Bioactivity Potential of Aesculus hippocastanum L. Flower: Phytochemical Profile, Antiradical Capacity and Protective Effects on Human Plasma Components under Oxidative/Nitrative Stress In Vitro

Horse chestnut (Aesculus hippocastanum) flower is a traditional medicine applied to alleviate symptoms of chronic venous insufficiency (CVI). However, its flavonoid-based composition has not been sufficiently recognized, and the data supporting its traditional application are lacking. In the work, 43 constituents were detected by UHPLC-PDA-ESI-TQ-MS/MS (flavonoids, phenolic acids, flavanols, and coumarins), including 31 reported in the flower for the first time. The quantitative HPLC-PDA study (developed and validated for quality control purposes) indicated the fractionated extraction as an efficient method for enhancing the total polyphenol content (TPHC) in the extracts (up to 414.06 mg/g) and kaempferol glycosides as their dominant constituents (75.05-82.14% TPHC). The activity studies showed significant scavenging properties of the extracts and their constituents towards reactive oxygen species (especially against highly reactive hydroxyl radical, with capacities up to 7.85 mmol ascorbic acid equivalents/g). Moreover, the analytes relevantly protected human plasma biomolecules from peroxynitrite-induced oxidative/nitrative damage; at 1-50 µg/mL, they hindered the protein nitration and lipid peroxidation, decreasing the levels of 3-nitrotyrosine (by up to 50%) and thiobarbituric acid reactive substances (by up to 70%), respectively. The extracts also averted the depletion of plasma thiols (by up to 67%) and improved the non-enzymatic antioxidant capacity of plasma. The demonstrated mechanisms might be partly responsible for the efficacy of the flower in CVI. Additionally, the anti-aggregatory and anticoagulant properties of the extracts were found only mild or negligible, which suggests that they may be safely applied with drugs impacting the coagulation process.

Potential Activity Mechanisms of Aesculus hippocastanum Bark: Antioxidant Effects in Chemical and Biological In Vitro Models

The bark of Aesculus hippocastanum is an herbal remedy used in conditions connected with vascular insufficiency; however, there is a lack of data concerning its mechanisms of action. The present work is a preliminary investigation into some of the potential directions of the bark activity. The phytochemically (qualitative UHPLC-PDA-MS/MS and quantitative UHPLC-PDA assays) characterized extract and its four main constituents (esculin, fraxin, (‒)-epicatechin and procyanidin A2) were first evaluated in terms of their antioxidant capacity. All analytes demonstrated dose-dependent scavenging potential towards the most common in vivo oxidants, with particularly advantageous capacity of the extract and its flavan-3-ol constituents against peroxynitrite (3.37–13.26 mmol AA/g), hydroxyl radical (5.03–8.91 mmol AA/g) and superoxide radical (3.50–5.50 mmol AA/g). Moreover, even at low concentrations (1–5 µg/mL), they protected components of human plasma against oxidative damage inflicted by peroxynitrite, preventing oxidation of plasma protein thiols and diminishing the tyrosine nitration and lipid peroxidation. High efficiency of the analytes was also demonstrated in preventing the peroxynitrite-induced nitrative changes of fibrinogen (up to 80% inhibition for (‒)-epicatechin at 50 µg/mL), an important protein of coagulation cascade. Additionally, the extract and its constituents had, at most, moderate inhibitory activity towards platelet aggregation induced by ADP and only negligible influence on clotting times. The results show that, among the investigated properties, the antioxidant activity might, to the highest extent, be responsible for the bark efficacy in vascular disorders, thus supporting its application in those conditions; they also indicate the directions for future research that would allow for better understanding of the bark activity.

Why Venous Leg Ulcers Have Difficulty Healing: Overview on Pathophysiology, Clinical Consequences, and Treatment

Venous leg ulcers (VLUs) are one of the most common ulcers of the lower extremity. VLU affects many individuals worldwide, could pose a significant socioeconomic burden to the healthcare system, and has major psychological and physical impacts on the affected individual. VLU often occurs in association with post-thrombotic syndrome, advanced chronic venous disease, varicose veins, and venous hypertension. Several demographic, genetic, and environmental factors could trigger chronic venous disease with venous dilation, incompetent valves, venous reflux, and venous hypertension. Endothelial cell injury and changes in the glycocalyx, venous shear-stress, and adhesion molecules could be initiating events in VLU. Increased endothelial cell permeability and leukocyte infiltration, and increases in inflammatory cytokines, matrix metalloproteinases (MMPs), reactive oxygen and nitrogen species, iron deposition, and tissue metabolites also contribute to the pathogenesis of VLU. Treatment of VLU includes compression therapy and endovenous ablation to occlude the axial reflux. Other interventional approaches such as subfascial endoscopic perforator surgery and iliac venous stent have shown mixed results. With good wound care and compression therapy, VLU usually heals within 6 months. VLU healing involves orchestrated processes including hemostasis, inflammation, proliferation, and remodeling and the contribution of different cells including leukocytes, platelets, fibroblasts, vascular smooth muscle cells, endothelial cells, and keratinocytes as well as the release of various biomolecules including transforming growth factor-β, cytokines, chemokines, MMPs, tissue inhibitors of MMPs (TIMPs), elastase, urokinase plasminogen activator, fibrin, collagen, and albumin. Alterations in any of these physiological wound closure processes could delay VLU healing. Also, these histological and soluble biomarkers can be used for VLU diagnosis and assessment of its progression, responsiveness to healing, and prognosis. If not treated adequately, VLU could progress to non-healed or granulating VLU, causing physical immobility, reduced quality of life, cellulitis, severe infections, osteomyelitis, and neoplastic transformation. Recalcitrant VLU shows prolonged healing time with advanced age, obesity, nutritional deficiencies, colder temperature, preexisting venous disease, deep venous thrombosis, and larger wound area. VLU also has a high, 50-70% recurrence rate, likely due to noncompliance with compression therapy, failure of surgical procedures, incorrect ulcer diagnosis, progression of venous disease, and poorly understood pathophysiology. Understanding the molecular pathways underlying VLU has led to new lines of therapy with significant promise including biologics such as bilayer living skin construct, fibroblast derivatives, and extracellular matrices and non-biologic products such as poly-N-acetyl glucosamine, human placental membranes amnion/chorion allografts, ACT1 peptide inhibitor of connexin 43, sulodexide, growth factors, silver dressings, MMP inhibitors, and modulators of reactive oxygen and nitrogen species, the immune response and tissue metabolites. Preventive measures including compression therapy and venotonics could also reduce the risk of progression to chronic venous insufficiency and VLU in susceptible individuals.

Effects of the oxidative stress and genetic changes in varicose vein patients

Background

Etiology of the varicose veins is still partly known. It has been proposed that varicose veins formation might be a cause of the oxidative stress and/or cause from genetical reasons.

Method

The levels of antioxidant defense system enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and an oxidative stress indicator, malondialdehyde, were measured in saphenous vein samples of varicose veins patients. Additionally, genetical polymorphism of glutathione S-transferase theta-1 has been studied.

Result

In this study, measurements revealed significant increase in catalase and malondialdehyde levels in the patient group, whereas superoxide dismutase and glutathione peroxidase and glutathione S-transferase enzyme activity and comparison of the null mutation frequency in the glutathione S-transferase theta-1 gene did not show a statistically significant difference.

Conclusion

We propose that the increase in catalase and malondialdehyde activities in our patient group may be related to each other. Increase in catalase levels, an antioxidant enzyme might be a compensatory response to the increase in malondialdehyde levels, an oxidative molecule.

Protease activity as a prognostic factor for wound healing in venous leg ulcers

BACKGROUND

Venous leg ulcers (VLUs) are a common type of complex wound that have a negative impact on people's lives and incur high costs for health services and society. It has been suggested that prolonged high levels of protease activity in the later stages of the healing of chronic wounds may be associated with delayed healing. Protease modulating treatments have been developed which seek to modulate protease activity and thereby promote healing in chronic wounds.

OBJECTIVES

To determine whether protease activity is an independent prognostic factor for the healing of venous leg ulcers.

SEARCH METHODS

In February 2018, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid Embase and CINAHL.

SELECTION CRITERIA

We included prospective and retrospective longitudinal studies with any follow-up period that recruited people with VLUs and investigated whether protease activity in wound fluid was associated with future healing of VLUs. We included randomised controlled trials (RCTs) analysed as cohort studies, provided interventions were taken into account in the analysis, and case-control studies if there were no available cohort studies. We also included prediction model studies provided they reported separately associations of individual prognostic factors (protease activity) with healing. Studies of any type of protease or combination of proteases were eligible, including proteases from bacteria, and the prognostic factor could be examined as a continuous or categorical variable; any cut-off point was permitted. The primary outcomes were time to healing (survival analysis) and the proportion of people with ulcers completely healed; the secondary outcome was change in ulcer size/rate of wound closure. We extracted unadjusted (simple) and adjusted (multivariable) associations between the prognostic factor and healing.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage, and undertook data extraction, assessment of risk of bias and GRADE assessment. We collected association statistics where available. No study reported adjusted analyses: instead we collected unadjusted results or calculated association measures from raw data. We calculated risk ratios when both outcome and prognostic factor were dichotomous variables. When the prognostic factor was reported as continuous data and healing outcomes were dichotomous, we either performed regression analysis or analysed the impact of healing on protease levels, analysing as the standardised mean difference. When both prognostic factor and outcome were continuous data, we reported correlation coefficients or calculated them from individual participant data.We displayed all results on forest plots to give an overall visual representation. We planned to conduct meta-analyses where this was appropriate, otherwise we summarised narratively.

MAIN RESULTS

We included 19 studies comprising 21 cohorts involving 646 participants. Only 11 studies (13 cohorts, 522 participants) had data available for analysis. Of these, five were prospective cohort studies, four were RCTs and two had a type of case-control design. Follow-up time ranged from four to 36 weeks. Studies covered 10 different matrix metalloproteases (MMPs) and two serine proteases (human neutrophil elastase and urokinase-type plasminogen activators). Two studies recorded complete healing as an outcome; other studies recorded partial healing measures. There was clinical and methodological heterogeneity across studies; for example, in the definition of healing, the type of protease and its measurement, the distribution of active and bound protease species, the types of treatment and the reporting of results. Therefore, meta-analysis was not performed. No study had conducted multivariable analyses and all included evidence was of very low certainty because of the lack of adjustment for confounders, the high risk of bias for all studies except one, imprecision around the measures of association and inconsistency in the direction of association. Collectively the research indicated complete uncertainty as to the association between protease activity and VLU healing.

AUTHORS' CONCLUSIONS

This review identified very low validity evidence regarding any association between protease activity and VLU healing and there is complete uncertainty regarding the relationship. The review offers information for both future research and systematic review methodology.

Plasma concentration of selected biochemical markers of endothelial dysfunction in women with various severity of chronic venous insufficiency (CVI)-A pilot study

BACKGROUND

Although the endothelial dysfunction is considered to be implicated in the pathogenesis of chronic venous insufficiency (CVI) the endothelial status in patients with venous disorders is still not fully evaluated. Therefore the aim of the study was to measure the concentration of selected markers of endothelial dysfunction: von Willebrand factor (vWf), soluble P-selectin (sP-selectin), soluble thrombomodulin (sTM) and soluble VE-cadherin (sVE-cadherin) in CVI women who constitute the most numerous group of patients suffering from venous disease.

MATERIALS AND METHODS

Forty four women with CVI were involved in the study and divided into subgroups based on CEAP classification. Concentration of vWf, sP-selectin, sTM and sVE-cadherin were measured and compared with those obtained in 25 healthy age and sex-matched women.

RESULTS

It was found that the concentration of sTM increased and sVEcadherin decreased along with disease severity in CVI women. A significant rise of sTM was observed especially in CVI women, with the highest inflammation status reflected by hsCRP or elastase concentration, and in CVI women with a high oxidative stress manifested by an increased plasma MDA. A significant fall of circulating sVE-cadherin was reported in CVI women with moderate to highest intensity of inflammation and oxidative stress. There was no change in vWF and sP-selectin concentration at any stage of CVI severity.

CONCLUSIONS

The results of the present study demonstrate the presence of endothelial dysfunction in women suffering from CVI which seems to progress with the disease severity and may be associated with inflammation and enhanced oxidative stress.

Oxidative stress and antioxidant strategies in dermatology

Oxidative stress results from a prooxidant-antioxidant imbalance, leading to cellular damage. It is mediated by free radicals, such as reactive oxygen species or reactive nitrogen species, that are generated during physiological aerobic metabolism and pathological inflammatory processes. Skin serves as a protective organ that plays an important role in defending both external and internal toxic stimuli and maintaining homeostasis. It is becoming increasingly evident that oxidative stress is involved in numerous skin diseases and that antioxidative strategies can serve as effective and easy methods for improving these conditions. Herein, we review dysregulated antioxidant systems and antioxidative therapeutic strategies in dermatology.

Ageing is a process where the growth effect of neuronal noradrenaline changes progressively in favour of the flow mediated, neurodegenerative and inflammatory effect of plasma noradrenaline

The noradrenaline stimulus has two components, one excitor, the other inhibitory. Neuronal noradrenaline is the excitor component and plasma noradrenaline is the inhibitory. The balance of effect between the two, the noradrenergic balance, is the controlled variable of the sympathetic system and determines the effect of noradrenaline. Neuronal noradrenaline stimulates tissues by diffusion from their sympathetic nerve endings, plasma noradrenaline does so by diffusion from their microcirculations. Changes in microcirculatory flow, by altering the flow mediated effect of plasma noradrenaline, are mainly responsible for altering the noradrenergic balance in the peripheral tissues; changes in CSF flow are speculated to be mainly responsible for doing the same in the brain, by altering the balance between synaptic noradrenaline in the brain and nonsynaptic noradrenaline in the subarachnoid CSF. When plasma noradrenaline alters the noradrenergic balance it triggers afferent sympathetic activity that alerts hypothalamic neurons to the event and they restore the balance and tissue homeostasis, within milliseconds, by adjusting the level of efferent sympathetic activity they project back to the affected tissue. Because the restoration is so rapid the effect of plasma noradrenaline is normally unobservable and dismissed as not having occurred. Because the hypothalamus is not involved with the responses of isolated canine lateral saphenous vein segments to noradrenaline, the effects of plasma noradrenaline in that preparation are not countered by reactive efferent activity and, consequently, are readily apparent in it. Quantitatively, they have been found to be a function of microcirculatory flow and noradrenaline concentration and, qualitatively, to be inhibitory, dilator, pro inflammatory and neurodegenerative. In life, due to a progressive increase in plasma noradrenaline concentration and, more so, in microcirculatory flow, the noradrenergic balance moves progressively in favour of the neurodegenerative and inflammatory effects of plasma noradrenaline. These observations are the basis of an hypothesis that ageing is caused by a genetically programmed shift in balance away from the growth and anti-inflammatory effects of neuronal noradrenaline, early in life, towards the neurodegenerative and pro-inflammatory effects of plasma noradrenalin, later in life. Death is believed to occur when plasma noradrenaline has damaged the structure of the sympathetic system so much that it can no longer create the minimum quantity of neurotransmitter needed to maintain the level of noradrenergic balance and homeostasis necessary for life.

Telomere shortening and increased oxidative stress are restricted to venous tissue in patients with varicose veins: A merely local disease?

Shortened telomere length (TL) and oxidative stress have been described in several vascular disorders at both the tissue and circulating level. However, to our knowledge, there are no reports about TL associated with varicose vein (VV) disease. This paper aimed to evaluate, at the tissue and circulating level, TL and oxidative stress in VV disease, compared to the corresponding counterparts from abdominal aortic aneurysm (AAA) patients and control healthy subjects. TL was measured using quantitative fluorescence in situ hybridization (Q-FISH). Oxidative stress was evaluated by measuring the malondialdehyde (MDA) concentration by thiobarbituric acid reactive substance/s (TBARS) assay. At the vascular tissue level, VV patients had shortened TL and a high MDA concentration, similarly to AAA patients. Conversely, blood lymphocytes and epidermal cells from VV patients had a TL similar to healthy controls and significantly longer than the same cells from AAA patients. Moreover, the MDA concentration in plasma from VV patients was significantly lower than from the AAA group. Linear regression analysis showed a statistically significant inverse correlation between the blood lymphocyte TL and plasma MDA level. Our results suggest that, unlike AAA, telomere attrition in VV tissue is not a systemic phenomenon but it may be attributable to tissue microenvironment conditions and possibly to high local oxidative stress.

A plasma oxidative stress global index in early stages of chronic venous insufficiency

BACKGROUND

Chronic venous insufficiency (CVI) represents a social and health care problem because it affects working age populations, particularly in jobs requiring orthostasis, has no effective pharmacologic treatment, and requires surgery. Oxidative stress is present in varicose veins, but whether this is reflected in the plasma is controversial. We aimed to quantify plasma oxidative stress biomarkers in the early stages of CVI and calculate a global index of oxidative stress representative of the disease.

METHODS

Plasma was obtained from blood samples of nine patients with CEAP C2 stage CVI and 10 healthy controls. Biomarkers related to antioxidant defense systems (total thiols, reduced glutathione, uric acid, total antioxidant capacity, catalase), oxidative damage (malondialdehyde-bound protein, protein carbonyls, advanced oxidation products, and 3-nitrotyrosine), and activity of enzymes producing key free radicals (xanthine oxidase and myeloperoxidase) were assessed.

RESULTS

Compared with the controls, CVI patients exhibited decreased catalase activity and thiol levels and increased malondialdehyde-bound protein and protein carbonyls. These parameters were used to calculate the global index of oxidative stress in CVI, which was significantly different between groups.

CONCLUSIONS

It is possible to detect significant changes in plasma oxidative stress biomarkers in early stages of CVI and to calculate a global index representative of the oxidative status in an individual. This index, with the appropriate validation in a larger population, could be used for early detection or progression of CVI.

Serum iron concentration and plasma oxidant-antioxidant balance in patients with chronic venous insufficency

Background

The aim of this study was to evaluate serum iron concentration and influence of this element on biomarkers of oxidative stress in patients affected by chronic venous insufficiency (CVI).

Material/Methods

Serum iron (SI) concentration and plasma parameters of oxidant–antioxidant balance (i.e., malonyldialdehyde [MDA], uric acid [UA] concentration, and total antioxidant capacity [TAC]) were compared between 35 patients divided into appropriate groups and 23 healthy individuals.

Results

The subgroups analysis showed that SI concentration was significantly higher only in patients with shorter duration of CVI in comparison with the control group (P=0.013). Significant, negative correlation was found between SI concentration and duration of the disease (r=−0.422, P=0.014), age of the patients (r=−0.542, P=0.001) and BMI (r=−0.408, P=0.018). Mean value of MDA concentration and TAC capacity were higher in patients with CVI in comparison with healthy individuals (P<0.05). UA concentration was decreased, especially in CVI patients with mild clinical stage of disease and shorter CVI duration (P=0.047; P=0.034). There was no significant correlation found between SI concentration and the parameters of oxidant–antioxidant balance.

Conclusions

High concentration of MDA and low UA level in blood of CVI patients suggests that oxidative stress plays an important role in the pathogenesis of the disease. The increase in SI concentration observed in the early stage of CVI can enhance free radicals formation; however, direct evidence has not been provided by the present study.

In vitro effect of calcium dobesilate on oxidative/inflammatory stress in human varicose veins

AIM

To determine whether calcium dobesilate can act in chronic venous insufficiency by similar antioxidant, anti-inflammatory mechanisms as in diabetic retinopathy.

METHODS

Calcium dobesilate was tested in vitro for its protective action against oxidative/inflammatory stress in human varicose veins. Varicose greater saphenous veins were obtained from 14 patients (11 men, 3 women) aged 53-65 years. Oxidative stress was induced exogenously in the vein segments, with the phenazine methosulphate (PMS)/NADH couple. Total antioxidant status (TAS) and malondialdehyde (MDA) contents were used as markers of oxidative stress.

RESULTS

Calcium dobesilate significantly prevented oxidative disturbances in the micromolar range. PMS/NADH-dependent TAS decrease was fully prevented with IC(50) = 11.4 ± 2.3 µmol/L (n = 6 veins), whereas MDA increase was fully prevented with IC(50) = (102 ± -3) µmol/L (n = 6 veins). Calcium dobesilate acted quali- and quantitatively like rutin, the reference compound. Comparison with pharmacokinetic data suggests that calcium dobesilate can act at therapeutic concentrations.

CONCLUSION

Calcium dobesilate protected human varicose veins against oxidative stress in vitro at levels that correspond to therapeutic concentrations. Further studies are required to investigate whether a similar action is found in varicose veins from patients orally treated with calcium dobesilate.

Epidemiology and aetiology of C4-6 disease

Although our understanding of chronic venous insufficiency (CVI) has improved, many important questions remain unanswered. Ensuring that patients are appropriately referred for specialist assessment and then receive evidence-based, cost-effective treatment continues to be challenging. The lifetime of risk of chronic venous ulceration (CVU) is around 1% with approximately 10% ulcers being open at any one time. The incidence skin changes disease is about 10 times greater (10%). However, many of the studies upon which these estimates are based are old and/or methodologically flawed. There is reason to believe that the incidence, prevalence and characteristics of CVI/CVU may have changed considerably over the last 10-20 years and that future change is likely. Further cross-sectional and longitudinal epidemiological studies are required to establish the size and nature of the health-care need going forward in developed and increasingly developing countries. CVI culminating CVU is primarily the result of sustained ambulatory venous hypertension, which in turn arises from superficial and/or deep venous reflux with or without deep vein obstruction. However, there are many other elements to this complex condition, for example, microvascular dysfunction; calf muscle pump efficiency; dermal inflammation; disordered fibroblast function and matrix production; failure of epithelialization; congenital and acquired thrombophilia; malnutrition, obesity and diet; and bacterial colonization. None of the currently available treatment modalities is entirely satisfactory and novel therapies based upon a clearer understanding of the disease at the psychological, genetic, mechanical, microvascular and microscopic level are required.