Antioxidant activity of Flemingia praecox and Mucuna pruriens and their implications for male fertility improvement

Globally, 15-24% couples are unable to conceive naturally and 50% of cases of this problem are due to infertility in males. Of this, about 50% of male infertility problems are developed due to unknown reasons called as idiopathic infertility. It is well established that, reactive oxygen species (ROS) have negative impact on male fertility and are involved in 80% of total idiopathic male infertility cases. Medicinal plants are considered as an alternative approach for mitigating the health problems. The plants with good antioxidant capacity can improve the male infertility symptoms generated by ROS. Such medicinal plants can be used to alleviate the symptoms of male infertility with their diverse phytoconstituents. Mucuna pruriens is a well-accepted herb, with its seeds being used to improve the male fertility in various ways and one of the ways is by eliminating the ROS. In our field survey, another plant, Flemingia praecox, although less known, its roots are used in all problems related to the male fertility by tribal people of the Gadchiroli district of Maharashtra, India. The study was conducted to determine in vitro antioxidant potential of F. praecox and compared the results with the well-established male fertility improving plant M. pruriens with special emphasis on medicinally important roots of F. praecox and seeds of M. pruriens. The objective of the study was investigated by studying their total phenol (TPC) and flavonoid (TFC) content, antioxidant parameters (DPPH, FRAP, ABTS, DMPD, β-carotene bleaching and TAA) and finally DNA damage protection capacity of the plant extracts was studied. The plant parts used for the medicinal purposes have been investigated along with other major parts (leaves, stem and roots of both the plants) and compared with synthetic antioxidants, BHA, BHT and ascorbic acid. Moreover, the inhibition of two male infertility enzyme markers, PDE5 and arginase by F. praecox root and M. pruriens seed extract was also studied in vitro. The results showed that F. praecox possesses higher antioxidant activity than M. pruriens in the majority of studies as observed in TFC, DPPH, TAA, ABTS and DMPD assays. However, M. pruriens seeds showed best results in TPC, FRAP and DNA damage protection assay. F. praecox root extract also gave better PDE5 inhibition value than M. pruriens seeds. This study will help to establish the authenticity of F. praecox used by tribal people and will encourage its further use in managing the male infertility problems.

Role of Erythrocytes in Nitric Oxide Metabolism and Paracrine Regulation of Endothelial Function

Emerging studies provide new data shedding some light on the complex and pivotal role of red blood cells (RBCs) in nitric oxide (NO) metabolism and paracrine regulation of endothelial function. NO is involved in the regulation of vasodilatation, platelet aggregation, inflammation, hypoxic adaptation, and oxidative stress. Even though tremendous knowledge about NO metabolism has been collected, the exact RBCs’ status still requires evaluation. This paper summarizes the actual knowledge regarding the role of erythrocytes as a mobile depot of amino acids necessary for NO biotransformation. Moreover, the complex regulation of RBCs’ translocases is presented with a particular focus on cationic amino acid transporters (CATs) responsible for the NO substrates and derivatives transport. The main part demonstrates the intraerythrocytic metabolism of L-arginine with its regulation by reactive oxygen species and arginase activity. Additionally, the process of nitrite and nitrate turnover was demonstrated to be another stable source of NO, with its reduction by xanthine oxidoreductase or hemoglobin. Additional function of hemoglobin in NO synthesis and its subsequent stabilization in steady intermediates is also discussed. Furthermore, RBCs regulate the vascular tone by releasing ATP, inducing smooth muscle cell relaxation, and decreasing platelet aggregation. Erythrocytes and intraerythrocytic NO metabolism are also responsible for the maintenance of normotension. Hence, RBCs became a promising new therapeutic target in restoring NO homeostasis in cardiovascular disorders.

Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals

INTRODUCTION

Up to 50% of all men over 50 years of age suffer from erectile dysfunction. Since the late 1990s erectile dysfunction has been treated mostly with phosphodiesterase 5 inhibitors (PDE5I). Over the past 20 years, numerous scientific findings on the development of erectile dysfunction have been collected, which have so far received little attention in the treatment of erectile dysfunction.

OBJECTIVES

The objectives of this study were to review the existing medical literature on erectile dysfunction regarding physiology, pathophysiology, and especially therapeutic options beyond treatment with PDE5I and to enable a more effective and especially sustainable treatment for erectile dysfunction.

METHODS

A literature review was performed by using PubMed from 1985 to 2020 regarding the physiology, pathophysiology, and treatment of erectile dysfunction.

RESULTS

Since the end of the 1990s an enormous amount of knowledge has been gained about the physiology/pathophysiology of erection/erectile dysfunction. Based on these findings, numerous physical, drug, and holistic therapeutic options (beyond the application of PDE5I) have been developed for the treatment of erectile dysfunction. However, these are still relatively rarely used in the therapeutic concept of erectile dysfunction today.

CONCLUSION

Based on scientific findings of the last 20 years, there are numerous therapeutic approaches, including lifestyle modification, specific pelvic floor exercises, shock wave treatment, and the application of different supplements. The long-term treatment of erectile dysfunction should now go beyond the purely symptomatic use of PDE5I. W-D Beecken, M Kersting, W Kunert, et al. Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals. Sex Med Rev 2021;9:445-463.

Serum adropin as a predictive biomarker of erectile dysfunction in coronary artery disease patients

Introduction

Erectile dysfunction (ED) is associated with various comorbidities and an early diagnosis and treatment is necessary to avoid the development of these comorbidities. Unfortunately, there is no biochemical marker that can be used for early diagnosis of ED. Nitric oxide (NO) is released by nerve and endothelial cells in the corpora cavernosa of the penis and is believed to be the main vasoactive chemical mediator of penile erection. Adropin is a regulatory peptide which has effects on NO bioavailability and energy homeostasis. We hypothesized that adropin may contribute to the pathogenesis of ED because of the presence of both metabolic effects and the influence on NO bioavailability. To confirm this hypothesis, we investigated the relationship between ED and serum adropin and NO levels.

Material and methods

Seventy-five ED patients were enrolled for this study and the patients were divided into two groups according to angiographic scoring. Serum NO and adropin levels were measured by the Griess reaction and ELISA method, respectively.

Results

Serum adropin and NO levels were found to be lower in the group which has higher angiographic score and the difference in NO was statistically significant. Also, adropin has a significant correlation between IIEF scores in ED patients.

Conclusions

This is the first study in the literature investigating the levels of adropin in ED patients having coronary artery disease. The adropin molecule shows a promising future in clarifying the etiopathogenesis of ED. More comprehensive and multicenter studies are needed to reveal the role of adropin in ED and the effects of treatment on this molecule.

Aqueous extract of Lespedeza cuneata improves male menopause by increase of nitric oxide and dihydrotestosterone

This study aimed to evaluate the effect of aqueous extract of Lespedeza cuneata (ALC) on men menopause induced erectile dysfunction (ED) and testosterone deficiency syndrome (TDS) in vitro and in vivo. Nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) have been fundamental factors of ED, and free testosterone such as dihydrotestosterone (DHT) has a crucial role in mitigation of TDS. ALC increased the production of NO in a dose-dependent manner in vitro and in vivo. The level of neuronal nitric oxide synthase and cGMP was increased in the ALC group. The level of DHT and 17-beta hydroxysteroid dehydrogenases (17β-HSD) was also increased in the ALC group. There was no significant change of hepatotoxicity, renal toxicity, lipid metabolism, and glucose. These results suggest that ALC enhanced NO, cGMP and free testosterone which could be developed as a health supplement for improving male menopause.

Treatment effect of l-Norvaline on the sexual performance of male rats with streptozotocin induced diabetes

Sexual impairment is an established risk factor in diabetes mellitus affecting about 75% of male diabetic population. In diabetes overexpression of arginase leads to decreased production of NO and diminished erectile response. Inhibition of arginase enzyme can lead to improvement in diabetes induced sexual dysfunction. In the present study diabetes mellitus was induced in adult male rats by intraperitoneal injection of single dose of streptozotocin (65mg/kg) in 0.1M Citrate buffer pH 4.5 and after 72h fasting serum glucose level was checked by glucose oxidase-peroxidase method and those animals showing FSG above 250mg/dl were selected. Diabetic animals were divided into four groups comprising six animals in each. l-Norvaline, potent arginase inhibitor was administered at a dose of 10mg/kg ip to the different groups of diabetic animals for a period of 30 days. Sildenafil at a dose of 5mg/kg orally was used as a standard drug. Mating behavior tests were performed at 0, 15th and 30th days. After 30 days, various biochemical and hormonal parameters (nitrates, LDH, urea, testosterone), testicular parameters (total protein, nitrates, LDH, total cholesterol, LDL, triglycerides, VLDL, HDL) were evaluated to find out the effect of l-Norvaline in sexual impairment. Sperm analysis was also carried out for the treated rats. l-Norvaline showed significant improvement in serum nitrates, urea, LDH, testosterone and testicular protein level as compared with diabetic group. It also improved sperm motility, count and viability in diabetic rats. Sildenafil showed no improvement in above parameters except restoration in serum nitrates level.

Effects of Two Different Dosages of Sildenafil on Patients With Erectile Dysfunction

To investigate the effects of two different dosages of sildenafil on patients with erectile dysfunction (ED), a total of 3,674 patients with ED were recruited to answer questionnaires designed specifically for this study. There were 977 patients in the 50 mg group and there were 2,697 patients in the 100 mg group. Both 50 mg and 100 mg of sildenafil therapy increased the ED patients' average monthly frequency of sexual intercourse, improved erectile function state in self-assessment, and elevated sexual satisfaction and enjoyment. Despite a higher rate of concomitant diseases, patients in the higher dosage of sildenafil group had a better outcome in the average monthly frequency of sexual intercourse and sexual enjoyment compared with those in the lower dosage. Such a study might be helpful for health care providers to choose sildenafil dosage for patients with ED.

Nitric oxide inhibition strategies

Nitric oxide is involved in many physiologic processes. There are efforts, described elsewhere in this volume, to deliver nitric oxide to tissues as a therapy. Nitric oxide also contributes to pathophysiologic processes. Inhibiting nitric oxide or its production can thus also be of therapeutic benefit. This article addresses such inhibitory strategies.

Nitrergic system and plasmatic methylarginines: Evidence of their role in the perinatal programming of cardiovascular diseases

Atherosclerosis, in turn preceded by endothelial dysfunction, underlies a series of important cardiovascular diseases. Reduced bioavailability of endothelial nitric oxide, by increasing vascular tone and promoting platelet aggregation, leukocyte adhesion, and smooth muscle cell proliferation, plays a key role in the onset of the majority of cardiovascular diseases. In addition, high blood levels of asymmetric dimethylarginine, a potent inhibitor of nitric oxide synthesis, are associated with future development of adverse cardiovascular events and cardiac death. Recent reports have demonstrated that another methylarginine, i.e., symmetric dimethylarginine, is also involved in the onset of endothelial dysfunction and hypertension. Almost a decade ago, prematurity at birth and intrauterine growth retardation were first associated with a potential negative influence on the cardiovascular apparatus, thus constituting risk factors or leading to early onset of cardiovascular diseases. This condition is referred to as cardiovascular perinatal programming. Accordingly, cardiovascular morbidity and mortality are higher among former preterm adults than in those born at term. The aim of this paper was to undertake a comprehensive literature review focusing on cellular and biochemical mechanisms resulting in both reduced nitric oxide bioavailability and increased methylarginine levels in subjects born preterm. Evidence of the involvement of these compounds in the perinatal programming of cardiovascular risk are also discussed.

Asymmetric dimethylarginine regulates the lipopolysaccharide-induced nitric oxide production in macrophages by suppressing the activation of NF-kappaB and iNOS expression

Two major effector systems are frequently implicated in the immune and endothelial cell alternations associated with inflammation. They include the enhanced production of reactive oxygen species and diminished bioavailability of nitric oxide (NO). Importantly, these processes can be regulated by endogenously produced methylarginines, inhibitors for NO derived from macrophages and endothelial cells. Therefore, the aim of this study was to show the potential pharmacological intervention of methylarginines (N(G)-methyl-L-arginine, L-NMMA; N(G), N(G)'-dimethyl-L-arginine-symmetric dimethylarginine, SDMA; and N(G), N(G)-dimethyl-L-arginine-asymmetric dimethylarginine, ADMA) in activation of murine peritoneal (RAW 264.7) and alveolar (MHS) macrophages with lipopolysaccharide from Gram-negative bacteria (LPS). The data presented in this study clearly declare that L-NMMA (1-50μM) and ADMA (10-50 μM) significantly inhibited the LPS-induced NO production from macrophages in a concentration-dependent manner. It was demonstrated, for the first time, that the ADMA- and L-NMMA-induced down regulation of NO production was accompanied by reduced expression of mRNA and protein for inducible NO synthase as well as decreased activation of nuclear factor-κB. Importantly, we found a negative correlation between the ADMA-dependent reduction of NO production and ADMA-increased superoxide formation, which indicates that ADMA can negatively affect the balance in LPS-induced macrophage-derived production of reactive mediators. The only effect of SDMA was observed for LPS-triggered superoxide production, which was significantly decreased in its highest concentration (50 μM). In summary, L-NMMA and ADMA can mediate their effects on macrophage activation via regulation of intracellular signaling pathways, which can affect critical functions in activated macrophages.

Chronic oral administration of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) improves erectile function in aged rats

Arginase expression and activity have been noted to be heightened in conditions associated with erectile dysfunction, including aging. Previously, arginase inhibition by chronic administration of the arginase inhibitor 2-(S)-amino-6-boronohexanoic acid (ABH) has been shown to improve endothelial dysfunction in aged rats. The objective of this study was to assess whether chronic oral ABH administration affects cavernosal erectile function. Rats were divided into 4 groups: young control, young treated with arginase inhibitor, aged control, and aged treated with arginase inhibitor. Arginase activity was measured and presented as a proportion of young untreated rats. In vivo erectile responses to cavernous nerve stimulation were measured in all cohorts. The cavernous nerve was stimulated with a graded electrical stimulus, and the intracavernosal/mean arterial pressure ratios and total intracavernosal pressure were recorded. Arginase activity was elevated in the aged rats compared with young controls; however, arginase activity was significantly decreased in aged rats treated with ABH. With the addition of ABH, erectile responses improved in the aged rats (P < .05). Oral inhibition of arginase with ABH results in improved erectile function in aged rats, resulting in erectile hemodynamics similar to young rats. This represents the first documentation of systemic arginase inhibition positively affecting corporal cavernosal function.

Biochemical and genetic markers of erectile dysfunction

Erectile dysfunction (ED) is a very common pathology, affecting over 150 million men worldwide. The pathogenesis is typically multifactorial, involving a kaleidoscope of organic, endocrine, and psychogenic factors. In general, ED is divided into organic and psychogenic impotence, but most men with organic etiologies have an associated psychogenic component. Given the high frequency of this pathology, the identification of biochemical and genetic correlates and/or markers is of pivotal interest not only for treating preciously these patients and preventing serious psychological consequences but also for the high risk for occult cardiovascular disease (CVD) that often accompanies or follows this pathology. A variety of cardiovascular risk factors have been associated with both the onset and the severity of ED, including markers of endothelial function, thrombosis, and especially dyslipidemia, so that their measurement should now be considered as an important part of the increased global cardiometabolic risk profile in patients with ED. While nitric oxide (NO), asymmetric dimethylarginine (ADMA), and endothelin (ET) hold some promises as biochemical markers of both CVD and ED, there are several technical and clinical drawbacks that make their measurement overall meaningless in the clinical practice. As regards genetic polymorphisms, controversial results have been provided so far. Although some genetic markers were consistently associated with ED, other studies failed to demonstrate significant associations, highlighting a substantial bias in standardization of methodologies and patient enrolment. Nevertheless, further research in this area should be encouraged, since the first promising evidence that gene therapy might be effective to restore the decline in ED has been provided in the animal model.

The usefulness of vibration perception threshold as a significant indicator for erectile dysfunction in patients with diabetes mellitus at a primary diabetes mellitus clinic

INTRODUCTION

The aim of this study is to clarify the relationship of erectile dysfunction (ED) and diabetes mellitus (DM) parameters (referred to with '1'), including peripheral neuropathy (referred to with '2').

METHODS

(1) The DM parameters including age, serum levels of blood sugar, hemoglobin A1c, duration of DM and number of DM complications were obtained from 145 patients at a general DM clinic. (2) The peripheral neuropathy examinations by vibration perception threshold (VPT) and Achilles tendon reflex were performed in 97 DM patients. Erectile functions in DM patients were evaluated by the International Index of Erectile Function (IIEF 5). The DM patients' parameters were compared with the IIEF 5 scores.

RESULTS

(1) The data showed IIEF 5 scores were significantly correlated with patient age, duration of DM and number of DM complications. (2) IIEF 5 scores were significantly correlated with VPT time. Furthermore, multiple regression analysis revealed that patient age and VPT time were independent risk factors for predicting ED in DM patients.

CONCLUSIONS

The severity of ED in DM patients depended on age, duration of DM, number of DM complications and VPT. Significantly, the age of DM patients and the measurement of VPT are considered to be simple and useful indicators to diagnose ED in DM patients.

To give or not to give? Lessons from the arginine paradox

Arginine is one of the 20 amino acids (AA) found in proteins and synthesized by human cells. However, arginine is also the substrate for a series of reactions leading to the synthesis of other AA and is an obligatory substrate for two enzymes with diverging actions, arginases and nitric oxide synthases (NOS), giving origin to urea and NO, respectively. NO is a very potent vasodilator when produced by endothelial NOS (eNOS). The 'arginine paradox' is the fact that, despite intracellular physiological concentration of arginine being several hundred micromoles per liter, far exceeding the ∼5 μM K(M) of eNOS, the acute provision of exogenous arginine still increases NO production. Clinically, an additional paradox is that the largest controlled study on chronic oral arginine supplementation in patients after myocardial infarction had to be interrupted for excess mortality in treated patients. Expression and activity of arginases, which produce urea and divert arginine from NOS, are positively related to exogenous arginine supplementation. Therefore, the more arginine is introduced, the more it is destroyed, eventually leading to impaired NO production. In this review, conditions influencing the low arginine concentrations found in plasma will be reviewed, revising the paradigm that simple replenishment of what is lacking will always produce beneficial consequences.

Arginase II deletion increases corpora cavernosa relaxation in diabetic mice

INTRODUCTION

Diabetes-induced erectile dysfunction involves elevated arginase (Arg) activity and expression. Because nitric oxide (NO) synthase and Arg share and compete for their substrate L-arginine, NO production is likely linked to regulation of Arg. Arg is highly expressed and implicated in erectile dysfunction.

AIM

It was hypothesized that Arg-II isoform deletion enhances relaxation function of corpora cavernosal (CC) smooth muscle in a streptozotocin (STZ) diabetic model.

METHODS

Eight weeks after STZ-induced diabetes, vascular functional studies, Arg activity assay, and protein expression levels of Arg and constitutive NOS (using Western blots) were assessed in CC tissues from nondiabetic wild type (WT), diabetic (D) WT (WT + D), Arg-II knockout (KO), and Arg-II KO+D mice (N = 8-10 per group).

MAIN OUTCOME MEASURES

Inhibition or lack of arginase results in facilitation of CC relaxation in diabetic CC.

RESULTS

Strips of CC from Arg-II KO mice exhibited an enhanced maximum endothelium-dependent relaxation (from 70 + 3% to 84 + 4%) and increased nitrergic relaxation (by 55%, 71%, 42%, 42%, and 24% for 1, 2, 4, 8 and 16 Hz, respectively) compared with WT mice. WT + D mice showed a significant reduction of endothelium-dependent maximum relaxation (44 + 8%), but this impairment of relaxation was significantly prevented in Arg-II KO+D mice (69 + 4%). Sympathetic-mediated and alpha-adrenergic agent-induced contractile responses also were increased in CC strips from D compared with non-D controls. Contractile responses were significantly lower in Arg-II KO control and D versus the WT groups. WT + D mice increased Arg activity (1.5-fold) and Arg-II protein expression and decreased total and phospho-eNOS at Ser-1177, and nNOS levels. These alterations were not seen in Arg-II KO mice. Additionally, the Arg inhibitor BEC (50 µM) enhanced nitrergic and endothelium-dependent relaxation in CC of WT + D mice.

CONCLUSION

These studies show for the first time that Arg-II deletion improves CC relaxation in type 1 diabetes.

Cardiovascular effects of arginase inhibition in spontaneously hypertensive rats with fully developed hypertension

AIMS

Growing evidence suggests that arginase misregulation plays a key role in the pathophysiology of essential hypertension. In the present study, we investigated the potential cardiovascular therapeutic effects of a long-term treatment with an arginase inhibitor in adult spontaneously hypertensive rats (SHR) with fully developed hypertension.

METHODS AND RESULTS

Treatment of 25-week-old SHR with the arginase inhibitor N(omega)-hydroxy-nor-L-arginine (nor-NOHA, 40 mg/day for 10 weeks) sustainably reduced systolic blood pressure (-30 mmHg, P < 0.05). The antihypertensive effect of nor-NOHA was associated with changes on mesenteric artery reactivity including the restoration of angiotensin-II-induced contraction and acetylcholine-induced vasodilation to the values of normotensive Wistar Kyoto rats. Both nitric oxide synthase and cyclooxygenase-dependent mechanisms account for the improvement of endothelial function afforded by the arginase inhibitor, which in addition blunted hypertension-induced endothelial arginase I overexpression in mesenteric arteries. Nor-NOHA also prevented the remodelling of aorta as measured by collagen content and media/lumen ratio, and improved the compliance of carotid artery in SHR. Cardiac fibrosis assessed by collagen content of left heart ventricle was reduced by nor-NOHA, with no significant effect on cardiac hypertrophy.

CONCLUSION

Our results report that a long-term treatment with an arginase inhibitor reduced blood pressure, improved vascular function, and reduced cardiac fibrosis in SHR with fully developed hypertension. These data suggest that arginase represents a promising novel target for pharmacological intervention in essential hypertension.