ARL6IP1 mediates small-molecule-induced alleviation of Alzheimer pathology through FXR1-dependent BACE1 translation initiation.

Exploring the potential lead compounds for Alzheimer's disease (AD) remains one of the challenging tasks. Here, we report that the plant extract conophylline (CNP) impeded amyloidogenesis by preferentially inhibiting BACE1 translation via the 5' untranslated region (5'UTR) and rescued cognitive decline in an animal model of APP/PS1 mice. ADP-ribosylation factor-like protein 6-interacting protein 1 (ARL6IP1) was then found to mediate the effect of CNP on BACE1 translation, amyloidogenesis, glial activation, and cognitive function. Through analysis of the 5'UTR-targetd RNA-binding proteins by RNA pulldown combined with LC-MS/MS, we found that FMR1 autosomal homolog 1 (FXR1) interacted with ARL6IP1 and mediated CNP-induced reduction of BACE1 by regulating the 5'UTR activity. Without altering the protein levels of ARL6IP1 and FXR1, CNP treatment promoted ARL6IP1 interaction with FXR1 and inhibited FXR1 binding to the 5'UTR both in vitro and in vivo. Collectively, CNP exhibited a therapeutic potential for AD via ARL6IP1. Through pharmacological manipulation, we uncovered a dynamic interaction between FXR1 and the 5'UTR in translational control of BACE1, adding to the understanding of the pathophysiology of AD.

Sesquiterpenoids from cigar tobacco leaves.

Phytochemical investigation on cigar tobacco leaves led to four unknown sesquiterpenoids as well as nine reported ones. Among of them, 3-acetoxy-ß-damascone was first found in tobacco leaves. All the structures were elucidated by intensive spectroscopic analyses and X-ray diffraction. The relationship between the newly isolates and known ones was tried to describe.

Ionones from cigar tobacco leaves.

Phytochemical studies on cigar tobacco leaves led to the isolation of 18 ionone-type compounds, including previously undescribed cigatobanes E (1) and F (2). Additionally, compounds vomifoliol acetate (3), dehydrovomifoliol (4), 8,9-dihydromegastigmane-4,6-diene-3-one (5), 7α,8α-epoxyblumenol B (6), 3-oxoactinidol (12), and loliolide acetate (15), 4ß-hydroxy-dihydroactinidiolide (17), were found in tobacco leaves for the first time. The structural elucidation of all compounds was accomplished through rigorous spectral analysis.

Nematocidal alkaloids from the roots of Stemona mairei (H.Lév.)K.Krause and identification of their pharmacophoric moiety.

Fifteen undescribed Stemona alkaloids, named as stemarines A-O (1-15), along with 25 known alkaloids (16-40), were isolated and identified from the roots of Stemona mairei (H.Lév.)K.Krause (Stemonaceae). Their structures were elucidated through the analysis of the NMR spectra, mass data, and computational chemistry. All the hitherto undescribed compounds possess a pyrrolo[1,2-α]azepine core structure but differ in important structural features, which reflects their nematocidal activities. Alkaloids 3-6 featured a carboxylic side chain and exhibited significant nematocidal activity against the nematode Caenorhabditis elegans. Transections of fresh roots combined with application of the Dragendorff' reagent on the tissue indicated accumulation of alkaloids mainly in the epidermis and the pith. These results suggest the key pharmacophore of these alkaloids lies in the aliphatic side chain of these compounds and its spatial distribution in the roots indicate protective effects against underground herbivores.

Two Novel Iboga-Type and an Oxindole Glucuronide Alkaloid from Tabernaemontana peduncularis Disclose Related Biosynthetic Pathways to Tabernaemontana divaricata.

Phytochemical investigation of the two Tabernaemontana species (Apocynaceae) T. peduncularis Wall. and T. divaricata (L.) R.Br. ex Roem. & Schult. indicated closely related biosynthetic pathways leading to lipophilic and hydrophilic alkaloids. In total, 18 specialized metabolites comprising indole-derived alkaloid aglycones, three oxindole-derived alkaloid glycosides, and two iridoid glucosides could be identified in the studied species. Among the alkaloids, the two Iboga-type alkaloids 3,7-coronaridine isoindolenine, coronaridine 3,4-iminium and a javaniside derivative bearing a glucuronic acid, named javanuronic acid, could be described by spectroscopic and spectrometric methods for the first time. A docking experiment using alpha-fold was performed to generate a protein model of the enzyme 7-deoxyloganetic acid glucosyl transferase. Performed bioassays exhibited a growth reduction of neonate Spodoptera littoralis larvae and reduced cell viability of HepG2 cells of the extracts containing Iboga alkaloids, whilst the javaniside derivatives containing hydrophilic fraction did not show any effects. These findings indicate a high flexibility in the formation of bioactive indole alkaloid aglycones by Tabernaemontana species and also evidence similar accumulation trends in both species as well as indicate that biosynthetic routes leading to oxindole alkaloids like javanisides are more widespread than reported. Furthermore, the incorporation of the three novel compounds into potential biosynthetic pathways is discussed.

Colored Dimeric Alkaloids from the Barks of Erythrina variegata and Their Neuroprotective Effects.

Five dimeric Erythrina alkaloids, named erythrivarines J-N, were isolated from the barks of Erythrina variegata L. (Fabaceae). The erythrivarines J-L featured a 6/6/5/6/6/5/6/6/6 ring system and super conjugated double bond systems, causing intense color from blue to wine red, while erythrivarines M-N looked orange. The structures of the isolated compounds were elucidated by 1D and 2D NMR experiments combined with MS and confirmed by the X-ray crystal diffraction technique. The performed bioassay using HEI-OC-1 cells revealed neuroprotective properties of erythrivarine N against the hearing loss causing antibiotics, neomycin.

3-Hydroxy-4-methyldecanoic Acid-Containing Cyclotetradepsipeptides from an Endolichenic Beauveria sp.

An investigation of an endolichenic Beauveria sp. led to the discovery of seven new cyclotetradepsipeptides, beauveamides A-G (2-8), along with the known beauverolide Ka (1). All incorporate a 3-hydroxy-4-methyldecanoic acid (HMDA) moiety in their structures. Their configuration was determined through Marfey's, J-based configuration analysis, and NMR computational methods, representing the first time that the stereostructures of HMDA-moiety-containing cyclotetradepsipeptides have been established. Compounds 1 and 2 exhibited protecting effects on HEI-OC1 cells at 10 µM, while 1, 4, and 5 could stimulate glucose uptake in cultured rat L6 myoblasts at 50 µM. Compound 1 showed dose-dependent activity in both L6 myoblasts and myotubes.

Trimeric and dimeric Aspidosperma-type alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'.

Continued interest in bioactive monoterpenoid indole alkaloids and the purpose to explore the artificial cultivation influence on the chemical composition in the same plant species, 8 undescribed Aspidosperma-type alkaloids including two unprecedented trimers, taberdivarines A-B (1-2), and six new dimers, taberdivarines CH (3-8), together with 9 known bisindoles were isolated from the leaves of Tabernaemontana divaricata 'Dwaft'. Notably, taberdivarines A and B were the first cases of Aspidosperma-Aspidosperma-Aspidosperma-type alkaloids with furan ring linkage patterns of the natural products. Their structures were elucidated by comprehensive spectroscopic analyse. Compounds 1-8 were screened for the cytotoxicity against three human cancer cell lines, SMMC-7721, HT-29 and A549. Among them, Compound 6 exhibited significant activity against three cell lines with IC50 values of 0.30, 0.75 and 3.41 µM, respectively (IC50 = 3.02, 0.14 and 2.23 µM for the positive control, vinorelbine). Compound 1, 3, 4, 6, 7 and 8 also expressed varying degrees of activity. The structure-activity relationships (SARs) of these alkaloids were discussed.

Indole Alkaloids from Hunteria zeylanica.

Six new bisindole alkaloids, hunterizeylines A-F (1-6), three new monomers, hunterizeylines G-I (7-9), and 13 known alkaloids were isolated from an aqueous MeOH extract of the twigs and leaves of Hunteria zeylanica. Hunterizeyline H, geissoschizol, and dihydrocorynantheol displayed weak insecticidal activity against the aphid Rhodobium porosum, with IC50 values of 168.2, 360.5, and 290.6 µM, respectively.

Two new lignans from twigs of Aglaia odorata.

HPLC-guided separation of twigs of Aglaia odorata led to the isolation of eight lignans, including two new ones, 3'-methoxy-N-demethylrocaglamide (1) and 4'-O-demethyl-deacetylaglaxiflorin A (2). Compound 1 showed excellent cytotoxicity against three human cancer cell lines, HeLa, SGC-7901 gastric cancer, and A-549 lung cancer with the values of 0.32, 0.12, and 0.25 µM, respectively.

A novel cold-adapted type I pullulanase of Paenibacillus polymyxa Nws-pp2: in vivo functional expression and biochemical characterization of glucans hydrolyzates analysis.

BACKGROUND: Pullulanase is an important debranching enzyme and has been widely utilized to hydrolyse the α-1,6 glucosidic linkages in starch/sugar industry. Selecting new bacterial strains or improving bacterial strains is a prerequisite and effective solution in industrial applications. Although many pullulanase genes have been cloned and sequenced, there is no report of P. polymyxa type I pullulanase gene or the recombinant strain. Meanwhile most of the type I pullulanase investigated exhibit thermophilic or mesophilic properties. There are just few reports of cold-adapted pullulanases, which have optimum activity at moderate temperature and exhibit rather high catalytic activity at cold. Previously, six strains showing distinct pullulan degradation ability were isolated using enrichment procedures. As containing novel bacterium resource and significant pullulanase activity, strain Nws-pp2 was selected for in-depth study. METHODS: In this study, a type I pullulanase gene (pulN) was obtained from the strain P. polymyxa Nws-pp2 by degenerate primers. Through optimization of induced conditions, the recombinant PulN achieved functional soluble expression by low temperature induction. The enzyme characterizations including the enzyme activity/stability, optimum temperature, optimum pH and substrate specificity were also described through protein purification. RESULTS: The pullulanase gene (named pulN), encoding a novel cold-adapted type I pullulanase (named PulN), was obtained from isolated strain Paenibacillus polymyxa Nws-pp2. The gene had an open reading frame of 2532-bp and was functionally expressed in Escherichia coli through optimization of induced conditions. The level of functional PulN-like protein reached the maximum after induction for 16 h at 20 °C and reached about 0.34 mg/ml (about 20 % of total protein) with an activity of 6.49 U/ml. The purified recombinant enzyme with an apparent molecular mass of about 96 kDa was able to attack specifically the α-1,6 linkages in pullulan to generate maltotriose as the major product. The purified PulN showed optimal activity at pH 6.0 and 35 °C, and retained more than 40 % of the maximum activity at 10 °C (showing cold-adapted). The pullulanase activity was significantly enhanced by Co(2+) and Mn(2+), meanwhile Cu(2+) and SDS inhibited pullulanase activity completely. The Km and Vmax values of purified PulN were 15.25 mg/ml and 20.1 U/mg, respectively. The PulN hydrolyzed pullulan, amylopectin, starch, and glycogen, but not amylose. Substrate specificity and products analysis proved that the purified pullulanase from Paenibacillus polymyxa Nws-pp2 belong to a type I pullulanase. CONCLUSIONS: This report of the novel type I pullulanase in Paenibacillus polymyxa would contribute to pullulanase research from Paenibacillus spp. significantly. Also, the cold-adapted pullulanase produced in recombinant strain shows the potential application.

Mimicking Livor Mortis: a Well-Known but Unsubstantiated Color Profile in Sapromyiophily.

By emitting strong scents resembling rotting organic materials suitable for oviposition and/or foraging of flies, sapromyiophilous flowers mimic the substrates that attract flies as pollinators. It has been suggested that the wide range of volatile organic compounds emitted by this deceptive pollination system reflects the trophic preferences of flies to different types of substrate, including herbivore and carnivore feces, carrion, and fruiting bodies of fungi. Previous studies suggest that floral scents play a particularly important role in sapromyiophily. However, few studies on the relative importance of floral color or synergy between visual and olfactory cues in sapromyiophily have been substantiated. In this study, we analyzed fetid floral odor, floral pigment composition, and reflectance of an Amorphophallus konjac C. Koch inflorescence, and we conducted bioassays with different visual and/or olfactory cues to explore an unsubstantiated color profile in sapromyiophily: mimicking livor mortis. Our analysis showed A. konjac can emit oligosulphide-dominated volatile blends similar to those emitted by carrion. Necrophagous flies cannot discriminate between the color of an inflorescence, livor mortis, and floral pigments. We concluded that mimicking livor mortis may represent a common tactic of pollinator attraction in "carrion flower" systems within angiosperms.

Cinchona alkaloids from Cinchona succirubra and Cinchona ledgeriana.

Seven new cinchona alkaloids, cinchonanines A-G (1-7), and 29 known alkaloids were isolated from the barks of Cinchona surrirubra and C. ledgeriana collected from Yunnan Province in China. The new structures were elucidated by extensive spectroscopic analysis. All compounds were evaluated for their cytotoxicity against five human cancer cell lines. Compounds 2, 13, 14, and 15 showed moderate cytotoxicity.

Insecticidal bisindole alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'.

Six undescribed bisindole alkaloids, namely taberdisines A-F (1-6), were isolated from the leaves of Tabernaemontana divaricata 'Dwaft'. Among them, alkaloids 1 and 2 were the first examples of strychnos-iboga type alkaloid with both C-C linkage patterns. Alkaloid 3, a new type of aspidosperma-iboga with a furan-ring, as well as other three undescribed ones was disclosed. Their structures were elucidated by comprehensive spectroscopic analyses. Alkaloids 1 and 5 showed insecticide activity on Sf9 cell and eggs of Spodoptera frugiperda in vivo, which might explain the potential of the plants for insect resistance.

Gelselegine-gelsedine type bisindoles as well as the units from Gelsemium elegans with promoting proliferation of oral mucosa fibroblast cells.

Two undescribed bisindole alkaloids, gelseginedine A (1) and its rearranged gelseginedine B (2), and seven unreported gelselegine-type oxindole alkaloids (3-9) were isolated from the stems and leaves of Gelsemium elegans, together with five known alkaloids (10-14). Compounds 1 and 2 represented the first examples of gelselegine-gelsedine type alkaloids which bridged two units by a double bond. Their structures with absolute configurations were elucidated by means of HRESIMS, NMR and calculational chemistry. The performed bioassay revealed that 14 could promote the proliferation of human oral mucosa fibroblast cells.

Search for Snail Repellents: Antimollusc Activities from Stemona parviflora and Six Other Chinese Stemona Species.

Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.

Gardovatine, a novel Strychnos-Strychnos bisindole alkaloid with cytotoxicity from Gardneria oveta.

Gardovatine (1), the first Strychnos-Strychnos alkaloid with a C3/C7 cleaved backbone, was isolated from twigs and leaves of Gardneria ovate, together with an analogue divarine (2). The structure was established by extensive spectroscopic methods. Both compounds showed potential cytotoxicities against five human cancer cell lines.

Melosuavines A-H, cytotoxic bisindole alkaloid derivatives from Melodinus suaveolens.

Eight new bisindole alkaloids, melosuavines A-C (1-3), having an aspidosperma-scandine linkage, melosuavines D-F (4-6), possessing an aspidosperma-aspidosperma skeleton, and melosuavines G and H (7 and 8) of the aspidosperma-venalatonine type, tenuicausine (9), and melodinine J (10) were isolated from the twigs and leaves of Melodinus suaveolens. The structures of 1-8 were elucidated by extensive spectroscopic methods, and compounds 9 and 10 were identified by comparison with data in the literature. The relative configuration 9 was determined from the ROESY spectrum, and some NMR signals were reassigned. Compounds 1, 2, 4-6, 8, and 10 exhibited low micromolar cytotoxicity against one or more of five human cancer cell lines.

Cytotoxic indole alkaloids from Tabernaemontana divaricata.

Five new vobasinyl-ibogan-type bisindole alkaloids, tabernaricatines A-E (1-5), two new monomers, tabernaricatines F and G (6 and 7), and 24 known indole alkaloids were isolated from the aerial parts of Tabernaemontana divaricata. Alkaloids 1 and 2 are the first vobasinyl-ibogan-type alkaloids possessing a six-membered ring via an ether linkage between C-17 and C-21. All compounds except for 3 were evaluated for their cytotoxicity against five human cancer cell lines; conophylline showed significant bioactivity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cells with IC50 values of 0.17, 0.35, 0.21, 1.02, and 1.49 µM, respectively.

Indole alkaloids from leaves and twigs of Rauvolfia verticillata.

Seven new indole alkaloids, rauverines A-G (1-7), and 19 known indole alkaloids were isolated from the leaves and twigs of Rauvolfia verticillata. All compounds showed no cytotoxicity against five human cancer cell lines, human myeloid leukemia (HL-60), hepatocellular carcinoma (SMMC-7721), lung cancer (A-549), breast cancer (MCF-7), and colon cancer (SW480) cells.