Screening biofilm eradication activity of ethanol extracts from foodstuffs: potent biofilm eradication activity of glabridin, a major flavonoid from licorice (Glycyrrhiza glabra), alone and in combination with ɛ-poly-L-lysine.

The ethanol extracts of 155 different foodstuffs containing medicinal plants were investigated for their biofilm eradication activities against pathogenic bacteria. A combined method of a colorimetric microbial viability assay based on reduction of a tetrazolium salt (WST-8) and a biofilm formation technique on the 96-pins of a microtiter plate lid was used to screen the biofilm eradication activities of foodstuffs. The ethanol extracts of licorice (Glycyrrhiza glabra) showed potent biofilm eradication activities against Streptococcus mutans, Staphylococcus aureus, and Porphyromonas gingivalis. Among the antimicrobial constituents in licorice, glabridin had the most potent eradication activities against microbial biofilms. The minimum biofilm eradication concentration of glabridin was 25-50 µg/ml. Furthermore, the combination of glabridin with ɛ-poly-L-lysine, a food additive, could result in broad biofilm eradication activities towards a wide variety of bacteria associated with infection, including Escherichia coli and Pseudomonas aeruginosa.

Anti-prediabetic effect of rose hip (Rosa canina) extract in spontaneously diabetic Torii rats.

BACKGROUND: Prediabetes, a high-risk state for developing diabetes showing impaired glucose tolerance but a normal fasting blood glucose level, has an increasing prevalence worldwide. However, no study investigating the prevention of impaired glucose tolerance at the prediabetic stage by anti-diabetic functional foods has been reported. Thus, the present study aimed to evaluate the anti-prediabetic effect of rose hip in a prediabetic rat model. RESULTS: Spontaneously diabetic Torii (SDT) rats were supplemented with hot-water extract of rose hip at a dose of 100 mg kg-1 body weight day-1 for 12 weeks. The results obtained showed that the supplementation of rose hip extract improved impaired glucose tolerance, promoted insulin secretion, preserved pancreatic beta-cell function and suppressed plasma advanced glycation end-products formation of methylglyoxal-derived hydroimidazolone (MG-H1) residue and Nϵ -carboxymethyl-lysine residues (e.g. MG-H1, control: 465.5 ± 43.8 versus rose hip: 59.1 ± 13.0 pmol mg protein-1 , P < 0.05) in SDT rats at the prediabetic stage (12-20 weeks old). CONCLUSION: The present study provides the first evidence showing that a hot-water extract of rose hip could exert an anti-prediabetic effect in a rat model. © 2017 Society of Chemical Industry.

Distribution of prolylhydroxyproline and its metabolites after oral administration in rats.

Prolylhydroxyproline (Pro-Hyp), which is derived from collagen hydrolysate, has been shown to be beneficial for skin and joint health. However, little is known about the distribution of Pro-Hyp in these tissues. In the present study, we investigated the biodistribution of orally administered [(14)C]Pro-Hyp in rats. Whole-body autoradiography at 30 min after administration of [(14)C]Pro-Hyp showed that radioactivity is widely distributed in tissues including skin and articular cartilage, with the highest level of radioactivity observed in the gastric and intestinal walls. Incorporation of radioactivity into cells known to respond to Pro-Hyp such as dermal fibroblasts, synovial cells, chondrocytes, osteoblasts, and osteoclasts was observed. The chemical form of [(14)C]Pro-Hyp-derived radioactivity detected in the tissues was investigated by thin layer chromatography. The radioactive constituents in cartilage extract were two proline-modified peptides (56%), intact Pro-Hyp (5%), and two nonpeptide metabolites (28%). Similar results were obtained for skin and bone marrow. Plasma analysis at 3 to 30 min post-dose suggested that the majority of Pro-Hyp is modified in its proline residue by a first-pass effect without peptide bond hydrolysis. In conclusion, we demonstrated that Pro-Hyp is partly distributed in observed tissues including skin and cartilage in its intact form, which might be responsible for its biological functions.

Is a "cloud-point curve" in aqueous poly(N-isopropylacrylamide) solution binodal?

Transmittance of light passing through an aqueous solution of a linear poly(N-isopropylacrylamide) (PNIPA) sample synthesized by living anionic polymerization was examined in detail in the vicinity of its cloud point. It is found that the transmittance approaches a constant value between 0 and 100% even at a temperature slightly higher than the cloud point, indicating that macroscopic phase separation does not take place at the cloud point in the solution and therefore the cloud-point curve dose not correspond to the binodal. Static and dynamic light scattering measurements were then carried out for aqueous solutions of the linear sample and also of another one synthesized by radical polymerization, which has random-branched structure, at some temperatures considerably lower than the cloud point. It was found that both the PNIPA samples in aqueous solutions form aggregates even at such temperatures, and the number, size, and density profile of the aggregates depend on the kind of chain end group and also on the primary structure.

Unidirectional movement of an actin filament taking advantage of temperature gradients.

An actin filament with heat acceptors attached to its Cys374 residue in each actin monomer could move unidirectionally even under heat pulsation alone, while in the total absence of both ATP and myosin. The prime driver for the movement was temperature gradients operating between locally heated portions on an actin filament and its cooler surroundings. In this report, we investigated how the mitigation of the temperature gradients induces a unidirectional movement of an actin filament. We then observed the transversal fluctuations of the filament in response to heat pulsation and their transition into longitudinally unidirectional movement. The transition was significantly accelerated when Cys374 and Lys336 were simultaneously excited within an actin monomer. These results suggest that the mitigation of the temperature gradients within each actin monomer first went through the energy transformation to transversal fluctuations of the filament, and then followed by the transformation further down to longitudinal movements of the filament. The faster mitigation of temperature gradients within actin monomer helps build up the transition from the transversal to longitudinal movements of the filament by coordinating the interaction between the neighboring monomers.

Fourier's law of heat transfer and its implication to cell motility.

Fourier's law of heat transfer addressing temperature differences is intrinsically selective in favoring the mitigation of the differences proceeding as fast as possible. We present an experimental demonstration of such selective behavior of material origin. When an actin filament equipped with nano-scale heat acceptors was placed under heat pulsation, it demonstrated a unidirectional movement without the presence of myosin or ATP. The prime factor for the unidirectional movement was the temperature differences between the locally heated portions on the actin filament and the cooler material bodies in the surroundings. The unidirectional movement could be enhanced in the process of mitigating the temperature differences as fast as possible.

Sexual interactions influence the molecular oscillations in DN1 pacemaker neurons in Drosophila melanogaster.

Circadian rhythms can synchronize to environmental time cues, such as light, temperature, humidity, and food availability. Previous studies have suggested that these rhythms can also be entrained by social interactions. Here, we used Drosophila melanogaster as a model to study the influence of socio-sexual interactions on the circadian clock in behavior and pacemaker neurons. If two flies of opposite sex were paired and kept in a small space, the daily activity patterns of the two flies were clearly different from the sum of the activity of single male and female flies. Compared with single flies, paired flies were more active in the night and morning, were more active during females' active phase, and were less active during males' active phase. These behavioral phenotypes are related to courtship behavior, but not to the circadian clock. Nevertheless, in male-female pairs of flies with clocks at different speeds (wild-type and per (S) flies), clock protein cycling in the DN1 pacemaker neurons in the male brain were slightly influenced by their partners. These results suggest that sexual interactions between male-female couples can serve as a weak zeitgeber for the DN1 pacemaker neurons, but the effect is not sufficient to alter rhythms of behavioral activity.

Pigment-dispersing factor is involved in age-dependent rhythm changes in Drosophila melanogaster.

Most animals show rest/activity rhythms that are regulated by an endogenous timing mechanism, the so-called circadian system. The rhythm becomes weaker with age, but the mechanism underlying the age-associated rhythm change remains to be elucidated. Here we employed Drosophila melanogaster as a model organism to study the aging effects on the rhythm. We first investigated activity rhythms under light-dark (LD) cycles and constant darkness (DD) in young (1-day-old) and middle-aged (30-, 40-, and 50-day-old) wild-type male flies. The middle-aged flies showed a reduced activity level in comparison with young flies. Additionally, the free-running period significantly lengthened in DD, and the rhythm strength was diminished. Immunohistochemistry against pigment-dispersing factor (PDF), a principal neurotransmitter of the Drosophila clock, revealed that PDF levels declined with age. We also found an attenuation of TIMELESS (TIM) oscillation in the cerebral clock neurons in elder flies. Intriguingly, overexpression of PDF suppressed age-associated changes not only in the period and strength of free-running locomotor rhythms but also in the amplitude of TIM oscillations in many pacemaker neurons in the elder flies, suggesting that the age-dependent PDF decline is responsible for the rhythm attenuation. These results suggest that the age-associated reduction of PDF may cause attenuation of intercellular communication in the circadian neuronal network and of TIM cycling, which may result in the age-related rhythm decay.