Effect of ginger, Paullinia cupana, muira puama and l- citrulline, singly or in combination, on modulation of the inducible nitric oxide- NO-cGMP pathway in rat penile smooth muscle cells

News and future perspectives of non-surgical treatments for erectile dysfunction

The significant discontinuation rate of available therapies and the paucity of curative options promoted the research on potential novel treatments suitable for erectile dysfunction patients. The aim of this study was to provide a summary of available evidence regarding the news and future perspectives related to the non-surgical treatment of erectile dysfunction. A narrative review of the literature was performed. A comprehensive search in the MEDLINE, Embase, and Scopus databases was done. Papers in English-language, published until April 2022, were included. No chronological restriction was applied. Retrospective and prospective clinical studies, as well as meta-analyses, were considered. Oro-dispersible formulations of phosphodiesterase type 5 inhibitors are particularly indicated in patients who have difficulty in swallowing solid dosage form; in addition, they constitute a discrete route of administration not requiring water. Low-intensity extracorporeal shock wave therapy is indicated in mild vasculogenic erectile dysfunction and in patients with vasculogenic erectile dysfunction poorly responsive to phosphodiesterase type 5 inhibitors. Stem cell therapy, platelet-rich plasma injections, and gene therapy seem promising regenerative treatments for selected patients with erectile dysfunction. Novel oral formulations of drugs commonly used in erectile dysfunction patients have recently become part of standard clinical practice. Regenerative treatments have been emerging in recent years and could become routine curative options in the near future. Further well-designed randomized controlled trials are needed to provide conclusive evidence on this topic and guide appropriate recommendations.

Network Pharmacology, Molecular Docking, and Molecular Dynamic-Based Investigation on the Mechanism of Compound Chrysanthemum in the Treatment of Asthenopia

As a clinical empirical prescription for ophthalmology, compound chrysanthemum has been used gradually and has a good effect on eye fatigue. However, the detailed mechanisms of antiasthenopia have not been studied. In order to clarify the mechanisms of the compound chrysanthemum in the treatment of asthenopia, network pharmacology was combined with experimental study in this paper. A total of 593 genes and 39 active chemicals were identified, and both were considered to be essential to the advancement of asthenopia research. The results of the molecular docking analysis demonstrated a certain affinity between PRKACA, PRKCA, PRKCB, and their related compounds; molecular dynamic simulations assessed the stability of these receptors and ligands. The effects of compound chrysanthemum extract on ciliary muscle were studied in vitro and in vivo. By using the MTT assay, compound chrysanthemum extracts (50, 100, 200, 400, and 800 g·mL-1) showed no effect on the proliferation of rCSMCs for 24 and 48 hours. It raised nitric oxide and decreased Ca²⁺ in ciliary muscle cells isolated from the eyeballs of rats. Besides, compound chrysanthemum extract had a direct relaxing effect on the isolated gastric smooth muscle of rats by reducing the contractile tension. Furthermore, in vivo experiment results showed that, compared to the incandescent lamp-irradiated rats (model group), SD rats treated with compound chrysanthemum extracts (660 mg·kg^-1 and 1320 mg·kg^-1, orally) displayed considerably retracted pupils and increased NO content. It is also found that compound chrysanthemum extract can downregulate the mRNA expression of PKA and PKC in the calcium signaling pathway. Overall, our results suggested that compound chrysanthemum extract may lessen visual fatigue through multiple components, multiple targets, and multiple pathways.

Ginger and its constituents: Role in treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD), with obscure etiology, are rising and are of worldwide concern. Of the various components of IBD pathogenesis and progression, irritation appears to play a major part. Investigations on the molecular and cellular pathways that activate the IBD provide the focus for the development of useful therapies. Ginger (the rhizome of Zingiber officinale) has a broad spectrum of clinical applications due to its anti-inflammatory and anti-oxidative functions. Inflammation and oxidative stress are the key pathogenic factors in many diseases, including IBD. The most established components of ginger are phenolic compounds called gingerols. A wide range of pharmacological activities of the potential therapeutic benefit of Z. officinale have been detailed. In this regard, the anti-inflammatory activity of ginger has been documented by many researchers. It was shown that ginger is a potent inhibitor of the nuclear factor kappa B (NF-κB), signal transducer of activators of transcription (STATs), Nod-like receptor family proteins (NLRPs), toll-like receptors (TLRs), mitogen-activated protein kinase (MAPKs), and mTOR (mTOR) pathways, as well as inhibiting various pro-inflammatory cytokines. In the present report, the potential application of ginger in the management of IBD is reviewed in detail, with an emphasis on the relevant properties of ginger and its bioactive components. The significance of the functions, side effects, and delivery of ginger to the digestive system for particular application in IBD are also considered.

Activation of the iNOS/NO/cGMP pathway by Revactin® in human corporal smooth muscle cells

Background

The combination of the nutraceuticals, Paullinia cupana, ginger rhizome, muira puama, and the amino acid L-citrulline (COMP-4) has been shown to stimulate the production of inducible nitric oxide synthase (iNOS), nitric oxide (NO), and cGMP in rat corpora cavernosa smooth muscle cells (CSMC). When administered to middle-aged rats, long-term treatment with COMP-4 resulted in both an increase in the number of CSMC and an improvement in erectile function. We, therefore, aimed to determine whether a commercial formulation of COMP-4, Revactin^®, could have a similar stimulatory effect on human CSMC.

Methods

Primary human CSMC cultures (HCSMC) were grown and incubated with Revactin® for up to 24 hours. cGMP generation and nitrite formation were determined by ELISA and Griess reaction, respectively. IBMX (1 mM), sildenafil (0.4 mM), and L-NIL (4 µM) were utilized as modulators of the NO-cGMP pathway. iNOS, endothelial NOS (eNOS), and neuronal NOS (nNOS) expressions were determined by Western blot.

Results

Revactin^® up-regulated both nitrite formation and cGMP expression, achieving the highest expression at 24 hours in the HCSMC. These effects were completely blocked by L-NIL. Revactin^® up-regulated iNOS expression, but not that of eNOS or nNOS.

Conclusions

The results presented in this study confirmed that Revactin^® activated the iNOS-NO-cGMP pathway intracellularly in HCSMC. It still needs to be determined whether the upregulation of this pathway would be an effective approach for counteracting the fibrosis and apoptosis of the corporal smooth muscle cells associated with aging.

The cold-soaking extract of Chinese yam (Dioscorea opposita Thunb.) protects against erectile dysfunction by ameliorating testicular function in hydrocortisone-induced KDS-Yang rats and in oxidatively damaged TM3 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Clinical applications and pharmacological research suggest that Dioscorea opposita Thunb. (Chinese yam), a well-known traditional Chinese medicine which has been used for more than 2000 years to nourish kidney-yang and protect the male reproductive system, might be efficacious for the treatment of erectile dysfunction (ED).

AIM OF THE STUDY

This study aimed to investigate the active component extract of Chinese yam, determine its effectiveness in hydrocortisone-induced "kidney-yang deficiency syndrome" (KDS-Yang) rats and in oxidatively damaged TM3 cells and explore the underlying mechanism on restoring erectile function.

MATERIALS AND METHODS

We clarified the Chinese yam cold-soaking extract (CYCSE) as the main active extract of Chinese yam by a CCK8 assay and further identified its composition. The KDS-Yang rats were induced by intragastric administration of hydrocortisone. After 10 d of CYCSE intervention, cavernous and testis morphology were stained with hematoxylin and eosin. Inducible nitric oxide synthase (iNOS), cyclic guanosine monophosphate (cGMP), testosterone, 8-hydroxy-2-deoxyguanosine (8-OHdG) and superoxide dismutase (SOD) levels were detected by enzyme-linked immunosorbent assay kits. Leydig cells were performed using immunohistochemistry. Reactive oxygen species were measured using a DCFH-DA fluorescent probe, and testicular collagenous fibers were stained with a Masson kit. Detection of testicular apoptosis was performed by a TUNEL assay. Nrf2 and NQO1 mRNA expression levels were measured by qRT-PCR. The protein expression levels of Nrf2, HO-1, TGF-β1 and SMAD2/3 were analyzed by Western blot.

RESULTS

We demonstrated in KDS-Yang rats and oxidatively damaged TM3 cells that CYCSE successfully restored erectile function through ameliorating testicular function. Our data suggested that CYCSE can stimulate the NO/cGMP pathway and restore the cavernous morphology to protect against KDS-Yang-induced ED. It also protected testis morphology, increased Leydig cell proliferation and stimulated testosterone secretion. In the damaged testes, excessive increases in 8-OHdG and inhibition of SOD activity were ameliorated, and the Nrf2/HO-1 signaling pathway was enhanced after treatment with CYCSE, indicating that the antioxidant defense system was activated. These findings were also validated in vitro. Additionally, fibrosis of the testes and TM3 cells was reversed by CYCSE through the TGF-β1/SMAD2/3 pathway.

CONCLUSION

CYCSE has a therapeutic effect on KDS-Yang-induced ED, and the mechanism includes stimulation of testosterone secretion, resistance to oxidative stress and prevention of fibrosis. These findings provide a new scientific verification for the application of Chinese yam in the treatment of KDS-Yang-induced ED.

Reduction of oxidative stress markers in the corpora cavernosa and media of penile dorsal artery in middle-aged rats treated with COMP-4

COMP-4, a nutraceutical combination consisting of ginger rhizome, muira puama, Paullinia cupana, and L-citrulline, enhances intracellular nitric oxide (NO) production by the corporal smooth muscle cells (CSMC). This study aims to determine if the previously shown beneficial effect of COMP-4 on the histology and function of the aging penis is associated with an antioxidative effect from endogenously produced NO. Ten-month-old male rats were treated daily for 2 months with COMP-4 or vehicle at which time the corpora and penile dorsal artery (PDA) were evaluated by immunohistochemistry for (a) apoptosis (b) proliferative cell nuclear antigen, (c) heme oxygenase-1 (HO-1), (d) myeloperoxidase (MPO), and (e) nitrotyrosine (NT). CSMC were cultured and incubated with COMP-4 in order to determine intracellular oxidative stress via the GSH/GSSG ratio. In both the corpora and PDA, daily treatment with COMP-4 resulted in an increase in both smooth muscle cell proliferation and HO-1 expression as well as a decrease in MPO. There was no change in either apoptosis or NT expression. In the CSMC cell culture, treatment with COMP-4 increased the intracellular GSH/GSSG ratio. COMP-4 appears to have an antioxidant effect on the aging vascular smooth muscle cells both in the corpora and peripheral vasculature.

Prevention of Osteoporosis in the Ovariectomized Rat by Oral Administration of a Nutraceutical Combination That Stimulates Nitric Oxide Production

Osteoporosis represents an imbalance between bone formation and bone resorption. As a result of low estrogen levels, it is markedly prevalent during menopause, thus making such patients susceptible to fractures. Both bone formation and resorption are modulated by nitric oxide (NO). Currently, there are no risk-free pharmaceutical prevention therapies for osteoporosis. COMB-4, a nutraceutical combination of Paullinia cupana, Muira puama, ginger, and L-citrulline, known to activate the NO-cGMP pathway, was reported to accelerate fracture healing in the rat. To determine whether COMB-4 could be effective in preventing menopausal osteoporosis, it was compared to estradiol (E2) in an ovariectomized (OVX) rat osteoporosis model. Nine-month-old female Sprague Dawley rats were divided into SHAM, OVX, OVX+E2, and OVX+COMB-4. After 100 days of treatment, bone mineral density (BMD) and bone mineral content (BMC) were measured by DXA scan. TRAP staining was performed in the femur and lumbar vertebrae. TRACP 5b and osteocalcin levels were assayed in the serum. MC3T3-E1 cells were differentiated into osteoblasts and treated with COMB-4 for one week in order to evaluate calcium deposition by Alizarin staining, cGMP production by ELISA, and upregulation of the nitric oxide synthase (NOS) enzymes by RT-PCR. OVX resulted in a decrease in BMD, BMC, and serum osteocalcin and an increase in serum TRACP 5b. Except for an increase in BMC with COMB-4, both E2 and COMB-4 reverted all bone and serum markers, as well as the number of osteoclasts in the vertebrae, to SHAM levels. Incubation of MC3T3-E1 cells with COMB-4 demonstrated an increase in the three NOS isoforms, cGMP, and calcium deposition. COMB-4 increased BMD in OVX rats by inhibiting bone resorption and increasing calcium deposition presumably via activation of the NO-cGMP pathway. It remains to be determined whether COMB-4 could be a potential nutraceutical therapy for the prevention of premenopausal bone loss.

Exogenous l-ARGININE does not stimulate production OF NO or cGMP within the rat corporal smooth muscle cells in culture

BACKGROUND AND AIM

Nitric oxide (NO) is the intracellular chemical responsible for initiating a penile erection. Despite conflicting clinical data, it continues to be publicized and promoted that orally administered l-arginine, the putative substrate for NO, enhances the erectile response presumably by stimulating NO production by the corporal tissues resulting in an increase in cGMP production. To shed light on this issue, an in vitro study was conducted to explore the effect of direct exogenous administration of l-arginine as well as its precursor and metabolite, l-citrulline, on the NO-cGMP pathway within the cavernosal smooth muscle (CSM) cell.

MATERIALS AND METHODS

CSM cells obtained from 8 to 10 week old Sprague-Dawley rats were grown in Dulbecco media with 20% fetal calf serum and then incubated with or without l-arginine (L-ARG) or l-citrulline (L-CIT) in a time course and dose-response manner. Sildenafil (0.4 mM), IBMX (1 mM), l-NAME (3 μM), ODQ (5 μM) and Deta Nonoate (10 μM) were used as either inhibitors or stimulators of the NO-cGMP pathway. mRNA and protein were extracted and used for the determination of the phosphodiesterase 5 (PDE5). PDE5 activity was determined by luminometry. cGMP content was determined by ELISA. Nitrite formation, an indicator of NO production, was measured in the cell culture media by a colorimetric assay. The cationic (CAT-1) and neutral (SNAT-1) amino acid transporters for L-ARG and L-CIT, respectively, were determined by Western blot.

RESULTS

When compared to untreated CSM cells, incubation with 0.25-4.0 mM of L-ARG or 0.3-4.8 mM of L-CIT anywhere between 3 and 24 h did not result in any additional nitrite or cGMP production. The addition of l-NAME, IBMX or ODQ to these L-ARG and L-CIT treated cells did not alter these results. L-CIT but not L-ARG increased PDE5 mRNA and protein content as well as the activity of the PDE5 enzyme. Both CAT-1 and SNAT-1 were expressed in the CSM cells.

CONCLUSIONS

This in vitro study demonstrates that exogenous administration of L-ARG or L-CIT failed to stimulate production of either NO or cGMP by the corporal CSM cells. A re-evaluation of the presumptive role of the exogenous administration of L-ARG in improving the synthesis of NO at least at the level of the CSM cells appears warranted.

Safety and efficacy of daily Revactin® in men with erectile dysfunction: a 3-month pilot study

Background

The earliest sign of an ongoing change in a man’s erectile function (EF) is the increase in his refractory period. This is due to the onset of an aging related apoptosis of the corporal smooth muscle cells (CSMC) as a result of oxidative stress (ROS) within the CSMC itself. In response, the CSMC begin to upregulate the inducible nitric oxide synthase (iNOS) enzyme presumably to achieve high levels of nitric oxide (NO) used to combat ROS. Treatment of aged rats for 2 months with the nutraceutical Revactin^®, known to stimulate the iNOS-NO-cGMP pathway in CSMC, resulted in (I) an increase in CSMC content with a decrease in corporal fibrosis, (II) decrease in systemic ROS, and (III) improvement in EF. To determine whether Revactin^® could be used in the clinical setting, a pilot safety study was conducted.

Methods

Fifty-four middle aged men (mean age 57.8±10.7; range, 33–77 years) were recruited for this safety study. Patients were given Revactin^® twice daily (total daily dose of 500 mg of ginger root, muira puama, and Paullinia cupana and 1,600 mg of L-citrulline) and were asked to complete the IIEF-15 questionnaire [domains: EF, orgasmic function (OF), sexual desire (SD), intercourse satisfaction (IS), overall satisfaction (OS)] at baseline (B), 1 month (M1), 2 months (M2) and 3 months (M3) and report any side effects. Those on erectogenic medications at B were requested to stop taking them during the trial. Data were analyzed using Wilcoxon paired test and Friedman rank test for trend.

Results

Revactin^® was safe with only 5 patients reporting treatment side effects (e.g., dyspepsia, heartburn, migraine) and none considered severe. For those who stayed on the regimen (M1 =32; M2 =22; M3 =16), there was an increase in median domain scores for EF, OF, SD, IS, and OS over 3 months compared to baseline median scores but statistical significance was found only in the EF, IS, and OS median domain scores. Trend analysis indicated significant trend in EF, OS & IS (P<0.05). For the EF domain, the median scores were: M1 =21, M2 =22, M3 =19 relative to the B =16, 15.5, and 14.5, respectively (P<0.05). Overall, approximately 50% of the patients reported a significant improvement in EF (P<0.05). The major reason for trial discontinuation (M1 =22, M2 =9 and M3 =6) was non-compliance with pro-erectile medications.

Conclusions

Revactin^®, a combination of 3 nutraceuticals packaged with L-citrulline, appears to have the same excellent safety profile known for each of its individual four components. The early improvement in EF seen in about 50% of these patients may be due to the elevated levels of cGMP produced via this iNOS-cGMP pathway. Further longitudinal studies with Revactin^® appear warranted.