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.

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.

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.

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.

Discovery and biological evaluation of a new type of dual inhibitors of indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase from ethnomedicinal plant Dactylicapnos scandens.

The root of Dactylicapnos scandens (D.Don.) Hutch (Papaveraceae), one of the most famous ethno-medicinal plants from the Bai communities in P. R. China, is used to treat various inflammations and tumours. Bioassay-guided phytochemical research on D. scandens followed by semi-synthesis led to a series of undescribed tetrahydroisoquinoline alkaloids with dual inhibitory activities against indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). The previously undescribed dark-green alkaloid dactycapnine A exhibited the best dual inhibitor effects among the identified compounds. Structure-activity relationship analysis revealed the importance of the base skeleton with a hyperconjugation system. The performed semi-synthesis further yielded bioactive dimeric and trimeric compounds with hyperconjugated systems. Performed STD NMR experiments disclosed direct interactions between dactycapnine A and IDO1/TDO. Inhibition kinetics indicated dactycapnine A as a mixed-type dual inhibitor. These findings provided a possible explanation for the anticancer properties of the ethno-medicinal plant species D. scandens.

Diverse aspidosperma-type alkaloids from the leaves of Tabernaemontana bovina with anti-hepatoma activity.

Seventeen undescribed Aspidosperma-type alkaloids (ASPs), along with nine known ones were isolated from the leaves of Tabernaemontana bovina. Taberbovermines A and B were assigned to tabersonine-type with a contracted A- and E-ring, respectively. Taberbovermine C was attributed to tabersonine without D ring. These structures of the ASPs were established on the basis of comprehensive spectroscopic data, electronic circular dichroism calculations and X-ray diffraction. The summaries of structure-activity relationship of tabersonine class were discussed based on hepatoma cells screening.

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.

Anti-inflammatory maistemonine-class alkaloids of Stemona japonica.

Three hitherto undescribed Stemona alkaloids, named stemajapines A-C (1-3), along with six known alkaloids (4-9), were isolated and identified from the roots of Stemona japonica (Blume) Miq. (Stemonaceae). Their structures were established by the analysis of the mass data, NMR spectra, and computational chemistry. Stemjapines A and B were degraded maistemonines without spiro-lactone ring and skeletal methyl from maistemonine. Concurrence of alkaloids 1 and 2 revealed an undescribed way to form diverse Stemona alkaloids. Bioassay results disclosed the anti-inflammatory natural constituents stemjapines A and C with IC50 values of 19.7 and 13.8 µM, respectively, compared to positive control dexamethasone with 11.7 µM. The findings may point out a new direction of Stemona alkaloids inaddition to its traditional antitussive and insecticide activities.

Identification of undescribed key impurities of homoharringtonine bulk drug.

The knowledge of impurities is an important issue and the base of quality control in modern drugs. To date, the quality control of the antitumor drug homoharringtonine (HHT) is still not sufficiently solved and needs to be improved. Six main impurities, drupacine, cephalotaxine, desmethylcephalotaxinone, harringtonine, 3-O-acetyl-cephalotaxine and 2'R,3'S-isoharringtonine were traced during HHT drug production by HPLC and LC-MS analyses. Additionally, we were able to isolate and identify three undescribed key trace impurities, neohomoharringtonines A-C. Their structures were established by 1D-, and 2D NMR experiments combined with mass spectrometry. An improved quality inspection ability of HHT was constructed.

Dimeric alkaloids from the barks of Erythrina variegata as well as their occurrence.

Thirteen undescribed dimeric Erythrina alkaloids, named as erythrivarines A1-A13, were isolated from the barks of Erythrina variegata L. and. Their structures were determined on the basis of NMR, UV and mass spectral analyses. Dimeric Erythrina alkaloid with a C-8/8' linkage in erythrivarine A1 was not yet reported. Representative dimers from titled plant were used to prove their occurrence as natural products by LC - MS detection. Additionally, simultaneous investigation enabled us to propose the natural property of seemingly artificial Erythrina alkaloid with acetonyl group.

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.

Enantiomeric Cephalotaxus alkaloids from seeds of Cephalotaxus oliveri.

Five undescribed alkaloids were isolated from the seeds of Cephalotaxus oliveri along with 27 known ones. The new structures were elucidated based on spectroscopic data including 1D and 2D NMR, MS and calculated ECD spectra. Among them, (+)-acetylcephalofortine C was an enantiomeric Cephalotaxine alkaloids. The performed bioassay revealed that those alkaloids were not cytotoxic against cancer cells and had no neuroprotective properties in the HEI-OC-1 cells model.

Cephalotaxine homologous alkaloids from seeds of Cephalotaxus oliveri Mast.

Six undescribed isoquinoline alkaloids, named as cephaloliverines A-F, were isolated from the seeds of Cephalotaxus oliveri. They were identified by NMR and MS spectroscopic data analyses, combined with the time-dependent density functional theory ECD calculation for cephaloliverines A and B and also by X-ray crystal diffraction for cephaloliverine E. Biosynthetic considerations suggest that cephaloliverines A-D are homologous of cephalotaxine-, homoerythrina- and Erythrina-type alkaloids. The performed bioassay revealed no cytotoxic activity against cancer cells and no neuroprotective properties on HEI-OC-1 cells model.

Dimeric Erythrina alkaloids as well as their key units from Erythrina variegata.

Ten dimeric and two monomeric Erythrina alkaloids, all of them are undescribed, were isolated from the bark of Erythrina variegata L. and named as erythrivarines O-Z. Their structures were determined on the basis of NMR and UV-spectroscopy and mass spectrometry. Dimeric Erythrina alkaloids with a C-10/11' linkage in erythrivarine O and a C-7/10' connectivity in erythrivarines P-U are not yet reported. The two identified monomeric alkaloids may be the precursors of the described dimeric derivatives. These co-occurring dimeric and monomeric alkaloids enabled us to propose a possible biosynthetic pathway leading to these dimers. Their effects of preventing hearing loss were additionally evaluated and erythrivarine T showed as a potential protector of the House Ear Institute-Organ of Corti 1 (HEI-OC-1) cells against neomycin.

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.

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.

Vincan- and eburnan-type alkaloids from Tabernaemontana bovina and their hypoglycemic activity.

Thirty-one Vincan- and two Eburnan-type alkaloids were isolated from the aerial parts of Tabernaemontana bovina, whereas 20 of them are described the first time. Within the purified alkaloids, the firstly described taberbovcamine A features a 6/5/6/6/5 ring system. All the chemical structures were elucidated by employing extensive spectroscopic, computational electronic circular dichroism and X-ray diffraction methods. The two Eburnan-type alkaloids, 10,11-dimethoxy-16-O-methyllisoeburnamenine and 10,11-dimethoxy-isoeburnamenine were simultaneously identified by using the mentioned spectroscopic methods. Within the identified alkaloids, 10-hydroxy-14,15-didehydrovincanmine, 14,15-didehydrovincanmine, 14,15-didehydroapovincanmine, and criocerine increased the glucose consumption in a L6 myotube model.