Cellular pharmacodynamic effects of Pycnogenol® in patients with severe osteoarthritis: a randomized controlled pilot study

Review of the pharmacokinetics of French maritime pine bark extract (Pycnogenol®) in humans

The French maritime pine bark extract Pycnogenol® is a proprietary product from Pinus pinaster Aiton. It complies with the quality specifications in the United States Pharmacopeia monograph "Pine extract" in the section of dietary supplements. Pycnogenol® is standardized to contain 65-75% procyanidins which are a variety of biopolymers consisting of catechin and epicatechin monomeric units. The effects of Pycnogenol® have been researched in a multitude of human studies. The basis for any in vivo activity is the bioavailability of constituents and metabolites of the extract. General principles of compound absorption, distribution, metabolism and elimination as well as specific data from studies with Pycnogenol® are summarized and discussed in this review. Based on plasma concentration profiles it can be concluded that low molecular weight constituents of the extract, such as catechin, caffeic and ferulic acid, taxifolin are readily absorbed from the small intestine into systemic circulation. Procyanidin oligomers and polymers are subjected to gut microbial degradation in the large intestine yielding small bioavailable metabolites such as 5-(3',4'-dihydroxyphenyl)-γ-valerolactone. After intake of Pycnogenol®, constituents and metabolites have been also detected in blood cells, synovial fluid and saliva indicating a substantial distribution in compartments other than serum. In studies simultaneously investigating concentrations in different specimen, a preferential distribution of individual compounds has been observed, e.g., of ferulic acid and 5-(3',4'-dihydroxyphenyl)-γ-valerolactone into synovial fluid compared to serum. The main route of elimination of constituents and metabolites of the French pine bark extract is the renal excretion. The broad knowledge accumulated regarding the pharmacokinetics of compounds and metabolites of Pycnogenol® constitute a rational basis for effects characterized on a cellular level and observed in human clinical studies.

Pycnogenol® French maritime pine bark extract in randomized, double-blind, placebo-controlled human clinical studies

Pycnogenol® French maritime pine bark extract is a well-known and thoroughly studied patented extract from the bark of Pinus pinaster Ait. ssp. Atlantica. In 39 randomized double-blind, placebo-controlled (RDP) human clinical trials including 2,009 subjects, Pycnogenol® French maritime pine bark extract supplementation for two weeks to six months has been shown to beneficially affect cardiovascular health, chronic venous insufficiency, cognition, joint health, skin health, eye health, women's health, respiratory health and allergies, oral health and sports performance. The mechanisms of action that can explain the respective effects on different conditions in the human body are discussed as well. As investigated in several in vitro, in vivo and in clinical studies, Pycnogenol® French maritime pine bark extract showed antioxidative effects, anti-inflammatory abilities, beneficial effects on endothelial function and reinforcing effects on the extracellular matrix. The present review aims to give a comprehensive overview of currently available "gold standard" RDP trials of Pycnogenol®'s benefits across various health domains compared to placebo. In addition, some of the processes on which the presented effects of Pycnogenol® French maritime pine bark extract are based will be elucidated and discussed. This broad overview of RDP studies on Pycnogenol® in different health domains can be used as a basis for further research on applications and mechanisms of this unique French maritime pine bark extract.

Bioactives and their roles in bone metabolism of osteoarthritis: evidence and mechanisms on gut-bone axis

Bioactives significantly modify and maintain human health. Available data suggest that Bioactives might play a beneficial role in chronic inflammatory diseases. Although promised, defining their mechanisms and opting to weigh their benefits and limitations is imperative. Detailed mechanisms by which critical Bioactives, including probiotics and prebiotics such as dietary lipids (DHA, EPA, alpha LA), vitamin D, polysaccharides (fructooligosaccharide), polyphenols (curcumin, resveratrol, and capsaicin) potentially modulate inflammation and bone metabolism is limited. Certain dietary bioactive significantly impact the gut microbiota, immune system, and pain response via the gut-immune-bone axis. This narrative review highlights a recent update on mechanistic evidence that bioactive is demonstrated demonstrated to reduce osteoarthritis pathophysiology.

Acute loading has minor influence on human articular cartilage gene expression and glycosaminoglycan composition in late-stage knee osteoarthritis: a randomised controlled trial

OBJECTIVE

Osteoarthritis (OA) remains clinically challenging. Regular physical exercise improves symptoms though it is unclear whether exercise influences cartilage at the molecular level. Thus, we aimed to determine the effect of acute loading on gene expression and glycosaminoglycan (GAG) content in human OA cartilage.

DESIGN

Patients with primary knee OA participated in this single-blind randomised controlled trial initiated 3.5 h prior to scheduled joint replacement surgery with or without loading by performing one bout of resistance exercise (one-legged leg press). Cartilage from the medial tibia condyle was sampled centrally, under the meniscus, and from peripheral osteophytes. Samples were analysed for gene expression by real-time reverse transcriptase polymerase chain reaction, and hyaluronidase-extracted matrix was analysed for GAG composition by immuno- and dimethyl-methylene blue assays.

RESULTS

Of 32 patients randomised, 31 completed the intervention: mean age 69 ± 7.5 years (SD), 58% female, BMI 29.4 ± 4.4 kg/m². Exercise increased chondroitin sulphate extractability [95% CI: 1.01 to 2.46; P = 0.0486] but cartilage relevant gene expression was unchanged. Regionally, the submeniscal area showed higher MMP-3, MMP-13, IGF-1Ea, and CTGF, together with lower lubricin and COMP expression compared to the central condylar region. Further, osteophyte expression of MMP-1, MMP-13, IGF-1Ea, and TGF-β3 was higher than articular cartilage and lower for aggrecan, COMP, and FGF-2. Hyaluronidase-extracted matrix from central condylar cartilage contained more GAGs but less chondroitin sulphate compared to submeniscal cartilage.

CONCLUSION

Acute exercise had minor influence on cartilage GAG dynamics, indicating that osteoarthritic cartilage is not significantly affected by acute exercise. However, the regional differences suggest a chronic mechanical influence on human cartilage.

CLINICALTRIALS

GOV REGISTRATION NUMBER

NCT03410745.

Small molecule inhibitors of osteoarthritis: Current development and future perspective

Osteoarthritis (OA) is one of the common degenerative joint diseases in clinic. It mainly damages articular cartilage, causing pain, swelling and stiffness around joints, and is the main cause of disability of the elderly. Due to the unclear pathogenesis of osteoarthritis and the poor self-healing ability of articular cartilage, the treatment options for this disease are limited. At present, NSAIDs, Glucocorticoid and Duloxetine are the most commonly used treatment choice for osteoarthritis. Although it is somewhat effective, the adverse reactions are frequent and serious. The development of safer and more effective anti-osteoarthritis drugs is essential and urgent. This review summarizes recent advances in the pharmacological treatment of OA, focusing on small molecule inhibitors targeting cartilage remodeling in osteoarthritis as well as the research idea of reducing adverse effects by optimizing the dosage form of traditional drugs for the treatment of osteoarthritis. It should provide a reference for exploration of new potential treatment options.

The protective activity of natural flavonoids against osteoarthritis by targeting NF-κB signaling pathway

Osteoarthritis (OA) is a typical joint disease associated with chronic inflammation. The nuclear factor-kappaB (NF-κB) pathway plays an important role in inflammatory activity and inhibiting NF-κB-mediated inflammation can be a potential strategy for treating OA. Flavonoids are a class of naturally occurring polyphenols with anti-inflammatory properties. Structurally, natural flavonoids can be divided into several sub-groups, including flavonols, flavones, flavanols/catechins, flavanones, anthocyanins, and isoflavones. Increasing evidence demonstrates that natural flavonoids exhibit protective activity against the pathological changes of OA by inhibiting the NF-κB signaling pathway. Potentially, natural flavonoids may suppress NF-κB signaling-mediated inflammatory responses, ECM degradation, and chondrocyte apoptosis. The different biological actions of natural flavonoids against the NF-κB signaling pathway in OA chondrocytes might be associated with the differentially substituted groups on the structures. In this review, the efficacy and action mechanism of natural flavonoids against the development of OA are discussed by targeting the NF-κB signaling pathway. Potentially, flavonoids could become useful inhibitors of the NF-κB signaling pathway for the therapeutic management of OA.

Natural Compounds: Potential Therapeutics for the Inhibition of Cartilage Matrix Degradation in Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease characterized by enzymatic degradation of the cartilage extracellular matrix (ECM) causing joint pain and disability. There is no disease-modifying drug available for the treatment of OA. An ideal drug is expected to stop cartilage ECM degradation and restore the degenerated ECM. The ECM primarily contains type II collagen and aggrecan but also has minor quantities of other collagen fibers and proteoglycans. In OA joints, the components of the cartilage ECM are degraded by matrix-degrading proteases and hydrolases which are produced by chondrocytes and synoviocytes. Matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS5) are the major collagenase and aggrecanase, respectively, which are highly expressed in OA cartilage and promote cartilage ECM degradation. Current studies using various in vitro and in vivo approaches show that natural compounds inhibit the expression and activity of MMP-13, ADAMTS4, and ADAMTS5 and increase the expression of ECM components. In this review, we have summarized recent advancements in OA research with a focus on natural compounds as potential therapeutics for the treatment of OA with emphasis on the prevention of cartilage ECM degradation and improvement of joint health.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Therapeutic Efficacy of Flavonoids in Allergies: A Systematic Review of Randomized Controlled Trials

Objective. To assess the clinical efficacy of flavonoid supplements on allergic diseases. Design. Systematic review. Data Sources. MEDLINE/PubMed, Scopus, Web of Science, and Embase databases were searched from inception to September 2021. Eligibility Criteria for Selecting Studies. Eligible study designs were randomized controlled trials that investigated the effect of flavonoids applied to allergic diseases. Results. This review included 15 randomized controlled trials, including allergic rhinitis/cedar pollinosis ( $n=10$ ), asthma ( $n=3$ ), and atopic dermatitis ( $n=2$ ). A total of 990 participants aged 6 to 69 years were included in these studies. Globally, 12 studies (80%) revealed some benefits of flavonoids (isolate or combined with other compounds) in allergic patients, while three studies (20%) reported no statistically significant impact on symptom scores and/or lung function. No severe adverse events related to treatment were reported. According to the GRADE system, the outcomes evaluated were of low to moderate quality of evidence. Conclusions. Overall, this review suggests that the administration of flavonoids may provide a viable strategy for mitigating allergic symptoms. Future trials with high methodological quality are needed to establish definitive conclusions. This trial is registered with PROSPERO registration no. CRD42021237403.

Effect of Dietary Polyphenols on Osteoarthritis—Molecular Mechanisms

Osteoarthritis is a common crippling and degenerative disease resulting in irreversible functional changes due to damage of the cartilage and other tissues of the joint. With limited safe and effective pharmaceutical treatments, the demand and use for alternative therapeutic approaches with symptomatic relief for OA patients have increased. Clinical, pre-clinical, and in vitro studies have demonstrated that polyphenols can exert pain-relieving symptoms coupled with increased functional capacity in OA models. This review will highlight studies carried out in the last five years to define the efficacies and underlying mechanisms in polyphenols such as quercetin, resveratrol, curcumin, epigallocatechin-3-gallate, rosmarinic acid, genistein, ginger, berries, silver fir, pine bark, and Boswellia. Most of these studies indicate that polyphenols exhibit their beneficial roles through regulating changes at the biochemical and molecular levels, inducing or inhibiting various signaling pathways related to inflammation and oxidative stress. Polyphenols have also been implicated in modulating microRNA at the posttranscriptional level to counteract OA pathogenesis.

Effect of Warm Acupuncture Combined with Bone Marrow Mesenchymal Stem Cells Transplantation on Cartilage Tissue in Rabbit Knee Osteoarthritis

The current study was designed to investigate the effect and underlying mechanism of warm acupuncture combined with bone marrow mesenchymal stem cells (BMSC) transplantation on cartilage tissue injury in rabbit knee osteoarthritis (KOA). In the study, 50 rabbits were randomly divided into 5 groups: blank group, KOA group, warm acupuncture group, BMSCs group, and warm acupuncture combined with BMSCs group. After warm acupuncture combined with BMSCs, the Modified Lequesne MG knee joint assessment scale was used to evaluate the degree of knee joint behavior, the Taiping Peng method generally observed the histomorphology changes of KOA rabbit cartilage, and hematoxylin-eosin staining, safranin O green staining, and toluidine blue staining were conducted to evaluate the extent of cartilage tissue pathology. Furthermore, transmission electron microscopy and TUNEL staining were used to observe cell apoptosis, and immunohistochemistry and qPCR analysis were used to detect the expression of apoptosis-related proteins and mRNA. Results showed that administration of warm acupuncture combined with BMSCs recovered the joint function and significantly decreased Lequesne MG score. The degree of cartilage tissue pathological damage has been improved, cartilage ultrastructure degeneration has recovered, peripheral blood vessels have mild edema, blood supply has gradually recovered, and even small amounts of red blood cells have appeared. In addition, warm acupuncture combined with BMSCs treatment suppressed chondrocyte apoptosis in rabbits with knee osteoarthritis by reduced TUNEL-positive chondrocytes and simultaneously reversed the mRNA expression of Bax, Bcl-2, and Caspase-3. These results indicate that warm acupuncture combined with BMSCs transplantation has a potential protective effect on rabbit KOA, which may be mediated by inhibiting chondrocyte apoptosis.

Chondroprotection and Molecular Mechanism of Action of Phytonutraceuticals on Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease and an important cause of incapacitation. There is a lack of drugs and effective treatments that stop or slow the OA progression. Modern pharmacological treatments, such as analgesics, have analgesic effects but do not affect the course of OA. Long-term use of these drugs can lead to serious side effects. Given the OA nature, it is likely that lifelong treatment will be required to stop or slow its progression. Therefore, there is an urgent need for disease-modifying OA treatments that are also safe for clinical use over long periods. Phytonutraceuticals are herbal products that provide a therapeutic effect, including disease prevention, which not only have favorable safety characteristics but may have an alleviating effect on the OA and its symptoms. An estimated 47% of OA patients use alternative drugs, including phytonutraceuticals. The review studies the efficacy and action mechanism of widely used phytonutraceuticals, analyzes the available experimental and clinical data on the effect of some phytonutraceuticals (phytoflavonoids, polyphenols, and bioflavonoids) on OA, and examines the known molecular effect and the possibility of their use for chondroprotection.

A Placebo-Controlled, Pseudo-Randomized, Crossover Trial of Botanical Agents for Gulf War Illness: Curcumin (Curcuma longa), Boswellia (Boswellia serrata), and French Maritime Pine Bark (Pinus pinaster)

This report is part of a larger study designed to rapidly and efficiently screen potential treatments for Gulf War Illness (GWI) by testing nine different botanicals. In this placebo-controlled, pseudo-randomized, crossover clinical trial of 20 men with GWI, we tested three botanical agents with putative peripheral and central anti-inflammatory actions: curcumin (Curcuma longa), boswellia (Boswellia serrata), and French maritime pine bark extract (Pinus pinaster). Participants completed 30 +/− 3 days of baseline symptom reports, followed by 30 +/− 3 days of placebo, 30 +/− 3 days of lower-dose botanical, and 30 +/− 3 days of higher-dose botanical. Participants then repeated the process with a new botanical until completing up to three botanical cycles. Data were analyzed using linear mixed models. Curcumin reduced GWI symptom severity significantly more than placebo at both the lower (p < 0.0001) and higher (p = 0.0003) dosages. Boswellia was not more effective than placebo at reducing GWI symptoms at either the lower (p = 0.726) or higher (p = 0.869) dosages. Maritime pine was not more effective than placebo at the lower dosage (p = 0.954) but was more effective than placebo at the higher dosage (p = 0.006). This study provides preliminary evidence that curcumin and maritime pine may help alleviate symptoms of GWI. As a screening study, a final determination of the efficacy of these compounds for all individuals with GWI cannot be made, and further studies will need to be conducted to determine strength and durability of effects, as well as optimal dosage. These results suggest that GWI may, at least in part, involve systemic inflammatory processes. This trial was registered on ClinicalTrials.gov (NCT02909686) on 13 September 2016.

Effects of pycnogenol on cardiometabolic health: A systematic review and meta-analysis of randomized controlled trials

AIM

Clinical trials on the effect of pycnogenol supplementation on cardiometabolic health have been controversial. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the potential effect of pycnogenol supplementation on cardiometabolic profile.

METHODS

PubMed, Scopus, and ISI Web of Science databases were searched until October 2018. RCTs that evaluated the effects of pycnogenol on cardiometabolic parameters were included. DerSimonian and Laird random-effect models were used to compute the weighted mean differences (WMDs) and 95% confidence intervals (CIs).

RESULTS

Twenty-four RCTs including 1594 participants were included in the meta-analysis. Pycnogenol significantly reduced fasting blood glucose (WMD: -5.86 mg/dl; 95% CI: -9.56, -2.15), glycated hemoglobin (WMD = -0.29%, 95%CI: -0.56, -0.01), systolic blood pressure (WMD: -2.54 mmhg; 95% CI: -4.08, -0.99), diastolic blood pressure (WMD: -1.76 mmhg; 95% CI: -3.12, -0.41), body mass index (WMD: -0.47 kg/m²; 95% CI: -0.90, -0.03), LDL cholesterol (WMD: -7.12 mg/dl; 95% CI: -13.66, -0.58) and increased HDL cholesterol (WMD: 3.27 mg/dl; 95% CI: 0.87, 5.66).

CONCLUSION

This meta-analysis suggests that pycnogenol may have a role in preventing cardiometabolic disease. However, further well-designed RCTs are recommended to evaluate its long-term effects and explore the optimal duration of use and dosage.

Osteoarthritis year in review 2018: biomarkers (biochemical markers)

OBJECTIVE

The aim of this narrative review is to summarize important findings from biochemical marker studies relevant to osteoarthritis (OA) in the context of new discoveries and clinical and scientific need.

DESIGN

We conducted a systematic search of electronic medical databases (Embase, Medline, Web of Science, Cochrane central) between 01-03-2017 and 31-03-2018. The search was restricted to human studies, English language and full text available publications while reviews were excluded. Only papers describing protein based biomarkers measured in human body fluids (blood, urine and synovial fluid (SF)) were included. Of the 992 papers, 86 were reviewed here, with inclusion primarily based on relevance to OA biochemical markers.

RESULTS

This review highlights a selection of studies based on their quality and perceived importance to the field mainly including those that¹ evaluate prognostic value of biomarkers for OA progression (i.e., biomarkers reflecting change in composition of joint tissues and biomarkers of inflammation)², help in assessment of intervention efficacy, and³ are innovative and uncover new candidate biomarkers, or use new approaches in biomarker discovery.

CONCLUSIONS

Key findings and implications for possible clinical utility of biochemical markers are summarized and discussed. Given the paucity of robust biomarkers within the field, and the heterogeneity of the condition, enormous works are needed for development and validation of novel and clinically applicable biomarkers to reduce the impact of this highly prevalent and debilitating condition.

Curcumin Inhibits Proliferation of Synovial Cells by Downregulating Expression of Matrix Metalloproteinase-3 in Osteoarthritis

Objective

To investigate the association between curcumin and the differentially expressed genes (DEG) in synovial tissues of osteoarthritis.

Methods

Microarray analysis was used to screen for the DEG in osteoarthritis synovial cells. Curcumin‐related genes were identified through the drug–gene interaction network STITCH (http://stitch.embl.de/cgi/input.pl). Expression levels of fibronectin 1 (FN1) and collagen III protein were measured by western blot. MTT assay was used to examine the effects of different concentrations of curcumin on cell viability. Western blot and quantitative real‐time polymerase chain reaction were used to validate the different expression levels of matrix metalloproteinase‐3 (MMP3). Clone formation assay, flow cytometry, and the TUNEL method were conducted for detecting the cell proliferation and apoptosis rate.

Results

In the two chips of GSE1919 and GSE55235, the average expression of MMP3 in the osteoarthritis group was 63.7% and 12.9% higher than that of the healthy control, respectively. The results of western blot also showed that the average expression of MMP3 in 30 osteoarthritis patients was 132% higher than that of the healthy group, which confirmed that MMP3 was highly expressed in osteoarthritis group. The results of MTT showed that at 72 h, the cell viability of 40 μmol/L curcumin was the lowest and 79.6% lower than for the 0 μmol/L group, so the final curcumin concentration of 40 μmol/L was selected for subsequent experiments. Western blot results further showed that the expression of MMP3 was 44% lower in the untreated groups compared with the curcumin group, and the expressions of FN1 and collagen III were increased by 112% and 84%, respectively, which indicated that curcumin inhibited MMP3 expression and decreased osteoarthritis synovial cell activity. Cloning formation experiments showed that cell numbers increased by 75% and 20.5% in untreated and curcumin groups, and compared with the untreated group, the cells in the curcumin group decreased by 30.8%. Flow cytometry showed that the apoptotic rate in the curcumin group increased by 85.1% compared with the untreated group, but for a single group, MMP3 decreased the apoptotic rate by 53.9% and 46.7%, respectively.

Conclusions

MMP3 was highly expressed in osteoarthritis synovial cells. Curcumin could reduce cell viability, inhibit cell proliferation, increase cell apoptosis, and eventually alleviate inflammation of osteoarthritis by inhibiting the expression of MMP3.

Pleiotropic Effects of French Maritime Pine Bark Extract to Promote Healthy Aging

Extension of the healthy life span is of primary importance for the aging society. Among exercise, healthy nutrition, and mental training, food supplements are widely used as preventive measures to postpone the diverse symptoms of aging. The extract from the bark of the French maritime pine, Pycnogenol, rich on flavonoids, has anti-inflammatory and antioxidative property, proven in in vivo studies. The extract reduces oxidative stress and improves endothelial health. Its antithrombotic properties are based on inhibition of platelet aggregation. In double-blind, placebo-controlled clinical studies, Pycnogenol shows diverse positive effects. With respect to cardiovascular symptoms, the extract has an antihypertensive effect, slows down the progression of atherosclerosis, and prevents venous thrombosis. As reported in studies in China and the United States, type 2 diabetes and diabetic retinopathy is improved with Pycnogenol. The extract restores mobility of seniors in case of patients suffering from osteoarthritis, Pycnogenol reduces pain and stiffness and use of analgesics. Furthermore, cognitive functions of elderly people, especially spatial memory, are significantly ameliorated. Climacteric symptoms are significantly alleviated by the pine bark extract. Urinary symptoms of benign prostatic hyperplasia are reduced by Pycnogenol. In combination with L-arginine, Pycnogenol restores erectile function in men with erectile dysfunction. The sum of these positive effects on relevant symptoms of aging suggests using Pycnogenol for a more extended period of healthy aging.

Investigational drugs for the treatment of osteoarthritis, an update on recent developments

INTRODUCTION

Osteoarthritis (OA) is the leading cause of pain, loss of function, and disability among elderly, with the knee the most affected joint. It is a heterogeneous condition characterized by complex and multifactorial etiologies which contribute to the broad variation in symptoms presentation and treatment responses that OA patients present. This poses a challenge for the development of effective treatment on OA.

AREAS COVERED

This review will discuss recent development of agents for the treatment of OA, updating our previous narrative review published in 2015. They include drugs for controlling local and systemic inflammation, regulating articular cartilage, targeting subchondral bone, and relieving pain.

EXPERT OPINION

Although new OA drugs such as monoclonal antibodies have shown marked effects and favorable tolerance, current treatment options for OA remain limited. The authors believe there is no miracle drug that can be used for all OA patients'; treatment and disease stage is crucial for the effectiveness of drugs. Therefore, early diagnosis, phenotyping OA patients and precise therapy would expedite the development of investigational drugs targeting at symptoms and disease progression of OA.

Nutraceuticals and osteoarthritis pain

Arthritis is a chronic disease of joints. It is highly prevalent, particularly in the elderly, and is commonly associated with pain that interferes with quality of life. Because of its chronic nature, pharmacological approaches to pain relief and joint repair must be safe for long term use, a quality many current therapies lack. Nutraceuticals refer to compounds or materials that can function as nutrition and exert a potential therapeutic effect, including the relief of pain, such as pain related to arthritis, of which osteoarthritis (OA) is the most common form. Of interest, nutraceuticals have recently been shown to have potential in relieving OA pain in human clinical trials. Emerging evidence indicates nutraceuticals may represent promising alternatives for the relief of OA pain. In this paper, we will overview OA pain and the use of nutraceuticals in OA pain management, focusing on those that have been evaluated by clinical trials. Furthermore, we discuss the biologic and pharmacologic actions underlying the nutraceutical effects on pain relief based on the potential active ingredients identified from traditional nutraceuticals in OA pain management and their potential for drug development. The review concludes by sharing our viewpoints that future studies should prioritize elucidating the mechanisms of action of nutraceuticals in OA and developing nutraceuticals that not only relieve OA pain, but also mitigate OA pathology.