Soyauxinine, a New Indolopyridoquinazoline Alkaloid from the Stem Bark of Araliopsis soyauxii Engl. (Rutaceae).

The chemical investigation of the total alkaloid extract (TAE) of the stem bark of Araliopsis soyauxii (Rutaceae) afforded an unreported indolopyridoquinazoline (compound 1) along with nine previously known alkaloids 2-10. In addition, six semi-synthetic derivatives 3a-c, 4b, 5a and 6a were prepared by allylation and acetonidation of soyauxinium nitrate (5), edulinine (3), ribalinine (4) and arborinine (6). The structures and spectroscopic data of five of them are reported herein for the first time. The suggested mechanism for the formation of the new N-allylindolopyridoquinazoline 5a is presented. The structures of natural and derived compounds were determined employing extensive NMR and MS techniques. The absolute configuration of stereogenic centers in compounds 2-4 were determined using NOESY technique and confirmed by the single-crystal X-ray diffraction (SC-XRD) technique. The use of SC-XRD further enabled us to carry out a structural revision of soyauxinium chloride recently isolated from the same plant to soyauxinium nitrate (5). The TAE, fractions, compounds 1-7 and 9, and semi-synthetic derivatives 3a-c, 4b, 5a and 6a were evaluated for their cytotoxic activity towards the cervix carcinoma cell line KB-3-1. No significant activity was recorded for most of the compounds except for 9, which showed moderate activity against the tested cancer cell lines.

Antimicrobial Furoquinoline Alkaloids from Vepris lecomteana (Pierre) Cheek & T. Heller (Rutaceae).

Three new prenylated furoquinoline alkaloids named lecomtequinoline A (1), B (2), and C (3), together with the known compounds anhydroevoxine (4), evoxine (5), dictamnine (6), N-methylflindersine (7), evoxanthine (8), hesperidin, lupeol, ß-sitosterol, stigmasterol, ß-sitosterol-3-O-ß-d-glucopyranoside, stearic acid, and myristyl alcohol, were isolated by bioassay-guided fractionation of the methanolic extracts of leaves and stem of Vepris lecomteana. The structures of compounds were determined by spectroscopic methods (NMR, MS, UV, and IR) and by comparison with previously reported data. Crude extracts of leaves and stem displayed high antimicrobial activity, with Minimum Inhibitory Concentration (MIC) (values of 10.1-16.5 and 10.2-20.5 µg/mL, respectively, against Escherichia coli, Bacillus subtilis, Pseudomonas agarici, Micrococcus luteus, and Staphylococcus warneri, while compounds 1-6 showed values ranging from 11.1 to 18.7 µg/mL or were inactive, suggesting synergistic effect. The extracts may find application in crude drug preparations in Western Africa where Vepris lecomteana is endemic, subject to negative toxicity results in vivo.

Oxidative burst inhibitory and cytotoxic activity of constituents of the fruits of Odyendyea gabonensis.

The methanol extract of dried fruits of Odyendyea gabonensis afforded one new quassinoid [(-)-odyendanol (1)], one new canthin-6-one alkaloid [9-hydroxy-5-methoxycanthin-6-one (4)], and two new steroids [22E, 24R-stigmasta-5,22-diene-3,7-dione (7) and 22E,24R-stigmast-22-ene-3,7-dione (8)] along with fourteen known compounds. The structures of all compounds were established by analyzing the spectroscopic data. The ¹³C-NMR values of (-)-odyendene (2) and (-)-odyendane (3), as well as the single-crystal X-ray structure of 5-methoxycanthin-6-one (6) are also reported.The oxidative burst inhibitory activity of pure compounds 1-12 was determined by the chemoluminescence assay, and cytotoxic activities of compounds 2-6 against the human prostate cancer cell PC-3 line were evaluated. Compounds 1-6 exhibited a clear suppressive effect on the phagocytosis response upon activation with serum-opsonized zymosan in the range of IC50 = 0.9-2.0 µM versus ibuprofen with IC50 = 12.1 µM, while all canthin-6-one alkaloids (4-6) displayed moderate cytotoxic activity against the human prostate cancer cell PC-3 line, with IC50 values ranging from 13.5-15.4 µM versus doxorubicine with IC50 = 1.5 µM.

Bioactive ß-indoloquinazoline alkaloids from Oricia renieri.

Three new ß-indoloquinazoline alkaloids, orirenierine A (1), B (2) and C (4), together with eleven known compounds were isolated from the methanol extract of the stems of Oricia renieri. The structures of all compounds were determined by comprehensive analyses of their spectroscopic data and comparison with literature information. The alkaloids 9-11 were isolated for the first time from this genus. All compounds were tested for their activity against bacteria, fungi, and plant pathogen oomycetes using the paper disk agar diffusion assay. The agar diffusion test gave only low antimicrobial activities, corresponding to MICs > 1 mg/mL. However, compounds 1-4 and 11 exhibited a strong suppressive effect on phagocytosis response upon activation with serum opsonized zymosan in the range of IC(50) = 2.6-6.5 µM, while low cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3 was observed with IC(50) values ranging from 22.9 to 39.4 µM.

O-prenylated acridone alkaloids from the stems of Balsamocitrus paniculata (Rutaceae).

Two new O-prenylated acridone alkaloids, balsacridone A (1) and B (2), together with eighteen known compounds were isolated from the methanol extract from the stems of Balsamocitrus paniculata, a Cameroonian medicinal plant. The structures of all compounds were determined by comprehensive analyses of their 1D and 2D NMR, mass spectral (EI and ESI) data, and chemical reactions. N-methyl-6-methoxybenzoxazolinone (16) was isolated for the first time from a natural source while compounds 13, 14, and 15 for the first time from this genus. Pure compounds were tested for their activity against bacteria, fungi, and plant pathogen oomycetes, using the paper disk agar diffusion assay. The agar diffusion test delivered low to missing antimicrobial activities, corresponding to MICs > 1 mg/mL. However, compounds 1-15 exhibited a strong suppressive effect on phagocytosis response upon activation with serum opsonized zymosan in the range of IC50 = 0.5-7.2 µM, and the acridone alkaloids (1-5), N-trans-p-coumaroyltyramine (13), and N-trans-pcoumaroyloctopamine (14) displayed weak cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3, with IC50 values ranging from 69.8 to 99.0 µM.