Discovery of NR2B-selective antagonists via scaffold hopping and pharmacokinetic profile optimization

Selective N-methyl-d-aspartate receptor subunit 2B (NR2B) antagonists show potential as analgesic drugs, and do not cause side effects associated with non-selective N-methyl-d-aspartate (NMDA) antagonists. Using a scaffold-hopping approach, we previously identified isoxazole derivative 4 as a potent selective NR2B antagonist. In this study, further scaffold hopping of isoxazole derivative 4 and optimization of its pharmacokinetic profile led to the discovery of the orally bioavailable compound 6v. In a rat study of analgesia, 6v demonstrated analgesic effects against neuropathic pain.     

Beckmann rearrangement products of methyl 3-oxo-tirucall-8, 24-dien-21-oate from Boswellia serrata gum and their anti-tumor activity

3-Oxo-tirucall-8, 24-dien-3-one-21-oic acid is a minor natural product isolated from Boswellia serrata gum apart from β-boswellic acids. Since oxidation of 3-hydroxy group of β-boswellic acids leads to unstable beta-keto acids, Beckmann rearrangement could not be tried. Hence A-ring modified 3-oxo-tirucall-8, 24-dien-21 methyl esters (2–6) were synthesized for the first time via Beckmann rearrangement and evaluated for their anticancer potential against five human cancer cell lines (MCF-7, SW-982, HeLa, PC-3 and IMR-132) by MTT assay. While naturally occurring 3-oxo-tirucallic acid (1) and its methyl ester (2) exhibited nearly the same antiproliferative activity, A-ring modified molecules displayed improved anti-tumor activity with methyl A-homo-4-aza-3-oxo-tirucall-8, 24, dien-3-one-21-oate (4) exhibiting significant effect against prostate cancer cell lines.     

Soluble factors from IL-1β-stimulated astrocytes activate NR1a/NR2B receptors: implications for HIV-1-induced neurodegeneration

Astrocytes play an important role in astrocyte-neuron homeostasis. In HIV-1-infected brain, interleukin 1 beta (IL-1β) activation of astrocytes contributes to neurodegeneration. However, the molecular mechanisms underlying IL-1β-activated-astrocytes-induced neurodegeneration in HIV-1-infected brain are largely unknown. We hypothesize that secretory factors from the activated astrocytes affect N-methyl-d-aspartate (NMDA) receptor, a major pathway implicated in HIV-1-associated neurodegeneration. To test this hypothesis, we studied effects of IL-1β-stimulated astrocyte conditioned medium (ACM+) for its ability to activate NR1a/NR2B receptors expressed on Xenopus oocytes. Astrocytes treated with IL-1β 20 ng/ml for 24 h induced CXCL8, CCL2, MMP1 and MMP7. Pressure ejection of the ACM(+) produced an inward current in NR1a/NR2B-expressing oocytes. The inward current produced by ACM(+) was blocked by NMDA receptor antagonist, APV but not by non-NMDA receptor antagonist, CNQX. These results suggest that IL-1β stimulated astrocytes activate NR1a/NR2B receptors which may have implications in HIV-1-associated neurodegeneration.     

Indolylmethylene benzo[h]thiazolo[2,3-b]quinazolinones: Synthesis,characterization and evaluation of anticancer and antimicrobial activities

A series of novel 10-((1H-indol-3-yl)methylene)-7-aryl-7,10-dihydro-5H-benzo[h]thiazolo[2,3-b]quinazolin-9(6H)-ones (8a–t) have been synthesized in good yields by the reaction of benzo[h]quinazoline-2(1H)-thiones (4a–f) with 2-chloro-N-phenylacetamide (5) followed by Knoevenagel condensation with various indole-3-carbaldehydes (7a–d) under conventional method. All the synthesized compounds were characterized by spectral studies and screened for their in vitro anticancer and antimicrobial activities. Compound 8c has exhibited excellent activity against MCF-7 (breast cancer cell line) than the standard drug Doxorubicin. Compound 8d against both the cancer cell lines, 8q against MCF-7 and 8c, 8h against HepG2 have also shown good activity. Remaining compounds have shown moderate activity against both the cell lines. Antimicrobial activity revealed that, the compound 8q and 8t against Staphylococcus aureus and 8i, 8k, 8l, 8q & 8t against Klebsiella pneumoniae have shown equipotent activity on comparing with the standard drug Streptomycin. Remaining compounds have shown significant antibacterial and comparable antifungal activities against all the tested microorganisms.     

Synthesis and NMDA receptor affinity of fluorinated dioxadrol analogues

A series of dioxadrol analogues with fluorine substituents in position 4 of the piperidine ring has been synthesized and pharmacologically evaluated. The key step in the synthesis was the fluorination of diastereomeric piperidones 6a and 6c as well as diastereomeric alcohols 9a and 9c with DAST. The reaction of the alcohols 9a and 9c took place with inversion of configuration. After removal of the Cbz-protective group, the NMDA receptor affinities of the resulting secondary amines 8a, 8c, 12b, and 12d were investigated in receptor binding studies. It was shown that the like-configuration of the ring junction was crucial for high NMDA receptor affinity. An axially oriented fluorine atom in position 4 led to 2-(2,2-diphenyl-1,3-dioxolan-4-yl)-4-fluoropiperidine (12d, WMS-2517) with a K_i-value of 27 nM. The NMDA receptor affinity of 8c (WMS-2513) with an additional fluorine atom in equatorial 4-position was slightly reduced (K_i = 81 nM). Both fluorinated dioxadrol derivatives 8c and 12d showed high selectivity against σ₁ and σ₂ receptors as well as the polyamine binding site of NR2B receptors.     

Anti-inflammatory,antimicrobial and acetylcholinesterase inhibitory activities of friedelanes from Maytenus robusta branches and isolation of further triterpenoids

The new pentacyclic triterpenoids friedel-1-en-3,16-dione (1), 1α,29-dihydroxyfriedelan-3-one (2) and 16β,28,29-trihydroxyfriedelan-3-one (3) were isolated from Maytenus robusta branches in addition to the known, but new for this species, triterpenoid 12α,29-dihydroxyfriedelan-3-one (4). The structures and stereochemistry of the novel triterpenoids were established by IR, 1D/2D NMR and HR-APCIMS spectral data. In addition, the biological activity of compound 2 and the previously isolated friedelanes 5–8 (friedelan-3,16-dione, 29-hydroxyfriedelan-3-one, 29-hydroxyfriedelan-3,16-dione and 16β,29-dihydroxyfriedelan-3-one) was investigated. Compounds 2 and 8 were tested for their acetylcholinesterase properties and antimicrobial activity against the bacteria Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes, Citrobacter freundii, and the fungus Candida albicans. Compound 2 was the most active compound for both assays, with values of 32.3% acetylcholinesterase inhibition, 42% activity against the fungus Candida albicans and 34% against the bacterium Pseudomonas aeruginosa. Compounds 5–8 were assayed for their antiedematogenic activity using the carrageenan-induced paw edema assay. At maximum inflammation after three hours, compounds 6 and 8 showed 42% and 57% activity, respectively. After four hours, compounds 5 and 7 showed activity of 71% and 75% compared to 79% of the control indomethacin.     

Post-translational control of nitrate reductase activity responding to light and photosynthesis evolved already in the early vascular plants

Regulation of nitrate reductase (NR) by reversible phosphorylation at a conserved motif is well established in higher plants, and enables regulation of NR in response to rapid fluctuations in light intensity. This regulation is not conserved in algae NR, and we wished to test the evolutionary origin of the regulatory mechanism by physiological examination of ancient land plants. Especially a member of the lycophytes is of interest since their NR is candidate for regulation by reversible phosphorylation based on sequence analysis. We compared Selaginella kraussiana, a member of the lycophytes and earliest vascular plants, with the angiosperm Arabidopsis thaliana, and also tested the moss Physcomitrella patens. Interestingly, optimization of assay conditions revealed that S. kraussiana NR used NADH as an electron donor like A. thaliana, whereas P. patens NR activity depended on NADPH. Examination of light/darkness effects showed that S. kraussiana NR was rapidly regulated similar to A. thaliana NR when a differential (Mg²⁺ contra EDTA) assay was used to reveal activity state of NR. This implies that already existing NR enzyme was post-translationally activated by light in both species. Light had a positive effect also on de novo synthesis of NR in S. kraussiana, which could be shown after the plants had been exposed to a prolonged dark period (7 days). Daily variations in NR activity were mainly caused by post-translational modifications. As for angiosperms, the post-translational light activation of NR in S. kraussiana was inhibited by 3-(3,4-dichlorophenyl)-1*1-dimethylurea (DCMU), an inhibitor of photosynthesis and stomata opening. Evolutionary, a post-translational control mechanism for NR have occurred before or in parallel with development of vascular tissue in land plants, and appears to be part of a complex mechanisms for coordination of CO₂ and nitrogen metabolism in these plants.     

Synthesis and biological evaluation of radio-iodinated benzimidazoles as SPECT imaging agents for NR2B subtype of NMDA receptor

In this study, the benzimidazole derivatives were synthesized and evaluated as imaging agents for the NR2B subtype of NMDA receptor. Among these ligands, 2-{[4-(4-iodobenzyl)piperidin-1-yl]methyl}benzimidazol-5-ol (8) and N-{2-[4-(4-iodobenzyl)-piperidin-1-ylmethyl]benzoimidazol-5-yl}-methanesulfonamide (9) exhibited high affinity for the NR2B subunit (K_i values; 7.28 nM for 8 and 5.75 nM for 9). In vitro autoradiography experiments demonstrated high accumulation in the forebrain regions but low in the cerebellum for both [¹²⁵I]8 and [¹²⁵I]9. These regional distributions of the radioligands correlated with the expression of the NR2B subunit. The in vitro binding of these ligands was inhibited by NR2B antagonist but not by other site ligands, which suggested the high selectivity of [¹²⁵I]8 and [¹²⁵I]9 for the NR2B subunit. In mice, the regional brain uptakes of [¹²⁵I]8 and [¹²⁵I]9 at 5–180 min after administration were 0.42–0.56% and 0.44–0.67% dose/g, respectively. The brain-to-blood ratio of [¹²⁵I]8 at 180 min was reduced by 34% in the presence of non-radioactive ligands and by 59% in the presence of the NR2B ligand Ro-25,6981. These results indicated that [¹²⁵I]8 could be partially bound to the NR2B subunit in vivo. Although the brain uptake of these benzimidazole derivatives was too low to allow for in vivo SPECT imaging, these compounds might be useful scaffolds for the development of imaging probes specific for the NMDA receptors.     

Two new flavonol derivatives from the whole plants of Centella asiatica and their cytotoxic activities

Centella asiatica is well known as an important medicinal plant because of its various pharmacological effects. However, most investigations on C. asiatica focused on the pharmacological activity of its extract or asiatic acid. In the present work, we aimed to explore the bioactive compounds of the whole plants of C. asiatica. As a result, seven compounds including two new flavonol derivates named 4′-hydroxyl-7-methoxyl-6-prenyl-3-O-trans-p-coumaroyl-flavonol (1) and (2R,3R,2″S)-3-furanoyl-brosimacutin E (2), and five known compounds (3-7) were isolated. Their chemical structures were elucidated on the basis of spectroscopic analyses. All the isolates were evaluated for in vitro cytotoxic effects on four human cancer cells including A549, HepG2, SGC-7901 and MCF-7. Among them, compounds 1 and 2 exhibited higher cytotoxic activities on HepG2 and SGC-7901 cells compared with 3-7. And compound 2 showed potential cytotoxic activities on HepG2 and SGC-7901 cells with IC₅₀ values of 4.52 and 7.03 μM, respectively.     

Glutamate receptor properties of human mesencephalic neural progenitor cells: NMDA enhances dopaminergic neurogenesis in vitro

Human midbrain‐derived neural progenitor cells (NPCs) may serve as a continuous source of dopaminergic neurons for the development of novel regenerative therapies in Parkinson’s disease. However, the molecular and functional characteristics of glutamate receptors in human NPCs are largely unknown. Here, we show that differentiated human mesencepahlic NPCs display a distinct pattern of glutamate receptors. In whole‐cell patch‐clamp recordings, l ‐glutamate and NMDA elicited currents in 93% of NPCs after 3 weeks of differentiation in vitro. The concentration‐response plots of differentiated NPCs yielded an EC₅₀ of 2.2 μM for glutamate and an EC₅₀ of 36 μM for NMDA. Glutamate‐induced currents were markedly inhibited by memantine in contrast to 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) suggesting a higher density of functional NMDA than alpha‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA)/kainate receptors. NMDA‐evoked currents and calcium signals were blocked by the NR2B‐subunit specific antagonist ifenprodil indicating functional expression of NMDA receptors containing subunits NR1 and NR2B. In calcium imaging experiments, the blockade of voltage‐gated calcium channels by verapamil abolished AMPA‐induced calcium responses but only partially reduced NMDA‐evoked transients suggesting the expression of calcium‐impermeable, GluR2‐containing AMPA receptors. Quantitative real‐time PCR showed a predominant expression of subunits NR2A and NR2B (NMDA), GluR2 (AMPA), GluR7 (kainate), and mGluR3 (metabotropic glutamate receptor). Treatment of NPCs with 100 μM NMDA in vitro during proliferation (2 weeks) and differentiation (1 week) increased the amount of tyrosine hydroxylase‐immunopositive cells significantly, which was reversed by addition of memantine. These data suggest that NMDA receptors in differentiating human mesencephalic NPCs are important regulators of dopaminergic neurogenesis in vitro.     

Synthesis and cytokinin activity of N-acylaminodeazapurines

Three 7-acylaminoimidazo[4,5-b]pyridines, namely 7-pentanoylaminoimidazo[4,5-b]pyridine (1), 7-benzoylaminoimidazo[4,5-b]pyridine(2), and 7-(2-furoylamino)imidazo[4,5-b]pyridine(3), six 4-acylaminoimidazo[4,5-c]pyridines, namely 4-propionylaminoimidazo[4,5-c]pyridine(4), 4-butyryl-aminoimidazo[4,5-c]pyridine(5), 4-pentanoylaminoimidazo[4,5-c]pyridine(6) 4-hexanoylaminoimidazo[4,5-c]pyridine(7),4-benzoylaminoimidazo[4,5-c]pyridine(8), and 4-(2-furoylamino)imidazo[4,5-c]-pyridine(9), and seven 7-acylaminoimidazo[4,5-c]pyridines, namely 7-propionylaminoimidazo[4,5-c]-pyridine(10), 7-butyrylaminoimidazo[4,5-c]pyridine(11), 7-pentanoylaminoimidazo[4,5-c]pyridine(12), 7-hexanoylaminoimidazo[4,5-c]pyridine(13), 7-benzoylaminoimidazo[4,5-c]pyridine(14), 7-phenylacetylaminoimidazo[4,5-c]pyridine(15), and 7-(2-furoylamino)imidazo[4,5-c]pyridine(16) were synthesized and tested for their cytokinin activity with the tobacco callus bioassay. 2 showed a cytokinin activity at 1 × 10⁻⁸ M and gave a callus yield about 72% of that produced by kinetin at 1 × 10⁻⁶ M. 1, 3 and 8 showed the optimum growth responses in the range of 10⁻⁷−10⁻⁶ M. 4, 5, 7, 9–16 were slightly active. These results support previous reports that a nitrogen atom at the 3-position in the purine ring plays an important role in conferring high cytokinin activity.     

An Endoplasmic Reticulum Retention Signal Located in the Extracellular Amino-terminal Domain of the NR2A Subunit of N-Methyl-d-aspartate Receptors

N-Methyl-d-aspartate (NMDA) receptors play critical roles in complex brain functions as well as pathogenesis of neurodegenerative diseases. There are many NMDA isoforms and subunit types that, together with subtype-specific assembly, give rise to significant functional heterogeneity of NMDA receptors. Conventional NMDA receptors are obligatory heterotetramers composed of two glycine-binding NR1 subunits and two glutamate-binding NR2 subunits. When individually expressed in heterogeneous cells, most of the NR1 splice variants and the NR2 subunits remain in the endoplasmic reticulum (ER) and do not form homomeric channels. The mechanisms underlying NMDA receptor trafficking and functional expression remain uncertain. Using truncated and chimeric NMDA receptor subunits expressed in heterogeneous cells and hippocampal neurons, together with immunostaining, biochemical, and functional analyses, we found that the NR2A amino-terminal domain (ATD) contains an ER retention signal, which can be specifically masked by the NR1a ATD. Interestingly, no such signal was found in the ATD of the NR2B subunit. We further identified the A2 segment of the NR2A ATD to be the primary determinant of ER retention. These findings indicate that NR2A-containing NMDA receptors may undergo a different ER quality control process from NR2B-containing NMDA receptors.Ionotropic glutamate receptors (iGluRs)² mediate most of the excitatory neurotransmission in the central nervous system. They play key roles in complex brain functions as well as in the pathogenesis of neurodegenerative diseases. Based on pharmacological properties and sequence similarities, iGluRs can be grouped into three major subtypes: GluR1 to -4 subunits form α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors, GluR5 to -7 and KA1 and -2 subunits make up kainate receptors, and NR1 together with NR2A to -D subunits comprise the NMDA receptors (1). All iGluR subunits share a unique membrane topology with a large extracellular NH₂-terminal domain, three transmembrane segments (TM1 (transmembrane domain 1), TM3, and TM4), a P-loop region, and a cytoplasmic COOH terminus (2, 3). Based on the sequence homology to bacterial periplasmic binding proteins, the NH₂-terminal domain of iGluRs can be divided into two domains in tandem: the amino-terminal domain (ATD), which includes the first 400 or so amino acids (4), and the following S1 domain preceding TM1, which forms the ligand-binding domain together with the extracellular loop between TM3 and TM4 (S2 domain) (5, 6).Among iGluRs, NMDA receptors are special in that conventional NMDA receptors are obligatory tetrameric membrane proteins composed of two glycine-binding NR1 and two glutamate-binding NR2 subunits. The NR1 subunit is essential for the formation of functional NMDA receptor channel, whereas the NR2 subunit modifies channel properties, such as current kinetics and channel conductance (1). The major NR1 splice variant and the NR2 subunits are retained in the ER when expressed alone in heterogeneous cells. Only when expressed together do they form functional receptors on the cell surface (7–9). In the last decade, enormous progress has been made in understanding the phenomenology and mechanisms of functional plasticity of NMDA receptors. However, much less is known about the mechanisms underlying the ER retention of NMDA receptor subunits. Previous studies focused on the COOH terminus have shown that the NR1a subunit contains an ER retention signal, RRR, in the C1 cassette, whereas a motif, HLFY, found in the NR2B subunit immediately following the TM4 (10) or, at least, the presence of any two amino acid residues after NR2 TM4 (11) is required for the export of NR1-NR2 complexes from the ER. Recently, novel ER retention signals were identified in the TM3 of both NR1 and NR2B subunits. In addition, TM3 of both NR1 and NR2B and TM4 of NR1 are necessary for masking ER retention signals found in TM3 (12).In the present study, we focused on the functional role of the ATD in the surface expression of NMDA receptors. Interestingly, we found an ER retention signal located in the ATD of the NR2A subunit but not in the corresponding domain of the NR2B. It is suggested that NR2A-containing NMDA receptors may undergo an ER quality control process different from that of NR2B-containing NMDA receptors.     

Chemical constituents from Oncocalyx glabratus and their biological activities

Chemical investigation of the aerial parts of Oncocalyx glabratus resulted in the isolation of three new flavan derivatives, 5,3′,4′-trihydroxyflavan 7-O-gallate (1), 5,4′-dihydroxyflavan 7-3′-O-digallate (2) and 5,3′-dihydroxyflavan 7-4′-O-digallate (3), named oncoglabrinol A, B and C, respectively, together with four known flavonols, (+)-catechin (4), (+)-catechin-7-O-gallate (5), catechin-7-4′-O-digallate (6A) and catechin-7-3′-O-digallate (6B). The structures of the compounds were established by 1D, 2D NMR and ESI-HRMS spectral analyses. The biological activity of the compounds was tested through a series of in vitro assays designed for determining cytotoxicity, antiviral activity against hepatitis B virus, and antidiabetic activity. All compounds were found non-toxic and showed moderate anti-HBV activity. Compounds 3 and 6 showed dual PPAR agonistic activity while others were not effective.     

Activation of N-Methyl-d-aspartate (NMDA) Receptors in the Dorsal Vagal Complex Lowers Glucose Production

Diabetes is characterized by hyperglycemia due partly to increased hepatic glucose production. The hypothalamus regulates hepatic glucose production in rodents. However, it is currently unknown whether other regions of the brain are sufficient in glucose production regulation. The N-methyl-d-aspartate (NMDA) receptor is composed of NR1 and NR2 subunits, which are activated by co-agonist glycine and glutamate or aspartate, respectively. Here we report that direct administration of either co-agonist glycine or NMDA into the dorsal vagal complex (DVC), targeting the nucleus of the solitary tract, lowered glucose production in vivo. Direct infusion of the NMDA receptor blocker MK-801 into the DVC negated the metabolic effect of glycine. To evaluate whether NR1 subunit of the NMDA receptor mediates the effect of glycine, NR1 in the DVC was inhibited by DVC NR1 antagonist 7-chlorokynurenic acid or DVC shRNA-NR1. Pharmacological and molecular inhibition of DVC NR1 negated the metabolic effect of glycine. To evaluate whether the NMDA receptors mediate the effects of NR2 agonist NMDA, DVC NMDA receptors were inhibited by antagonist d-2-amino-5-phosphonovaleric acid (d-APV). DVC d-APV fully negated the ability of DVC NMDA to lower glucose production. Finally, hepatic vagotomy negated the DVC glycine ability to lower glucose production. These findings demonstrate that activation of NR1 and NR2 subunits of the NMDA receptors in the DVC is sufficient to trigger a brain-liver axis to lower glucose production, and suggest that DVC NMDA receptors serve as a therapeutic target for diabetes and obesity.     

New derivatives of tenvermectins through biotransformation as potential insecticides

Tenvermectins (TVMs) belongs to the 16-membered macrolactone family antibiotics with attractive insecticidal properties. In order to discover more potent TVM derivatives, microbial transformation of TVM-A and TVM-B by Penicilium griseofulvum CICC 40293 and Bacillus subtilis ATCC 6633 were investigated and offered us six new metabolites (1-5, 7) with regioselectivity, especially rare glycosuccinylated products, in addition to two known compounds (6, 8). Their chemical structures were well characterized via HR-ESI-MS and 1D/2D NMR spectra. All these metabolites exhibited good acaricidal and nematicidal activities against Tetranychus cinnabarinus and Bursaphelenchus xylophilus. These results indicated that the metabolites 1-8 can serve as potential leads for future development of new insecticides.     

Synthesis,GluN2B affinity and selectivity of benzo[7]annulen-7-amines

Due to their beneficial side effect profile, NMDA receptor antagonists interacting selectively with the allosteric ifenprodil binding site of the GluN2B subunit are of major interest for the treatment of neurological and neurodegenerative disorders. A series of benzo[7]annulen-7-amines 6 was designed by conformational restriction of ifenprodil (1). At first the benzo[7]annulen-7-one 11 was prepared in a three-step synthesis comprising of a double Knoevenagel condensation of phthalaldehyde (7) with dimethyl 3-oxoglutarate (8), hydrogenation of 9 and saponification/decarboxylation of 10. Reductive amination of the ketone 11 with primary amines and NaBH(OAc)₃ led to the secondary amines 6a–d, cis-6h and trans-6i. The tertiary amines 6e–g were obtained by S_N2-substitution of the nosylate 13. Although H-bond forming substituents in 2- and 5-position are missing, the amines 6 exhibit high affinity towards GluN2B containing NMDA receptors. A distance of four to five bond lengths between the basic amino moiety and the phenyl ring in the side chain appears to be optimal for high GluN2B affinity. The phenylcyclohexylamine cis-6h and the 4-benzylpiperidine 6g show the highest GluN2B affinities (K_i = 2.3 nM and 2.9 nM, respectively). With respect to selectivity against the PCP binding site, σ₁ and σ₂ receptors the phenylpiperazine 6f is the most promising GluN2B antagonist.     

New p-terphenyls from the endophytic fungus Aspergillus sp. YXf3

Five new p-terphenyls named prenylterphenyllin D (1), prenylterphenyllin E (2), 2′-O-methylprenylterphenyllin (3), 4-O-methylprenylterphenyllin (4) and 3′-O-methylterphenyllin (5) together with seven known compounds (6–12), were isolated from cultures of Aspergillus sp. YXf3. The structures of the new compounds were elucidated by extensive MS and NMR analyses. The NMR and MS data of 5 is reported for the first time, as its structure was listed in SciFinder Scholar with no associated reference. Compounds 6 and 7 were distinguished from each other on the basis of 2D NMR experiments. Compounds 1, 2, 3 and 8 showed antibacterial activities against X. oryzae pv. oryzicola Swings and E. amylovora with the same MIC values of 20 μg/mL while 10 exhibited activities against E. amylovora with an MIC value of 10 μg/mL.     

Isolation of hopane triterpenes and other constituents from Machaerium brasiliense vogel (Fabaceae)

Phytochemical study of Machaerium brasiliense leaves extract afforded three hopane triterpenes 3,4-seco-21β-H-hop-22 (29)-en-3-oic acid (1), hopenone B (2), hopene B (3). In addition, lupeol (4), stigmasterol (5), β-sitosterol (6), daucosterol (7), uracil (8), allantoin (9) and trans-4-hydroxy-N-methylproline (10) were isolated. The structures of these compounds were established based on spectroscopic data in comparison to those described in literature. Considering the chemotaxonomic relevance of the isolated compounds, this is the first report of triterpenes 1, 2 and 3 in Fabaceae family and compounds 7, 8 and 9 in the genus Machaerium. Besides, preliminary screening on antiproliferative and antioxidant activities was performed for MBEB and its fractions.     

Ansamycin derivatives from the marine-derived Streptomyces sp. SCSGAA 0027 and their cytotoxic and antiviral activities

Fourteen ansamycin derivatives including seven new herbimycins G–L (1–6) and divergolide O (7), and seven known analogues were isolated from a culture broth of the marine-derived Streptomyces sp. SCSGAA 0027. Their complete structures were determined by detailed analysis of spectroscopic data and quantum chemical calculations. Compounds 1–5 and 7 featured an additional eight-membered O-heterocycle that has rarely been reported for ansamycins, and the Z,Z- and E,E-configurations for Δ²,Δ⁴ were reported for the first time in geldanamycin analogues. Compound 1 exhibited weak inhibition activity towards Hsp90α with an IC₅₀ value of 96 µM, 2–5 showed mild cytotoxicity against four human cancer cell lines with IC₅₀ values ranging from 13 μM to 86 μM, and 7 had moderate anti-HSV-1 activity with an IC₅₀ value of 19 µM and very weak cytotoxicity towards Vero cell. The possible biosynthetic pathways for 1–5 were proposed. And their structure-bioactivity relationship was also discussed.     

Novel autophagy modulators: Design and synthesis of (+)-epogymnolactam analogues and structure-activity relationship

(+)-Epogymnolactam (1) was discovered as a novel autophagy inducer from a culture of Gymnopus sp. in our laboratory. To determine structure-activity relationships among (+)-epogymnolactam analogues comparing with cerulenin (2), we synthesized 5 analogues including (?)-epogymnolactam (3) having each different functional group, and 3 analogues with different side-chain lengths. Five analogues, 3, 4, 5, 6, and 7 did not significantly increase the ratio of LC3-II to LC3-I as an autophagy marker in NIH3T3 cells. These results suggest that presence and stereochemistry of (2R,3S)-epoxy group and cyclic syn-form (1b) of 1 are important for the activity as autophagy inducer. Hexyl analogue (8) as well as 1 having butyl side-chain dose-dependently increased the ratio of LC3-II to LC3-I, whereas octyl analogue (9) and 2 rather decreased the ratio. Decyl analogue (10) did not give a change in the ratio. Although 8 seemed to be an excellent autophagy inducer, it dose-dependently increased SQSTM1 (p62) as in the case of 2, whereas 1 showed a slight dose-dependent decrease of p62 as an index of autophagic protein degradation. These observations suggest that 8 is an autophagy modulator with different molecular target from 1 or 2.