The efficacy of high- and low-dose curcumin in knee osteoarthritis: A systematic review and meta-analysis

Curcumin-PLGA NPs coated with targeting biomimetic personalized stem cell membranes for osteoarthritis therapy

Traditional drug delivery systems for OA treatments face limitations due to rapid clearance within the joint and low biocompatibility. Moreover, the inflammation associated with OA exacerbates tissue damage and delays the regenerative capacity of therapeutics. To overcome these limitations, an OA-specific drug delivery system designated dCOL2-CM-Cur-PNPs is developed herein to target OA cartilage for anti-inflammatory and cartilage regeneration purposes. This system is constructed using cell membranes obtained from induced pluripotent stem cell -derived mesenchymal stem cells (iMSC-CMs), poly(D,l-lactide-co-glycolide) (PLGA) nanoparticles loaded with the well-known anti-inflammatory and cartilage-regenerating agent curcumin (Cur-PNPs), and damaged type II collagen (dCOL2)-targeting phospholipids. Coating the Cur-PNPs with iMSC-CMs enhances the sustained release of curcumin and improves its cellular uptake by OA-induced chondrocytes. The dCOL2-CM-Cur-PNPs restores the chondrogenic properties of the OA-induced chondrocytes, inhibit the pro-inflammatory function of M1 macrophages, and promote the anti-inflammatory function of M2 macrophages. The dCOL2-targeting phospholipids integrated on the surface of the iMSC-CMs facilitate specific binding to OA cartilage, as validated by in-vitro and in-vivo experiments. Additionally, the dCOL2-CM-Cur-PNPs alleviate OA progression in a DMM rat model. This drug delivery system based on iMSC-CMs modified with dCOL2-targeting phospholipids demonstrates significant potential as a next-generation platform for promoting cartilage regeneration through OA-specific therapy.

Efficacy and Safety of a Novel Low-Dose Water-Dispersible Turmeric Extract in the Management of Knee Osteoarthritis: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Purpose

Turmeric extract is a well-known nutraceutical ingredient recognized for its benefits in managing musculoskeletal health. This study evaluated the efficacy and safety of a novel low-dose water-dispersible turmeric extract containing 60% natural curcuminoids (WDTE60N) in participants with mild-to-moderate knee osteoarthritis.

Patients and Methods

This double-blind, randomized, placebo-controlled trial was conducted at two orthopedic centers in Uttar Pradesh, India (July 2023-November 2023). Participants aged 45-75 years with unilateral or bilateral OA of the knee for >3 months were randomized in 1:1 ratio to receive WDTE60N (250 mg) or placebo capsules once daily for three months. Study endpoints included assessment of changes from baseline to day 90 in pain intensity (visual analog scale [VAS], knee injury and osteoarthritis outcome score [KOOS]), inflammatory biomarkers, and safety profile. Data were analyzed using independent t-test, chi-square test, and analysis of co-variance test.

Results

In total, 139 participants (WDTE60N, n = 70; placebo, n = 69) with mean age and BMI of 56.35 years and 23.89 kg/m2, respectively, were included. The mean reduction (95% CI) in VAS score from baseline to day 90 was significantly higher in the WDTE60N group than in the placebo group (14.41 [13.08, 15.75] vs 6.02 [5.00, 7.05]; p < 0.0001). In the WDTE60N group, the mean change in VAS scores was significantly reduced from as early as day 07 (p = 0.0076), which continued until day 90 (p < 0.0001), compared to the placebo group. Improvement in the mean KOOS scores (baseline-Day 90) was evident, with significantly higher mean scores for each domain (pain, symptoms, activities of daily living, function in sport and recreation, and knee-related quality of life [QoL]) on Day 90 in the WDTE60N group than in the placebo group (p < 0.05). Inflammatory biomarkers (hsCRP, TNF-α, IL-6, and IL-1β) were significantly reduced from baseline to day 90 in the WDTE60N group compared to the placebo group (p < 0.0001). Four mild adverse events were reported during the study period.

Conclusion

Supplementation with the low-dose water-dispersible turmeric extract containing 60% natural curcuminoids for three months was safe and effective in alleviating pain, improving functional status and quality of life and reducing inflammation in participants with mild-to-moderate knee osteoarthritis.

CTRI Registration Number

CTRI/2023/07/055411.

Efficacy of Curcuma longa in relieving pain symptoms of knee osteoarthritis patients: a systematic review and meta-analysis of clinical trials

Objective

Osteoarthritis (OA), particularly knee OA, affects 24% of adults and is a significant cause of disability. Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used but have many adverse effects. Antioxidant and anti-iflammatory properties of Curcuma longa might decrease pain thus improving joint function.

Methods

This systematic review and meta-analysis evaluated randomized controlled trials (RCTs) on Curcuma longa efficacy for knee OA. We reported mean differences (MD) with 95% confidence interval (CI) for continuous outcomes and evaluated Visual Analog Scale (VAS) for pain and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) total score over 4 to 6 weeks for treatment effects.

Results

Ten RCTs with 786 patients were included. Curcuma longa significantly improved VAS for pain than placebo (MD 18.25, 95% CI 7.79 to 28.72, p=0.0006). It was not inferior to NSAIDs in WOMAC total score improvement (MD -11.99, 95% CI -39.21 to 15.23, p=0.39). Both dosages (<1,000 and ≥1,000 mg/day) of Curcuma longa demonstrated similar improvement in VAS for pain compared to placebo (MD 27.02, 95% CI 1.45 to 52.60, p=0.04; MD 21.48, 95% CI 1.78 to 41.18, p=0.03).

Conclusion

Curcuma longa benefits knee OA pain and function, being more effective than placebo and comparable to NSAIDs. Despite positive results, limitation and heterogeneity of the studies necessitates further research to explore optimal dosages and administration methods of Curcuma longa as therapeutic option for knee OA.

Activation of cannabinoid receptor 2 by turmeric oleoresin reduces inflammation and oxidative stress in an osteoarthritis in vitro model

Introduction

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by the progressive degradation of articular cartilage, resulting in pain and reduced mobility. Turmeric (Curcuma longa L.) has been widely recognized for its anti-inflammatory and antioxidant properties, but the molecular mechanisms underlying its therapeutic effects remain inadequately explored. This study investigates the potential of turmeric oleoresin (TUR) to activate Cannabinoid Receptor 2 (CBR2) and its role in mediating anti-inflammatory and antioxidant effects in an in vitro OA model.

Material and methods

Molecular docking and cAMP quantification assays were used to evaluate TUR's agonistic activity on CBR2. Human chondrosarcoma cells (SW-1353) were treated with TUR under oxidative stress induced by menadione or inflammatory conditions simulated with IL-1β and TNF-α. The effects of TUR were assessed in the presence and absence of the CBR2 antagonist SR144528. Outcomes included changes in reactive oxygen species (ROS) production, inflammatory marker expression, oxidative defense markers and endocannabinoid system components and receptors.

Results

TUR was confirmed as a CBR2 agonist and significantly reduced ROS production, downregulated pro-inflammatory cytokines (IL-6, COX-2, metalloproteases), and suppressed signaling pathways such as NFKB1, ERK 1/2, and c-Myc. These effects were reversed upon CBR2 inhibition. TUR also enhanced HMOX-1 expression and modulated endocannabinoid-related enzymes, highlighting its impact on oxidative stress and the endocannabinoid system.

Discussion

These findings suggest that CBR2 activation is central to TUR's anti-inflammatory and antioxidant effects. By modulating key pathways and endocannabinoid system components, TUR demonstrates potential as a novel therapeutic agent for OA management. Future studies could explore its clinical applications and further validate its molecular mechanisms in vivo.

Efficacy and safety of an oral complementary medicine combination in people with symptomatic knee osteoarthritis: Protocol for the double-blind, randomized, placebo-controlled ATLAS trial

Objective

To investigate the efficacy and safety of an oral complementary medicine combination formulation relative to placebo, on changes in pain intensity from baseline to week 12, in people with knee osteoarthritis (OA).

Design

A placebo-controlled, double-blind, two-arm, superiority, phase II, Randomized Controlled Trial (RCT) (ACTRN12623000380695). We will recruit 82 participants (∼41 per arm), aged ≥40 years, with a clinical diagnosis of symptomatic knee OA and radiographic change on x-ray (Kellgren-Lawrence Grade ≥2). Participants will be randomly allocated to receive either a complementary medicine formulation containing a daily dose of Boswellia serrata extract (Boswellin® Super, 250 ​mg/day), pine bark extract (Fenoprolic™ 70 Organic 100 ​mg/day), curcumin (500 ​mg/day), piperine (5 ​mg/day), and methylsulfonylmethane (MSM, 1500 ​mg/day), or placebo, for 12-weeks. The primary endpoint will be change from baseline in average knee pain intensity at 12-weeks (visual analogue scale). Secondary endpoints will include change in knee pain from baseline to 12-weeks in the Knee Injury and Osteoarthritis Outcome Score (KOOS), global assessment of disease activity, global rating of change, and health-related quality of life (AQoL-8D).

Ethics and dissemination

This protocol has been approved by the University of Sydney Human Research Ethics Committee (#2021/877). Dissemination will occur through lay summaries, infographics, conference abstracts, oral presentations, theses, and scientific publications.

Conclusion

This RCT will provide credible evidence about the efficacy and safety of this complementary medicine combination and inform updates to international clinical practice standards on the use of complementary medicines in the management of symptomatic knee OA.

Exploring the Interaction of Lipid Bilayers with Curcumin-Laponite Nanoparticles: Implications for Drug Delivery and Therapeutic Applications

Curcumin, the active compound in turmeric, is renowned for its anti-inflammatory, antioxidant, and antimicrobial properties, making it beneficial for treating conditions like arthritis, neurodegenerative diseases, and various cancers. Despite its promising therapeutic potential, curcumin's poor bioavailability-due to its rapid metabolism and low solubility-limits its clinical efficacy. To address this, recent research has focused on enhancing curcumin delivery using nanoparticles, liposomes, and novel nanomaterials. Among these, laponite, a synthetic nanoclay, has shown promise in improving curcumin delivery due to its unique properties, including large surface area, dual charge, and stability in solution. This study explores the use of curcumin-laponite nanoparticles as carrier vehicles for controlled delivery to in vitro model membranes. Utilizing advanced techniques such as neutron reflectometry, atomic force microscopy, quartz crystal microbalance with dissipation, and infrared spectroscopy, the interaction between curcumin-laponite nanoparticles and solid-supported lipid bilayers is monitored, revealing enhanced stability and controlled release of curcumin across the membrane. These findings pave the way for the development of curcumin-based therapies targeting cardiovascular, neurological, and oncological diseases, leveraging the synergistic effects of curcumin's biological activity and laponite's delivery capabilities.

Bioactive Compounds in Osteoarthritis: Molecular Mechanisms and Therapeutic Roles

Osteoarthritis (OA) is the most common and debilitating form of arthritis. Current therapies focus on pain relief and efforts to slow disease progression through a combination of drug and non-drug treatments. Bioactive compounds derived from plants show significant promise due to their anti-inflammatory, antioxidant, and tissue-protective properties. These natural compounds can help regulate the inflammatory processes and metabolic pathways involved in OA, thereby alleviating symptoms and potentially slowing disease progression. Investigating the efficacy of these natural agents in treating osteoarthritis addresses a growing demand for natural health solutions and creates new opportunities for managing this increasingly prevalent age-related condition. The aim of this review is to provide an overview of the use of some bioactive compounds from plants in modulating the progression of osteoarthritis and alleviating associated pain.

Exploring the impact of curcumin on osteoarthritis symptomatology: correlations and insights from a Bulgarian cohort

INTRODUCTION

Osteoarthritis is a prevalent degenerative joint disorder associated with pain and functional impairment. Curcumin, a natural anti-inflammatory compound, has garnered attention for its potential therapeutic benefits in osteoarthritis management.

Multifaceted physiological and therapeutical impact of curcumin on hormone-related endocrine dysfunctions: A comprehensive review

Over the past five decades, Curcumin (Cur), derived from turmeric (Curcuma longa), has gained considerable attention for its potential therapeutic applications. Synthesizing insights from clinical trials conducted over the last 25 years, this review delves into diseases where Cur has demonstrated promise, offering a nuanced understanding of its pharmacokinetics, safety, and effectiveness. Focusing on specific examples, the impact of Cur on various human diseases is explored. Endocrine glands and associated signaling pathways are highlighted, elucidating how Cur influences cellular signaling. The article underscores molecular mechanisms such as hormone level alteration, receptor interaction, cytokine and adipokine expression inhibition, antioxidant enzyme activity, and modulation of transcription factors. Cur showcases diverse protective mechanisms against inflammation and oxidative damage by suppressing antiapoptotic genes and impeding tumor promotion. This comprehensive overview emphasizes the potential of Cur as a natural agent for countering aging and degenerative diseases, calling for further dedicated research in this realm.

The efficacy of curcumin in relieving osteoarthritis: A meta-analysis of meta-analyses

Osteoarthritis (OA) is one of the most prevalent degenerative joint diseases. Several meta-analyses have shown that curcumin could improve the function of the knee and alleviate pain in OA, while some meta-analyses demonstrate controversial results. Hence, we assessed curcumin's effects on knee OA in an umbrella meta-analysis. PubMed, Scopus, Embase, and Web of Science databases were employed to find English-language meta-analyses of randomized controlled trials investigating the effect of curcumin supplementation on OA outcomes up to September 2023. The visual analog scale (VAS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, function, and stiffness scales were analyzed. Effect sizes and 95% confidence intervals were utilized to obtain the overall effect size. A random-effects model was applied to perform the meta-analysis. Heterogeneity was determined by I2 statistics and the Cochrane Q-test. The pooled effect of the 11 included meta-analyses showed that curcumin could significantly decrease the VAS score (weighted mean difference [WMD] and standardized mean difference [SMD]), WOMAC-total (SMD and WMD), WOMAC-Function (SMD and WMD), WOMAC-Pain (SMD), and WOMAC-Stiffness scores (SMD) (p ≤ 0.001, ≤0.001, ≤0.001, 0.007, ≤0.001, 0.002, ≤0.001, ≤0.001, respectively). The results strongly support curcuminoid supplementation in relieving pain, improving joint mobility and stiffness, and shortening medication usage of OA patients.

Pterostilbene Protects against Osteoarthritis through NLRP3 Inflammasome Inactivation and Improves Gut Microbiota as Evidenced by In Vivo and In Vitro Studies

Osteoarthritis (OA) is a persistent inflammatory disease, and long-term clinical treatment often leads to side effects. In this study, we evaluated pterostilbene (PT), a natural anti-inflammatory substance, for its protective effects and safety during prolonged use on OA. Results showed that PT alleviated the loss of chondrocytes and widened the narrow joint space in an octacalcium phosphate (OCP)-induced OA mouse model (n = 3). In vitro experiments demonstrate that PT reduced NLRP3 inflammation activation (relative protein expression: C: 1 ± 0.09, lipopolysaccharide (LPS): 1.14 ± 0.07, PT: 0.91 ± 0.07, LPS + PT: 0.68 ± 0.04) and the release of inflammatory cytokines through NF-κB signaling inactivation (relative protein expression: C: 1 ± 0.03, LPS: 3.49 ± 0.02, PT: 0.66 ± 0.08, LPS + PT: 2.78 ± 0.05), ultimately preventing cartilage catabolism. Interestingly, PT also altered gut microbiota by reducing inflammation-associated flora and increasing the abundance of healthy bacteria in OA groups. Collectively, these results suggest that the PT can be considered as a protective strategy for OA.

Curcumin regulates autophagy through SIRT3-SOD2-ROS signaling pathway to improve quadriceps femoris muscle atrophy in KOA rat model

Knee osteoarthritis (KOA) usually leads to quadriceps femoris atrophy, which in turn can further aggravate the progression of KOA. Curcumin (CUR) has anti-inflammatory and antioxidant effects and has been shown to be a protective agent for skeletal muscle. CUR has been shown to have a protective effect on skeletal muscle. However, there are no studies related to whether CUR improves KOA-induced quadriceps femoris muscle atrophy. We established a model of KOA in rats. Rats in the experimental group were fed CUR for 5 weeks. Changes in autophagy levels, reactive oxygen species (ROS) levels, and changes in the expression of the Sirutin3 (SIRT3)-superoxide dismutase 2 (SOD2) pathway were detected in the quadriceps femoris muscle of rats. KOA led to quadriceps femoris muscle atrophy, in which autophagy was induced and ROS levels were increased. CUR increased SIRT3 expression, decreased SOD2 acetylation and ROS levels, inhibited the over-activation of autophagy, thereby alleviating quadriceps femoris muscle atrophy and improving KOA. CUR has a protective effect against quadriceps femoris muscle atrophy, and KOA is alleviated after improvement of quadriceps femoris muscle atrophy, with the possible mechanism being the reduction of ROS-induced autophagy via the SIRT3-SOD2 pathway.

Bioavailability of Oral Curcumin in Systematic Reviews: A Methodological Study

Curcumin is a natural compound found in turmeric that exhibits diverse biological activities. However, its poor bioavailability limits its therapeutic application, which has led to the development of various bioavailability-improved formulations. In this methodological study, we analyzed whether systematic reviews on curcumin considered the bioavailability of systemic oral curcumin formulations when synthesizing evidence from human clinical trials. A total of 171 systematic reviews published between 2003 and 2022 were included in the study. From the included studies, we extracted data on study characteristics; type of curcumin; methods; and reporting regarding bioavailability, funding, and conflict of interest. Our results show that systematic reviews rarely consider the variable bioavailability of tested curcumin formulations. Relevant statistical subgroup and/or sensitivity analyses were reported in the methods and results of only 3.5% and 6.4% of reviews, respectively. However, more reviews mentioned bioavailability in their discussion (57%) or conclusion (13%). The detailed analysis of the included systematic reviews suggests that there is broad recognition of product bioavailability as a crucial factor affecting the health effects of curcumin, which is not accompanied by adequate evidence synthesis. Therefore, the results of most systematic reviews on orally administered curcumin should be taken with caution.

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.

A Systemic Review on Nutraceutical Supplements used in the Management of Osteoarthritis

Osteoarthritis (OA) is a progressive degenerative joint disease. It basically impairs the structural integrity of articulate cartilage and imbalances the catabolic and anabolic signals in the joint. A degenerative disease is characterized by swelling, pain, and joint stiffness. The treatment and management of osteoarthritis are based on analgesic and anti-inflammatory agents, whereas the exact cause of OA is not known yet. The negative effects of synthetic medications have led to a daily rise in the usage of nutraceuticals and dietary supplements. Clinicians are aware of these treatments, and they also recommend nutraceuticals in addition to the currently preferred therapy. Many in-vitro and in-vivo experiments have been performed in past years to evaluate the function of these on osteoarthritis. The collection of articles was published on search engines like PubMed, Scopus, Google Scholar, ResearchGate, and ScienceDirect. The evaluation covers every potential nutraceutical utilized in osteoarthritis, together with its supporting data and mode of action. The present review discusses nutraceuticals, including devil's claw, vitamin D, boswellic acid, capsaicin, ginger, curcumin, krill oil, ginger, and avocado/soybean unsaponifiable.

[Complementary methods in the treatment of complex regional pain syndrome]

BACKGROUND

Complex regional pain syndrome (CRPS) affects 10-15% of patients following injuries (fractures, surgery) to the outer extremities and people after a stroke. The affected area hurts, is inflamed and lacks strength, while mobility and sensitivity are restricted. Complementary medicine as part of integrative medicine offers additional effective treatment options.

RESEARCH QUESTION

Complementary therapies that extend the guideline recommendations, demonstrate clinical evidence and/or are plausible are presented.

RESULTS

Mind-body medicine procedures (mindfulness, relaxation, yoga, Qi Gong, etc.) support the patient's self-efficacy and stimulate the vagus nerve as well as promoting the reduction of pain, depression and anxiety and improving quality of life. Phytotherapeutics such as turmeric or stinging nettle have an anti-inflammatory effect. Water treatments reduce pain, and acupuncture and neural therapy can be tried.

CONCLUSIONS

Integrative, complementary medical therapy options support the CRPS patient in coping with their disease and the related pain. These options can play an important role in the multimodal, interdisciplinary treatment of this disease.

Personalized Nutritional Strategies to Reduce Knee Osteoarthritis Severity and Ameliorate Sarcopenic Obesity Indices: A Practical Guide in an Orthopedic Setting

Knee osteoarthritis (KOA) is one of the most common joint diseases, especially in individuals with obesity. Another condition within this population, and which presents frequently, is sarcopenic obesity (SO), defined as an increase in body fat and a decrease in muscle mass and strength. The current paper aims to describe recent nutritional strategies which can generally improve KOA clinical severity and, at the same time, ameliorate SO indices. Searches were carried out in the PubMed and Science Direct databases and data were summarized using a narrative approach. Certain key findings have been revealed. Firstly, the screening and identification of SO in patients with KOA is important, and to this end, simple physical performance tests and anthropometric measures are available in the literature. Secondly, adherence to a Mediterranean diet and the achievement of significant body weight loss by means of low-calorie diets (LCDs) remain the cornerstone nutritional treatment in this population. Thirdly, supplementation with certain micronutrients such as vitamin D, essential and non-essential amino acids, as well as whey protein, also appear to be beneficial. In conclusion, in the current review, we presented a detailed flowchart of three different nutritional tracks that can be adopted to improve both KOA and SO based on joint disease clinical severity.

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.

The effects of antioxidants on knee osteoarthritis: A systematic review and meta-analysis

Objective

Knee osteoarthritis (KOA) is one of the growing health problems with a considerable burden. With recent research on the possible effectiveness of antioxidants in the remission of KOA symptoms, a systematic review and meta-analysis was required to confirm this hypothesis.

Design

Literature studies were searched on the most comprehensive databases such as PubMed, International Scientific Indexing, and Scopus, with no language and time restrictions. On 17 July 2021, a search strategy was developed based on the roots of "osteoarthritis (OA)" and "antioxidants," with no time or language limitations. As the primary outcome, pain was evaluated based on all indicators for evaluating pain [e.g., Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores, the visual analog scale (VAS), and the numerical rating scale (NRS)]. The symptoms and functions of KOA and quality of life (QOL) were also considered as secondary outcomes, each of which was measured and reported by the corresponding instrument in the studies. To measure the changes in pain, symptoms, and functions of participants, we included randomized controlled trials with a placebo control or other medical therapeutic interventions. Publication bias was assessed using Begg's funnel plot and Egger's regression test, which was deemed to be statistically significant at 0.1, and the results were checked by the trim-and-fill test.

Results

After refinement, data were extracted from 31 documents from 7,698 primary searched papers. Using the VAS as a reliable psychometric measuring instrument, the present study revealed that a significant difference in the characteristics of disease-related symptoms of patients with KOA was reached after antioxidant therapy (standardized mean difference (SMD): 0.467, 95% confidence interval (CI): 0.303-0.632, p < 0.0001). The results reported by WOMAC confirmed no significant difference in the combined score, difficulty score, pain score, and stiffness score.

Conclusion

As the first comprehensive systematic review of the association between antioxidant supplementation and KOA, this study showed that antioxidants can decrease disease-related symptoms in patients with KOA. The results can be useful for health policy decisions and future related studies.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022351060, identifier: CRD42022351060.

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.

Effects of Resveratrol, Curcumin and Quercetin Supplementation on Bone Metabolism—A Systematic Review

Phenolic compounds are natural phytochemicals that have recently reported numerous health benefits. Resveratrol, curcumin, and quercetin have recently received the most attention among these molecules due to their documented antioxidant effects. The review aims to investigate the effects of these molecules on bone metabolism and their role in several diseases such as osteopenia and osteoporosis, bone tumours, and periodontitis. The PubMed/Medline, Web of Science, Google Scholar, Scopus, Cochrane Library, and Embase electronic databases were searched for papers in line with the study topic. According to an English language restriction, the screening period was from January 2012 to 3 July 2022, with the following Boolean keywords: (“resveratrol” AND “bone”); (“curcumin” AND “bone”); (“quercetin” AND “bone”). A total of 36 papers were identified as relevant to the purpose of our investigation. The studies reported the positive effects of the investigated phenolic compounds on bone metabolism and their potential application as adjuvant treatments for osteoporosis, bone tumours, and periodontitis. Furthermore, their use on the titanium surfaces of orthopaedic prostheses could represent a possible application to improve the osteogenic processes and osseointegration. According to the study findings, resveratrol, curcumin, and quercetin are reported to have a wide variety of beneficial effects as supplement therapies. The investigated phenolic compounds seem to positively mediate bone metabolism and osteoclast-related pathologies.

Zingiberaceae plants/curcumin consumption and multiple health outcomes: An umbrella review of systematic reviews and meta-analyses of randomized controlled trials in humans

This umbrella review is to recapitulate and grade the available evidence of associations between consumption of Zingiberaceae plants/curcumin (Cur) and multiple health-related outcomes. This study included 161 meta-analyses of randomized controlled trials in 76 articles with 67 unique health outcomes. Data on heterogeneity and publication bias are considered to assess the quality of evidence. Based on the different impact of Zingiberaceae plants/Cur on human health, the advantages outweigh the disadvantages. Zingiberaceae plants/Cur can mainly improve metabolic syndrome, non-alcoholic fatty liver disease, cardiovascular disease, and some chronic inflammatory diseases, likewise, obviously relief the pain of osteoarthritis and related diseases. Ginger supplements have been shown to improve vomiting during pregnancy and to relieve nausea and vomiting caused by chemotherapy and surgery. The surgery is any type of surgery, including laparoscopic surgery, gynecological surgery and mixed surgery. Beneficial associations were found with Cur intervention in gastrointestinal, neurological and oral diseases. Zingiberaceae plants/Cur are generally safe and favorable for multiple health outcomes in humans. High-quality research is further needed to prove the observed associations.

A Meta-Analysis of the Impact of Nutritional Supplementation on Osteoarthritis Symptoms

Conflicting evidence exists concerning the effects of nutrient intake in osteoarthritis (OA). A systematic literature review and meta-analysis were performed using PubMed, EMBASE, and Cochrane Library up to November 2021 to assess the effects of nutrients on pain, stiffness, function, quality of life, and inflammation markers. We obtained 52 references including 50 on knee OA. Twelve studies compared 724 curcumin patients and 714 controls. Using the standardized mean difference, improvement was significant with regard to pain and function in the curcumin group compared to placebo, but not with active treatment (i.e., nonsteroidal anti-inflammatory drugs, chondroitin, or paracetamol). Three studies assessed the effects of ginger on OA symptoms in 166 patients compared to 164 placebo controls. Pain was the only clinical parameter that significantly decreased. Vitamin D supplementation caused a significant decrease in pain and function. Omega-3 and vitamin E caused no changes in OA parameters. Herbal formulations effects were significant only for stiffness compared to placebo, but not with active treatment. A significant decrease in inflammatory markers was found, especially with ginger. Thus, curcumin and ginger supplementation can have a favorable impact on knee OA symptoms. Other studies are needed to better assess the effects of omega-3 and vitamin D.

In Silico and In Vitro Screening of 50 Curcumin Compounds as EGFR and NF-κB Inhibitors

The improvement of cancer chemotherapy remains a major challenge, and thus new drugs are urgently required to develop new treatment regimes. Curcumin, a polyphenolic antioxidant derived from the rhizome of turmeric (Curcuma longa L.), has undergone extensive preclinical investigations and, thereby, displayed remarkable efficacy in vitro and in vivo against cancer and other disorders. However, pharmacological limitations of curcumin stimulated the synthesis of numerous novel curcumin analogs, which need to be evaluated for their therapeutic potential. In the present study, we calculated the binding affinities of 50 curcumin derivatives to known cancer-related target proteins of curcumin, i.e., epidermal growth factor receptor (EGFR) and nuclear factor κB (NF-κB) by using a molecular docking approach. The binding energies for EGFR were in a range of −12.12 (±0.21) to −7.34 (±0.07) kcal/mol and those for NF-κB ranged from −12.97 (±0.47) to −6.24 (±0.06) kcal/mol, indicating similar binding affinities of the curcumin compounds for both target proteins. The predicted receptor-ligand binding constants for EGFR and curcumin derivatives were in a range of 0.00013 (±0.00006) to 3.45 (±0.10) µM and for NF-κB in a range of 0.0004 (±0.0003) to 10.05 (±4.03) µM, indicating that the receptor-ligand binding was more stable for EGFR than for NF-κB. Twenty out of 50 curcumin compounds showed binding energies to NF-κB smaller than −10 kcal/mol, while curcumin as a lead compound revealed free binding energies of >−10 kcal/mol. Comparable data were obtained for EGFR: 15 out of 50 curcumin compounds were bound to EGFR with free binding energies of <−10 kcal/mol, while the binding affinity of curcumin itself was >−10 kcal/mol. This indicates that the derivatization of curcumin may indeed be a promising strategy to improve targe specificity and to obtain more effective anticancer drug candidates. The in silico results have been exemplarily validated using microscale thermophoresis. The bioactivity has been further investigated by using resazurin cell viability assay, lactate dehydrogenase assay, flow cytometric measurement of reactive oxygen species, and annexin V/propidium iodide assay. In conclusion, molecular docking represents a valuable approach to facilitate and speed up the identification of novel targeted curcumin-based drugs to treat cancer.

Quality of Evidence Supporting the Role of Curcuma Longa Extract/Curcumin for the Treatment of Osteoarthritis: An Overview of Systematic Reviews

Background

Well known for its good anti-inflammatory effect, curcuma longa extract (CLE)/curcumin (C) has a potential effect on osteoarthritis (OA), and a large number of researchers have completed several systematic reviews/meta-analyses (SRs/MAs) in this research area. However, the methodological and evidentiary quality of these SRs/MAs need to be further evaluated, and whether these findings provide reliable evidence for clinicians remains controversial.

Methods

Two researchers collected data from seven databases for SRs/MAs that are about randomized controlled trials (RCTs) on CLE/C for OA. Assessment was made for the SRs/MAs included in this article by means of the Assessment System for Evaluating Methodological Quality 2 (AMSTAR-2), the Risk of Bias in Systematic (ROBIS) scale, the list of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.

Results

Nine published SRs/MAs were included in our study. According to the results of the AMSTAR-2 assessment, only one SR/MA was assessed as high quality. According to the ROBIS evaluation results, only 2 SRs/MAs have a low risk of bias. According to the results of the PRISMA checklist assessment, only 2 SRs/MAs studies fully reported the checklist, while other studies had reporting flaws. According to GRADE, a total of 59 effect sizes extracted from the included SRs/MAs were evaluated, among which no effect size was rated as high.

Conclusions

CLE/C may be an effective and safe complementary treatment for OA. However, further standard SRs/MAs and RCTs are needed to provide an evidence-based medical rationale for this.

Therapeutic deep eutectic solvent-based microemulsion enhances anti-inflammatory efficacy of curcuminoids and aromatic-turmerone extracted from Curcuma longa L

To diminish chemical waste and improve the delivery of Curcuma longa L. (CL) constituents, microemulsions based on hydrophobic deep eutectic solvents (HDESs) were designed as ready-to-use solvents for CL extraction. The microemulsion (ME) of the ME-23 formulation (HDES/Tween 80 : propylene glycol (1 : 1)/water, 25/70/5) displayed CL extraction yields of 1.69, 3.04, 7.36, and 1.39 wt% of bisdemethoxycurcumin, demethoxycurcumin, curcumin, and aromatic-turmerone, respectively. The ME-23 without CL chemical constituents and ME-23-based CL extract inhibited NO production with an IC₅₀ value of 0.0136 ± 0.0023%v/v and a curcumin IC₅₀ value of 75.2 ± 6.7 nM, respectively, and simultaneously lowered inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6, and IL-1β production in lipopolysaccharide-activated murine macrophages. Authentic curcumin in ME-23 possessed superior NO inhibitory activity, which was 103-fold more effective than curcumin prepared in the conventional solvent dimethyl sulfoxide. ME-23 was also capable of delivering curcumin into murine macrophages. After 30 days of storage in HDES and HDES-based ME, curcumin remained more than 90%. ME-23 provides advantages for CL extraction, constituent delivery, and anti-inflammatory functions that can be applied to pharmaceutical and cosmetic products.

A novel HDES-based microemulsion system with anti-inflammatory activity serves as an extraction solvent of Curcuma longa L.

An Investigation into the Effects of a Curcumin Extract (Curcugen®) on Osteoarthritis Pain of the Knee: A Randomised, Double-Blind, Placebo-Controlled Study

Curcumin, a phytochemical from the spice turmeric, has anti-inflammatory properties and has been shown to have pain-relieving effects. In this 8-week, randomised, double-blind, placebo-controlled study, 101 adults with knee osteoarthritis received either 500 mg twice daily of a standardised curcumin extract (Curcugen^®) or placebo. Outcome measures included the Knee Injury and Osteoarthritis Outcome Score (KOOS), knee pain ratings, Japanese Orthopaedic Association Score for Osteoarthritic Knees (JOA), PROMIS-29, and performance-based testing comprising the 40-m fast-paced walk test, 6-min walk test, timed up-and-go test, and 30-s chair stand test. Compared to the placebo, curcumin significantly reduced the KOOS knee pain score (p = 0.009) and numeric knee pain ratings (p = 0.001). Curcumin was also associated with greater improvements (p ≤ 0.05) than the placebo on the timed up-and-go test, 6-min walk test, and the JOA total score; but not the 30-s chair stand test or 40-m fast-paced walk test. Pain-relieving medication was reduced in 37% of participants on curcumin compared to 13% on placebo. The findings support the potential efficacy of curcumin for the treatment of osteoarthritis of the knee but studies of longer duration, varying treatment doses, differing curcumin extracts, and the use of other objective outcome measures will be helpful to expand on these findings.