Bioactivity of alginetin, a caramelization product of pectin: Cytometric analysis of rat thymic lymphocytes using fluorescent probes.

Alginetin is the major product formed from pentoses and hexurionic acids. Alginetin is producted by cooking process of food including pection, a naturally-occurring polysacharride found in many plants. However, the biological interaction and toxicity of alginetin are not known at all. The aim of the present study was to investigate the cellular actions of alginetin on rat thymic lymphocytes. The effects of alginetin on the cell were examined using flow cytometry with fluorescent probes. Alginetin increased cellular content of non-protein thiols ([NPT]i) and elevated intracellular Zn2+ levels ([Zn2+]i). Chelation of intracellular Zn2+ reduced the effect of alginetin on [NPT]i, and chelation of external Zn2+ almost completely diminished alginetin-induced elevation of [Zn2+]i, indicating that alginetin treatment increased Zn2+ influx. Increased [NPT]i and [Zn2+]i levels in response to alginetin were positively correlated. Alginetin protected cells against oxidative stress induced by hydrogen peroxide and Ca2+ overload by calcium ionophore. It is considered that the increases in [NPT]i and [Zn2+]i are responsible for the cytoprotective activity of alginetin because NPT attenuates oxidative stress and Zn2+ competes with Ca2+. Alginetin may be produced during manufacturing of jam, which may provide additional health benefits of jam.

Change in membrane potential induced by streptolysin O, a pore-forming toxin: flow cytometric analysis using a voltage-sensitive fluorescent probe and rat thymic lymphocytes.

Streptolysin O (SLO) is a bacterial pore-forming toxin that is employed to permeabilize cell membranes in some biological experiments. SLO forms various types of pores with different shapes, increasing membrane ion permeability and subsequently inducing changes in membrane potential. To characterize the pores formed by SLO, the changes in membrane potential induced by SLO in rat lymphocytes were considered using flow cytometry with a voltage-sensitive fluorescent probe, bis-(1,3-dibutylbarbituric acid)trimethine oxonol (Oxonol). SLO caused three types of membrane potential responses accessed with Oxonol. One type induces a great decrease in Oxonol fluorescence (large hyperpolarization) that may be elicited via the increase of Ca2+ -dependent K+ permeability by SLO-induced influx of external Ca2+ . A second type is an increase in Oxonol fluorescence (depolarization) that may be caused by a nonspecific increase in membrane cation permeability. The third type is a small decrease in Oxonol fluorescence (small hyperpolarization), probably via an increase in Cl- permeability. That SLO transitionally changes membrane ion permeability may have implications in the pathology of pyogenic group streptococci infections in which SLO is thought to be one of the key virulence factors.

Involvement of adenosine triphosphate-binding cassette subfamily B member 1 in the augmentation of triacylglycerol excretion by Propionibacterium acnes in differentiated hamster sebocytes.

An onset of acne, a common inflammatory skin disease, is associated with excess sebum production and secretion in sebaceous glands. Because Propionibacterium acnes has been reported to augment intracellular sebum accumulation in sebaceous glands in hamsters, it remains unclear whether P. acnes influences sebum secretion from differentiated sebocytes. Both P. acnes culture media (Acnes73-CM) and formalin-killed P. acnes (F-Acnes73) dose-dependently increased the extracellular levels of triacylglycerol (TG), a major sebum component, and Rhodamine 123, a substrate of adenosine triphosphate-binding cassette (ABC) transporter, from differentiated hamster sebocytes (DHS). In addition, the gene expression of the ABC subfamily B member 1 (ABCB1) was dose-dependently augmented by adding Acnes73-CM and F-Acnes73 into DHS. Furthermore, the F-Acnes73-induced increase of TG excretion was suppressed by PSC833, a selective ABCB1 inhibitor. On the other hand, peptidoglycan (PGN), which is a Toll-like receptor 2 (TLR2) ligand in P. acnes, increased extracellular TG levels, transporter activity and ABCB1 mRNA expression in DHS. The PGN-augmented TG excretion was suppressed by PSC833. Thus, these results provide novel evidence that P. acnes facilitates sebum secretion due to the activation of ABCB1 concomitantly with the increased ABCB1 expression, which may result from the activation of the TLR2 pathway in DHS. Therefore, the ABCB1 inhibitor is likely to become a candidate as a possible therapeutic for the treatment of acne.