Records of Natural Products Articles

Jatroidaine A (1), a new tetranortirucallane-type triterpene, and two known analogues (2−3) were isolated from the leaves and branches of Jatropha multifida. Their structures were fully elucidated by extensive spectroscopic methods and comparison to known compounds. The absolute configuration of 1 was assigned by single-crystal X-ray diffraction analysis. All compounds were evaluated for their anti-inflammatory and thioredoxin reductase (TrxR) inhibitory activities. Unfortunately, no significant activity was observed.

One new, 10, 11-dioxo-6,7α-erythraline epoxide (A1) and four known erythrinan alkaloids 10, 11-dioxo-erythraline (A2), erysodine (A3), 8-oxo-erythraline (A4) and erythraline (A5) were isolated from the 70% methanolic extract of stems of E. Corallodendron (Fabaceae). The isolated compounds were elucidated by exploiting 1D/2D NMR, and HR-ESI-MS analysis. The absolute configuration of A1 was determined by electronic circular dichroism (ECD). Mono Amine Oxidase inhibitory activity of the isolated alkaloids was investigated in vitro using kynuramine deamination assay on recombinant human MAO-A and B enzymes. The binding modes were predicted by molecular docking and the structure activity relationships of erythrinans were then evaluated. All isolated alkaloids demonstrated preferential activity against MAO-B. A1 displayed the highest potency and selectivity against MAO-B with IC50 of 25.18 μM, (SI >3.97). The selective inhibition exhibited by erythrinan alkaloids against MAO-B is in line with the expected biological impact of Erythrina in the treatment of neurodegenerative diseases and presents this chemical class as promising leads for managing AD and PD diseases.

A new hydrocinnamoyl glucoside, 1-O-(4-hydroxyhydrocinnamoyl)-β-D-glucopyranose (1), together with fifteen known glycosides, including two phenylethanoid glycosides (2–3), two cinnamoyl glycosides (4–5), six phenolic glycosides (6–11), one lignan glycoside (12) and four megastigmane glycosides (13–16) were isolated from a 95% EtOH extract of the Typhonium giganteum rhizomes. The sixteen glycosides were structurally characterized by NMR, HRESIMS, enzymatic hydrolysis and comparison with literature. Upon evaluating inhibitory activities of compounds 1–16 against mushroom tyrosinase at 25 μM, compounds 10 and 11 exhibited obvious inhibitory activities, with %inhibition values of 20.94±0.59%, 23.28±1.09%, respectively, with arbutin used as the positive control (26.21±0.58%).

Inhibition of protein disulfide isomerase (PDI) has been attempted as a promising anti-cancer strategy. However, there is still no currently available PDI inhibitors approved for clinical use. Here, we isolated seven high yield alkaloids from Stephaniae tetrandrae Radix (STR), a medical herb frequently prescribed in anti-tumor condition, and  identified two potent natural PDI inhibitors, dicentrine and dicentrinone. Among the seven alkaloids isolated, dicentrinone (1), dicentrine (2), tetrandrine (4), and fangchinoline (5) could significantly reduce cell viability in a dosage dependent manner detected by MTT assay in human hepatoma cells. To examine whether the candidate compounds are potent PDI inhibitors, we performed insulin turbidity assay and found dicentrine and dicentrinone, but not tetrandrine  and fangchinoline, could effectively inhibit PDI activity, with IC50 of 56.70 μM and 43.95 μM  respectively. Meanwhile, dicentrine and dicentrinone failed to further reduce the cell number index when co-treated with siRNA of PDI, suggesting the compounds behave as PDI inhibitors. Furthermore, dicentrinone and dicentrine have been successfully docked to the active pocket of PDI (PDB #3UEM) by molecular docking, suggesting the existence of physical interaction between compounds and PDI. Our results suggested that dicentrine and dicentrinone may be developed into safe PDI inhibitors.

A new cyclic tetrapeptide (1) named aspergilpeptide A, together with a known cyclic tetrapeptide penicopeptide A (2) and chaetominine (3) were obtained from the endophytic fungus Aspergillus versicolor E-2 isolated from the medicinal plant Euphorbia royleana. The structures of compounds (1-3) were elucidated using NMR and MS methods.

A new coumarin, angedahurin A (1), and seven known analogues (2−8), were isolated from the roots of Angelica dahurica. Their structures were identified by extensive NMR, IR, and HR-ESIMS spectroscopic analyses. The cytotoxicities of coumarins 1−8 against MG-63 human osteosarcoma cell lines were screened. Compound 1 showed significant cytotoxic effects against MG-63 with an IC50 value of 7.2 uM，for comparison, the positive control, 5-FU, had an IC50 value of 32.4 uM. Morphological features of apoptosis activities were evaluated in 1-induced MG-63 cells and the results confirmed MG-63 cell apoptosis in a dose-dependent manner.

A phytochemical investigation of the methanolic extract of Endiandra kingiana (bark) led to the isolation of four major compounds which are kingianic acid A (1), tsangibeilin B (2), kingianin A (3) and kingianin F (4). The structures were determined by 1D- and 2D-NMR analysis in combination with HRMS experiments. The compounds were screened for their in vitro α-glucosidase inhibition activity. Among them, compounds 3-4 showed potent α-glucosidase inhibition activity with IC50 value at 11.9 ± 2.0 µM and 19.7 ± 1.5 µM, respectively. The molecular docking study found that both compounds were bound into the active site of the N-terminal of MGAM, and thus agreed with the in vitro α-glucosidase enzyme inhibition activity results.

Different species of the genus Selaginella are exploited for various ethnomedicinal purposes around the globe; mainly to cure fever, jaundice, hepatic disorders, cardiac diseases, cirrhosis, diarrhea, cholecystitis, sore throat, cough of lungs, promotes blood circulation, removes blood stasis and stops external bleeding after trauma and separation of the umbilical cord. Though, high content of various phytochemicals has been isolated from Selaginella species, flavonoids have been recognized as the most active component in the genus. Crude extract and different bioactive compounds of this plant have revealed various in vitro bioactivities such as, antimicrobial, antiviral, anti-diabetic, anti-mutagenic, anti-inflammatory, anti-nociceptive, anti-spasmodic, anticancer and anti-Alzheimer. However, more studies into the pharmacological activities are needed, since none of the professed bioactivity of this plant have ever been fully evaluated. Therefore, this review aims to discuss the evidence-based ethnomedicinal and ethnopharmacological uses, phytochemicals and bioactive potential of Selaginella species. It will provide an updated knowledge for ethnobotanists, ethnopharmacologists and other scientific communities to rethink over the possible usage of Selaginella in medicine. Moreover, further explorations are needed to formulate a novel medicinal product from Selaginella extracts for the improvement of human health, together with toxicity evaluations, necessary to ensure about the safety of these medicinal lycophytes.

A new eudesmane sesquiterpene (1), named sapleudesone, together with four known analogs (25) were isolated from the aerial parts of Salvia plebeia. The structure of compound 1 was established by NMR and HRESIMS data, and the absolute configuration of 1 was determined by comparing the experimental ECD spectrum with the calculated ECD spectra. The known compounds were identified to be salplebeone A (2), linderolide I (3), chlorantene D (4), and chlomultin B (5) by comparing the NMR data and specific rotations with reported data. All five compounds were tested for the inhibitory effects against NO production in LPS-activated RAW 264.7 macrophages, As a result, compound 2 exhibited weak inhibitory effects with an IC50 value of 42.3  1.4 uM.

The goal of the work is to determine the bioactive pharmaceutical metabolites produced by the Fusarium oxysporum YP9B isolate. Ten new natural compounds were isolated from the ethyl acetate extract of the F. oxysporum YP9B strain.  Their structures were elucidated by spectroscopic methods using 1D and 2D NMR, UV, FT-IR, and mass spectra (LC-QTOF MS and GC-FID/MS). Identified compounds were named as; (1-benzyl-2-methoxy-2-oxoethyl)-2-hydroxy-3-methylbutanoate (1), 2-oxo-8-azatricyclo[9.3.1.13,7]-hexadeca-1(15),3(16),4,6,11,13-hexaen-10-one (2), 2,3-dihydroxypropanoic, hexadecanoic anhydride (3a), 2,3-dihydroxypropanoic (9Z)-octadecenoic anhydride (3b), 2,3-dihydroxy-propanoic (9Z,12Z)-octadecadienoic anhydride (3c), 2,3-dihydroxypropanoic (11Z)-octadecenoic anhydride (4a), 2,3-dihydroxypropanoic, (9E,12E)-octadecadienoic anhydride (4b), 3-hydroxy-1,2,6,10-tetramethylundecyl hexzadecanoate (5a), 3-hydroxy-1,2,6,10-tetramethylundecyl (9E)-octadecaenoate (5b),  and 3-hydroxy-1,2,6,10-tetramethylundecyl octadecanoate (5c). Antimicrobial activities of the isolates obtained from the YP9B strain were determined. Cytotoxic and antiviral activities were tested for the isolates against VERO, MCF-7, PC-3, and A549. Compounds 5a-c, 1, and 3a-c showed bacteriostatic activity at low concentrations, and 4a-b and 2 were found to be bactericides. MIC and MBC values against Mycobacterium smegmatis for the compounds 5a-c and 1 were determined to be ​​ <0.5 µg/mL and 0.46 µg/mL, respectively. The experimental result showed that compounds 2, 5a-c and 1 have strong cytotoxic (7.51±1.38 and 19.13± 0.68 (µM) IC50) activity. The antiviral activity against HSV type-1 was determined to be 1.25 µM for compounds 4a-c and 0.312 µM for compound 1.

7-methoxy-8-hydroxy cycloanthranilylproline (2), a new natural product with pyrrolobenzodiazepine (PBD) framework, was isolated from marine-derived actinobacterium Streptomyces cacaoi 14CM034, together with cycloanthranilylproline (1). Structural elucidation of the compounds was based on FTIR, 1D- (1H and 13C NMR), 2D-NMR (COSY, HMBC and NOESY) and HR-MS analyses. Compounds 1 and 2 exhibited notable antimicrobial activity. The presence of PBD derivatives in S. cacaoi was first demonstrated with this study.