Inhibitory effect of Scutia buxifolia extracts, fractions, and ursolic acid on Na(+), K(+)-ATPase activity in vitro in membranes purified from rat hearts

Antibiotic Combination Therapy: A Strategy to Overcome Bacterial Resistance to Aminoglycoside Antibiotics

After the first aminoglycoside antibiotic streptomycin being applied in clinical practice in the mid-1940s, aminoglycoside antibiotics (AGAs) are widely used to treat clinical bacterial infections and bacterial resistance to AGAs is increasing. The bacterial resistance to AGAs is owed to aminoglycoside modifying enzyme modification, active efflux pump gene overexpression and 16S rRNA ribosomal subunit methylation, leading to modification of AGAs' structures and decreased concentration of drugs within bacteria. As AGAs's side effects and bacterial resistance, the development of AGAs is time-consuming and difficult. Because bacterial resistance may occur in a short time after application in clinical practice, it was found that the antibacterial effect of the combination was not only better than that of AGAs alone but also reduce the dosage of antibiotics, thereby reducing the occurrence of side effects. This article reviews the clinical use of AGAs, the antibacterial mechanisms, the molecular mechanisms of bacterial resistance, and especially focuses a recent development of the combination of AGAs with other drugs to exert a synergistic antibacterial effect to provide a new strategy to overcome bacterial resistance to AGAs.

Impact of drying processes on Bryophyllum pinnatum phenolic constituents and its anti-inflammatory and antioxidative activities in human erythrocytes

The effect of drying on the phytoconstituents, antioxidative, and anti-inflammatory properties of Bryophyllum pinnatum leaves was investigated. The phenolic constituents were characterized using HPLC-DAD. The aqueous extraction was done and various assays (Inhibition of membrane stabilization, albumin Denaturation and heat-induced hemolysis, malondialdehyde (MDA), and reduced glutathione (GSH) contents, as well as superoxide dismutase (SOD) activity), were carried out on human erythrocytes. The fresh portion (89.12 µg/ml) exhibited the highest potential to inhibit heat-induced hemolysis compared to the standard drug-Diclofenac (91.51 µg/ml). Freeze-dried sample showed the highest inhibitory potential on albumin denaturation ([Freeze-dried-330.72 µg/ml], [Diclofenac-318.63 µg/ml]) and membrane destabilization ([Freeze-dried-331.93 µg/ml], [Diclofenac-289.57 µg/ml]) when compared with Diclofenac. Similarly, the freeze-dried sample showed the highest GSH and SOD level and lowest MDA level when human erythrocytes challenged with tertiary butyl hydroperoxide (tBHP) were treated with the extract. This study confirms the retention of a considerable quantity of bioactive constituents of plants when freeze-dried. PRACTICAL APPLICATIONS: The ideal method of drying Bryophyllum pinnatum and possible anti-inflammatory potential was investigated. This work may apply to the development of anti-inflammatory agents from a natural source with little or no side effect in managing inflammation.

In vitro antioxidant activities and inhibitory effects of phenolic extract of Senecio biafrae (Oliv and Hiern) against key enzymes linked with type II diabetes mellitus and Alzheimer's disease

The phenolic extract of Senecio biafrae leaves was investigated to determine the in vitro antioxidant, phenolic profiles, and inhibition of key enzymes relevant to type II diabetes mellitus (α-amylase and α-glucosidase) and Alzheimer's disease (acetylcholinesterase and butrylcholinesterase). The phenolic extract demonstrated significant scavenging abilities against all in vitro antioxidant parameters assessed. Reversed-phase HPLC of the extract revealed the presence of gallic acid, chlorogenic, caffeic acid, rutin, quercetin, and kaempferol. The extract also inhibited activities of α-amylase (IC 50 = 126.90 μg/ml), α-glucosidase (IC 50 = 139.66 μg/ml), acetylcholinesterase (IC 50 = 347.22 μg/ml), and butrylcholinesterase (IC 50 = 378.79 μg/ml), which may be attributed to the antioxidant potential of the extract and its phenolic composition. Therefore, this study suggests that the leaves of S. biafrae may be useful in the management of diabetes mellitus and Alzheimer's disease.

Quercetin treatment regulates the Na+,K+-ATPase activity, peripheral cholinergic enzymes, and oxidative stress in a rat model of demyelination

Quercetin is reported to exert a plethora of health benefits through many different mechanisms of action. This versatility and presence in the human diet has attracted the attention of the scientific community, resulting in a huge output of in vitro and in vivo (preclinical) studies. Therefore, we hypothesized that quercetin can protect Na⁺,K⁺-ATPase activity in the central nervous system, reestablish the peripheral cholinesterases activities, and reduce oxidative stress during demyelination events in rats. In line with this expectation, our study aims to find out how quercetin acts on the Na⁺,K⁺-ATPase activity in the central nervous system, peripheral cholinesterases, and stress oxidative markers in an experimental model of demyelinating disease. Wistar rats were divided into 4 groups: vehicle, quercetin, ethidium bromide (EB), and EB plus quercetin groups. The animals were treated once a day with vehicle (ethanol 20%) or quercetin 50 mg/kg for 7 (demyelination phase, by gavage) or 21 days (remyelination phase) after EB (0.1%, 10 μL) injection (intrapontine).The encephalon was removed, and the pons, hypothalamus, cerebral cortex, hippocampus, striatum, and cerebellum were dissected to verify the Na⁺,K⁺-ATPase activity. Our results showed that quercetin protected against reduction in Na⁺,K⁺-ATPase in the pons and cerebellum in the demyelination phase, and it increased the activity of this enzyme in the remyelination phase. During the demyelination, quercetin promoted the increase in acetylcholinesterase activity in whole blood and lymphocytes induced by EB, and it reduced the increase in acetylcholinesterase activity in lymphocytes in the remyelination phase. On day 7, EB increased the superoxide dismutase and decreased catalase activities, as well as increased the thiobarbituric acid-reactive substance levels. Taken together, these results indicated that quercetin regulates the Na⁺,K⁺-ATPase activity, affects the alterations of redox state, and participates in the reestablishment of peripheral cholinergic activity during demyelinating and remyelination events.

Topical antiedematogenic and anti-inflammatory effect of Scutia buxifolia Reissek gel and stability study

Scutia buxifolia Reissek (Rhamnaceae), popularly known in Brazil as "coronilha", is a plant species used in folk medicine for several disorders, including inflammation. However, no studies have been done with this species to confirm its topical anti-inflammatory action. In this study we evaluate the topical antiedematogenic and anti-inflammatory effects of the gel containing crude extract (CE) and the gel containing ethyl acetate (EtOAc) fraction of S. buxifolia on croton oil or UVB radiation-induced ear edema in mice, and perform gel stability study. Antiedematogenic and anti-inflammatory effects were evaluated through ear edema induced by irritant agent croton oil, UVB irradiation-induced skin injury model and neutrophil infiltration. The gel stability study was performed by analyzing organoleptical aspects, pH, viscosity, and quantification of quercetin and rutin by HPLC. The topical treatment with S. buxifolia gel reduced the ear edema and myeloperoxidase activity. Antiedematogenic and anti-inflammatory effects of S. buxifolia were obtained with concentrations of 0.3, 1 and 3%, with maximal inhibition in the concentration of 1% for gel containing CE (inhibitions of 100, 73±0.05 and 97±0.08% for croton oil- or UVB irradiation-induced ear edema and myeloperoxidase activity, respectively) and EtOAc fraction (inhibitions of 79±0.05, 73±0.05 and 89±0.04% for croton oil- or UVB irradiation-induced ear edema and myeloperoxidase activity, respectively). Such effects may be attributed, at least in part, to rutin and quercetin, as well as other compounds found in this species. No important changes were detected in the stability study, in all aspects analyzed in temperature below 25°C. Our results demonstrate that topically applied S. buxifolia gel presented anti-inflammatory effects, provided that it was maintained at a temperature below 25°C.