New bisbenzylisoquinoline alkaloids from Cocculus laurifolius

Two new bisbenzylisoquinoline alkaloids, alpha, alpha'-dioxo-7'-O-demethylstebisimine (1) and 7'-O-demethylstebisimine (2), along with 14 known alkaloids, were isolated from the roots of Cocculus laurifolius. These alkaloids were characterized mainly by spectroscopic methods.     

Quaternary isoquinoline alkaloids from Stephania cepharantha

From the quaternary alkaloidal fraction of the dried tubers of Stephania cepharantha, two new isoquinoline alkaloids, stecepharine and tetradehydroreticuline have been isolated along with the known compounds, magnoflorine, menisperine, steponine, cyclanoline, oblongine, cis-N-methylcapaurine and 2'-N-methylisotetrandrine. cis-N-Methylcapaurine (=9-O-methylstecepharine) was isolated as a natural product for the first time. Their structures were determined on the basis of spectroscopic evidence.     

New cholinesterase inhibiting bisbenzylisoquinoline alkaloids from Cocculus pendulus

Phytochemical investigation on Cocculus pendulus (J. R. & G. FORST.) resulted in the isolation of two new and three known bisbenzylisoquinoline alkaloids. The structures of the new alkaloids, kurramine-2'-beta-N-oxide (1) and kurramine-2'-alpha-N-oxide (2), were elucidated with the help of spectroscopic techniques. The cholinesterase inhibitory activities of these bisbenzylisoquinoline alkaloids are reported here for the first time.     

Structure elucidation of antiproliferative bisbenzylisoquinoline alkaloids from Anisocycla grandidieri from the Madagascar dry forest

Antiproliferative bioassay‐guided fractionation of the ethanol extract of the stems of Anisocycla grandidieri led to the isolation of the known alkaloids stebisimine (1), (+)‐1,2‐dehydrotelobine (2), (+)‐2'‐norcocsuline (3) and puetogaline B (4). Herein, we report the full NMR assignments of all compounds and the X‐ray crystallography of single crystals of compounds 1 and 3. Compounds 2 and 3 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with IC₅₀ values of 4.1 ± 0.3 and 2.7 ± 0.3 μM, respectively, and they also displayed selective activity toward the H460 (large cell lung cancer), MCF‐7 (breast ductal carcinoma), and UACC‐257 (melanoma) cell lines. Copyright © 2013 John Wiley & Sons, Ltd.     

Structure elucidation of two new bisbenzylisoquinoline alkaloids and NMR assignments of the alkaloids from the fruits of Tiliacora racemosa

Besides three known biphenyldibenzodioxinbisbenzylisoquinoline alkaloids, two novel alkaloids of the same group have been isolated from the fruits of Tiliacora racemosa. The structures of these new compounds designated tiliaimine and nordinklacorine were established on the basis of 1D and 2D NMR spectroscopy, including COSY, TOCSY, ROESY, HMBC and HSQC experiments. Preliminary antibacterial activity studies on the known compounds (tiliarine, 2′‐nortiliacorinine, 2′‐nortiliacorine) from the fruits of the plant showed strong activity against three bacterial strains viz. Escherichia coli strain VT3 (Verotoxigenic E.coli), Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6623 but were inactive against the strains Vibrio cholerae O1 (NB2) and Pseudomonas aeruginosa ATCC 15442. Copyright © 2010 John Wiley & Sons, Ltd.     

Antiplasmodial Securinega alkaloids from Phyllanthus fraternus: Discovery of natural (+)-allonorsecurinine

The chemical investigation of the antimalarial plant Phyllanthus fraternus G. L. Webster (Phyllanthaceae) resulted in the discovery of the Securinega alkaloid (+)-allonorsecurinine (1), previously reported as a synthetic compound, together with the known ent-norsecurinine (2), nirurine (3), bubbialine (4), epibubbialine (5) and the lignan phyllanthin (6). The structure and absolute configuration of the new compound were elucidated on the basis of extensive spectroscopic analysis, optical rotation, and GIAO NMR shift calculation followed by CP3 analysis. The antiplasmodial activity of these compounds was evaluated against chloroquine-resistant (W2) and -sensitive (3D7) strains of Plasmodium falciparum. Among them, ent-norsecurinine (2) and (+)-allonorsecurinine (1) showed the strongest activity (IC₅₀: 1.14 ± 0.32 and 2.57 ± 0.53 µM) respectively, against W2 but one of the weakest against 3D7.     

Determination of bisbenzylisoquinoline alkaloids by high-performance liquid chromatography (II)

After the earlier analysis of nine bisbenzylisoquinoline alkaloids with ion pair chromatography, seven other bisbenzylisoquinoline alkaloids were analyzed using gradient elution with an acetonitrile-phosphate buffer (pH 8.0) mixture, and UV detection. Four alkaloids were detected in the stem woods of a Lauraceous plant, Dehaasia triandra Merr. and their contents determined. LC-MS suggested that a major unknown compound in the plant was also a bisbenzylisoquinoline alkaloid.     

Stereochemical aspects and 13C NMR spectroscopy of the berbamine class of bisbenzylisoquinoline alkaloids

An analysis of the ¹³C NMR spectra of bisbenzylisoquinoline alkaloids of the berbamine type shows the dependence of spectroscopic properties on preferred conformation.     

Inhibitory effect of bisbenzylisoquinoline alkaloids on the quick death of mice treated with BCG/LPS

Three bisbenzylisoqinoline alkaloids, chondocurine (Chon), berbamine (Ber), and cycleanine (Cyc) were tested for their protective effect on the quick death of mice primed with bacillus Calmette Guerin (BCG) and elicited with lipopolysaccharide (LPS). Seven-consecutive treatments with Chon or Cyc at a dose of 10 mg/kg following BCG priming resulted in significant improvement in the survival rate. A single dose of Chon also protected the BCG/LPS-treated mice from death if it was given immediately after, not 4 h after, LPS elicitation. These data show that bisbenzylisoquinoline alkaloids can protect mice from the lethal toxicity induced by the BCG/LPS combination treatment by inhibiting the priming with BCG or the elicitation with LPS.     

Chaetoindicins A-C, three isoquinoline alkaloids from the fungus Chaetomium indicum

[structure: see text] Chaetoindicins A-C (1-3), three isoquinolines with novel skeletons, were isolated from the solid-state fermented culture of Chaetomiumindicum. Their structures were elucidated on the basis of spectral data. X-ray crystallographic analysis confirmed the structure of 2.