA) were first found from the pickled radish. The structures of three phenolic compounds were elucidated by analysis of their nuclear magnetic resonance and high-resolution electro-spray ionization mass spectrometry data. All these phenolic compounds showed good free radical scavenging capacity except HBA. Both DHAP and 4-HPEA also showed high ferric reducing ability. DHAP showed good antimicrobial activity against Escherichia coli, Bacillus subtilis, and Canidia albicans. HBA demonstrated antimicrobial activity against E. coli and C. albicans but not B. subtilis. Based on the results of MTT assay, these compounds did not show cytotoxicity to LO2 cell line. All results indicated the pickled radish had antioxidant and antimicrobial phenolic compounds. To the best of our knowledge, this report is the first to answer partially the question of why pickled foods can be kept at room temperature for years without spoilage based on the evidence of three phenolic compounds.

Pharmacological activity of novel 2-hydroxyacetophenone isatin derivatives on cardiac and vascular smooth muscles in rats

Isatin (1H-indole-2,3 dione) is an endogenous compound with biological activities. Many of its derivatives have pharmacological effects, including inhibition of cyclic guanosine monophosphate levels in cardiac tissue; sedative-hypnotic profiles; anticonvulsant, analgesic, antithermic, and anti-inflammatory activities; and anxiolytic, antimicrobial, and proapoptotic effects. Carbamates derived from isatin have a vasorelaxant profile. This study investigated the activity of 2 novel 2-hydroxyacetophenone derivatives of isatin (named MB101 and MB130) on the contractility of rat aorta and papillary muscles. Both compounds induced a concentration-dependent relaxation (5-100 μM) in the endothelium-intact aorta that was abolished by N-nitro-L-arginine methyl ester. Atropine, a muscarinic receptor antagonist, significantly prevented vasodilatation of 100 μM MB101. In contrast, atropine caused no significant alteration in MB130-induced vasorelaxation. Naloxone, a nonselective opioid receptor antagonist, completely prevented the relaxing effect of MB101 and MB130 at all concentrations. In papillary muscles, only MB130 induced a significant depression, and this contractile response was not altered by propranolol and atropine. Both the compounds reduced systolic and diastolic pressures in a dose-dependent manner in anesthetized rats. The 2-hydroxyacetophenones produced direct effects on vascular tonus through either muscarinic or opioid pathways. MB130 produced cardiac depression by opioid receptors and bradykinin because pretreatment HOE140 or with naloxone, an antagonist of type-2, bradykinin were able to partially block the decrease in twitch amplitude in papillary muscles induced by MB130. These findings provide information for designing new strategies for the treatment of cardiovascular disorders.

Differential effects of hydroxyacetophenone analogues on the transcytotic vesicular pathway in rat liver

Insertion of transporter proteins into the apical canalicular membrane via vesicular transport is one of several choleretic mechanisms. Based on different choleretic activities of hydroxyacetophenone analogues including 4-mono; 2,6-di and 2,4,6-trihydroxy-acetophenone (MHA, DHA and THA), the present study aims to determine if these compounds stimulated vesicular transport in hepatocytes. Hydroxyacetophenone was continuously infused into the duodenum of the bile fistula rat. Bile flow rate was allowed to stabilize and then followed by an intraportal injection of horseradish peroxidase, a marker of the transcytotic vesicle pathway. MHA which stimulates bile acid independent flow, showed a dose-dependent increase in both the early (paracellular) and late (transcellular) peak of horseradish peroxidase excretion in bile. THA, which stimulates both bile acid dependent flow and bile acid independent flow, did not alter the pattern of horseradish peroxidase excretion into bile. However, DHA, which is more hydrophobic and increases only bile acid dependent flow, decreased the late peak. The stimulating effects of MHA on bile flow and horseradish peroxidase excretion were markedly inhibited by colchicine, suggesting that its choleretic action involves stimulation of exocytosis, as well as increase in paracellular permeability. In contrast, the lack of a stimulatory effect of THA and DHA on biliary horseradish peroxidase excretion suggested that their choleretic action is not associated with vesicular exocytosis. These results demonstrate a variable effect of hydroxyacetophenones on the transcytotic vesicular pathway reflecting different choleretic mechanisms and therapeutic potential.