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

Evaluation of the antiplasmodial and anti-Toxoplasma activities of several Indonesian medicinal plant extracts

ETHNOPHARMACOLOGICAL RELEVANCE

Malaria, caused by Plasmodium parasites, remains a significant global health challenge, particularly in tropical and subtropical regions. At the same time, the prevalence of toxoplasmosis has been reported to be 30% worldwide. Traditional medicines have long played a vital role in discovering and developing novel drugs, and this approach is essential in the face of increasing resistance to current antimalarial and anti-Toxoplasma drugs. In Indonesian traditional medicine, various plants are used for their therapeutic properties. This study focuses on eleven medicinal plants from which nineteen extracts were obtained and screened for their potential medicinal benefits against malaria and toxoplasmosis.

AIMS OF THE STUDY

The aim of this study was to evaluate the efficacy of extracts from Indonesian medicinal plants to inhibit Plasmodium falciparum, a parasite responsible for malaria, and Toxoplasma gondii, an opportunistic parasite responsible for toxoplasmosis.

METHODS

Nineteen extracts from eleven plants were subjected to in vitro screening against P. falciparum 3D7 (a chloroquine-sensitive strain) and the T. gondii RH strain. In vitro treatments were conducted on P. falciparum 3D7 and K1 (multidrug-resistant strains) using the potent extracts, and in vivo assessments were carried out with mice infected with P. yoelii 17XNL. LCMS analysis was also conducted to identify the main components of the most effective extract.

RESULTS

Seven extracts showed significant antiplasmodial activity (>80% inhibition) at a concentration of 100 μg/ml. These extracts were obtained from Dysoxylum parasiticum (Osbeck) Kosterm., Elaeocarpus glaber (Bl.) Bijdr., Eleutherine americana Merr., Kleinhovia hospita L., Peronema canescens Jack, and Plectranthus scutellarioides (L.) R.Br. Notably, the D. parasiticum ethyl acetate extract exhibited high selectivity and efficacy both in vitro and in vivo. Herein, the key active compounds oleamide and erucamide were identified, which had IC50 values (P. falciparum 3D7/K1) of 17.49/23.63 μM and 32.49/51.59 μM, respectively.

CONCLUSIONS

The results of this study highlight the antimalarial potential of plant extracts collected from Indonesia. Particularly, extracts from D. parasiticum EtOH and EtOAc stood out for their low toxicity and strong antiplasmodial properties, with the EtOAc extract emerging as a notably promising antimalarial candidate. Key compounds identified within this extract demonstrate the complexity of extracts' action against malaria, potentially targeting both the parasite and the host. This suggests a promising approach for developing new antimalarial strategies that tackle the multifaceted challenges of drug resistance and disease management. Future investigations are necessary to unlock the full therapeutic potential of these extracts.

Advanced researches of traditional uses, phytochemistry, pharmacology, and toxicology of medical Uncariae Ramulus Cum Uncis

ETHNOPHARMACOLOGICAL RELEVANCE

Medical Uncariae Ramulus Cum Uncis consists of Uncaria rhynchophylla (Miq.) Miq. ex Havil, Uncaria macrophylla Wall, Uncaria sinensis (Oliv.) Havil, Uncaria hirsuta Havil, and Uncaria sessilifructus Roxb, which belongs to the species widely used in the genus Uncaria. These species resource widely distributed in China and abroad, and the hook-bearing stem is the primary constituent enrichment site. There are many different forms and architectures of chemicals, depending on the extraction site. Traditional remedies employing URCU had been used widely in antiquity and were first compiled in renowned ancient masterpiece 'Mingyi Bielu ()' written by Hongjing Tao. In modern pharmacological studies, both the total extracts and the phytoconstituents isolated from URCU have been shown to have neuroprotective, antioxidant, anti-inflammatory, anticancer, antibacterial, and autophagy-enhancer properties.

AIM OF THE STUDY

This review concentrates on the traditional uses, phytochemistry, pharmacology, toxicology, and nanomaterials studies of URCU, with a perspective to assist with further research and advance.

MATERIAL AND METHODS

The Chinese and English literature studies of this review are based on these database searches including Science Direct, CNKI, Wiley online library, Spring Link, Web of Science, PubMed, Medalink, Google scholar, Elsevier, ACS Publications, iPlant, Missouri Botanical Garden, Plant of the World Online. The pertinent data on URCU was gathered.

RESULTS

Based on the examination of the genus Uncaria, 107 newly marked chemical compositions have been identified from URCU from 2015 to present, including alkaloids, terpenoids, flavonoids, steroids, and others. Pharmacological studies have demonstrated that URCU has a variety of benefits in diseases such as neurodegenerative diseases, cancer, cardiovascular diseases, diabetes, and migraine, due to its neuroprotective, anti-inflammatory, antioxidant, anti-tumor, anti-bacterial and anti-viral properties. According to metabolic and toxicological studies, the dosage, frequency, and interactions of the drugs that occur in vivo are of great significance for determining whether the organic bodies can perform efficacy or produce toxicity. The research on URCU-mediated nanomaterials is expanding and increasing in order to address the inadequacies of conventional Chinese medicine. The alkaloids in URCU have the capability to self-assemble with other classes of components in addition to being biologically active.

CONCLUSION

URCU plants are widely distributed, abundant in chemical constituents, and widely used in both traditional and modern medicine for a variety of pharmacological effects. The utilization of herbal medicines can be raised by assessing the pharmacological distinctions among several species within the same genus and may accelerate the modernization of traditional Chinese medicine. Controlling the concentration of drug administration, monitoring metabolic markers, and inventing novel nanotechnologies are effective strategies for synergistic influence and detoxification to alleviate the main obstacles that toxicity, low bioavailability, and poor permeability. This review can assist further research and advances.

Unified Strategy Enables the Collective Syntheses of Structurally Diverse Indole Alkaloids

Natural products and their analogues are significant sources of therapeutic lead compounds. However, synthetic strategies for generating large collections of these molecules remain a significant challenge. The most difficult step in their synthesis is the design of a common intermediate that can be easily transformed into natural products belonging to different families. This study demonstrates the evolution of synthetic tactics designed to assemble the functionalized piperidines present in indole alkaloids from a common intermediate. More importantly, we also report a previously unknown Ir- and Er-catalyzed dehydrogenative spirocyclization reaction that enables direct access to spirocyclic oxindole alkaloids. As a practical application, the asymmetric total syntheses of 29 natural alkaloids belonging to different families were accomplished by following a uniform synthetic route. The proposed methodology extends the capability of the iridium-catalyzed dehydrogenative coupling reaction to the realm of indole-alkaloid synthesis and provides new opportunities for the efficient preparation of natural product-like molecules.

Chemical constituents from Uncaria laevigata and their anti-inflammatory activities and action mechanism

A new alkaloid 1* (scandine Z) and fourteen known natural products were isolated from 95% ethanol extract of Uncaria laevigata for the first time. Besides compound 1*, these fourteen compounds were firstly isolated from Uncaria laevigata. Excitedly, compound 4 exhibited strong anti-inflammatory activity (IC50 = 8.12 μmol/L), which wasn't described before. Moreover, compound 1* also de--monstrated certain anti-inflammatory activity (IC50 = 10.34 μmol/L). Network pharmacology suggested that compound 4 was involved in the IL-17 signalling pathway and the regulation of inflammation pathway. Molecular docking confirmed that it showed strong binding activity with the target protein (peroxisome proliferator-activated receptor γ, PPAR). Overall, compounds 1* and 4 exhibited strong anti-inflammatory activity and served as lead compounds and anti-inflammatory molecules for further study in vivo.

Minor alkaloids from an aqueous extract of the hook-bearing stem of Uncaria rhynchophylla

Seven new monoterpene alkaloids (1 - 7), along with 16 known analogues, were isolated from an aqueous decoction of the hook-bearing stems of Uncaria rhynchophylla (Gou-teng). Their structures were determined by spectroscopic data analysis, single crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 are stereoisomers belonging to a novel type of pseudoindoxyl monoterpene alkaloids, 3 is the first monoterpene furoindole alkaloid from nature, and 4 - 7 are derivatives of the known monoterpene alkaloids featuring different structures.

Malondialdehyde and TNF-α lowering effects of purified gambier (Uncaria gambir Roxb.) in diabetic rats

BACKGROUND

Malondialdehyde (MDA) is one of a dominat marker in oxidative stress condition, and when inflammation occurred tumor necrosis factor- α (TNF-α) played a significant influence in the propagation this process. Purified gambier (Uncaria gambier Roxb.) contained 90% catechin which is proven to have antioxidant activity and may prevent unwanted inflammatory responses during diabetic state.

OBJECTIVE

The objective of this research was to assess how purified gambier affected plasma MDA and TNF- α levels in alloxan-induced diabetic rats.

MATERIAL AND METHODS

In this study, 35 rats were used. Alloxan 120 mg/kg BW intraperitoneal injection was administered to induce diabetes conditions in rats. All animals were divided into 5 groups, diabetic control group treated with vehicle, positive control group treated with glibenclamide dose 0.45 mg/kg BW), and treatment groups treated with purified gambier dose of 2.5; 5 and 10 mg/kg BW. All animals were treated respectively for 14 days. Plasma MDA and TNF- α levels were measured on day 3, and 14.

RESULTS

Two-way ANOVA was applied to analyze all of the data, these findings suggested that purified gambier has antioxidant-related anti-inflammation actions. possesses blood sugar-lowering activity (p<0.05). The plasma MDA and TNF- α level of treatment group were significantly reduced (p<0.05) compared to diabetes control group.

CONCLUSION

These results depicted that at doses of 2.5-10 mg/kg BW, purified gambier has antioxidant-associated anti-inflammation effects when given for 14 days on diabetic rat model by reducing plasma levels MDA and TNF-α.

Comparative and phylogenetic analysis of the complete chloroplast genomes of Uncaria (Rubiaceae) species

The genus Uncaria is famous for its high medicinal value. However, the high morphological similarities and unclear interspecific genetic relationships have posed challenges to the classification and identification of Uncaria species. Here, we newly sequenced six chloroplast genomes of Uncaria species: U. hirsuta, U. rhynchophylla, U. rhynchophylloides, U. homomalla, U. sinensis, and U. lancifolia. Comparisons among the chloroplast genomes of Uncaria species showed their conservation in structure, gene content, and order. Ten highly variable loci could be potentially used as specific molecular markers in the identification of Uncaria species. The third position of codons tended to use A/U base, and natural selection contributed more to the formation of codon usage bias in comparison to mutation pressure. Four genes (rbcL, ndhF, rps8, and ycf2) were detected to be subjected to positive selection. Phylogenetic analysis showed that the genus Uncaria was a monophyletic group, belonging to the tribe Naucleeae. Moreover, U. sinensis was not a variant of U. rhynchophylla. U. rhynchophylloides and U. rhynchophylla were not the same species. The results of the comparative and phylogenetic analysis provide valuable references for further research studies of classification, identification, breeding improvement, and phylogenetic relationships in Uncaria species.

Amazonian medicinal plants efficiently inactivate Herpes and Chikungunya viruses

The Amazonian species investigated in this research are commonly utilized for their anti-inflammatory properties and their potential against various diseases. However, there is a lack of scientifically supported information validating their biological activities. In this study, a total of seventeen ethanolic or aqueous extracts derived from eight Amazonian medicinal plants were evaluated for their activity against Herpes Simplex type 1 (HSV-1) and Chikungunya viruses (CHIKV). Cytotoxicity was assessed using the sulforhodamine B method, and the antiviral potential was determined through a plaque number reduction assay. Virucidal tests were conducted according to EN 14476 standards for the most potent extracts. Additionally, the chemical composition of the most active extracts was investigated. Notably, the LMLE10, LMBA11, MEBE13, and VABE17 extracts exhibited significant activity against CHIKV and the non-acyclovir-resistant strain of HSV-1 (KOS) (SI > 9). The MEBE13 extract demonstrated unique inhibition against the acyclovir-resistant strain of HSV-1 (29-R). Virucidal assays indicated a higher level of virucidal activity compared to their antiviral activity. Moreover, the virucidal capacity of the most active extracts was sustained when tested in the presence of protein solutions against HSV-1 (KOS). In the application of EN 14476 against HSV-1 (KOS), the LMBA11 extract achieved a 99.9% inhibition rate, while the VABE17 extract reached a 90% inhibition rate. This study contributes to the understanding of medicinal species native to the Brazilian Amazon, revealing their potential in combating viral infections that have plagued humanity for centuries (HSV-1) or currently lack specific therapeutic interventions (CHIKV).

Phytocompounds and their molecular targets in immunomodulation: a review

Immune cells are important for the healthy function of every organ. The homeostasis of the immune system is selfregulated by T-cells, B-cells, and natural killer cells. The immunomodulation process of immune cells is part of the immunotherapy. According to therapeutic methods of immune responses are categorized as inducing (immunostimulant), amplification (immune booster), attenuation (immunomodulation), and prevention (immunosuppressive) actions. The prevalence of chronic immunological diseases like viral infections, allergies, and cancer is mainly due to the over-activation of the immune system. Further, immunomodulators are reported to manage the severity of chronic immunological disorders. Moreover, these immunomodulator-acting proteins are identified as potential molecular targets for the regulation of the immune system. Moreover, natural compound like phytocompounds are known to bind these targets and modulates the immune system. The specialized phytocompounds like curcumin, quercetin, stilbenes, flavonoids, and lignans are shown the immunomodulatory actions and ameliorate the immunological disorders. The present scenario of a COVID-19 pandemic situation has taught us the need to focus on strengthening the immune system and the development of the most promising immunotherapeutics. This review is focused on an overview of various phytocompounds and their molecular targets for the management of immunological disorders via immunosuppressants and immunostimulants actions.

Discovery and Biomimetic Semisynthesis of Spirophyllines A-D from Uncaria rhynchophylla

Spirophyllines A-D (1-4), four new spirooxindole alkaloids all characterized by the spiro[pyrrolidin-3,3'-oxindole] core and a rare isoxazolidine ring, were isolated from Uncaria rhynchophylla. Their structures were determined by spectroscopic methods and confirmed by X-ray crystallography. Based on the biomimetic semisynthesis strategy, compounds 1-8 were synthesized in three steps via the key reactions of 1,3-dipolar cycloaddition and Krapcho decarboxylation from corynoxeine. Interestingly, compound 3 showed moderate inhibitory activity against the Kv1.5 potassium channel (IC50 = 9.1 μM).

Comprehensive evaluation of corrosion inhibition performance and ecotoxicological effect of cinchona IIa as a green corrosion inhibitor for pickling of Q235 steel

Here, to prevent the corrosion of Q235 steel in the pickling and discover novel green corrosion inhibitors, the corrosion inhibition performance and eco-toxicity of cinchonain IIa were evaluated. Electrochemical experiments confirms that 200 mg/L cinchonain IIa reveals good corrosion inhibition performance with 94.08% on Q235 steel in HCl for 48 h. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations suggest that cinchonain IIa can be firmly attached to the metal surface by forming a barrier film. The X-ray photoelectron spectroscopy (XPS) results further verify the bonding interaction between the functional groups and the steel matrix, and indicate the existence of protective film on the steel. Meanwhile, the inhibition mechanism at the molecular/atomic level is revealed through molecular dynamics simulation. Additionally, acute toxicity test shows that cinchonain IIa is a low toxic corrosion inhibitor. Moreover, the antioxidant enzyme activity experiments confirm that cinchonain IIa discloses no obvious damage to the antioxidant system of zebrafish. Overall, cinchonain IIa exhibits low potential risks to the healthy development of aquatic organisms and ecosystems. As a proven green and low toxic corrosion inhibitor, cinchonain IIa has a sustainable application in the anti-corrosion industry.

Chloroplast genome characterization of Uncaria guianensis and Uncaria tomentosa and evolutive dynamics of the Cinchonoideae subfamily

Uncaria species are used in traditional medicine and are considered of high therapeutic value and economic importance. This work describes the assembly and annotation of the chloroplast genomes of U. guianensis and U. tomentosa, as well as a comparative analysis. The genomes were sequenced on MiSeq Illumina, assembled with NovoPlasty, and annotated using CHLOROBOX GeSeq. Addictionaly, comparative analysis were performed with six species from NCBI databases and primers were designed in Primer3 for hypervariable regions based on the consensus sequence of 16 species of the Rubiaceae family and validated on an in-silico PCR in OpenPrimeR. The genome size of U. guianensis and U. tomentosa was 155,505 bp and 156,390 bp, respectively. Both Species have 131 genes and GC content of 37.50%. The regions rpl32-ccsA, ycf1, and ndhF-ccsA showed the three highest values of nucleotide diversity within the species of the Rubiaceae family and within the Uncaria genus, these regions were trnH-psbA, psbM-trnY, and rps16-psbK. Our results indicates that the primer of the region ndhA had an amplification success for all species tested and can be promising for usage in the Rubiaceae family. The phylogenetic analysis recovered a congruent topology to APG IV. The gene content and the chloroplast genome structure of the analyzed species are conserved and most of the genes are under negative selection. We provide the cpDNA of Neotropical Uncaria species, an important genomic resource for evolutionary studies of the group.

Identification of three key enzymes involved in the biosynthesis of tetracyclic oxindole alkaloids in Uncaria rhynchophylla

Tetracyclic oxindole alkaloids (TOAs), main active ingredients of Uncaria rhynchophylla (UR), has inspired the interest of pharmacologists and chemists because of its great potential in the treatment of the diseases of the nervous system and cardiovascular system and its special spirooxindole scaffold, but the biosynthetic pathway of this compounds is still unknown. In this work, the metabolomics and transcriptomics of hook, leaf and stem of UR were analyzed, and 31 alkaloids and 47,423 unigenes were identified, as well as the relative contents of these alkaloids were evaluated. Based on the above results and literatures, a proposal biosynthetic pathway for TOAs was devised. Furthermore, three unigenes were suggested mediating the biosynthesis of TOAs through the integrated analysis of metabolomics and transcriptomics, and three enzymes, tryptophan decarboxylase, strictosidine synthase and strictosidine-β-d-glucosidase, were identified as important catalytic enzymes for the synthesis of tryptamine, strictosidine (7) and 4,21-dehydrogeissochizine, respectively, which are considered as the important precursors of TOAs.

Uncarialines A-E, new alkaloids from Uncaria rhynchophylla and their anticoagulant activity

Uncarialines A-E (1-5), five undescribed monoterpene indole alkaloids, together with five known analogues were obtained from the stems of Uncaria rhynchophylla. Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with a 6/5/10 ring system, while 4 and 5 possessed a rare rearranged scaffold originated from corynantheine-type alkaloids with C-2/C-7 oxidation. Their structures were characterized by a comprehensive analysis of MS, NMR, and ECD. Their effects on blood clotting times of human plasma were evaluated and alkaloid 5 had a slight prolongation effect on both thrombin time and activated partial thromboplastin time (p < 0.001).

Network pharmacology, molecular docking, and experimental validation to explore the potential mechanism of Long Mu Qing Xin mixture for the treatment of attention deficit hyperactivity disorder

Background: Long Mu Qing Xin Mixture (LMQXM) has shown potentially positive effects in alleviating attention deficit hyperactivity disorder (ADHD); however, the action mechanism is still not fully understood. This study aimed to predict the potential mechanism of LMQXM for ADHD using network pharmacology and molecular docking, which were then validated using animal experiments.

Methods: Network pharmacology and molecular docking techniques were used to predict the core targets and potential pathways of LMQXMQ for ADHD, and KEGG pathway enrichment analysis revealed the potential significance of dopamine (DA) and cyclic adenosine monophosphate (cAMP) signaling pathways. To verify the hypothesis, we conducted an animal experiment. In the animal experiment, the young spontaneously hypertensive rats (SHRs) were randomly divided into the model group (SHR), the methylphenidate hydrochloride group (MPH, 4.22 mg/kg), and 3 LMQXM groups (low-dose (LD) group, 5.28 ml/kg; medium-dose (MD) group, 10.56 ml/kg; and high-dose (HD) group, 21.12 ml/kg), and administered by gavage for 4 weeks; the WKY rats were set as the control group. The open field test and Morris water maze test were used to evaluate the behavioral performance of rats, high performance liquid chromatography mass spectrometry (LC-MS) was used to analyze DA levels in the prefrontal cortex (PFC) and striatum of rats, ELISA was used to detect cAMP concentrations in the PFC and striatum, and immunohistochemistry and qPCR were used to analyze positive cell expression and mRNA expression for indicators related to DA and cAMP pathways.

Results: The results showed that beta-sitosterol, stigmasterol, rhynchophylline, baicalein, and formononetin might be key components of LMQXM for ADHD and that these components bind well to the core targets, DA receptors (DRD1 and DRD2). Furthermore, LMQXM might act through the DA and cAMP signaling pathways. In the animal experiment, we found that MPH and LMQXM-MD controlled hyperactivity and improved learning and memory in SHRs, while LMQXM-HD only controlled hyperactivity in SHRs; meanwhile, MPH and LMQXM-MD upregulated DA and cAMP levels, mean optical density (MOD) of cAMP, and MOD and mRNA expression of DRD1 and PKA in the prefrontal cortex (PFC) and striatum of SHRs, while LMQXM-LD and LMQXM-HD upregulated DA and cAMP levels in the striatum, MOD of cAMP in the PFC, and mRNA expression of PKA in the PFC. However, we did not find a significant regulatory effect of LMQXM on DRD2.

Conclusion: To sum up, this study demonstrated that LMQXM may increase DA levels mainly by activating the cAMP/PKA signaling pathway through DRD1, thereby controlling the behavioral disorders of SHRs, which is most effective at moderate doses, and this may be a key mechanism for LMQXM in the treatment of ADHD.

Dipolarophile-Controlled Regioselective 1,3-Dipolar Cycloaddition: A Switchable Divergent Access to Functionalized N-Fused Pyrrolidinyl Spirooxindoles

N-fused pyrrolidinyl spirooxindole belongs to a class of privileged heterocyclic scaffolds and is prevalent in natural alkaloids and synthetic pharmaceutical molecules. To realize the switchable synthesis of divergent N-fused pyrrolidinyl spirooxindoles for further biological activity evaluation via a substrate-controlled strategy, a chemically sustainable, catalysis-free, and dipolarophile-controlled three-component 1,3-dipolar cycloaddition of isatin-derived azomethine ylides with diverse dipolarophiles is described in this work. A total of 40 functionalized N-fused pyrrolidinyl spirooxindoles were synthesized in 76-95% yields with excellent diastereoselectivities (up to >99:1 dr). The scaffolds of these products can be well-controlled by employing different 1,4-enedione derivatives as dipolarophiles in EtOH at room temperature. This study provides an efficient strategy to afford a spectrum of natural-like and potentially bioactive N-fused pyrrolidinyl spirooxindoles.

Triterpenoids from Uncaria macrophylla as ferroptosis inhibitors

Seven undescribed triterpenoids were obtained from the ethanol extract of the dried stems of Uncaria macrophylla Wall. (Rubiaceae).All of the isolates were urs-28-oic acid or olean-28-oic acid skeletons, including three triterpenoids with rare 3β,23-(1R-4-hydroxy-butyl-1,1-dioxy) or 23-(2R-tetrahydrofuran-2-oxy) substituents. Five triterpenoids showed promising inhibitory activity against erastin-induced ferroptosis in PC12 cells, while 3β,6α,23-trihydroxy-olean-12-en-28-oic acid was the most significant inhibitor to resist ferroptosis by activating the Nrf2/SLC7A11/GPx4 axis with an EC₅₀ value of 4.2 ± 0.7 μM.

Gene coexpression networks allow the discovery of two strictosidine synthases underlying monoterpene indole alkaloid biosynthesis in Uncaria rhynchophylla

Plant-derived monoterpene indole alkaloids (MIAs) from Uncaria rhynchophylla (UR) have huge medicinal properties in treating Alzheimer's disease, Parkinson's disease, and depression. Although many bioactive UR-MIA products have been isolated as drugs, their biosynthetic pathway remains largely unexplored. In this study, untargeted metabolome identified 79 MIA features in UR tissues (leaf, branch stem, hook stem, and stem), of which 30 MIAs were differentially accumulated among different tissues. Short time series expression analysis captured 58 pathway genes and 12 hub regulators responsible for UR-MIA biosynthesis and regulation, which were strong links with main UR-MIA features. Coexpression networks further pointed to two strictosidine synthases (UrSTR1/5) that were coregulated with multiple MIA-related genes and highly correlated with UR-MIA features (r > 0.7, P < 0.005). Both UrSTR1/5 catalyzed the formation of strictosidine with tryptamine and secologanin as substrates, highlighting the importance of key residues (UrSTR1: Glu309, Tyr155; UrSTR5: Glu295, Tyr141). Further, overexpression of UrSTR1/5 in UR hairy roots constitutively increased the biosynthesis of bioactive UR-MIAs (rhynchophylline, isorhynchophylline, corynoxeine, etc), whereas RNAi of UrSTR1/5 significantly decreased UR-MIA biosynthesis. Collectively, our work not only provides candidates for reconstituting the biosynthesis of bioactive UR-MIAs in heterologous hosts but also highlights a powerful strategy for mining natural product biosynthesis in medicinal plants.

Simultaneous extraction and determination of alkaloids and organic acids in Uncariae Ramulas Cum Unicis by vortex-assisted matrix solid phase dispersion extraction coupled with UHPLC-MS/MS

A simple and efficient vortex-assisted matrix solid phase dispersion with a ultra-high-performance liquid chromatography-triple quadrupole mass spectrometer (VA-MSPD-UHPLC-MS/MS) was applied for simultaneous extraction and determination of seven alkaloids and three organic acids from Uncariae Ramulas Cum Unicis. The optimal extraction conditions of the target components were obtained by Box-Behnken design (BBD) combined with response surface methodology (RSM). The results of the method validation showed that this analytical method displayed good linearity with a correlation coefficient (r) no lower than 0.9990. The recoveries of ten active ingredients from Uncariae Ramulas Cum Unicis ranged from 95.9% to 103% (RSD ≤ 2.77%). The RSDs of intra-day and inter-day precisions were all below 2.97%. The present method exhibited not only lower solvent and sample usage, but also shorter sample processing and analysis time. Consequently, the developed VA-MSPD-UHPLC-MS/MS method could be successfully and effectively used for the extraction and analysis of ten active components from Uncariae Ramulas Cum Unicis.

Metabolites identification and pharmacokinetic profile of hirsuteine, a bioactive component in Uncaria in rats by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Hirsuteine is one of the major bioactive tetracyclic indole alkaloids found in Uncaria rhynchophylla (Miq.) Jacks, possessing a wide range of pharmacological activities including neuroprotective, anticonvulsant, antihypertensive, sedative and hypnotic, and so forth. The present study was undertaken to assess the metabolism and plasma pharmacokinetics of hirsuteine in rats. After oral administration of hirsuteine at the dose of 30 mg/kg, 13, 21, and 8 metabolites were detected in rat plasma, urine, and bile by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry, respectively. Furthermore, plasma concentrations of hirsuteine and its four metabolites, 4-hirsuteine N-oxide, 3,4-dehydrohirsuteine, 11-hydroxyhirsuteine, and 11-hydroxyhirsuteine-11-O-glucuronide were simultaneously quantified in rat plasma, using carbamazepine as the internal standard. The linear calibration curve of hirsuteine was in the concentration range of 0.005-5.0 μg/ml. The lower limit of quantitation in the rat plasma was 5 ng/ml for hirsuteine. This study is the first to comprehensively investigate the metabolism process of hirsuteine and the pharmacokinetic profiles of hirsuteine and its major metabolite, and will provide a scientific basis to further elucidate the pharmacodynamic material basis and therapeutic mechanism of Uncaria prescriptions.

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.

Palladium-Catalyzed Intramolecular Heck/Aminocarbonylation of Alkene-Tethered Iodobenzenes with Nitro Compounds: Synthesis of Carbamoyl-Substituted Benzoheterocycles

A palladium-catalyzed intramolecular Heck/aminocarbonylation of alkene-tethered iodobenzenes with nitro compounds has been developed for the synthesis of carbamoyl-substituted benzoheterocycles. Using Mo(CO)₆ as a solid CO source, no external reductant or additives were needed in this procedure. Both nitroarenes and nitroalkanes were well tolerated. A range of carbamoyl-substituted dihydrobenzofurans and indolines were prepared in moderate to high yields.

Identification of antidiabetic components in Uncariae Rammulus Cum Uncis based on phytochemical isolation and spectrum-effect relationship analysis

OBJECTIVES

Uncariae Rammulus Cum Uncis (URCU) is a commonly used herbal medicine to treat diabetes. This work is aimed to discover and identify the antidiabetic components from URCU extract.

METHODS

Column chromatography and recrystallisation were used to separate individual compounds from URCU extract, and the obtained individual compounds were used for determination of α-glucosidase inhibitory activity. Molecular docking was applied to predict the molecular interactions. High-performance liquid chromatography (HPLC) was used for fingerprint analysis of 12 batches of URCU. HPLC fingerprints were assessed by the similarity analysis (SA) and hierarchical clustering analysis (HCA). The spectrum-effect relationship analysis of URCU was assessed by orthogonal partial least squares (OPLS) and bivariate correlation analysis (BCA).

RESULTS

A total of 10 potential bioactive compounds were isolated and six of them showed potent α-glucosidase inhibitory activity (IC₅₀  = 4.21-166.10 μM). The molecular docking results revealed that the binding energy was consistent with the results of α-glucosidase inhibition activity analysis (-8.55 to -4.84 kcal/mol). The ethanol extracts of the 12 batches of URCU showed inhibitory effect on α-glucosidase in a dose-dependent manner, and the IC₅₀ values ranged from 0.94 μg/mL to 12.57 μg/mL. The spectrum-effect relationship analysis results indicated that 13 peaks might be potential antidiabetic compounds in URCU, including 18 (hyperoside) and 19 (rutin).

CONCLUSION

A comprehensive connection between URCU chemical components and α-glucosidase inhibitory activity was established for the first time by using a spectrum-effect relationship model, which might be applicable to the quality control of URCU.

Dissecting the Regulation of Arachidonic Acid Metabolites by Uncaria rhynchophylla (Miq). Miq. in Spontaneously Hypertensive Rats and the Predictive Target sEH in the Anti-Hypertensive Effect Based on Metabolomics and Molecular Docking

Uncariarhynchophylla (Miq). Miq. (UR), as a traditional Chinese medicine, was employed in treating hypertension as a safe and effective therapy. The pharmacological properties of UR have characteristics of multiple biological targets and multiple functional pathways. Hypertension is related to impaired metabolic homeostasis and is especially associated with the abnormal regulation of arachidonic acid metabolites, the classical cardiovascular active compounds. This study aimed to examine the anti-hypertensive effect of UR extract (URE) and its regulating role in differential metabolic pathways. The results showed that daily administration of URE at a dose of 4 g crude drug/kg orally could exert hypotensive effects on spontaneously hypertensive rats (SHRs) for 8 weeks. Non-targeted metabolomics analysis of the plasma samples suggested that the anti-hypertension effect of URE in SHRs was associated with the reorganization of the perturbed metabolic network, such as the pathways of glycerophospholipid metabolism, linoleic acid metabolism, and arachidonic acid metabolism. For the targeted metabolomics, twenty-eight arachidonic acid metabolites in SHRs were quantitatively analyzed for the first time based on ultra-high performance liquid chromatography-tandem mass spectrometry method after URE administration. URE restored the functions of these cardiovascular active compounds and rebalanced the dynamics of arachidonic acid metabolic flux. Among them, the inhibition of soluble epoxide hydrolase (sEH) enzyme activity and up-regulation of vasodilators epoxyeicosatrienoic acids (EETs) were identified as contributors to the anti-hypertension effect of URE on SHRs, and sEH represented an attractive and promising drug-binding target of URE. With the molecular docking approach, 13 potential anti-hypertension ingredients as well as sEH inhibitors were discovered, which were worthy of further investigation and verification in future studies.

The complete chloroplast genome of Uncaria macrophylla Wall. (Rubiaceae) and its phylogenetic analysis

Uncaria macrophylla Wall. 1824 is one of the five original plants of Uncariae Ramulus cum Uncis, and its molecular genetic relationship with other four remains unclear. Here, we reported the complete chloroplast genome of U. macrophylla. The chloroplast genome is 155,145 bp in length, which includes paired inverted repeat regions of 25,665 bp, a large single-copy region of 85,758 bp and a small single-copy region of 18,057 bp. In total, 127 genes were predicted, including 81 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. The phylogenetic analysis based on whole chloroplast genome sequences showed that U. macrophylla is closely related to U. rhynchophylla.

Minor monoterpene derivatives from an aqueous extract of the hook-bearing stem of Uncaria rhynchophylla

Seven new minor monoterpene derivatives (1-7), together with six known analogues, were isolated from an aqueous decoction of the hook-bearing stems of Uncaria rhynchophylla (Gou-teng). Their structures were determined by spectroscopic data analysis and electronic circular dichroism (ECD) calculations, of which 1 was confirmed by single crystal X-ray diffraction.

Transcriptome revealing the dual regulatory mechanism of ethylene on the rhynchophylline and isorhynchophylline in Uncaria rhynchophylla

Rhynchophylline (RIN) and isorhynchophylline (IRN) are extracted from Uncaria rhynchophylla, which are used to treat Alzheimer's disease. However, the massive accumulation of RIN and IRN in U. rhynchophylla requires exogenous stimulation. Ethylene is a potential stimulant for RIN and IRN biosynthesis, but there is no study on the role of ethylene in RIN or IRN synthesis. This study investigated the regulation of ethylene in RIN and IRN biosynthesis in U. rhynchophylla. An increase in the content of RIN and IRN was observed that could be attributed to the release of ethylene from 18 mM ethephon, while ethylene released from 36 mM ethephon reduced the content of RIN and IRN. The transcriptome and weighted gene co-expression network analysis indicated the up-regulation of seven key enzyme genes related to the RIN/IRN biosynthesis pathway and starch/sucrose metabolism pathway favored RIN/IRN synthesis. In comparison, the down-regulation of these seven key enzyme genes contributed to the reduction of RIN/IRN. Moreover, the inhibition of photosynthesis is associated with a reduction in RIN/IRN. Photosynthesis was restrained owing to the down-regulation of Lhcb1 and Lhcb6 after 36 mM ethephon treatment and further prevented supply of primary metabolites (such as α-D-glucose) for RIN/IRN synthesis. However, uninterrupted photosynthesis ensured a normal supply of primary metabolites at 18 mM ethephon treatment. AP2/ERF1, bHLH1, and bHLH2 may positively regulate the RIN/IRN accumulation, while NAC1 may play a negative regulatory role. Our results construct the potential bidirectional model for ethylene regulation on RIN/IRN synthesis and provide novel insight into the ethylene-mediated regulation of the metabolism of terpenoid indole alkaloids.

Efficient enantioselective synthesis of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine]s via organocatalytic cycloaddition

A novel kind of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine] has been achieved via an organocatalyzed 1,3-dipole reaction.

Synergistic Effects of Natural Product Combinations in Protecting the Endothelium Against Cardiovascular Risk Factors

Endothelial dysfunction is an early hallmark of cardiovascular diseases (CVDs). Monotherapies are limited due to the complex, multifactorial pathways. The multi-component and multi-targeted approach of natural products have the potential to manage CVDs.

This review aims to provide a comprehensive insight into the synergistic mechanism of natural product combinations in protecting the endothelium against various cardiovascular risk factors.

Databases (PubMed, MEDLINE and EMBASE) and Google Scholar were searched, and studies in English published between January 2000 and February 2022 were collated. Clinical and pre-clinical studies of natural product combinations with or without pharmaceutical medicines, compared with monotherapy and/or proposing the underlying mechanism in protecting endothelial function, were included.

Four clinical studies demonstrated that natural product combinations or natural product-pharmaceutical combinations improved endothelial function. This was associated with multi-targeted effects or improved absorption of the active substances in the body. Seventeen preclinical studies showed that natural product combinations produced synergistic (demonstrated by combination index or Bliss independence model) or enhanced effects in protecting the endothelium against hyperlipidemia, hypertension, diabetes mellitus, platelet activation, oxidative stress and hyperhomocysteinemia. The molecular targets included reactive oxygen species, Nrf2-HO-1, p38MAPK, P13K/Akt and NF-κB.

Thus, the current available evidence of natural product combinations in targeting endothelial dysfunction is predominantly from preclinical studies. These have demonstrated synergistic/enhanced pharmacological activities and proposed associated mechanisms. However, evidence from larger, well-designed clinical trials remains weak. More cohesion is required between preclinical and clinical data to support natural product combinations in preventing or slowing the progression of CVDs.

Nickel-Catalyzed Arylcarbamoylation of Alkenes of N-(o-Iodoaryl)acrylamides with Nitroarenes via Reductive Aminocarbonylation: Facile Synthesis of Carbamoyl-Substituted Oxindoles

Nickel-catalyzed arylcarbamoylation reactions of alkenes of N-(o-haloaryl)acrylamides with CO and nitroarenes via reductive aminocarbonylation to produce carbamoyl-substituted oxindoles with an all-carbon quaternary stereogenic center are presented. Starting with N-(o-haloaryl)acrylamides, simple CO, and inexpensive nitroarenes and using a Ni catalyst, a dinitrogen-based ligand, a Zn reductant, a TMSCl additive, and a base system, this protocol enables the synthesis of various carbamoyl-substituted oxindoles and allows the efficient late-stage derivatization of valuable molecules.

Traditional Herbal Medicine Discovery for the Treatment and Prevention of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary artery remodeling that may subsequently culminate in right heart failure and premature death. Although there are currently both non-pharmacological (lung transplantation, etc.) and pharmacological (Sildenafil, Bosentan, and new oral drugs on trial) therapies available, PAH remains a serious and fatal pulmonary disease. As a unique medical treatment, traditional herbal medicine (THM) treatment has gradually exerted its advantages in treating PAH worldwide through a multi-level and multi-target approach. Additionally, the potential mechanisms of THM were deciphered, including suppression of proliferation and apoptosis of pulmonary artery smooth muscle cells, controlling the processes of inflammation and oxidative stress, and regulating vasoconstriction and ion channels. In this review, the effects and mechanisms of the frequently studied compound THM, single herbal preparations, and multiple active components from THM are comprehensively summarized, as well as their related mechanisms on several classical preclinical PAH models. It is worth mentioning that sodium tanshinone IIA sulfonate sodium and tetramethylpyrazine are under clinical trials and are considered the most promoting medicines for PAH treatment. Last, reverse pharmacology, a strategy to discover THM or THM-derived components, has also been proposed here for PAH. This review discusses the current state of THM, their working mechanisms against PAH, and prospects of reverse pharmacology, which are expected to facilitate the natural anti-PAH medicine discovery and development and its bench-to-bedside transformation.

Minor alkaloids from an aqueous extract of the hook-bearing stem of Uncaria rhynchophylla

Seven new monoterpene alkaloids (1-7), along with 18 known analogues, were isolated from an aqueous decoction of the hook-bearing stems of Uncaria rhynchophylla (Gou-teng). Their structures were determined by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Compound 1 is the first monoterpene 22-norindoloquinolizidine alkaloid with a ketene unit, while 2 and 3 are unusual indoloquinolizidine alkaloids having an oxazinane ring.[Formula: see text].

Tengdan Capsule Prevents Hypertensive Kidney Damage in SHR by Inhibiting Periostin-Mediated Renal Fibrosis

BACKGROUND: Hypertension-induced renal damage is a serious and complex condition that has not been effectively treated by conventional blood pressure-lowering drugs. Tengdan capsule (TDC) is a China FDA-approved compound herbal medicine for treating hypertension; however, its chemical basis and pharmacological efficacy have not been fully investigated in a preclinical setting.

METHODS: High-performance liquid chromatography (HPLC) was used to identify and quantify the major chemical components of TDC extracted from ultrapure water. Adult spontaneously hypertensive rats (SHR) and age/sex-matched Wistar Kyoto normotensive rats (WKY) were both treated with TDC, losartan, or saline for one month, and their blood pressure (BP) was monitored at the same time by tail-cuff BP system. Biochemical indexes such as urine creatinine (CRE) and blood urea nitrogen (BUN) were determined. Kidney tissue sections were examined with (H&E), and Masson staining to evaluate the pathological effect of TDC on SHR’s kidneys. After TDC treatment, the differentially expressed proteins in the kidneys of SHR were identified by the TMT-based quantitative proteomics analysis, which may provide the targets and possible mechanisms of TDC action. In addition, Western blot analysis, RT-qPCR, and ELISA assays were carried out to further verify the proteomics findings. Finally, two different models involving in vitro renal injuries were established using human kidney HEK293 cells; and the molecular mechanism of TDC kidney protection was demonstrated.

RESULTS: Seven chemical compounds, namely Notoginsenoside R1, Ginsenoside RG1, Ginsenoside Re, Ginsenoside Rb1, Sodium Danshensu, Protocatechualdehyde, and Salvianolic acid B, were identified and quantified from the water-soluble extracts of TDC by HPLC. In vivo study using rats showed that TDC effectively reduced BP, BUN, and CRE levels and attenuated renal fibrosis in SHR, and ameliorated damage to the kidneys. Proteomics and subsequent bioinformatics analyses indicated that periostin-mediated inflammatory response and TGFβ/Smad signaling pathway proteins were closely related to the therapeutic effect of TDC in rat kidneys. Western blot analysis and RT-qPCR showed that TDC markedly downregulated the mRNA and protein expression of periostin in renal tissues compared to the untreated SHR. In addition, TGF-β and COL1A1 mRNA levels also decreased in SHR renal tissues following TDC treatment. In vitro studies showed that low to medium doses of TDC down-regulated the expression of periostin in the injury model of HEK293 cell. In addition, medium to high doses of TDC significantly inhibited collagen deposition in TGFβ1-induced HEK293 cell fibrosis.

CONCLUSIONS: Major components from the compound herbal medicine Tengdan Capsule are identified and quantified. TDC effectively lowers blood pressure and protects against renal damage caused by hypertension in SHR. Mechanistically, TDC blocks periostin by regulating the TGF-β/Smad signaling pathway in the kidney, both in vivo and in vitro. Preventing periostin-mediated renal fibrosis and inflammation might be a promising strategy for treating a hypertensive renal injury.

Matrix-Assisted DOSY for Analysis of Indole Alkaloid Mixtures

Diffusion-ordered spectroscopy (DOSY) is a powerful tool for investigating mixtures and identifying peaks of chemical components. However, similar diffusion coefficients of the components, particularly for complex mixtures that contain crowded resonances, limit resolution and restrict application of the DOSY technique. In this paper, matrix-assisted DOSY were used to explore whether the diffusion resolution of a complex model involving indole alkaloid mixtures can be realized. Furthermore, we investigated the influence of different factors on the separation effect. The results showed that the changes in diffusion coefficient differences were achieved more obviously when using sodium dodecyl sulfate (SDS) micelles as the matrix. In addition, we also found that increasing the concentration of SDS can improve the resolution of the DOSY spectrum. Finally, after investigating the influence factors and NMR conditions, we demonstrated the applications of the SDS-assisted DOSY on analyzing the total alkaloid extract of Alstonia Mairei, and the virtual separation of mixtures was achieved.