Isolation and Structural Elucidation of Compounds from Pleiocarpa bicarpellata and Their In Vitro Antiprotozoal Activity.

Species of the genus Pleiocarpa are used in traditional medicine against fever and malaria. The present study focuses on the isolation and identification of bioactive compounds from P. bicarpellata extracts, and the evaluation of their antiprotozoal activity. Fractionation and isolation combined to LC-HRMS/MS-based dereplication provided 16 compounds: seven indole alkaloids, four indoline alkaloids, two secoiridoid glycosides, two iridoid glycosides, and one phenolic glucoside. One of the quaternary indole alkaloids (7) and one indoline alkaloid (15) have never been reported before. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR experiments, UV, IR, and HRESIMS data. The absolute configurations were determined by comparison of the experimental and calculated ECD data. The extracts and isolated compounds were evaluated for their antiprotozoal activity towards Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum, as well as for their cytotoxicity against rat skeletal myoblast L6 cells. The dichloromethane/methanol (1:1) root extract showed strong activity against P. falciparum (IC50 value of 3.5 µg/mL). Among the compounds isolated, tubotaiwine (13) displayed the most significant antiplasmodial activity with an IC50 value of 8.5 µM and a selectivity index of 23.4. Therefore, P. bicarpallata extract can be considered as a source of indole alkaloids with antiplasmodial activity.

Carbazole-, Aspidofractinine-, and Aspidocarpamine-Type Alkaloids from Pleiocarpa pycnantha.

Three new alkaloids, janetinine (1a), pleiokomenine A (2), and huncaniterine B (3a), and 13 known compounds, pleiomutinine (3b), huncaniterine A (3c), 1-carbomethoxy-ß-carboline (4), evoxanthine (5), deformyltalbotine acid lactone (6), pleiocarpamine (7), N4-methyl-10-hydroxygeissoschizol (8), spegatrine (9), neosarpagine (10), aspidofractinine (11), N1-methylkopsinin (12), pleiocarpine (13), and N1-methylkopsinin- N4-oxide (14), were isolated from the stem bark of Pleiocarpa pycnantha. Janetinine (1a) is a carbazole alkaloid; in pleiokomenine A (2), two aspidofractinine-type alkaloids are bridged by a methylene unit in an unprecedented way, and huncaniterine B (3a) is a pleiocarpamine-aspidofractinine-type dimer. The structures and relative configurations of these compounds were elucidated on the basis of NMR and MS analyses. Their absolute configurations were defined by means of experimental and calculated ECD data, and additionally, the structures of 5 and 13 were determined by single crystal X-ray diffraction. Compounds 1a, 2, 3b, 4, 6, 9, and 12 displayed cancer chemopreventive properties through either quinone reductase induction ( CD = 30.7, 30.2, 29.9, 43.5, and 36.7 µM for 1a, 4, 6, 9, and 12, respectively) and/or NF-κB inhibition with IC50 values of 13.1, 8.4, 9.4, and 8.8 µM for 2, 3b, 6, and 12, respectively.

A new C-glucosylflavone from Sorindeia juglandifolia.

Phytochemical investigation of the leaves of Sorindeia juglandifolia A. Rich. led to the isolation and identification of a new C-glucosylflavone, 2",6"-di-O-acetyl-7-O-methyl vitexin (1), together with seven known compounds, 2"-O-acetyl-7-O-methyl vitexin (2), mearnsitrin (3), robustaflavone (4), 3-O-galloyl catechin (5), tachioside (2-methoxy-benzene-1,4-diol-1-O-beta-glucopyranoside) (6), 3beta-O-D-glucopyranosyl-beta-stigmasterol (7), and methyl gallate (8). The structures of 1 and the known compounds were established by IR, UV, MS, 1D, and 2D NMR spectra and by comparison with those of related compounds.

Contortamide, a new anti-colon cancer cerebroside and other constituents from Tabernaemontana contorta Stapf (Apocynaceae).

A new cerebroside, Contortamide (1) together with nine known compounds spegatrine (2), affinisine (3), Nb-methylaffinisine (4), ursolic acid (5), α-amyrin (6), bauerenol acetate (7), lupeol (8), betulinic acid (9) and ß-sitosterolglycoside (10) were isolated from the trunk bark of Tabernaemontana contorta Stapf. The new compound 1 showed significant activity against Caco-2 colon cancer cells with the MTT method. Compounds 1-4 and 6-9 were isolated for the first time from this species.

New Azulene-Type Sesquiterpenoids from the Fruiting Bodies of Lactarius deliciosus.

In the 1H NMR-guided fractionation of extracts from the edible mushroom Lactarius deliciosus, two new azulene-type sesquiterpenoids, 7-isopropenyl-4-methyl-azulene-1-carboxylic acid (1) and 15-hydroxy-3,6-dihydrolactarazulene (2), together with seven known compounds were characterized. Their structures were determined on basis of spectroscopic evidence, as well as by comparing with literature data. Amongst the known metabolites, the 13C NMR assignment of 15-hydroxy-6,7-dihydrolactarazulene (3) is reported here for the first time. Moreover, 7-acetyl-4-methylazulene-1-carbaldehyde (5) displayed a moderate antibacterial activity against Staphylococcus aureus. *Digital image of L. deliciosus. Retrieved March 17, 2017 from https://upload.wikimedia.org/wikipedia/commons/e/e3/Lactarius_deliciosus_1_(1).jpg .

Cytotoxic flavonoids and other constituents from the stem bark of Ochna schweinfurthiana.

Seven flavonoids, hemerocallone (1), 6,7-dimethoxy-3',4'-dimethoxyisoflavone (2), amentoflavone (4), agathisflavone (6), cupressuflavone (8), robustaflavone (9) and epicatechin (10), together with three other compounds, lithospermoside (3), ß-D-fructofuranosyl-α-D-glucopyranoside (5) and 3ß-O-D-glucopyranosyl-ß-stigmasterol (7), were isolated from the ethyl acetate extract of the stem bark of Ochna schweinfurthiana F. Hoffm. All the compounds were characterised by spectroscopic and mass spectrometric methods, and by comparison with literature data. Cytotoxicity of the extracts and compounds against cervical adenocarcinoma (HeLa) cells was evaluated by MTT assay. Compounds 4 and 6 exhibited good cytotoxic activity, with IC50 values of 20.7 and 10.0 µM, respectively.