Complete 1H and 13C NMR assignments of two phytosterols from roots of Piper nigrum

Constituents of the Stem Bark of Trichilia monadelpha (Thonn.) J. J. De Wilde (Meliaceae) and Their Antibacterial and Antiplasmodial Activities

The chemical investigation of the EtOH extract from the stem bark of Trichilia monadelpha (Thonn.) J. J. De Wilde afforded two new limonoids (1 and 2): 24-acetoxy-21,25-dihydroxy-21,23-epoxytirucall-7-en-3-one (1) and (6R)-1-O-deacetylkhayanolide E (2), together with eleven known compounds (3-13), including additional limonoids, flavonoids, triterpenoids, steroids, and fatty acid. Their structures were determined using 1D- and 2D-NMR experiments, ESI mass spectrometry, and single crystal X-ray diffraction analysis. The antibacterial and antiplasmodial activities of the extracts, sub-extracts, fractions, and some of the isolated compounds were evaluated in known pathogenic strains, including Staphylococcus aureus and Plasmodium falciparum. Fraction E (n-Hex/EtOAc 30:70, v/v) showed significant activity against S. aureus ATCC 25923 with a MIC value of 3.90 µg/mL, while one of its constituents (epicatechin (9)) exhibited significant activity with MIC values of 7.80 µg/mL. Interestingly, grandifotane A (6) (IC₅₀ = 1.37 µM) and khayanolide D (5) (IC₅₀ = 1.68 µM) were highly active against the chloroquine-sensitive/sulfadoxine-resistant plasmodium falciparum 3D7 strain, unlike their corresponding plant extract and fractions.

Phytochemical Characterizations of Maranthes polyandra (Benth.) Prance

Two new ursane-type triterpenoids, named Polyanside A (1) and B (2), along with eleven known compounds (3-13), were isolated and elucidated from Maranthes polyandra (Benth.) Prance. The structures of these compounds were elucidated based on chemical evidence and multiple spectroscopic data. Isolated compounds were evaluated for anti-cancer, anti-inflammatory activities, and cytotoxicity on a normal human cell line (BJ). None of them showed activity and cytotoxicity. The hexane fraction was analyzed by GC-MS, resulting in the identification of forty-one compounds. This is the first comprehensive study on the phytochemistry of M. polyandra.

New bioactive monoterpene indole alkaloid from Rinorea yaundensis Engl

Extraction of the aerial part of Rinorea yaundensis has led to the isolation of a new monoterpene indole alkaloid (1) along with 10 known compounds (2-11) for the first time from this plant. Their structures were determined by HRMS and NMR spectroscopic analyses as yaundentine hydrochloride (1), N_b-oxide of iso-reserpiline (2), iso-reserpiline (3), iso-carapanaubine (4), lichenxanthone (5), stigmastane-3,6-dione (6), methyl β-orcinol carboxylate (7), β-sitosterol-3-O-β-D-glucoside (8), betulinic acid (9), ursolic acid (10) and benzoic acid (11) while the stereochemistry and absolute configuration of 1 was confirmed by single crystal x-ray crystallography and circular dichroism CD spectrum. Yaundentine hydrochloride (1) exhibited pronounced antioxidant, urease and lipoxygenase inhibitory activities with IC₅₀ values of 35.6 ± 0.23, 20.3 ± 0.58 and 29.6 ± 0.77 µM, respectively. Compound 1 also showed good antimicrobial activity against some Gram positive and negative bacteria.

Xidaosterols A and B, two new steroids with unusual α-keto-enol functionality from the South China Sea sponge Neopetrosia chaliniformis

Two new C29 steroids, xidaosterols A (1) and B (2), characterised by a common unusual α-keto-enol functionality bearing A-ring, together with three related known ones (3-5), were isolated from the South China Sea sponge Neopetrosia chaliniformis. Their structures were elucidated by extensive spectroscopic analyses and comparison with the spectral data reported in the literature, Xidaosterol B is an A-nor derivative of 1.

Two New Abietane Diterpenoids from Selaginella moellendorffii Hieron

Two new abietane diterpenoids, (3S,5R,10S)-3-hydroxy-12-O-demethyl-11-deoxy-19(4→3)-abeo-cryptojaponol, 12,19-dihydroxyabieta-8,11,13-trien-7-one, were isolated from Selaginella moellendorffii Hieron., together with one known abietane diterpenoid and four known tetracyclic triterpenoids. Their structures were characterized by their 1D- and 2D-NMR, ECD and mass spectral studies. All compounds were tested for their inhibitory effects on proliferation of three human cancer cells (human non-small-cell lung carcinoma cell lines A549 and human breast adenocarcinoma cell lines MDA-MB-231 and MCF-7) in vitro. Among them, three compounds displayed modest cytotoxic activities against the above three human cancer cell lines with IC₅₀ values ranging from 16.28 to 40.67 μM.

Phytochemicals and Tyrosinase Inhibitory Activity from Piper caninum and Piper magnibaccum

Background: Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In the present study, we attempted to isolate the phytochemicals from Piper caninum and Piper magnibaccum and evaluate their tyrosinase inhibitory activity. Methods: Phytochemical constituents of the extracts were investigated using various chromatographic and spectroscopic methods. The structures of the isolated phytochemicals were established by analysis of their spectroscopic data, as compared to that of reported data. Tyrosinase inhibitory activity was also tested on the extracts and selected compounds using mushroom tyrosinase as the enzyme. Results: Fractionation and purification of the extracts of Piper caninum and Piper magni­baccum afforded nine known compounds which were cepharanone A (1), cepharadione A (2), aristolactam AII (3), 5,7-dimethoxyflavone (4), 24-methylenecycloartan-3-one (5), β-sitosterol (6), piperumbellactam A (7), 24S-ethylcholesta-5,22,25-trien-3β-ol (8) and stigmast-3,6-dione (9). Ethyl acetate extracts from leaves of P. magnibaccum gave the highest inhibition value at 48.35%, while the tested compounds displayed weak tyrosinase activity compared to the positive control, kojic acid. Conclusion: These phytochemical results suggested that the extracts could assist as a potential source of bioactive compounds. Further research is needed in which the extract could possibly be exploited for pharmaceutical use.

Chemical constituents from Penianthus camerounensis Dekker (Menispermaceae)

The phytochemical study of the roots, leaves and twigs of Penianthus camerounensis Dekker (Menispermaceae) has led to the isolation and the characterization of 20 compounds. A ceramide, camerounamide (1), and a furoclerodanediterpenoid, camerounin (2), have not been described previously, while the compounds xylopic acid (3), syringaresinol (4), iso-propylmethylcyclohexa-1,4-diol (5), 1-(28-hydroxyoctacosanoyl)glycerol (6), scoparone (7), friedelin (8), friedelanol (9) and betulinic acid (10) are being reported for the first time from the genus Penianthus alongside 10 known compounds (11–20). Chemical structures were determined using 1D- and 2D-NMR spectroscopy, MS and chemical analysis. Their chemotaxonomic importance is discussed.

α-Glucosidase inhibitors from the bark of Mangifera mekongensis

Background

Mangifera mekongensis (Anacardiaceae) is cultivated for its edible fruit and has been used in traditional Vietnamese medicine for its anti-aging properties and for treating diabetes, vermifuge, and dysentery. As part of a search for biologically active compounds with reduction of the rate of glucose absorption, a screening has been initiated to evaluate natural product extracts for the inhibition of enzyme α-glucosidase. A n-hexane extract of the bark of M. mekongensis showed strong α-glucosidase inhibitory activity with IC₅₀ value of 1.71 µg/mL. Thus, the constituents of this plant were examined.

Results

Two new steroids named mekongsterol A (1) and mekongsterol B (2), were isolated from the n-hexane extract of the bark of M. mekongensis (Anacardiaceae), together with seven known compounds (3–9). Their chemical structures were elucidated on the basis of spectroscopic data. All compounds possessed significant α-glucosidase inhibitory activity in a concentration-dependent manner, except for 3 and 4. Compounds 1, 2, 5–9 showed more potent inhibitory activity, with IC₅₀ values ranging from 1.2 to 112.0 µM, than that of a positive control acarbose (IC₅₀, 214.5 µM).

Conclusions

These results suggested that the traditional use of the bark of M. mekongensis for the treatment of diabetes diseases in Vietnam may be attributable to the α-glucosidase inhibitory activity of its steroid and cycloartane constituents.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-016-0193-9) contains supplementary material, which is available to authorized users.

New ursane triterpenoids from Ficus pandurata and their binding affinity for human cannabinoid and opioid receptors

Phytochemical investigation of Ficus pandurata Hance (Moraceae) fruits has led to the isolation of two new triterpenoids, ficupanduratin A [1β-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (11) and ficupanduratin B [21α-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (17), along with 20 known compounds: α-amyrin acetate (1), α-amyrin (2), 3β-acetoxy-20-taraxasten-22-one (3), 3β-acetoxy-11α-methoxy-olean-12-ene (4), 3β-acetoxy-11α-methoxy-12-ursene (5), 11-oxo-α-amyrin acetate (6), 11-oxo-β-amyrin acetate (7), palmitic acid (8), stigmast-4,22-diene-3,6-dione (9), stigmast-4-ene-3,6-dione (10), stigmasterol (12), β-sitosterol (13), stigmast-22-ene-3,6-dione (14), stigmastane-3,6-dione (15), 3β,21β-dihydroxy-11α-methoxy-olean-12-ene (16), 3β-hydroxy-11α-methoxyurs-12-ene (18), 6-hydroxystigmast-4,22-diene-3-one (19), 6-hydroxystigmast-4-ene-3-one (20), 11α,21α-dihydroxy-3β-acetoxy-urs-12-ene (21), and β-sitosterol-3-O-β-D-glucopyranoside (22). Compound 21 is reported for the first time from a natural source. The structures of the 20 compounds were elucidated on the basis of IR, 1D ((1)H and (13)C), 2D ((1)H-(1)H COSY, HSQC, HMBC and NOESY) NMR and MS spectroscopic data, in addition to comparison with literature data. The isolated compounds were evaluated for their anti-microbial, anti-malarial, anti-leishmanial, and cytotoxic activities. In addition, their radioligand displacement affinity on opioid and cannabinoid receptors was assessed. Compounds 4, 11, and 15 exhibited good affinity towards the CB2 receptor, with displacement values of 69.7, 62.5 and 86.5 %, respectively. Furthermore, the binding mode of the active compounds in the active site of the CB2 cannabinoid receptors was investigated through molecular modelling.

Osteoclast-Forming Suppressive Compounds from Makomotake,Zizania latifoliaInfected withUstilago esculenta

A novel compound (1) and a known one (2) were isolated from Makomotake, Zizania latifolia infected with Ustilago esculenta, as osteoclast-forming suppressive substances.

Two New Triterpenoids from Gelsemium Elegans and Aglaia odorata

Eleganoside A (1) and odoratanone A (15), a triterpenoid trisaccharide glycoside and a nortriterpenoid, together with twelve known compounds (2–13) and a mixture of cerebrosides (14) were isolated from Gelsemium elegans and Aglaia odorata. Their structures were elucidated by extensive spectroscopic and spectrometric analysis. Eleganoside A (1) features a 3- O-α-L-rhamnopyranosyl (1→4)-β-D-glucopyranosyl (1→4)-β-D-glucopyranoside of a peculiar 3,16-dihydroxyl-lanosta-8,24-dien-26-oic acid triterpenoid skeleton, and odoratanone A (15) is a 29-norcycloartane-type triterpenoid bearing an unusual five-membered methyl acetal ring. Anti-acetylcholinesterase/butyrylcholinesterase (AChE/BChE) assay indicated that at 50 μM, ethyl caffeate (5) was promising as a dual inhibitor of AChE and BChE, and paeonol (3) and 24-hydroperoxy-24-vinylcholesterol (9) exhibited BChE-selective inhibition.

Antitumor activity of terpenoids against classical and atypical multidrug resistant cancer cells

Nineteen terpenoids, including macrocyclic diterpenes, diterpenic lactones and other polycyclic diterpenes, steroids and a triterpene isolated from the methanolic extracts of Euphorbia species, were evaluated for their potential antineoplastic activity in various human cancer cell lines that were derived from three tumor entities: gastric (EPG85-257), pancreatic (EPP85-181) and colon (HT-29) carcinomas. Furthermore, different multidrug-resistant variants of these cancer cell lines with over-expression of MDR1/P-gp or no MDR1/P-gp expression were also investigated. In parental drug-sensitive cell lines, the tested compounds showed a moderate/weak antiproliferative effect or were inactive. Most of them were found more effective in drug-resistant cells than in the parental, drug-sensitive ones, and some of them showed high antineoplastic efficacy in classical or atypical drug-resistant cells. The most active compounds were the lathyrane diterpenes latilagascenes C and D, and the diterpenic lactones 3beta-acetoxy-helioscopinolide B and helioscopinolide E which exhibited high antineoplastic activities against the drug-resistant subline EPG85-257RDB derived from gastric carcinoma. In addition, the macrocyclic lathyrane diterpene jolkinol B was found to be highly effective in the multidrug-resistant variant HT-29RNOV.

3-Keto-22-epi-28-nor-cathasterone, a brassinosteroid-related metabolite from Cystoseira myrica

Bioassay-guided purification of an ethanolic extract of Cystoseira myrica against HEPG-2 (liver) and HCT116 (colon) human cancer cell lines led to the isolation of 3-keto-22-epi-28-nor-cathasterone, 1 and cholest-4-ene-3,6-dione, 2. This finding allowed us to report for the first time that a brassinosteroid-related metabolite occurs in seaweed. These compounds showed activity in the range of 12.38-1.16 microM with selective activity of compound 2 to liver cancer cell lines.

Ketosteroids and hydroxyketosteroids, minor metabolites of sugarcane wax

Besides beta-sitosterol and stigmasterol, the major steroids of sugarcane, the following minor steroids have been isolated and identified from sugarcane wax: 3,6-diketosteroids, Delta(4)-3-keto steroids, and Delta(4)-6-hydroxy-3-keto steroids. Their structures were established by spectroscopic techniques and chemical correlations.