Tetracyclic Oxindole Alkaloids Research Articles

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.

The activation of spliced X-box binding protein 1 by isorhynchophylline therapy improves diabetic encephalopathy.

The primary symptom of diabetic encephalopathy (DE), a kind of central diabetic neuropathy caused by diabetes mellitus (DM), is cognitive impairment. In addition, the tetracyclic oxindole alkaloid isorhynchophylline (IRN) helps lessen cognitive impairment. However, it is still unclear how IRN affects DM and DE and what mechanisms are involved. The effectiveness of IRN on brain insulin resistance was carefully examined in this work, both in vitro and in vivo. We found that IRN accelerates spliced form of X-box binding protein 1 (sXBP1) translocation into the nucleus under high glucose conditions in vitro. IRN also facilitates the nuclear association of pCREB with sXBP1 and the binding of regulatory subunits of phosphatidylinositol 3-kinase (PI3K) p85α or p85β with XBP1 to restore high glucose impairment. Also, IRN treatment improves high glucose-mediated impairment of insulin signaling, endoplasmic reticulum stress, and pyroptosis/apoptosis by depending on sXBP1 in vitro. In vivo studies suggested that IRN attenuates cognitive impairment, ameliorating peripheral insulin resistance, activating insulin signaling, inactivating activating transcription factor 6 (ATF6) and C/EBP homology protein (CHOP), and mitigating pyroptosis/apoptosis by stimulation of sXBP1 nuclear translocation in the brain. In summary, these data indicate that IRN contributes to maintaining insulin homeostasis by activating sXBP1 in the brain. Thus, IRN is a potent antidiabetic agent as well as an sXBP1 activator that has promising potential for the prevention or treatment of DE.

GlucoMedix®, an extract of Stevia rebaudiana and Uncaria tomentosa, reduces hyperglycemia, hyperlipidemia, and hypertension in rat models without toxicity: a treatment for metabolic syndrome

BackgroundThe objective of this in vivo study is to evaluate in five rat models the pharmacologic effects and toxicity of a commercial hydro-alcoholic extract, GlucoMedix®, derived from Stevia rebaudiana and the pentacyclic chemotype of Uncaria Tomentosa (Willd.) DC, for use as a treatment for metabolic syndrome. The extract contains phytochemicals of Stevia (e.g., steviol glycosides) and Uncaria (e.g., pentacyclic oxindole alkaloids, but lacks tetracyclic oxindole alkaloids).MethodsThe pharmacologic assessments in three rat models include reductions in chemically induced hyperglycemia, hyperlipidemia (cholesterol and triglycerides), and hypertension, all of which are comorbidities of metabolic syndrome. Acute toxicity and 28-day subacute toxicity were assessed in rat models at doses higher than those used in the efficacy models.ResultsThe acute oral toxicity was evaluated in Holtzman rats and the extract did not produce acute toxic effects or lethality, with the LD50 > 5000 mg/kg (extract wet weight). Furthermore, subacute oral toxicity was evaluated in rats for 28 days at daily doses as high as 2000 mg/kg without toxicity or abnormal clinical chemistry or hematological effects. Daily oral doses of 250 - 1000 mg/kg were used to evaluate the treatment effects in hyperglycemic (alloxan-induced and glibenclamide-controlled), hyperlipidemic (cholesterol-induced and atorvastatin-controlled), and hypertensive (L-NAME-induced and enalapril-controlled) rat models. Alloxan-induced hyperglycemia was reduced in a dose-dependent manner within 28 days or less. Cholesterol-induced hyperlipidemic rats exhibited dose-dependent reductions in cholesterol and triglycerides at 21 days. Furthermore, GlucoMedix® produced a dose-dependent decrease in systolic and diastolic arterial blood pressure in L-NAME-induced hypertensive rats at 28 days.ConclusionsThe five in vivo rat models revealed that the all-natural phytotherapy GlucoMedix® is a safe and effective treatment for hyperglycemia, hyperlipidemia, and hypertension. This extract is expected to affect multiple comorbidities of metabolic syndrome, without any acute or subacute oral toxicity in humans. Although multiple prescription drugs are well known for the treatment of individual comorbidities of metabolic syndrome, no drug monotherapy concurrently treats all three comorbidities.

Isorhynchophylline Ameliorates Cerebral Ischemia/Reperfusion Injury by Inhibiting CX3CR1-Mediated Microglial Activation and Neuroinflammation.

Reperfusion therapy is an effective way to rescue cerebral ischemic injury, but this therapy also shows the detrimental risk of devastating disorders and death due to the possible inflammatory responses involved in the pathologies. Hence, the therapy of ischemia/reperfusion (I/R) injury is a great challenge currently. Isorhynchophylline (IRN), a tetracyclic oxindole alkaloid extracted from Uncaria rhynchophylla, has previously shown neuroprotective and anti-inflammatory effects in microglial cells. This study systematically investigates the effect of IRN on I/R injury and its underlying mechanism. The effects of IRN on neuronal injury and microglia-mediated inflammatory response were assessed on a rat model with middle cerebral artery occlusion (MCAO) and reperfusion-induced injury. We found that IRN treatment attenuated the infarct volume and improved the neurological function in I/R injury rats. IRN treatment also reduced the neuronal death rate, brain water content, and aquaporin-4 expression in the ischemic penumbra of I/R injury rats’ brains. Besides, IRN treatment could inhibit the following process, including IκB-α degradation, NF-κB p65 activation, and CX3CR1 expression, as well as the microglial activation and inflammatory response. These findings suggest that IRN is a promising candidate to treat the cerebral I/R injury via inhibiting microglia activation and neuroinflammation.

Cautions and Opportunities for Botanicals in COVID-19 Patients: A Comment on the Position of the French Agency for Food, Environmental and Occupational Health & Safety.

Cautions and Opportunities for Botanicals in COVID-19 Patients: A Comment on the Position of the French Agency for Food, Environmental and Occupational Health & Safety.

Uncaria tomentosa reduces osteoclastic bone loss in vivo

BackgroundThe genus Uncaria (Rubiaceae) has several biological properties significant to human health. However, the mechanisms underlying the protective effect of this plant on bone diseases are uncertain. PurposeThe present study investigated the role of Uncaria tomentosa extract (UTE) on alveolar bone loss in rats and on osteoclastogenesis in vitro. MaterialsUTE was characterized by an Acquity UPLC (Waters) system, coupled to an Electrospray Ionization (ESI) interface and Quadrupole/Flight Time (QTOF, Waters) Mass Spectrometry system (MS). The effect of UTE treatment for 11 days on the ligature-induced bone loss was assessed focusing on several aspects: macroscopic and histological analysis of bone loss, neutrophil and osteoclast infiltration, and anabolic effect. The effect of UTE on bone marrow cell differentiation to osteoclasts was assessed in vitro. ResultsThe analysis of UTE by UPLC-ESI-QTOF-MS/MS identified 24 compounds, among pentacyclic or tetracyclic oxindole alkaloids and phenols. The administration of UTE for 11 days on ligature-induced rat attenuated the periodontal attachment loss and alveolar bone resorption. It also diminished neutrophil migration to the gingiva tissue, demonstrated by a lower level of MPO. UTE treatment also decreased the level of RANKL/OPG ratio, the main osteoclast differentiation-related genes, followed by reduced TRAP-positive cell number lining the alveolar bone. Additionally, the level of bone-specific alkaline phosphatase, an anabolic bone marker, was elevated in the plasma of UTE treated rats. Next, we determined a possible direct effect of UTE on osteoclast differentiation in vitro. The incubation of primary osteoclast with UTE decreased RANKL-induced osteoclast differentiation without affecting cell viability. This effect was supported by downregulation of the nuclear factor activated T-cells, cytoplasmic 1 expression, a master regulator of osteoclast differentiation, and other osteoclast-specific activity markers, such as cathepsin K and TRAP. ConclusionUTE exhibited an effective anti-resorptive and anabolic effects, which highlight it as a potential natural product for the treatment of certain osteolytic diseases, such as periodontitis.

Rhynchophylline Loaded-mPEG-PLGA Nanoparticles Coated with Tween-80 for Preliminary Study in Alzheimer's Disease.

PurposeAlzheimer’s disease (AD) is a growing concern in the modern society. The current drugs approved by FDA are not very promising. Rhynchophylline (RIN) is a major active tetracyclic oxindole alkaloid stem from traditional Chinese medicine uncaria species, which has potential activities beneficial for the treatment of AD. However, the application of rhynchophylline for AD treatment is restricted by the low water solubility, low concentration in brain tissue and low bioavailability. And there is no study of brain-targeting therapy with RIN. In this work, we prepared rhynchophylline loaded methoxy poly (ethylene glycol)–poly (dl-lactide-co-glycolic acid) (mPEG-PLGA) nanoparticles (NPS-RIN), which coupled with Tween 80 (T80) further for brain targeting delivery (T80-NPS-RIN).MethodsPreparation and characterization of T80-NPS-RIN were followed by the detection of transportation across the blood–brain barrier (BBB) model in vitro, biodistribution and neuroprotective effects of nanoparticles.ResultsThe results indicated T80-NPS-RIN could usefully assist RIN to pass through the BBB to the brain. T80-NPS-RIN treatment regulated the activity of neurons in vitro.ConclusionThe presented data confirmed that rhynchophylline encapsulated mPEG-PLGA nanoparticles coated with Tween 80 could across through the BBB and exhibited efficient neuroprotective effects. The T80-NPS-RIN nanoparticles have a chance to be an alternative drug to the therapy of AD.

Isorhynchophylline enhances Nrf2 and inhibits MAPK pathway in cardiac hypertrophy.

Isorhynchophylline (IRN) is one of the major tetracyclic oxindole alkaloids found in Uncaria rhynchophylla. Studies have found that IRN has diverse biological activities including antioxidant, anti-apoptosis, and neuroprotection. However, little is known about the effect of IRN on the development of cardiac hypertrophy. In this study, we investigated the change of the cell surface area and nascent protein synthesis of cultured H9c2 cardiomyocytes on exposure to phenylephrine (PE) plus IRN, and thus confirmed that IRN ameliorated cardiomyocyte hypertrophy induced by PE in vitro. Meanwhile, it turns out that IRN is also effective in neonatal rat ventricular myocytes (NRVMs) stimulated with angiotensin II (AngII). We also showed that IRN prevented cardiac dysfunction in mice with pressure overload due to transverse aortic constriction (TAC) and attenuated cardiac hypertrophy and fibrosis. IRN treatment improved the cardiac function assessed by echocardiographic parameters fractional shortening (FS) as well as suppressed the cardiac hypertrophy phenotypes, such as the increasing of ventricular mass/body weight and myocyte cross-sectional area. RT-PCR analysis showed that IRN treatment also alleviated the expression of fetal genes of ANP, BNP, Myh7, and the correlated fibrosis genes including TGF-β1, collagen I, collagen III, and CTGF in vivo. Meanwhile, IRN had anti-oxidative effects on cardiac remodeling with suppressed 4-HNE and MDA. Western blot analysis showed that the Nrf2 nuclear translocation and MAPK pathway were involved in the potential mechanisms of IRN on cardiac hypertrophy inhibition. The results of our study provide further evidence that IRN is a promising drug for the treatment of cardiac hypertrophy.

Isorhynchophylline exerts anti-inflammatory and anti-oxidative activities in LPS-stimulated murine alveolar macrophages

AimsExcessive inflammatory response and oxidative stress are considered as important pathogenic factors in the development of acute lung injury. Isorhynchophylline (IRN), a tetracyclic oxindole alkaloid isolated from Uncaria rhynchophylla, possesses anti-inflammatory and anti-oxidant activities. Our study aimed to investigate the effects and potential mechanisms of IRN on lipopolysaccharide (LPS)-stimulated murine alveolar macrophage cell lines MH-S and NR8383. Main methodsCCK-8 assay was used to evaluate the cytotoxicity of IRN and LPS. Inflammatory response was assessed by detecting the mRNA expressions and release of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, IL-6, and plasminogen activator inhibitor-1 (PAI-1) using qRT-PCR and ELISA. The expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 were examined by qRT-PCR and western blot. Oxidative stress was evaluated by detecting malondialdehyde (MDA) level and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). The changes of the toll like receptor (TLR4)/nuclear factor-kappa B (NF-κB)/nod-like receptor protein 3 (NLRP3) inflammasome pathway was detected by western blot. Key findingsTreatment with LPS or IRN for 24 h showed no cytotoxicity on MH-S and NR8383 cells. IRN pretreatment inhibited LPS-induced production of inflammatory cytokines, expressions of iNOS and COX-2, and oxidative stress in murine alveolar macrophages. Additionally, IRN inhibited LPS-induced activation of TLR4/NF-κB/NLRP3 inflammasome pathway in MH-S cells. Mechanistically, inhibition of TLR4/NF-κB/NLRP3 inflammasome pathway by si-TLR4 suppressed LPS-induced inflammation and oxidative stress in murine alveolar macrophages. SignificanceIRN exerted anti-inflammatory and anti-oxidant effects on LPS-stimulated murine alveolar macrophages via inhibition of the TLR4/NF-κB/NLRP3 inflammasome pathway.

Evidence on Integrating Pharmacokinetics to Find Truly Therapeutic Agent for Alzheimer's Disease: Comparative Pharmacokinetics and Disposition Kinetics Profiles of Stereoisomers Isorhynchophylline and Rhynchophylline in Rats.

Isorhynchophylline (IRN) and rhynchophylline (RN), a pair of stereoisomers, are tetracyclic oxindole alkaloids isolated from Uncaria rhynchophylla, a commonly used Chinese medicinal herb. These two compounds have drawn extensive attention due to their potent neuroprotective effects with promising therapeutic potential for the treatment of Alzheimer's disease (AD). However, IRN and RN can interconvert into each other in vivo after oral administration. The present study aimed to elucidate the pharmacokinetic profiles and disposition kinetics of the administered and generated stereoisomers in the brain and cerebrospinal fluid (CSF) after oral administration of equal dose of IRN or RN to rats. Our study demonstrated that after oral administration, RN showed significantly higher systemic exposure (6.5 folds of IRN, p < 0.001) and disposition in the brain (2.5 folds of IRN, p < 0.01) and CSF (3 folds of IRN, p < 0.001) than IRN. The results indicated that interconversion between IRN and RN occurred. Notably, regardless of the orally administered IRN or RN, RN would always be one of the major or predominant forms present in the body. Our results provided sound evidence supporting further development of RN as a potential therapeutic agent for the treatment of AD. Moreover, the present study sets a solid example that integrating pharmacokinetics is crucial to identify the truly therapeutic agent.

Neuroprotection Against MPP+-Induced Cytotoxicity Through the Activation of PI3-K/Akt/GSK3β/MEF2D Signaling Pathway by Rhynchophylline, the Major Tetracyclic Oxindole Alkaloid Isolated From Uncaria rhynchophylla.

Rhynchophylline is a major tetracyclic oxindole alkaloid in Uncaria rhynchophylla, which has been extensively used as traditional herb medicine for the prevention of convulsions and hypertension. However, there is still little evidence about the neuroprotective effects of rhynchophylline for Parkinson’s disease (PD), a neurodegenerative condition currently without any effective cure. In this present study, the neuroprotective molecular mechanisms of rhynchophylline were investigated in a cellular model associated with PD. It is shown that rhynchophylline (10–50 μM) greatly prevented neurotoxicity caused by 1-methyl-4-phenylpyridinium ion (MPP+) in primary cerebellar granule neurons, as evidenced by the promotion of cell viability as well as the reversal of dysregulated protein expression of Bax/Bcl-2 ratio. Very encouragingly, we found that rhynchophylline markedly enhanced the activity of the transcription factor myocyte enhancer factor 2D (MEF2D) at both basal and pathological conditions using luciferase reporter gene assay, and reversed the inhibition of MEF2D caused by MPP+. Additionally, pharmacological inhibition of PI3-Kinase or short hairpin RNA-mediated gene down-regulation of MEF2D abrogated the protection provided by rhynchophylline. Furthermore, Western blot analysis revealed that rhynchophylline could potentiate PI3-K/Akt to attenuate GSK3β (the MEF2D inhibitor) in response to MPP+ insult. In conclusion, rhynchophylline inhibits MPP+-triggered neurotoxicity by stimulating MEF2D via activating PI3-K/Akt/GSK3β cascade. Rhynchophylline is served as a novel MEF2D enhancer and might be a potential candidate for further preclinical study in the prevention of PD.

Uncaria tomentosa Leaves Decoction Modulates Differently ROS Production in Cancer and Normal Cells, and Effects Cisplatin Cytotoxicity.

Uncaria tomentosa is a woody vine with a long history of use in traditional Peruvian medicine and nowadays supplements containing this vine as ingredient are available. Immunomodulating, anti-inflammatory and anticancer properties of Uncaria tomentosa have been suggested and attributed mainly to the presence of tetracyclic or pentacyclic oxindole alkaloids. However, the synergic action of different compounds occurring in extracts and modulation of redox processes may significantly influence the anticancer activity of Uncaria tomentosa. The aim of the present study was to investigate for the first time the cytotoxic effects of the tetracyclic alkaloids free aqueous extract (decoction) of dried Uncaria tomentosa leaf blades in normal and cancer cells, and to assess the effect of the tested extract on cisplatin (CDDP) cytotoxicity. Tested Uncaria tomentosa extract was not cytotoxic for NHDF cells, but demonstrated cytotoxic effect against HepG2 cells. The extract increased ROS production in HepG2 cells, which resulted in decreased GSH level, leading to apoptosis of these cells through activation of caspase-3 and caspase-7. A reduction of NF-κB active form was observed in cancer cells. In normal cells the extract did not affect ROS production, GSH level and NF-κB activity, and maintained cell viability. HepG2 cells incubation with Uncaria tomentosa decoction and simultaneously with CDDP resulted in an increase in CDPP cytotoxic activity against HepG2, while under the same conditions Uncaria tomentosa prevents NHDF cell viability reduction due to CDDP. The results indicate that Uncaria tomentosa leaves decoction modulates differently cancer and normal cells oxidative metabolism and, enhanced cytotoxicity of CDDP against cancer cells and at the same time increased normal healthy cells resistance to cisplatin. Further studies are needed to confirm our observations and to describe underlying molecular mechanism, and the potential usefulness of Uncaria tomentosa decoction in adjuvant therapy for cancer.

Genotoxicity and cytotoxicity of oxindole alkaloids from Uncaria tomentosa (cat's claw): Chemotype relevance

Ethnopharmacological relevanceUncaria tomentosa (Willdenow ex Roemer & Schultes) DC. (Rubiaceae) or cat's claw is a climber vine from the South American rainforest used in folk medicine for cancer treatment. Its antitumor activity has been mostly ascribed to pentacyclic oxindole alkaloids (POA) from stem bark and leaves while the activity of tetracyclic oxindole alkaloids (TOA) remains unknown. In recent times, the occurrence of three chemotypes based on its oxindole alkaloid profile was noticed in U. tomentosa, namely, chemotype I (POA cis D/E ring junction); chemotype II (POA trans D/E ring junction) or chemotype III (TOA). Consequently, the relationship between the chemotype and cytotoxic and genotoxic activities deserves attention. Aim of the studyTo evaluate the influence of cat's claw chemotypes on genotoxicity and cytotoxicity against non malignant and malignant human cell line models. Material and methodsFour authentic stem bark cat's claw samples (SI-SIV) and two leaf samples (LII and LIII) were analyzed by HPLC-PDA, properly extracted and fractioned by ion-exchange to obtain oxindole alkaloid purified fractions (OAPFs). The freeze-dried fractions were assayed for genotoxicity and cytotoxicity against human leukocytes (non malignant cell line) by the micronuclei frequency method and the alkaline comet DNA assay, and the trypan blue method, respectively. Moreover, the cytotoxicity of each OAPF was evaluated against a human bladder cancer cell line (T24) and human glioblastoma cell line (U-251-MG) by MTT method (malignant cell lines). Additionally, the isomerization of oxindole alkaloids throughout the course of cell incubation was monitored by HPLC-PDA. ResultsBased on HPLC-PDA analyses, sample SI was characterized as chemotype I, while samples SII and LII were characterized as chemotype II, and samples SIII, SIV and LIII as chemotype III. The chemotypes showed comparable cytotoxic activity toward malignant cell lines (T24 and U-251-MG) unlike human leukocytes (non malignant cell line), where this activity was clearly distinct. Chemotype II (POA trans D/E ring junction) showed a higher selectivity index (SI) against malignant cells (SI=1.11–3.04) than chemotype I (SI=0.10−0.19) and III (SI=0.21–0.57). No important genotoxic potential was found by micronuclei frequency and alkaline comet DNA assays. Despite the isomerization of oxindole alkaloids during the cell incubation, the chemotype of the cat's claw samples remained unchanged. ConclusionCat's claw chemotypes showed different selectivity against human malignant cells, so that the correct identification of each chemotype seems to be important to better understand its antitumor potential.

Pharmacokinetic study of isocorynoxeine metabolites mediated by cytochrome P450 enzymes in rat and human liver microsomes

Isocorynoxeine (ICN) is one of the major bioactive tetracyclic oxindole alkaloids found in Uncaria rhynchophylla (Miq.) Jacks. that is widely used for the treatment of hypertension, vascular dementia, and stroke. The present study was undertaken to assess the plasma pharmacokinetic characteristics of major ICN metabolites, and the role of simulated gastric and intestinal fluid (SGF and SIF), human and rat liver microsomes (HLMs and RLMs), and seven recombinant human CYP enzymes in the major metabolic pathway of ICN. A rapid, sensitive and accurate UHPLC/Q-TOF MS method was validated for the simultaneous determination of ICN and its seven metabolites in rat plasma after oral administration of ICN at 40mg/kg. It was found that 18.19-dehydrocorynoxinic acid (DCA) and 5-oxoisocorynoxeinic acid (5-O-ICA) were both key and predominant metabolites, rather than ICN itself, due to the rapid and extensive metabolism of ICN in vivo. The further study indicated that ICN was mainly metabolized in human or rat liver, and CYPs 2C19, 3A4 and 2D6 were the major enzymes responsible for the biotransformation of ICN to DCA and 5-O-ICA in human. These findings are of significance in understanding of the pharmacokinetic nature of tetracyclic oxindole alkaloids, and provide helpful information for the clinical co-administration of the herbal preparations containing U. rhynchophylla with antihypertensive drugs that are mainly metabolized by CYP3A4 and CYP2C19.

Rhynchophylline, One of Major Constituents ofUncariae Ramulus et UncusEnhances Pentobarbital-induced Sleep Behaviors and Rapid Eye Movement Sleep in Rodents

Rhynchophylline (RP) is a major tetracyclic oxindole alkaloid of Uncariae Ramulus et Uncus which has been used to treat hypertension, seizures, pain and anxiety in the oriental countries. A recent report revealed that RP attenuated ischemia-induced neuronal damage and kainite-induced convulsions in animals. This study was performed to investigate whether RP enhances pentobarbital-induced sleep behaviors and modulates sleep architecture in mice. Locomotor activity was significantly inhibited by RP at 0.25 and 0.5 mg/kg, similar to 2 mg/kg diazepam (a benzodiazepine agonist) in mice. RP shortened sleep latency and increased total sleep time in a dose-dependent manner when administrated with pentobarbital (42 mg/kg, i.p.). RP also increased the number of sleeping mice and total sleep time by concomitant administration with the sub-hypnotic dosage of pentobarbital (28mg/kg, i.p.). On the other hand, RP (0.25mg/kg, p.o.) itself significantly inhibited sleep-wake cycles, prolonged total sleep time, and rapid eye movement in rats. In addition, RP also increased chloride influx in the primary cultured hypothalamic neuronal cells. In addition, we found that glutamic acid decarboxylase (GAD65/67) was activated by RP. In conclusion, RP augments pentobarbital-induced sleeping behaviors, and can be a candidate for treating insomnia.

Rhynchophylline Protects Against the Amyloid β-Induced Increase of Spontaneous Discharges in the Hippocampal CA1 Region of Rats.

Accumulated soluble amyloid β (Aβ)-induced aberrant neuronal network activity has been recognized as a key causative factor leading to cognitive deficits which are the most outstanding characteristic of Alzheimer's disease (AD). As an important structure associated with learning and memory, the hippocampus is one of the brain regions that are impaired very early in AD, and the hippocampal CA1 region is selectively vulnerable to soluble Aβ oligomers. Our recent study showed that soluble Aβ1-42 oligomers induced hyperactivity and perturbed the firing patterns in hippocampal neurons. Rhynchophylline (RIN) is an important active tetracyclic oxindole alkaloid isolated from Uncaria rhynchophylla which is a traditional Chinese medicine and often used to treat central nervous system illnesses such as hypertension, convulsions, tremor, stroke etc. Previous evidence showed that RIN possessed neuroprotective effects of improving the cognitive function of mice with Alzheimer-like symptoms. In the present study, we aimed to investigate the protective effect of RIN against soluble Aβ1-42 oligomers-induced hippocampal hyperactivity. The results showed that (1) the mean frequency of spontaneous discharge was increased by the local application of 3 μM soluble Aβ1-42 oligomers; (2) 30 μM RIN did not exert any obvious effects on basal physiological discharges; and (3) treatment with RIN effectively inhibited the soluble Aβ1-42 oligomers-induced enhancement of spontaneous discharge, in a concentration-dependent manner with an IC50 = 9.0 μM. These in vivo electrophysiological results indicate that RIN can remold the spontaneous discharges disturbed by Aβ and counteract the deleterious effect of Aβ1-42 on neural circuit. The experimental findings provide further evidence to affirm the potential of RIN as a worthy candidate for further development into a therapeutic agent for AD.

ChemInform Abstract: Speradines B—D, Oxygenated Cyclopiazonic Acid Alkaloids from the Sponge‐Derived Fungus Aspergillus flavus MXH‐X104.

Abstractisolation, structure elucidation and bioassay screening

Speradines B-D, oxygenated cyclopiazonic acid alkaloids from the sponge-derived fungus Aspergillus flavus MXH-X104

Two new highly oxygenated hexacyclic cyclopiazonic acid (CPA) alkaloids, speradines B and C (1 and 2), together with one new related tetracyclic oxindole alkaloid, speradine D (3), were isolated from the sponge derived fungus Aspergillus flavus MXH-X104. Among them, speradine C (2) possesses unprecedented 6/5/6/5/5/6 hexacyclic ring system and 4-oxo-1, 3-oxazinane ring. The structures including absolute configurations of 1–3 were deduced from the spectroscopic data, X-ray diffraction analysis and the computational method including the calculation of the chemical shifts and the electronic circular dichroism (ECD) spectra.

ChemInform Abstract: Speradines F—H, Three New Oxindole Alkaloids from the Marine‐Derived Fungus Aspergillus oryzae.

Abstractisolation, structural elucidation and cytotoxicity of a rare hexacyclic oxindole alkaloid, speradine F (I), together with two novel tetracyclic oxindole alkaloids, speradines G (II) and H (III)

Metabolites of isocorynoxeine in rats after its oral administration

This work presents the metabolites of isocorynoxeine (ICOR), which is one of four bioactive tetracyclic oxindole alkaloids isolated from Uncaria hooks used commonly in the traditional Chinese medicines and Kampo medicines. After oral administration of 40 mg kg− 1 ICOR to rats, bile was drained and analyzed by LC-MS. Two phase I metabolites, namely 11-hydroxyisocorynoxeine (M1) and 10-hydroxyisocorynoxeine (M2), and two phase II metabolites, namely 11-hydroxyisocorynoxeine 11-O-β-d-glucuronide (M3) and 10-hydroxyisocorynoxeine 10-O-β-d-glucuronide (M4), were isolated from rat excreta and bile, respectively, whose structures were elucidated on the basis of CD, NMR, and MS.