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Twenty-five amide alkaloids (1-25) from Piper boehmeriifolium and 10 synthetic amide alkaloid derivatives (39-48) were evaluated for antiproliferative activity against eight human tumor cell lines, including chemosensitive and multidrug-resistant (MDR) cell lines. The results suggested tumor type-selectivity. 1-[7-(3,4,5-Trimethoxyphenyl)heptanoyl]piperidine (46) exhibited the best inhibitory activity (IC50=4.94 μM) against the P-glycoprotein (P-gp)-overexpressing KBvin MDR sub-line, while it and all other tested compounds, except 9, were inactive (IC50 >40 μM) against MDA-MB-231 and SK-BR-3. Structure-activity relationships (SARs) indicated that (i) 3,4,5-trimethoxy phenyl substitution is critical for selectivity against KBvin, (ii) the 4-methoxy group in this pattern is crucial for antiproliferative activity, (iii) double bonds in the side chain are not needed for activity, and (iv), in arylalkenylacyl amide alkaloids, replacement of an isobutylamino group with pyrrolidin-1-yl or piperidin-1-yl significantly improved activity. Further study on Piper amides is warranted, particularly whether side chain length affects the ability to overcome the MDR cancer phenotype., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A novel pyrrolidine alkaloid, (2R*,3S*,5S*)-N,2-dimethyl-3-hydroxy-5-(10-phenyldecyl)pyrrolidine (1), and 17 known compounds were isolated from Arisaema franchetianum Engl. (Araceae) tubers. The 17 compounds were bergenin (2), emodin (3), caffeic acid (4), nobiletin (5), 3-O-β-d-galactopyranosyl-hederagenin 28-O-β-d-xylopyranosyl(1 → 6)-β-d-galactopyranosyl ester (6), coniferin (7), qingyangshengenin (8), methylconiferin (9), syringaresinol 4'-O-β-d-glucopyranoside (10), gagaminine (11), perlolyrine (12), (S)-1-(1'-hydroxyethyl)-β-carboline (13), 1-(β-carboline-1-yl)-3,4,5-trihydroxy-1-pentanone (14), 1-methoxycarbonyl-β-carboline (15), indolo[2,3-α]carbazole (16), 4-hydroxycinnamic acid methyl ester (17), and methyl 4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl)ethyl] ferulate (18). The inhibitory activities of compound 1 and its N-methyl derivative (1a) against porcine respiratory and reproductive syndrome virus (PRRSV), human leukemic K562 cells, and human breast cancer MCF-7 cells were evaluated. Compounds 1 [50% inhibited concentration (IC(50)) = 12.5 ± 0.6 μM] and 1a (IC(50) = 15.7 ± 0.9 μM) were cytotoxic against K562 cells. Compound 1a also had a weak effect on PRRSV with an IC(50) value of 31.9 ± 6.0 μM [selectivity index (SI) = 18.7].

Eight new amide alkaloids (1-8) and 19 known ones were isolated from the whole plant of Piper boehmeriaefolium. Their structures were determined through spectroscopic data analyses. Cytotoxic activity of these amides against human cervical carcinoma HeLa cells was evaluated, and 1-[(9E)-10-(3,4-methylenedioxyphenyl)-9-decenoyl]pyrrolidine (9) exhibited significant inhibitory activity with an IC(50) value of 2.7 μg/mL.

Palhinine A, a novel C(16)N-type Lycopodium alkaloid with a unique 5/6/6/9 tetracyclic ring system, was isolated from the whole plant of Palhinhaea cernua L. (Lycopodiaceae). Its structure was elucidated by spectroscopic methods, and the absolute configuration was determined by single-crystal X-ray diffraction analysis using the Flack parameter. Palhinine A is reported as the first example of Lycopodium alkaloids of which C-16 is fused to a new ring through a C-16-C-4 lingkage.

Two new aporphine alkaloids, semiimmersumines A (1) and B (2), along with 20 known compounds, were isolated from the aerial parts of Piper semiimmersum (Piperaceae). The structures of the new compounds were elucidated based on the analysis of 1D and 2D NMR, MS, and CD data. The absolute configuration of semiimmersumine A (1) was determined by single crystal X-ray diffraction analysis using anomalous dispersion with copper radiation. The effects of all compounds from the plant on rabbit platelet aggregation induced by thrombin (IIa) or PAF were also evaluated. [ABSTRACT FROM AUTHOR]

Two new aporphine alkaloids, semiimmersumines A (1) and B (2), along with 20 known compounds, were isolated from the aerial parts of Piper semiimmersum (Piperaceae). The structures of the new compounds were elucidated based on the analysis of 1D and 2D NMR, MS, and CD data. The absolute configuration of semiimmersumine A (1) was determined by single crystal X-ray diffraction analysis using anomalous dispersion with copper radiation. The effects of all compounds from the plant on rabbit platelet aggregation induced by thrombin (IIa) or PAF were also evaluated. [ABSTRACT FROM AUTHOR]