ABSTRACT: Alzheimer's disease (AD) is a severe condition in aging societies. Although research on this disease is advancing rapidly, thus far few very effective drugs are available for AD patients. The currently widely used medicines such as donepezil and galantamine transiently improve the symptoms of patients with mild to moderate AD. They are hardly capable of preventing, halting or reversing the progression of this disease. In the long history of development of traditional Chinese medicine, many herbs have been discovered and employed to treat dementia diseases in clinics in China. In recent decades, a number of agents were isolated from these herbs and their efficacies against AD were tested. Some flavonoids, alkaloids, phenylpropanoids, triterpenoid saponins, and polysaccharides were demonstrated to have potential efficacies against AD via targeting multiple pathological changes of this disease. In this article, we reviewed research progress on the efficacies and underlying mechanisms of these agents.
A series of new 1,3,4-oxadiazole and 1,2,4-triazole derivatives were synthesized. The structures were confirmed by IR, 1H-NMR, and MS. The compounds were evaluated for their antiproliferative activity against K562 (human erythromyeloblastoid leukemia cell line), MDA-MB-231 (human breast adenocarcinoma cell line), HT29 (human colon adenocarcinoma grade II cell line) and HepG2 (human hepatocellular liver carcinoma cell line) in vitro. The result showed that 7 compounds displayed inhibitory activities against K562 with the inhibition rate more than 50%. Especially, compound 5f exhibited the most potent activity against K562 with 85% inhibition ratio and could be used as lead compound to search new 1,3,4-oxadiazole derivatives as antiproliferative agent.
Naturally occurring flavonoids have been reported to possess antimicrobial activity against a wide range of pathogens. However, the antimicrobial action mechanism of these compounds has not yet been elucidated. This study investigated the mechanism underlying the antibacterial activity of four flavonoids: 6,8-diprenyleriodictyol (1), isobavachalcone (2), 6-prenylapigenin (3) and 4-hydroxylonchocarpin (4). In addition, the toxicity of these compounds was evaluated. Determination of the minimum inhibitory concentrations (MICs) was performed by microbroth dilution method. Radiolabeled thymidine, uridine, and methionine were used to evaluate the effect of the compounds on the biosynthesis of DNA, RNA, and proteins while the sensitive cyanine dye DiS-C3-(5) (3,3'-dipropylthiadicarbocyanine iodide) was used for the effect on membrane potential. Bactericidal/bacteriolysis activities were performed by time-kill kinetic method. In the toxicity study, the numbers of survivors was recorded after injection of compounds into the hemolymph of silkworm larvae. Compounds showed significant antibacterial activity against Staphylococcusaureus including methicillin-resistant S. aureus (MRSA) strains with MICs values ranged between 0.5-128 μg/mL. Depolarization of membrane and inhibition of DNA, RNA, and proteins synthesis were observed in S. aureus when treated with those flavonoids. At 5-fold minimum inhibitory concentration, compounds reduced rapidly the bacterial cell density and caused lysis of S. aureus. Compounds 1, 2, and 4 did not show obvious toxic effects in silkworm larvae up to 625 μg/g of body weight. Flavonoids from Dorstenia species, 6,8-diprenyleriodictyol, isobavachalcone, and 4-hydroxylonchocarpin are bactericidal compounds. They cause damage of cell membrane, leading to the inhibition of macromolecular synthesis. Taking into account the in vivo safety and their significant antimicrobial potency, these flavonoids are promising leads for further drug development.
Sertoli cells, the sole somatic cell type in the seminiferous epithelium, play an essential role in spermatogenesis and spermiogenesis by nursing germ cells for their survival and differentiation as well as physically inhibiting the entrance of harmful substances into the seminiferous tubules. Sertoli cells possess the characteristics of immune cells; they express pattern recognition receptors, secrete antimicrobial proteins, and engulf dead or dying cells. In this study, we determined the mechanism by which Sertoli cells engulf and kill bacteria compared to that of macrophages. When the primary cultured Sertoli cells of rats were incubated with Staphylococcus aureus, they produced the mRNA of neutrophil protein 3, an antimicrobial peptide of the α-defensin family, but not superoxide or nitric oxide, in contrast to mouse peritoneal macrophages. Sertoli cells effectively phagocytosed S. aureus in a manner that was accompanied by cytoskeleton rearrangement and dependent on phosphatidylinositol 3-kinase. Engulfed bacteria appeared to stay alive in Sertoli cells, while they were rapidly killed in macrophages. These results collectively suggest that Sertoli cells eliminate bacteria that have invaded the seminiferous epithelium without evoking inflammation, unlike macrophages.
Acetaminophen (AP) is widely used as the antipyretic and analgesic drug in clinic, and it can induce serious liver injury in the case of excessive abuse. The present study showed that AP (400 mg/kg) induced obvious liver injury, while in male mice the hepatotoxicity induced by AP was much more serious than in female mice as indicated by the results of alanine aminotransferase (ALT) activity and reduced glutathione (GSH) amount. Further, the enzymatic activity and protein expression of glutamate-cysteine ligase (GCL) and glutathione peroxidase (GPx) were all higher in female mice liver than in male after the administration of AP (200 mg/kg). Meanwhile, AP (10 mM) decreased GCL and GPx activity in isolated mouse hepatocytes in the time-dependent manner, while the inhibitors of GCL and GPx can augment AP induced-cytotoxicity. Taken together, our results demonstrate the gender-related liver injury induced by AP and the important role of GCL and GPx in regulating such hepatotoxicity.
Plants that contain anthracene-derived compounds such as anthraquinones have been reported to act as anticancer besides their use for millennia to treat constipation, but the mechanism of action is still unfolding. Therefore we pursue this study to explore a new horizon in the anticancer property of these agents with relevance to mitotic arrest. To achieve this goal, the antimitotic activity of a series of naturally occurring anthracene-derived anthraquinones including anthrone, alizarin (1,2-dihydroxyanthraquinone), quinizarin (1,4-dihydroxyanthraquinone), rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid), emodin (1,6,8-trihydroxy-3-methyl-anthraquinone), and aloe emodin (1,8-dihydroxy-3-hydroxymethyl- anthraquinone) were evaluated using Allium cepa root tips. Initial results revealed that the mitosis was inhibited after 3, 6, and 24 h, respectively, of incubation with 500, 250, and 125 ppm of each compound in a dose-dependent manner. Furthermore, alizarin at 500 ppm was proved to be the most active compound to arrest the mitosis after 24 h followed by emodin, aloe emodin, rhein, and finally quinizarin. Interestingly, this inhibition of mitosis was irreversible in root tips incubated with each compound at concentration of 500 ppm but not with 250 ppm or 125 ppm, where the roots regained their normal mitotic activity after 96 h post-incubation in water. This re-evaluation of an old remedy suggests that several bioactive anthraquinones possess promising anti-mitotic activity that may have the potential to be lead compounds for the development of a new class of multifaceted natural anticancer/antimitotic agents.
Surfactant-free emulsions by adding jojoba oil, squalane, olive oil, or glyceryl trioctanoate (medium chain fatty acid triglycerides, MCT) to electrolytic-reduction ion water containing lithium magnesium sodium silicate (GE-100) were prepared, and their physiochemical properties (thixotropy, zeta potential, and mean particle diameter) were evaluated. At an oil concentration of 10%, the zeta potential was ‒22.3 ‒ ‒26.8 mV, showing no marked differences among the emulsions of various types of oil, but the mean particle diameters in the olive oil emulsion (327 nm) and MCT emulsion (295 nm) were smaller than those in the other oil emulsions (452-471 nm). In addition, measurement of the hysteresis loop area of each type of emulsion revealed extremely high thixotropy of the emulsion containing MCT at a low concentration and the olive emulsion. Based on these results, since surfactants and antiseptic agents markedly damage sensitive skin tissue such as that with atopic dermatitis, surfactant- and antiseptic-free emulsions are expected to be new bases for drugs for external use.