Polyphenolic Composition and Antioxidant Activity of Uncaria tomentosa Commercial Bark Products

Alzheimer's disease: Molecular aspects and treatment opportunities using herbal drugs

Alzheimer's disease (AD), also called senile dementia, is the most common neurological disorder. Around 50 million people, mostly of advanced age, are suffering from dementia worldwide and this is expected to reach 100-130 million between 2040 and 2050. AD is characterized by impaired glutamatergic and cholinergic neurotransmission, which is associated with clinical and pathological symptoms. AD is characterized clinically by loss of cognition and memory impairment and pathologically by senile plaques formed by Amyloid β deposits or neurofibrillary tangles (NFT) consisting of aggregated tau proteins. Amyloid β deposits are responsible for glutamatergic dysfunction that develops NMDA dependent Ca2+ influx into postsynaptic neurons generating slow excitotoxicity process leading to oxidative stress and finally impaired cognition and neuronal loss. Amyloid decreases acetylcholine release, synthesis and neuronal transport. The decreased levels of neurotransmitter acetylcholine, neuronal loss, tau aggregation, amyloid β plaques, increased oxidative stress, neuroinflammation, bio-metal dyshomeostasis, autophagy, cell cycle dysregulation, mitochondrial dysfunction, and endoplasmic reticulum dysfunction are the factors responsible for the pathogenesis of AD. Acetylcholinesterase, NMDA, Glutamate, BACE1, 5HT6, and RAGE (Receptors for Advanced Glycation End products) are receptors targeted in treatment of AD. The FDA approved acetylcholinesterase inhibitors Donepezil, Galantamine and Rivastigmine and N-methyl-D-aspartate antagonist Memantine provide symptomatic relief. Different therapies such as amyloid β therapies, tau-based therapies, neurotransmitter-based therapies, autophagy-based therapies, multi-target therapeutic strategies, and gene therapy modify the natural course of the disease. Herbal and food intake is also important as preventive strategy and recently focus has also been placed on herbal drugs for treatment. This review focuses on the molecular aspects, pathogenesis and recent studies that signifies the potential of medicinal plants and their extracts or chemical constituents for the treatment of degenerative symptoms related to AD.

A comprehensive overview of juvenile idiopathic arthritis: From pathophysiology to management

Rheumatoid Arthritis (RA) is a progressive autoimmune disease. It is among the most widespread chronic illnesses in children, with an annual incidence of 1.6 to 23 new instances per 100,000 adolescents. About 1 child in every 1000 develops Juvenile Idiopathic Arthritis (JIA) type of chronic arthritis. The cause of JIA is not well known but what known is that it involves inflammation of the synovium and destruction of tissues in joints which can cause early-onset of oligo articular JIA. It is challenging to diagnose the condition in some children who initially complain of pain and joint swelling as there is no blood test discovered that can confirm the diagnoses of JIA. As JIA patients are immunosuppressed due to the use of drugs, making them vulnerable to catch infections like COVID 19 which can lead to cardiovascular diseases having high rate of morbidity and mortality. The comorbidity like Diabetes has higher incidence in these patients resulting in synergistic effect on inflammation. Currently, the connection of genetics in JIA provides evidence that HLA Class I and II alleles have a role in the pathophysiology of various subtypes of JIA which includes inflammation in the axial skeletal. The primary objective of therapy in juvenile idiopathic arthritis is the suppression of clinical symptoms. The pharmacological approach includes use of medications like DMARDs, NSAIDs etc. and non-pharmacological approach includes physiotherapy, which helps in restoring normal joint function and herbs as adjuvants which has the benefit of no side effects.

Medicinal Plants in Peru as a Source of Immunomodulatory Drugs Potentially Useful Against COVID-19

The current COVID-19 pandemic, characterized by a highly contagious severe acute respiratory syndrome, led us to look for medicinal plants as an alternative to obtain new drugs, especially those with immunomodulatory abilities, capable of acting against the pulmonary infection caused by coronavirus 2 (SARS-CoV-2). Despite medical advances with COVID-19 drugs and vaccines, plant-based compounds could provide an array of suitable candidates to test against this virus, or at the very least, to alleviate some symptoms. Therefore, this review explores some plants widely used in Peru that show immunomodulatory properties or, even more, contain phytoconstituents potentially useful to prevent or alleviate the COVID-19 infection. More interestingly, the present review highlights relevant information from those plants to support the development of new drugs to boost the immune system. We used three criteria to choose nine vegetal species, and a descriptive search was then conducted from 1978 to 2021 on different databases, using keywords focused on the immune system that included information such as pharmacological properties, phytochemical, botanical, ethnobotanical uses, and some clinical trials. From these literature data, our results displayed considerable immunomodulation activity along with anti-inflammatory, antiviral, antioxidant, and antitumoral activities. Noticeably, these pharmacological activities are related with a wide variety of bioactive phytoconstituents (mixtures or isolated compounds) which may be beneficial in modulating the overt inflammatory response in severe COVID-19. Further scientific research on the pharmacological activities and clinical utilization of these potential plants are warranted.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-023-00367-w.

Application of the Extracts of Uncaria tomentosa in Endodontics and Oral Medicine: Scoping Review

Background: The main purpose of endodontic treatment is to eliminate the bacteria that are responsible for the contamination and infection of the internal surfaces in order to resolve any pulp or periapical pathology. In fact, some bacteria, such as Enterococcus faecalis, can escape the action of root canal irrigants by aggregating into a biofilm and penetrating deeply into the dentinal tubules. Uncaria tomentosa is a plant belonging to the Rubiaceae family and also commonly known as cat’s claw due to the shape and position of the spines; it is a traditional Peruvian medicinal plant of Amazonian origin. Applications in the dental field have been described both in the prevention and treatment of stomatitis and as an antibacterial and anti-inflammatory agent; it has also been investigated as an additive in irrigants and specifically as gels in endodontic cements. The aim of this scoping review is to summarize all the scientific evidence on the possible applications of Uncaria tomentosa extracts in endodontics and, more generally, in oral medicine, in order to understand whether the active ingredients extracted from Uncaria tomentosa can bring a real advantage in endodontics, in the reduction of endodontic failures and in the onset of recurrent endodontic lesions. Methods: The scoping review was carried out strictly following the PRISMA-ScR checklist; the search was carried out on five databases (PubMed, Scopus, Science Direct, EBSCO and Web of Science) and a register (Cochrane library). Results: The research produced a number of bibliographic sources totaling 2104. With the removal of duplicates, 670 were obtained; potentially eligible articles amounted to 23, of which only seven in vitro studies (four microbiological studies), five clinical studies (three randomized trials) and a case report were included. Conclusions: From the data in the literature, it can be stated that the active ingredients present in Uncaria tomentosa could represent an interesting product to be used in the endodontic field, both in endocanalary cements and as a gel.

Hybrid Nanoparticles of Proanthocyanidins from Uncaria tomentosa Leaves: QTOF-ESI MS Characterization, Antioxidant Activity and Immune Cellular Response

Previous studies in Uncaria tomentosa have shown promising results concerning the characterization of polyphenols with leaves yielding more diverse proanthocyanidins and higher bioactivities values. However, the polyphenols-microbiota interaction at the colonic level and their catabolites avoid the beneficial effects that can be exerted by this medicinal plant when consumed. In this regard, a new generation of hybrid nanoparticles has demonstrated improvements in natural compounds’ activity by increasing their bioavailability. In this line, we report a detailed study of the characterization of a proanthocyanidin-enriched extract (PA-E) from U. tomentosa leaves from Costa Rica using UPLC-QTOF-ESI MS. Moreover, two types of hybrid nanoparticles, a polymeric-lipid (F-1) and a protein-lipid (F-2) loaded with PA-E were synthesized and their characterization was conducted by dynamic light scattering (DLS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR), high-resolution transmission electron microscopy (HR-TEM), and encapsulation efficiency (%EE). In addition, in vitro release, antioxidant activity through 2,2-diphenyl-1-picrylhidrazyl (DPPH) as well as in vivo delayed-type hypersensitivity (DTH) reaction was evaluated. Results allowed the identification of 50 different compounds. The PA-E loaded nanoparticles F-1 and F-2 achieved encapsulation efficiency of ≥92%. The formulations exhibited porosity and spherical shapes with a size average of 26.1 ± 0.8 and 11.8 ± 3.3 nm for F-1 and F-2, respectively. PA-E increased its release rate from the nanoparticles compared to the free extract in water and antioxidant activity in an aqueous solution. In vivo, the delayed-type hypersensitive test shows the higher immune stimulation of the flavan-3-ols with higher molecular weight from U. tomentosa when administered as a nanoformulation, resulting in augmented antigen-specific responses. The present work constitutes to our knowledge, the first report on these bioactivities for proanthocyanidins from Uncaria tomentosa leaves when administrated by nanosystems, hence, enhancing the cellular response in mice, confirming their role in immune modulation.

HRMS Characterization, Antioxidant and Cytotoxic Activities of Polyphenols in Malus domestica Cultivars from Costa Rica

There is increasing interest in research into fruits as sources of secondary metabolites because of their potential bioactivities. In this study, the phenolic profiles of Malus domestica Anna and Jonagold cultivars from Costa Rica were determined by Ultra Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry (HRMS) using a quadrupole-time-of-flight analyzer (UPLC-QTOF-ESI MS), on enriched-phenolic extracts from skins and flesh, obtained through Pressurized Liquid Extraction (PLE). In total, 48 different phenolic compounds were identified in the skin and flesh extracts, comprising 17 flavan-3-ols, 12 flavonoids, 4 chalcones, 1 glycosylated isoprenoid and 14 hydroxycinnamic acids and derivatives. Among extracts, the flesh of Jonagold exhibits a larger number of polyphenols and is especially rich in procyanidin trimers, tetramers and pentamers. Evaluating total phenolic content (TPC) and antioxidant activities using ORAC and DPPH procedures yields higher values for this extract (608.8 mg GAE/g extract; 14.80 mmol TE/g extract and IC50 = 3.96 µg/mL, respectively). In addition, cytotoxicity evaluated against SW620 colon cancer cell lines and AGS gastric cancer cell lines also delivered better effects for Jonagold flesh (IC50 = 62.4 and 60.0 µg/mL, respectively). In addition, a significant negative correlation (p < 0.05) was found between TPC and cytotoxicity values against SW620 and AGS adenocarcinoma (r = -0.908, and -0.902, respectively). Furthermore, a significant negative correlation (p < 0.05) was also found between the number of procyanidins and both antioxidant activities and cytotoxicity towards SW620 (r = -0.978) and AGS (r = -0.894) cell lines. These results align with Jonagold flesh exhibiting the highest abundance in procyanidin oligomers and yielding better cytotoxic and antioxidant results. In sum, our findings suggest the need for further studies on these Costa Rican apple extracts-and particularly on the extracts from Jonagold flesh-to increase the knowledge on their potential benefits for health.

Design of Hybrid Polymeric-Lipid Nanoparticles Using Curcumin as a Model: Preparation, Characterization, and In Vitro Evaluation of Demethoxycurcumin and Bisdemethoxycurcumin-Loaded Nanoparticles

Polymeric lipid hybrid nanoparticles (PLHNs) are the new generation of drug delivery systems that has emerged as a combination of a polymeric core and lipid shell. We designed and optimized a simple method for the preparation of Pluronic F-127-based PLHNs able to load separately demethoxycurcumin (DMC) and bisdemethoycurcumin (BDM). CUR was used as a model compound due to its greater availability from turmeric and its structure similarity with DMC and BDM. The developed method produced DMC and BDM-loaded PLHNs with a size average of 75.55 ± 0.51 and 15.13 ± 0.014 nm for DMC and BDM, respectively. An FT-IR analysis confirmed the encapsulation and TEM images showed their spherical shape. Both formulations achieved an encapsulation efficiency ≥ 92% and an exhibited significantly increased release from the PLHN compared with free compounds in water. The antioxidant activity was enhanced as well, in agreement with the improvement in water dissolution; obtaining IC₅₀ values of 12.74 ± 0.09 and 16.03 ± 0.55 for DMC and BDM-loaded PLHNs, respectively, while free curcuminoids exhibited considerably lower antioxidant values in an aqueous solution. Hence, the optimized PHLN synthesis method using CUR as a model and then successfully applied to obtain DMC and BDM-loaded PLHNs can be extended to curcuminoids and molecules with a similar backbone structure to improve their bioactivities.

Polyphenolic QTOF-ESI MS Characterization and the Antioxidant and Cytotoxic Activities of Prunus domestica Commercial Cultivars from Costa Rica

There is an increased interest in plum research because of their metabolites' potential bioactivities. In this study, the phenolic profiles of Prunus domestica commercial cultivars (Methley, Pisardii and Satsuma) in Costa Rica were determined by Ultra Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry using a quadrupole-time-of-flight analyzer (UPLC-ESI-QTOF MS) on enriched phenolic extracts obtained through Pressurized Liquid Extraction (PLE) under acidic and neutral extraction conditions. In total, 41 different phenolic compounds were identified in the skin and flesh extracts, comprising 11 flavan-3-ols, 14 flavonoids and 16 hydroxycinnamic acids and derivatives. Neutral extractions for the skins and flesh from all of the cultivars yielded a larger number of compounds, and were particularly rich in the number of procyanidin trimers and tetramers when compared to the acid extractions. The total phenolic content (TPC) and antioxidant potential using the DPPH and ORAC methods exhibited better results for neutral extracts with Satsuma skins and Methley flesh, which showed the best values (685.0 and 801.6 mg GAE/g extract; IC₅₀ = 4.85 and 4.39 µg/mL; and 12.55 and 12.22 mmol TE/g extract, respectively). A Two-Way ANOVA for cytotoxicity towards AGS gastric adenocarcinoma and SW620 colon adenocarcinoma indicated a significant difference (p < 0.05) for PLE conditions, with better results for neutral extractions, with Satsuma skin delivering the best results (IC₅₀ = 60.7 and 46.7 µg/mL respectively) along with Methley flesh (IC₅₀ = 76.3 and 60.9 µg/mL, respectively). In addition, a significant positive correlation was found between TPC and ORAC (r = 0.929, p < 0.05), as well as a significant negative correlation (p < 0.05) between TPC and cytotoxicity towards AGS and SW620 cell lines (r = -0.776, and -0.751, respectively). A particularly high, significant, negative correlation (p < 0.05) was found between the number of procyanidins and cytotoxicity against the AGS (r = -0.868) and SW620 (r = -0.855) cell lines. Finally, the PCA clearly corroborated that neutral extracts are a more homogenous group exhibiting higher antioxidant and cytotoxic results regardless of the part or cultivar; therefore, our findings suggest that PLE extracts under neutral conditions would be of interest for further studies on their potential health benefits.

Antioxidant, Mineralogenic and Osteogenic Activities of Spartina alterniflora and Salicornia fragilis Extracts Rich in Polyphenols

Osteoporosis is an aging-related disease and a worldwide health issue. Current therapeutics have failed to reduce the prevalence of osteoporosis in the human population, thus the discovery of compounds with bone anabolic properties that could be the basis of next generation drugs is a priority. Marine plants contain a wide range of bioactive compounds and the presence of osteoactive phytochemicals was investigated in two halophytes collected in Brittany (France): the invasive Spartina alterniflora and the native Salicornia fragilis. Two semi-purified fractions, prepared through liquid-liquid extraction, were assessed for phenolic and flavonoid contents, and for the presence of antioxidant, mineralogenic and osteogenic bioactivities. Ethyl acetate fraction (EAF) was rich in phenolic compounds and exhibited the highest antioxidant activity. While S. fragilis EAF only triggered a weak proliferative effect in vitro, S. alterniflora EAF potently induced extracellular matrix mineralization (7-fold at 250 μg/mL). A strong osteogenic effect was also observed in vivo using zebrafish operculum assay (2.5-fold at 10 μg/mL in 9-dpf larvae). Results indicate that polyphenol rich EAF of S. alterniflora has both antioxidant and bone anabolic activities. As an invasive species, this marine plant may represent a sustainable source of molecules for therapeutic applications in bone disorders.

Assessment of modulatory activity of Uncaria tomentosa extract against fipronil immunotoxicity in male rats

This study has investigated the effect of using the Uncaria tomentosa (UT) extract against immunotoxicity that induced by fipronil (FP) in male Wistar rats. Twenty-eight, male Wistar rats were assigned randomly into four groups (7 rats each). Control group received distilled water. FP group received FP 9.7 mg/kg b. wt orally via gastric tube. UT group received 120 mg/kg b. wt. of UT extract orally. FP-UT group received both FP and UT (9.7 and 120 mg/kg b.wt, respectively) for 30 days. Hematological parameters, malondialdehyde (MDA), total antioxidant capacity (TAC), estradiol, histamine and immunoglobulin E (IGE) were assayed. Histopathological and electron microscopical examinations were performed to the lymphoid organs. Hematological parameters, were decreased in the FP group than the control group. There was a rise in MDA of FP group followed by a decrease in TAC content with histological and ultrastructure degenerative changes. UT extract treatment ameliorated the FP-induced perturbations for the former parameters. The results showed that FP treatment exerted an immunotoxic effect through acting as an endocrine disruptor and allergic, pro-inflammatory that was confirmed by histopathological and ultrastructure study of the lymphoid organs. Uncaria tomentosa extract could successfully modulate FP-induced immunotoxicity by diminishing all the studied parameters.

Non-pharmacological remedies for post-viral acute cough

The post-viral acute cough (PAC) is a widespread symptom, mainly in childhood and adolescence, and is usually associated with an acute upper respiratory infection, namely the common cold. The use of cough relievers is, therefore, impressive, as documented by the market data. There are many medical devices and dietary supplements for treating PAC, which contain non-pharmacological components. Ancient people used traditional herbs to treat PAC. Thus, a well-established tradition considers natural remedies as an effective and safe way to relieve PAC. The herbal agents include polyphenols, flavonoids, saponins, glucosides, and alkaloids. Also, the European Medicine Agency has recognized the value of plant extracts and other natural substances to treat PAC. Nevertheless, a few studies investigated the role of non-pharmacologic remedies for PAC. There is some evidence for honey, glycerol, Althea officinalis, Drosera rotundifolia, Grindelia, Hedera helix, Pelargonium sidoides, Sambucus nigra, Thymus vulgaris, hyaluronic acid, and saline solutions. However, further rigorous studies should confirm natural products' efficacy and safety to relieve PAC.

Targeting P2 receptors in purinergic signaling: a new strategy of active ingredients in traditional Chinese herbals for diseases treatment

Adenosine triphosphate (ATP) and its metabolites adenosine diphosphate, adenosine monophosphate, and adenosine in purinergic signaling pathway play important roles in many diseases. Activation of P2 receptors (P2R) channels and subsequent membrane depolarization can induce accumulation of extracellular ATP, and furtherly cause kinds of diseases, such as pain- and immune-related diseases, cardiac dysfunction, and tumorigenesis. Active ingredients of traditional Chinese herbals which exhibit superior pharmacological activities on diversified P2R channels have been considered as an alternative strategy of disease treatment. Experimental evidence of potential ingredients in Chinese herbs targeting P2R and their pharmacological activities were outlined in the study.

Changes in Human Erythrocyte Membrane Exposed to Aqueous and Ethanolic Extracts from Uncaria tomentosa

Uncaria tomentosa (Willd.) DC is a woody climber species originating from South and Central America that has been used in the therapy of asthma, rheumatism, hypertension, and blood purification. Our previous study showed that U. tomentosa extracts altered human erythrocyte shape, which could be due to incorporation of the compounds contained in extracts into the erythrocyte membrane. The aim of the present study was to determine how the compounds contained in U. tomentosa extracts incorporate into the human erythrocyte membrane. The study has assessed the effect of aqueous and ethanolic extracts from leaves and bark of U. tomentosa on the osmotic resistance of the human erythrocyte, the viscosity of erythrocyte interior, and the fluidity of erythrocyte plasma membrane. Human erythrocytes were incubated with the studied extracts in the concentrations of 100, 250, and 500 µg/mL for 2, 5, and 24 h. All extracts tested caused a decrease in erythrocyte membrane fluidity and increased erythrocyte osmotic sensitivity. The ethanolic extracts from the bark and leaves increased viscosity of the erythrocytes. The largest changes in the studied parameters were observed in the cells incubated with bark ethanolic extract. We consider that the compounds from U. tomentosa extracts mainly build into the outer, hydrophilic monolayer of the erythrocyte membrane, thus protecting the erythrocytes against the adverse effects of oxidative stress.

Dietary Plant Extracts Improve the Antioxidant Reserves in Weaned Piglets

Reducing the use of antibiotics in livestock in order to contain antibiotic resistance and studying natural substance additives are key to sustainability. Among the various biological activities of plant extracts, antioxidant activity plays an important role. The present study assesses the total antioxidant activity and antioxidant reserves using the Kit Radicaux Libres test (KRL™ Kirial International, Couternon, France). One hundred and sixty piglets (Topics × Tempo) weaned at 28 days of age were divided into four dietary treatment groups that were fed a commercial diet (the control group, C); 500 mg/kg Boswellia extract (BOS); 200 and 50 mg/kg Uncaria and Tanacetum extracts (UT) respectively; and 225 mg/kg of an antioxidant plant extract mixture (AOX). The blood antioxidant activity of the piglets was measured using the KRL test and the reserves were analyzed on whole blood samples after hydrolysis with glucosidase, sulfatase and glucuronidase. No significant differences were observed in growth performance. The delta KRL values of the whole blood showed a significantly higher total antioxidant status of the piglets from the BOS and AOX groups than the UT and C groups (+30.7 BOS; +27.7 AOX vs. +17.81 UT +13.30 C; p = 0.002) between 18 and 28 days post-weaning. The delta KRL values of red blood cells (RBCs) showed a significantly higher total antioxidant status of the piglets from the AOX groups than the UT and BOS groups (+22.2 AOX; vs. +9.90 UT +9.4 BOS; p = 0.016) between the two sampling times. Reserves of UT and AOX were higher than C and BOS for all enzymes, glucosides, sulphates, and glucuronides. The biological KRL test proved to be an extremely sensitive tool to evaluate the piglets' antioxidant status. Determining the antioxidant reserve also provides a better understanding of the real antioxidant status of pigs.

COMPARATIVE ACTIVITY OF TOTAL POLYPHENOLS AND ANTIOXIDANT COMPOUNDS FROM UNCARIA TOMENTOSA ENHANCED WITH CITRIC ACID

Uncaria tomentosa, a climbing vine notable for containing high concentrations of oxindole alkaloids and phenolic compounds, is commonly used in traditional medicine as an anti-inflammatory and antioxidant agent. Also, the citric acid is a food additive widely used for conservation, due to its low cost. In this way, this study aims to evaluate the content of phenolic compounds from Uncaria tomentosa and investigate its antioxidant activity when citric acid, at different concentrations, is added to the extract. For this purpose, a gradient of citric acid concentrations was established, and the antioxidant profile from a aqueous extracts of the plant leaves and bark was analyzed by Folin-Ciocalteu essay; inhibition of the free radical of 2,2-diphenyl-1-picrylhydrazyl (DPPH); ferric reducing antioxidant power (FRAP), and scavenging capacity of cationic free radicals of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The results showed a synergistic effect between citric acid and antioxidant compounds from Uncaria tomentosa, presenting highly statistical significance, the synergistic effect was more efficient in the bark than in the leaves.

Extracts from Uncaria tomentosa as antiplatelet agents and thrombin inhibitors - The in vitro and in silico study

ETHNOPHARMACOLOGICAL RELEVANCE

A wide range of traditional medicine applications of Uncaria tomentosa (Willd. ex Schult.) DC., commonly known as 'vilcacora' or 'cat's claw', includes blood purification, its anticoagulant properties and its use in haemorrhage therapy.

AIM OF THE STUDY

Our work is devoted to the effects of ethanol and aqueous extracts (1-50 μg/ml) from U. tomentosa leaves and bark on the haemostatic system. The study is based on two main questions: Can these extracts influence the coagulation cascade of blood plasma or the activation of blood platelets? Do they feature any anticoagulant properties?

MATERIALS AND METHODS

Blood platelet aggregation was measured in human platelet-rich plasma; the anticoagulant tests were based on the thrombin, prothrombin and the activated partial thromboplastin time. For the thrombin (TH)-inhibitory activity evaluation, the chromogenic substrate S-2238 and fibrinogen, i.e. physiological substrate for this enzyme, were used. In silico studies included the interactions of TH and the main components of the extracts.

RESULTS

The examined extracts demonstrated slight antiplatelet activity. The thrombin time was slightly prolonged. The most efficient TH inhibitor was the ethanolic fraction from leaves (IC₅₀ = 5.86 and 12.48 μg/ml, for the amidolytic and proteolytic assay, respectively). The plant ingredients interacted with TH within and outside the active site, dependently on the compound. The higher binding affinity was found for procyanidins B2 and C1.

CONCLUSIONS

The examined extracts demonstrated slight antiplatelet effects; however, they may be promising candidates for the natural inhibitors of TH, which is critical for the formation of fibrin clot.

Uncaria tomentosa (cat's claw): a promising herbal medicine against SARS-CoV-2/ACE-2 junction and SARS-CoV-2 spike protein based on molecular modeling

COVID-19 is a novel severe acute respiratory syndrome coronavirus. Currently, there is no effective treatment and vaccines seem to be the solution in the future. Virtual screening of potential drugs against the S protein of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) has provided small molecular compounds with a high binding affinity. Unfortunately, most of these drugs do not attach with the binding interface of the receptor-binding domain (RBD)–angiotensin-converting enzyme-2 (ACE-2) complex in host cells. Molecular modeling was carried out to evaluate the potential antiviral properties of the components of the medicinal herb Uncaria tomentosa (cat’s claw) focusing on the binding interface of the RBD–ACE-2 and the viral spike protein. The in silico approach starts with protein–ligand docking of 26 Cat’s claw key components followed by molecular dynamics simulations and re-docked calculations. Finally, we carried out drug-likeness calculations for the most qualified cat’s claw components. The structural bioinformatics approaches led to the identification of several bioactive compounds of U. tomentosa with potential therapeutic effect by dual strong interaction with interface of the RBD–ACE-2 and the ACE-2 binding site on SARS-CoV-2 RBD viral spike. In addition, in silico drug-likeness indices for these components were calculated and showed good predicted therapeutic profiles of these phytochemicals found in U. tomentosa (cat’s claw). Our findings suggest the potential effectiveness of cat’s claw as complementary and/or alternative medicine for COVID-19 treatment.

Communicated by Ramaswamy H. Sarma

Investigating Potential Inhibitory Effect of Uncaria tomentosa (Cat's Claw) against the Main Protease 3CLpro of SARS-CoV-2 by Molecular Modeling

COVID-19 is a disease caused by severe acute respiratory syndrome coronavirus 2. Presently, there is no effective treatment for COVID-19. As part of the worldwide efforts to find efficient therapies and preventions, it has been reported the crystalline structure of the SARS-CoV-2 main protease Mpro (also called 3CLpro) bound to a synthetic inhibitor, which represents a major druggable target. The druggability of Mpro could be used for discovering drugs to treat COVID-19. A multilevel computational study was carried out to evaluate the potential antiviral properties of the components of the medicinal herb Uncaria tomentosa (Cat's claw), focusing on the inhibition of Mpro. The in silico approach starts with protein-ligand docking of 26 Cat's claw key components, followed by ligand pathway calculations, molecular dynamics simulations, and MM-GBSA calculation of the free energy of binding for the best docked candidates. The structural bioinformatics approaches led to identification of three bioactive compounds of Uncaria tomentosa (speciophylline, cadambine, and proanthocyanidin B2) with potential therapeutic effects by strong interaction with 3CLpro. Additionally, in silico drug-likeness indices for these components were calculated and showed good predicted therapeutic profiles of these phytochemicals. Our findings suggest the potential effectiveness of Cat's claw as complementary and/or alternative medicine for COVID-19 treatment.

Medicinal plants used against various inflammatory biomarkers for the management of rheumatoid arthritis

OBJECTIVES

Rheumatoid arthritis is a chronic autoimmune disease manifested clinically by polyarthralgia associated with joint dysfunction triggering the antibodies targeting against the self-neoepitopes determined by autoimmune responses associated with chronic arthritic attacks. The activation of macrophages and other defence cells in response to self-epitopes as biomarkers in RA provides a better understanding of pathogenesis of disease and has led to the development of novel therapeutic approaches acting as potent inhibitors of these cells.

KEY FINDINGS

The current review retrieved the various medicinal plants possessing an active phytoconstituents with anti-inflammatory and antioxidant properties, which tends to be effective alternative approach over the synthetic drugs concerned with high toxic effects. The current available literature provided an evident data concluding that the active constituents like fatty acids, flavonoids, terpenes and sesquiterpene lactones attenuate the RA symptoms by targeting the inflammatory biomarkers involved in the pathogenesis of RA.

SUMMARY

Despite the various synthetic treatment approaches targeting immune cells, cytokines improved the quality of life but still the drug management is challenging due to toxic and chronic teratogenic effects with anti-arthritic drugs. The current review has elaborated the selected traditionally used herbal medicinal plants with phytoconstituents possessing anti-inflammatory activity by suppressing the inflammatory biomarkers with lesser side effects and providing the future exploration of natural drug therapy for rheumatoid arthritis.

Postulated Adjuvant Therapeutic Strategies for COVID-19

The number of COVID-19 patients is still growing exponentially worldwide due to the high transmissibility of the SARS-CoV-2 virus. Therapeutic agents currently under investigation are antiviral drugs, vaccines, and other adjuvants that could relieve symptoms or improve the healing process. In this review, twelve therapeutic agents that could play a role in prophylaxis or improvement of the COVID-19-associated symptoms (as add-on substances) are discussed. Agents were identified based on their known pharmacologic mechanism of action in viral and/or nonviral fields and are postulated to interact with one or more of the seven known mechanisms associated with the SARS-CoV-2 virus: (i) regulation of the immune system; (ii) virus entrance in the cell; (iii) virus replication; (iv) hyperinflammation; (v) oxidative stress; (vi) thrombosis; and (vii) endotheliitis. Selected agents were immune transfer factor (oligo- and polypeptides from porcine spleen, ultrafiltered at <10 kDa; Imuno TF®), anti-inflammatory natural blend (Uncaria tomentosa, Endopleura uchi and Haematoccocus pluvialis; Miodesin®), zinc, selenium, ascorbic acid, cholecalciferol, ferulic acid, spirulina, N-acetylcysteine, glucosamine sulfate potassium hydrochloride, trans-resveratrol, and maltodextrin-stabilized orthosilicic acid (SiliciuMax®). This review gives the scientific background on the hypothesis that these therapeutic agents can act in synergy in the prevention and improvement of COVID-19-associated symptoms.

Uncaria tomentosa (Willd. ex Schult.) DC.: A Review on Chemical Constituents and Biological Activities

Uncaria tomentosa (Willd. ex Schult.) DC. (Family: Rubiaceae), commonly known as cat’s claw, is a tropical medicinal vine originating at the Amazon rainforest and other areas of South and Central America. It has been traditionally used to treat asthma, abscesses, fever, urinary tract infections, viral infections, and wounds and found to be effective as an immune system rejuvenator, antioxidant, antimicrobial, and anti-inflammatory agent. U. tomentosa is rich in many phytoconstituents such as oxindole and indole alkaloids, glycosides, organic acids, proanthocyanidins, sterols, and triterpenes. Biological activities of U. tomentosa have been examined against various microorganisms and parasites, including pathogenic bacteria, viruses, and Plasmodium, Babesia and Theileria parasites. Several formulations of cat’s claw (e.g., tinctures, decoctions, capsules, extracts, and teas) are recently available in the market. The current review covers the chemical constituents, biological activities, pharmacokinetics, and toxic properties of U. tomentosa extracts.