Isolation of Bioactive Rotenoids and Isoflavonoids from the Fruits of Millettia caerulea.

Three new rotenoids (1-3), two new isoflavonoids (4 and 5), and six known analogues (6-11) were isolated from an n-hexane partition of a methanol extract of the fruits of Millettia caerulea, with the structures of the new compounds elucidated by analysis of their spectroscopic data. The relative configurations of the rotenoids were determined by interpretation of their NMR spectroscopic data, and their absolute configurations were established using electronic circular dichroism spectra and specific rotation values. All compounds isolated were evaluated for their cell growth inhibitory activity against the HT-29 human colon cancer cell line, and the known compounds, (-)-3-hydroxyrotenone (6) and (-)-rotenone (7), were found to be potently active. When tested in an NF-κB inhibition assay, compound 6 showed activity. This compound, along with the new compound, (-)-caeruleanone D (1), and the known compound, ichthynone (8), exhibited K-Ras inhibitory potency. Further bioactivity studies showed that the new compounds, (-)-3-deoxycaeruleanone D (2) and (-)-3-hydroxycaeruleanone A (3), and the known compounds 8 and 11 induced quinone reductase in murine Hepa 1c1c7 cells.

New Bioactive Lupane Triterpene Coumaroyl Esters Isolated from Buxus cochinchinensis.

Five new lupane triterpene coumaroyl esters (1-5), together with betulin (6) and a known Buxus alkaloid, N-3-benzoyldihydrocyclomicrophylline F (7), were isolated from a CHCl3-soluble partition of a methanol extract of Buxus cochinchinensis Pierre ex Gagnep. (Buxaceae) collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29). The structures of the new compounds (1-5) were determined on the basis of spectroscopic data interpretation. In addition to their cytotoxicity against HT-29 cells and nuclear factor-kappa B (p65) inhibitory activity in an enzyme-linked immunosorbent assay, all isolates as well as two semisynthetic compounds derived from betulin and 5, respectively, were also evaluated for their in vitro antiplasmodial activities against the drug-resistant Dd2 strain of Plasmodium falciparum and antifungal effects on the growth of the pathogenic yeast Candida albicans. The new lupane triterpene coumaroyl esters (1-5), along with a betulin derivative and the known Buxus alkaloid, were found to show significant in vitro antimalarial activities, with IC50 values ranging from 0.26 to 2.07 µM.

Sphenostylisins A-K: bioactive modified isoflavonoid constituents of the root bark of Sphenostylis marginata ssp. erecta.

Sphenostylisins A-C (1-3), three complex dimeric compounds representing two novel carbon skeletons, along with an additional eight new compounds, sphenostylisins D-K (4-11), were isolated from the active chloroform-soluble extract of the root bark of Sphenostylis marginata ssp. erecta using a bioactivity-guided isolation approach. The structures were elucidated by means of detailed spectroscopic analysis, including NMR and HRESIMS analysis, and tandem MS fragmentation was utilized to further support the structures of 1-3. The absolute configuration of sphenostylisin C (3) was established by electronic circular dichroism analysis. Plausible biogenetic relationships between the modified isoflavonoids 1-11 are proposed, and a cyclization reaction of 9 was conducted to support one of the biogenetic proposals made. All of these pure isolates were evaluated against a panel of in vitro bioassays, and among the results obtained, sphenostylisin A (1) was found to be a very potent NF-κB inhibitor (IC50 = 6 nM).

Bioactive Constituents from an Endophytic Fungus, Penicillium polonicum NFW9, Associated with Taxus fauna.

BACKGROUND: Endophytic fungi are being recognized as vital and untapped sources of a variety of structurally novel and unique bioactive secondary metabolites in the field of natural products drug discovery. Herein, this study reports the isolation and characterization of secondary metabolites from an endophytic fungus Penicillium polonicum (NFW9) associated with Taxus fuana. METHOD: The extracts of the endophytic fungus cultured on potato dextrose agar were purified using several chromatographic techniques. Biological evaluation was performed based on their abilities to inhibit tumor necrosis factor-alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) and cytotoxicity assays. RESULTS: Bioactivity-directed fractionation of the ethyl acetate extract of a fermentation culture of an endophytic fungus, Penicillium polonicum led to the isolation of a dimeric anthraquinone, (R)- 1,1',3,3',5,5'-hexahydroxy-7,7'-dimethyl[2,2'-bianthracene]-9,9',10,10'-tetraone (1), a steroidal furanoid (-)-wortmannolone (2), along with three other compounds (3-4). Moreover, this is the first report on the isolation of compound 1 from an endophytic fungus. All purified metabolites were characterized by NMR and MS data analyses. The stereo structure of compound 1 was determined by the measurement of specific optical rotation and CD spectrum. The relative stereochemistry of 2 was confirmed by single-crystal X-ray diffraction. Compounds 2-3 showed inhibitory activities in the TNF-α-induced NF-κB assay with IC50 values in the range of 0.47-2.11 µM. Compounds 1, 4 and 5 showed moderate inhibition against NF-κB and cancer cell lines. CONCLUSION: The endophytic fungus Penicillium polonicum of Taxus fuana is capable of producing biologically active natural compounds. Our results provide a scientific rationale for further chemical investigations into endophyte-producing natural products, drug discovery and development.

New acyclic bis phenylpropanoid and neolignans, from Myristica fragrans Houtt., exhibiting PARP-1 and NF-κB inhibitory effects.

The bioassay-guided fractionation of the aril of Myristica fragrans (mace spice) yielded five phenolic compounds, one new acyclic bis phenylpropanoid (1) and four previously known phenolic compounds: compounds (1) (S) 1-(3,4,5-trimethoxyphenyl)-2-(3-methoxy-5-(prop-1-yl) phenyl)-propan-1-ol, (2) benzenemethanol; α-[1-[2,6-dimethoxy-4-(2-propen-1-yl)phenoxy]ethyl]-3,4-dimethoxy-1-acetate, (3) odoratisol A, phenol, 4-[(2S,3S)-2,3-dihydro-7-methoxy-3-methyl-5-(1E)-1-propenyl-2-benzofuranyl]-2,6-dimethoxy, (4) 1,3-benzodioxate-5-methanol,α-[1-[2,6-dimethoxy-4-(2-propenyl)phenoxy]ethyl]-acetate, (5) licarin C; benzofuran,2,3-dihydro-7-methoxy-3-methyl-5-(1E)-1-yl-2-(3,4,5-trimethoxyphenyl). An NMR tube Mosher ester reaction was used in an approach to characterize and determine the assignment of the absolute configuration of the new isolated chiral alcohol (1). The PARP-1 inhibitory activity was evaluated for compound (1) (IC50=3.04µM), compound (2) (IC50=0.001µM), compound (4) (IC50=22.07µM) and compound (5) (IC50=3.11µM). Furthermore, the isolated secondary metabolites were tested for NF-κB and K-Ras inhibitory activities. When tested in the p65 assay, compounds (2) and (4) displayed potent NF-κB inhibition (IC50=1.5 nM and 3.4nM, respectively).

Caeruleanone A, a rotenoid with a new arrangement of the D-ring from the fruits of Millettia caerulea.

Caeruleanone A (1), a novel rotenoid with an unprecedented arrangement of the D-ring, was isolated with another two new analogues, caeruleanones B (2) and C (3), together with 11 known rotenoids from the fruits of Millettia caerulea. The structures of the new compounds were determined by spectroscopic data analysis, with that of 1 being confirmed by single-crystal X-ray diffraction. Compounds 2 and 3 displayed potent mitochondrial transmembrane potential inhibitory and quinone reductase induction activities.

Bioactive indole alkaloids isolated from Alstonia angustifolia.

Bioassay-guided fractionation was conducted on a CHCl3-soluble extract of the stem bark of Alstonia angustifolia (Apocynaceae) collected in Vietnam using the HT-29 human colon cancer cell line, and led to the isolation of a new sarpagine-type indole alkaloid (1), together with nine known alkaloids, including four macroline-derived alkaloids (2-5), a sarpagine-type alkaloid (6), and four macroline-pleiocarpamine bisindole alkaloids (7-10). The structure of the new compound (1) was determined on the basis of spectroscopic data interpretation. Compounds 1-10 were evaluated in vitro for their NF-κB (p65) inhibitory activity against the Hela cells in an ELISA assay. The new sarpagine alkaloid, N(4)-methyltalpinine (1), was found to show significant NF-κB inhibitory activity (ED50 = 1.2 µM). Furthermore, all the isolates (1-10) were evaluated in vitro for their antileishmanial activity, and compounds (1-4, 6 and 8-10) exhibited leishmaniacidal activity against promastigotes of Leishmania mexicana.

Cytotoxic epipolythiodioxopiperazine alkaloids from filamentous fungi of the Bionectriaceae.

Bioactivity-directed fractionation of the organic extracts of two filamentous fungi of the Bionectriaceae, strains MSX 64546 and MSX 59553 from the Mycosynthetix library, led to the isolation of a new dimeric epipolythiodioxopiperazine alkaloid, verticillin H (1), along with six related analogs, Sch 52900 (2), verticillin A (3), gliocladicillin C (4), Sch 52901 (5), 11'-deoxyverticillin A (6) and gliocladicillin A (7). The structures of compounds 1-7 were determined by extensive NMR and HRMS analyses, as well as by comparisons to the literature. All compounds (1-7) were evaluated for cytotoxicity against a panel of human cancer cell lines, displaying IC(50) values ranging from 1.2 µM to 10 nM. Compounds 1-5 were examined for activity in the NF-κB assay, where compounds 2 and 3 revealed activity in the sub-micromolar range. Additionally, compounds 1, 3 and 4 were tested for EGFR inhibition using an enzymatic assay, while compound 3 was examined against an overexpressing EGFR(+ve) cancer cell line.