Current Research of Phytochemical, Medicinal and Non-Medicinal Uses of Uncaria gambir Roxb.: A Review.

Uncaria gambir Roxb. is a plant from Southeast Asia and is widely used as an alternative medicine with various applications. This plant has been widely used in traditional medicine. This paper aims to provide information on U. gambir, a summary of data on phytochemicals and on medical and nonmedical activities. Phytochemical studies reveal biologically active constituents such as flavonoids, phenolics, and alkaloids. Various studies have shown that extracts and compounds obtained from U. gambir have medical uses for their antioxidant, antibacterial, anti-helminthic, anticancer, antifungal, anti-inflammatory, anti-hyperglycemic, anti-hyperuricemic, anti-lipid peroxidation, antihyperlipidemic and other properties. In addition, this extract has other uses, such as adsorbent for dyes and metal ions, as well as corrosion inhibition. Thus, U. gambir, which is commonly used in traditional medicine, is a potential plant for many therapeutic applications and prospects for drug development as well as other applications such as adsorbent and corrosion inhibition.

[Two new monoterpenoid indole alkaloids from hook-bearing branches of Uncaria sessilifructus].

The present study investigated the chemical constituents from Uncaria sessilifructus and their neuroprotective activities. The compounds were separated and purified from the 90% ethanol extract of U. sessilifructus by various chromatographic methods, including silica gel, Sephadex LH-20, and semi-preparative HPLC. Seven compounds were obtained, and their structures were identified as uncanidine J(1), uncanidine K(2), 17-O-ethylhirsutine(3), tetrahydroalstonine(4), akuammigine(5), hirsutine(6), and hirsuteine(7) by physicochemical properties and various spectral techniques, including UV, IR, MS, and NMR. Compounds 1 and 2 are two new compounds. Compound 3 is a new natural product, and compound 4 was isolated from U. sessilifructus for the first time. In addition, the isolated compounds were evaluated for their neuroprotective effects on oxygen and glucose deprivation/reoxygenation(OGD/R) injury in primary cortical neurons in rats. The results showed that compounds 1-7 had different degrees of protective effects on OGD/R injury. The EC_(50) values of compounds 2-4 were(0.17±0.03),(1.70±0.38), and(1.79±0.23) µmol·L~(-1), respectively.

Rapid screening of hepatotoxic components in Uncariae Ramulus Cum Uncis based on "component-target-pathway" network.

As a multi-base source traditional Chinese medicine, the hepatotoxicity of Uncariae Ramulus Cum Uncis (URCU) has been reported repeatedly in recent years. The lack of clarity of toxic components and toxicity mechanisms is a key issue that needs to be addressed. In this article, a "component-target-pathway" network strategy was established to firstly predicting the hepatotoxic components and the toxicity mechanism of URCU. Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and data post-processing technology were used to classify and identify the main components in Uncaria rhynchophylla (Miq.) Miq. ex Havil. (UR) and Uncaria sinensis (Oliv.) Havil. (US). Then, the potential hepatotoxic components were screened by network pharmacology and molecular docking. As a result, 40 components and 39 ingredients were identified in UR and US, respectively. Cadambine, rhynchophylline, corynoxeine, isocorynoxeine, strictosamide and mitraphylline were screened as the potential hepatotoxic ingredients contained both in UR and US. The network pharmacology showed that the potential hepatotoxic components could affect the IL-17 signaling pathway by regulating related targets such as MAPK1 and MAPK14, which might lead to the occurrence of liver injury. This study not only provided a reasonable strategy for the rapid screening of hepatotoxic components in URCU, but also supplied reference and guidance for the rational clinical application and scientific supervision of URCU.

Biotransformation and pharmacokinetic studies of four alkaloids from Uncaria rhynchophylla in rat plasma by ultra-performance liquid chromatography with tandem mass spectrometry.

Uncaria rhynchophylla (Miq.) Miq. ex Havil (U. rhynchophylla), a traditional Chinese medicine that has been officially included in the Chinese Pharmacopeia, is used to treat cardiovascular and central nervous system diseases. The major alkaloids isolated from U. rhynchophylla are two pairs of epimer including rhynchophylline (RIN) and isorhynchophylline (IRN), along with corynoxeine (CN) and isocorynoxeine (ICN). An ultra-performance liquid chromatography with tandem mass spectrometry method (UHPLC-MS/MS), which was highly accurate, stable and sensitive, was established and validated for the simultaneous determination of four alkaloid compounds (RIN, IRN, CN, ICN) in rat plasma samples after oral administration of RIN, IRN, CN, ICN and U. rhynchophylla extract. In this study, the biotransformation and pharmacokinetics of RIN, IRN, CN and ICN were determined for the first time. An ACQUITY UPLC®HSS T3 column (1.8 µm, 2.1 mm × 100 mm) was used to complete the chromatographic separation within 3 min. The isocratic mobile phase was composed of 0.1 % formic acid water (v/v) and acetonitrile, and the flow rate was 0.2 mL/min. The multireaction monitoring mode was adopted, and the tandem mass spectrometry in the positive ion mode was detected by the electrospray ionization source. The method was fully verified and linear at a wide concentration (r > 0.9913), and the linear concentration range was 0.1552-124.5 ng/mL. The intraday and interday precisions of the four analytes were lower than 8.20 % and 13.42 %, respectively. The accuracy range was - 2.64 % and 13.63 %. The extraction recoveries of the analytes exceeded 83.74 %, and the matrix effect range was 98.43-103.7 % in the plasma samples. The four alkaloids can be quickly absorbed into the blood (Tmax, 0.22-3.83 h) and cleared comparatively slowly (T1/2, 7.67-12.13 h). This method has been successfully applied to the biotransformation and pharmacokinetic studies of SD rat plasma after oral administration of U. rhynchophylla extracts. This proved that RIN with IRN and CN with ICN can transform into each other in vivo. The results are of great significance for determining the mechanism of action and guiding the clinical application of U. rhynchophylla extracts.

[Steroids from Uncaria rhynchophylla].

Thirteen steroids(1-13) were isolated from the non-alkaloid constituents of Uncaria rhynchophylla by column chromatography on silica gel, ODS, Sephadex LH-20, and preparative HPLC chromatography, and their structures were elucidated by analyses of the MS and NMR spectral data. All the compounds were isolated from the genus Uncaria for the first time, and 1 was a new compound. The ~1H-NMR and ~(13)C-NMR data of two compounds(12 and 13) in deuteron-chloroform were completely assigned. This study enriched the steroid constituents of U. rhynchophylla and provided scientific references for the elucidation of active constituents and further development and utilization of U. rhynchophylla.

An enhanced strategy integrating offline two-dimensional separation with data independent acquisition mode and deconvolution: Characterization of metabolites of Uncaria rhynchophylla in rat plasma as a case.

The importance to clarify the drug metabolites is beyond doubt in view of their potential efficacy and safety. However, due to the complex matrix interference, relatively low content and the co-eluting effect, it is of a great challenge to comprehensively and systematically characterize the metabolites in vivo, especially for the traditional Chinese medicines (TCMs) due to the numerous types of components. In the present study, a comprehensive off-line two-dimensional separation system combining with data independent acquisition (DIA) mode and multi-dimensional data deconvolution method was established for chromatographic separation, data acquisition and data procession of indole alkaloids in rat plasma after intragastrically administrated with the extract of Uncaria rhynchophylla at the dose of 1 g/kg. The orthogonality of the off-line 2D separation system consisting of HILIC for first-dimensional separation and the PRLC for second-dimensional separation was valuated with the "asterisk" equations, and the results showed that off-line 2D separation system had passable orthogonality (A0 = 53.3%). Furthermore, the DIA mode was applied to capture MS/MS spectra in view of its advantage in acquiring MS data, and an effective multi-dimensional deconvolution method integrating the calculation of chemical formula, the extraction of diagnostic ion, the filter of ring double bond (RDB) and the judgement of neutral loss was established to parse the spectra for the complicated DIA data for comprehensive analysis of metabolites in rat plasma. Ultimately, a total of 127 indole alkaloids were tentatively characterized, and the main metabolic pathways were inferred as demethylation, dehydrogenation, hydroxylation and deglycosylation. The off-line two-dimensional separation system was applied for the comprehensive characterization of metabolites in vivo for the first time. This study suggested a new approach to enable the enrichment, separation and analysis of the low content components in vivo.

Configuration of the ion exchange chromatography, hydrophilic interaction chromatography, and reversed-phase chromatography as off-line three-dimensional chromatography coupled with high-resolution quadrupole-Orbitrap mass spectrometry for the multicomponent characterization of Uncaria sessilifructus.

Herbs represent complex chemical systems involving various primary and secondary metabolites that are featured by large spans of acid-base property, polarity, molecular mass, and content, etc., which thus poses great challenges to characterize the metabolites contained. Here, the combination of multiple-mechanism chromatography coupled with improved data-dependent-MS2 acquisition (DDA-MS2) is presented as a strategy to support the deep metabolites characterization. Targeting Uncaria sessilifructus, a reputable medicinal herb containing alkaloids and triterpenic acids (TAs) as the main pharmacologically bioactive ingredients, a three-dimensional liquid chromatography (3D-LC) system was established by integrating ion exchange chromatography, hydrophilic interaction chromatography, and reversed-phase chromatography (IEC-HILIC-RPC). The first-dimensional chromatography, configuring a PhenoSphere SCX column eluted by methanol/20 mM ammonium acetate-0.05% formic acid in water, could well fractionate the total extract into two fractions (unretained ingredients and alkaloids). The subsequent HILIC using an XAmide column and RPC by a CSH Phenyl-Hexyl column achieved the sufficient resolution of the total TAs and total alkaloids, respectively. A polarity-switching precursor ions list-including DDA approach by Q-Orbitrap-MS enabled the high-efficiency, coverage-enhanced identification of alkaloids and TAs. This 3D-LC/Q-Orbitrap-MS system was validated as precise (RSD < 5% for intra-day/inter-day precision), Up to 308 components were separated from U. sessilifructus, and 128 thereof (including 85 alkaloids, 29 TAs, and 14 others) were identified or tentatively characterized, exhibiting superiority over the conventional one-dimensional LC/MS. Conclusively, 3D-LC/MS in an off-line mode can facilitate the flexible configuration of multiple chromatography to accomplish the fit-for-purpose characterization of the metabolites from an herbal extract or a biosample.

Effects of Tianma (Rhizoma Gastrodiae) and Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis) on cytochrome P450 enzyme activities in rats.

OBJECTIVE: To investigate the efficacy of Tianma (Rhizoma Gastrodiae) and Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis) on cytochrome P450 (CYP450) enzyme activities in rats. METHODS: A cocktail strategy was followed to evaluate the influence of Tianma (Rhizoma Gastrodiae) and Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis) on the activities of CYP450 isoforms (CYP1A2, CYP3A4, CYP2E1, CYP2C19, CYP2C9, CYP2D6), which were determined by changes in the pharmacokinetic parameters of six probe drugs, theophylline, dapsone, chlorzoxazone, omeprazole, tolbutamide and dextromethorphan. Study groups included, Control group (CG), Tianma (Rhizoma Gastrodiae) group (TM), Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis) group (GT) and Tianma Gouteng (Gastrodia Uncaria) group (TMGT). RESULTS: No significant differences between Tianma (Rhizoma Gastrodiae) and control groups were found. Compared with the control group, in the Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis) group both the AUC and t1/2 of dapsone and tolbutamide were reduced, whereas the CL (clearance rate) of dapsone and tolbutamide were increased. Compared with the control group, in the Tianma Gouteng group, the AUC and t1/2 of dapsone and tolbutamide were reduced, the CL of dapsone and tolbutamide were increased, and the AUC and t1/2 of chlorzoxazone were increased and the CL of chlorzoxazone was reduced. CONCLUSION: Tianma (Rhizoma Gastrodiae) has no significant effect on the six CYP450 subtypes. The activities of CYP3A4 and CYP2C9 were increased by Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis). The activities of CYP3A4 and CYP2C9 were increased, whereas the activity of CYP32E1 was reduced by combined Tianma (Rhizoma Gastrodiae) and Gouteng (Ramulus Uncariae Rhynchophyllae cum Uncis).

The Main Alkaloids in Uncaria rhynchophylla and Their Anti-Alzheimer's Disease Mechanism Determined by a Network Pharmacology Approach.

Alzheimer's disease (AD) is a growing concern in modern society, and effective drugs for its treatment are lacking. Uncaria rhynchophylla (UR) and its main alkaloids have been studied to treat neurodegenerative diseases such as AD. This study aimed to uncover the key components and mechanism of the anti-AD effect of UR alkaloids through a network pharmacology approach. The analysis identified 10 alkaloids from UR based on HPLC that corresponded to 90 anti-AD targets. A potential alkaloid target-AD target network indicated that corynoxine, corynantheine, isorhynchophylline, dihydrocorynatheine, and isocorynoxeine are likely to become key components for AD treatment. KEGG pathway enrichment analysis revealed the Alzheimers disease (hsa05010) was the pathway most significantly enriched in alkaloids against AD. Further analysis revealed that 28 out of 90 targets were significantly correlated with Aß and tau pathology. These targets were validated using a Gene Expression Omnibus (GEO) dataset. Molecular docking studies were carried out to verify the binding of corynoxine and corynantheine to core targets related to Aß and tau pathology. In addition, the cholinergic synapse (hsa04725) and dopaminergic synapse (hsa04728) pathways were significantly enriched. Our findings indicate that UR alkaloids directly exert an AD treatment effect by acting on multiple pathological processes in AD.

Recent research progress of Uncaria spp. based on alkaloids: phytochemistry, pharmacology and structural chemistry.

Medicinal plants are well-known in affording clinically useful agents, with rich medicinal values by combining with disease targets through various mechanisms. Plant secondary metabolites as lead compounds lay the foundation for the discovery and development of new drugs in disease treatment. Genus Uncaria from Rubiaceae family is a significant plant source of active alkaloids, with anti-hypertensive, sedative, anti-Alzheimer's disease, anti-drug addiction and anti-inflammatory effects. This review summarizes and discuss the research progress of Uncaria based on alkaloids in the past 15 years, mainly in the past 5 years, including biosynthesis, phytochemistry, pharmacology and structural chemistry. Among, focusing on representative compounds rhynchophylline and isorhynchophylline, the pharmacological activities surrounding the central nervous system and cardiovascular system are described in detail. On the basis of case studies, this article provides a brief overview of the synthesis and analogues of representative compounds types. In summary, this review provides an early basis for further searching for new targets and activities, discussing the mechanisms of pharmacological activity and studying the structure-activity relationships of active molecules.

Uncaria rhynchophylla ameliorates unpredictable chronic mild stress-induced depression in mice via activating 5-HT1A receptor: Insights from transcriptomics.

BACKGROUND: Depression is a pervasive or persistent mental disorder that causes mood, cognitive and memory deficits. Uncaria rhynchophylla has been widely used to treat central nervous system diseases for a long history, although its efficacy and potential mechanism are still uncertain. PURPOSE: The present study aimed to investigate anti-depression effect and potential mechanism of U. rhynchophylla extract (URE). STUDY DESIGN AND METHODS: A mouse depression model was established using unpredictable chronic mild stress (UCMS). Effects of URE on depression-like behaviours, neurotransmitters, and neuroendocrine hormones were investigated in UCMS-induced mice. The potential target of URE was analyzed by transcriptomics and bioinformatics methods and validated by RT-PCR and Western blot. The agonistic effect on 5-HT1A receptor was assayed by dual-luciferase reporter system. RESULTS: URE ameliorated depression-like behaviours, and modulated levels of neurotransmitters and neuroendocrine hormones, including 5-hydroxytryptamine (5-HT), 5-hydroxyindole acetic acid (5-HIAA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), corticosterone (CORT), corticotropin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH), in UCMS-induced mice. Transcriptomics and bioinformatics results indicated that URE could regulate glutamatergic, cholinergic, serotonergic, and GABAergic systems, especially neuroactive ligand-receptor and cAMP signaling pathways, revealing that Htr1a encoding 5-HT1A receptor was a potential target of URE. The expression levels of downstream proteins of 5-HT1A signaling pathway 5-HT1A, CREB, BDNF, and PKA were increased in UCMS-induced mice after URE administration, and URE also displayed an agonistic effect against 5-HT1A receptor with an EC50 value of 17.42 µg/ml. CONCLUSION: U. rhynchophylla ameliorated depression-like behaviours in UCMS-induced mice through activating 5-HT1A receptor.

The genus Uncaria: A review on phytochemical metabolites and biological aspects.

The genus Uncaira (Rubiaceae) comprises of 34 species, many of which are usually used as traditional Chinese medicines (TCMs) to treat hypertension, fever, headache, gastrointestinal illness, and fungal infection. Over the past twenty years, Uncaira species have been paid the considerable attentions in phytochemical and biological aspects, and about 100 new secondary metabolites, including alkaloids, triterpenes, and flavonoids, have been elucidated. This review aims to present a comprehensive and up-to date overview of the biological source, structures and their biosynthetic pathways, as well as the pharmacological of the compounds reported in the genus Uncaria for the past two decades. It would provide an insight into the emerging pharmacological applications of the genus Uncaria.

The inhibition effect of uncarialin A on voltage-dependent L-type calcium channel subunit alpha-1C: Inhibition potential and molecular stimulation.

Cardiovascular diseases, such as hypertension and cardiac failure, have become the most major and global cause for threatening human health in recent years. Uncaria rhynchophylla as a traditional Chinese medicine is widely used to treat hypertension for a long history, whereas its medicinal effective components and potential action mechanism are uncertain. Therefore, twenty-four alkaloids (1-24) isolated from U. rhynchophylla were assayed for their relaxant effects against phenylephrine (Phe)-induced contraction of rat mesenteric arteries. Among them, we surprisingly found that uncarialin A (21) exhibited most potent relaxation effect against Phe-induced contraction (IC50 = 0.18 µM) in the manner of independent on endothelium-derived vasorelaxing factors and endothelium. All the experiments including measurement of Ca2+ in vascular smooth muscle cells (VSMCs) by fluorescence microscopy, whole-cell path clamp, molecular docking, and molecular dynamics, demonstrated that uncarialin A (21) could significantly inhibit L-type calcium channel subunit alpha-1C (Cav1.2) via the hydrogen bond interaction with amino acid residue Met1186, allowing the inhibition of Ca2+ inward current. Our results suggested that uncarialin A (21) could be served as a potential L-type Cav1.2 blocker in the effective treatment of cardiovascular diseases.

A Network-Based Approach to Explore the Mechanisms of Uncaria Alkaloids in Treating Hypertension and Alleviating Alzheimer's Disease.

Uncaria alkaloids are the major bioactive chemicals found in the Uncaria genus, which have a long history of clinical application in treating cardiovascular and mental diseases in traditional Chinese medicine (TCM). However, there are gaps in understanding the multiple targets, pathways, and biological activities of Uncaria alkaloids. By constructing the interactions among drug-targets-diseases, network pharmacology provides a systemic methodology and a novel perspective to present the intricate connections among drugs, potential targets, and related pathways. It is a valuable tool for studying TCM drugs with multiple indications, and how these multi-indication drugs are affected by complex interactions in the biological system. To better understand the mechanisms and targets of Uncaria alkaloids, we built an integrated analytical platform based on network pharmacology, including target prediction, protein-protein interaction (PPI) network, topology analysis, gene enrichment analysis, and molecular docking. Using this platform, we revealed the underlying mechanisms of Uncaria alkaloids' anti-hypertensive effects and explored the possible application of Uncaria alkaloids in preventing Alzheimer's disease. These results were further evaluated and refined using biological experiments. Our study provides a novel strategy for understanding the holistic pharmacology of TCM, as well as for exploring the multi-indication properties of TCM beyond its traditional applications.

The Effect of Rutin and Extracts of Uncaria guianensis (Aubl.) J. F. Gmeland on Primary Endometriotic Cells: A 2D and 3D Study.

There is increasing interest in the potential of natural compounds to treat diseases, such as endometriosis, a gynecological disorder that affects 10-15% of women of reproductive age, and it is related to severe pelvic pain and infertility. We have evaluated the in vitro effects of rutin and the aqueous bark, roots, and leaf extracts (ABE, ARE, and ALE, respectively) and isolated components of Uncaria guianensis on stromal cells from eutopic endometrium and lesions of patients with endometriosis. Two- and three-dimensional cultures were used to assess the cell death and production of reactive oxygen species (ROS), cytokines and growth factors of cells following exposure to these natural products. The applied treatments did not reduce cellular viability, but ROS production did increase. In addition, significant increases in the levels of interleukin (IL)-15, IL-17A, IL-4, IL-6, tumor necrosis factor-α, and vascular endothelium growth factor were observed when 2D-cells from endometrium of patients with endometriosis were treated with ABE, while exposure to ALE induced significant increases in epidermal growth factor in lesion cells.

Optimization of chitosan-tapioca starch composite as polymer in the formulation of gingival mucoadhesive patch film for delivery of gambier (Uncaria gambir Roxb) leaf extract.

The present study was intended to prepare and optimize the mucoadhesive buccal patch of gambier leaf extract using chitosan (CH) and tapioca starch (TS) composite as the polymer complexes. The patch formulation was designed based on 22 factorial design in order to optimize the composition of CH and TS. The physical and chemical characteristics of the prepared patches, including mass and thickness uniformity, folding endurance, surface pH, swelling index, percent of elongation, and mucoadhesive time were successfully evaluated. Based on statistical analysis, the optimum concentration of CH and TS was 900 mg and 300 mg, respectively, with desirability percent of 0.968. The characterization of the optimum patch showed that the variability coefficient of the mass and thickness uniformity was 0.4805 ± 0.1887% and 0.9716 ± 1.2026%, surface pH of the patch was 6, folding endurance >300 times, elongation percent was 53.333 ± 0.1082%, and mucoadhesive time was 320 ± 1.1547 min. The catechin content, as the active agent of the gambier leaf extract, was 92.1667 ± 0.3626%, and the FT-IR characterization indicated that there are no chemical interactions between each patch component.

A metabolomics strategy for authentication of plant medicines with multiple botanical origins, a case study of Uncariae Rammulus Cum Uncis.

Source authentication of herbal medicines was essential for ensuring their safety, efficacy and quality consistency, especially those with multiple botanical origins. This study proposed a metabolomics strategy for species discrimination and source recognition. Uncariae Rammulus Cum Uncis, officially stipulating the stems with hooks of five Uncaria species as its origins, was taken as a case study. Firstly, an untargeted MSE method was developed by ultra-high performance liquid chromatography hyphenated with quadrupole time-of-flight mass spectrometry for global metabolite characterization. Subsequently, data pretreatment was conducted by using Progenesis QI software and screening rules. The obtained metabolite features were defined as variables for statistical analyses. Principal component analysis and chemical fingerprinting spectra suggested that five official species were differentiated from each other except for Uncaria hirsuta and Uncaria sinensis. Furthermore, orthogonal partial least squares discrimination analysis was performed to discriminate confused two species, and resulted in the discovery of nine contributing markers. Ultimately, a Support Vector Machine model was developed to recognize five species and predict origins of commercial materials. The study demonstrated that the developed strategy was effective in discrimination and recognition of confused species, and promising in tracking botanical origins of commercial materials.

In vitro and in vivo evaluation of the neuroprotective activity of Uncaria hirsuta Haviland.

The incidence of neurodegeneration leading to the conditions such as Alzheimer's and Parkinson's diseases are on the increase, they require the approaches that focus on protection prevention rather than treatment. Plants are rich sources of many compounds which possess medicinal properties. We sought to investigate the neuroprotective effects of Uncariahirsuta and its compounds on d-galactose-induced stress in BALB/c mice as well as 6-hydroxydopamine (6-OHDA)-induced stress in mouse nerve growth factor (mNGF)-differentiated PC12 cells. Our results demonstrate that the 95% ethanol extract of U. hirsuta reversed the d-galactose-induced learning and memory dysfunctions and decreased the malodialdehyde levels. Furthermore, the isolated compounds, 5ß-carboxystrictosidine (1) and chlorogenic acid (2), protected mNGF-differentiated PC12 cells against toxicity induced by 6-OHDA by acting as antiapoptotic agents. The 50% inhibitory concentration (IC50) for intracellular reactive oxygen species (ROS) scavenging was found to be 24.5 (for 1) and 19.7 µM (for 2), and both 1 and 2 reduced intracellular calcium levels with respective IC50 values of 46.9 and 27 µM. Interestingly, both compounds inhibited caspase 3 and 9 activities with respective IC50 values of 25.6 and 24.5 µM for 1 and 19.4 and 16.3 µM for 2. Our results identify U. hirsuta and its active compounds as potential neuroprotective agents and deserve further evaluation for drug development for neuroprotection in the future.

Uncaria rhynchophylla and its Major Constituents on Central Nervous System: A Review on Their Pharmacological Actions.

BACKGROUND: Uncaria rhynchophylla (Miq.) Jacks (Rubinaceae), a common herbal medicine known as Gou-teng in Chinese, is commonly used in Chinese medicine practice for the treatment of convulsions, hypertension, epilepsy, eclampsia and other cerebral diseases. The major active components of U. rhynchophylla are alkaloids, terpenoids and flavonoids. The protective effects of U. rhynchophylla and its major components on central nervous system (CNS) have become a focus of research in recent decades. OBJECTIVE: The study aimed to systematically summarize the pharmacological activities of U. rhynchophylla and its major components on the CNS. METHODS: This review summarized the experimental findings from our laboratories, together with other literature data obtained through a comprehensive search of databases including the Pubmed and the Web of Science. RESULTS: U. rhynchophylla and its major components such as rhynchophylline and isorhynchophylline have been shown to have neuroprotective effects on Alzheimer's disease, Parkinson's disease, depression, cerebral ischaemia through a number of mechanisms including anti-oxidant, anti-inflammatory actions and regulation on neurotransmitters. CONCLUSION: U. rhynchophylla and its major components have multiple beneficial pharmacological effects on CNS. Further studies on U. rhynchophylla and its major components are warranted to fully illustrate the underlying molecular mechanisms, pharmacokinetics, and toxicological profiles of these naturally occurring compounds and their potential for clinical application.

Two folate-derived analogues from an aqueous decoction of Uncaria rhynchophylla.

Two new folate-derived analogues, named uncarophyllofolic acids A (1) and B (2), respectively, were isolated from the Uncaria rhynchophylla hook bearing stem (Gouteng in Chinese). The distinct stereochemical structures of 1 and 2 were determined by spectroscopic data analysis in combination with acidic hydrolysis and Marfey's derivatization, along with comparison of their specific rotation and Cotton effect (CE) data with those of the biogenetically related known derivatives as well as theoretical calculations of electronic circular dichroism (ECD) spectra. A plausible biosynthetic pathway of 1 and 2, associating to folate metabolism and the previously reported orychophragines A-C from Orychophragmus violaceus, is discussed.