Three new phenylpropanoid glucosides and a new tyramine-type alkamide from Piper puberulum.

Three new phenylpropanoid glycosides, piperpubelide (1), 1-propionyl-3-hydroxy-phenyl-4-O-ß-D-glucopyranoside (2), and 1-propionyl-4-hydroxy-phenyl-3-O-ß-D-glucopyranoside (3), a new tyramine-type alkamide, puberulumine L (4), together with thirteen known compounds (5-17) were isolated from Piper puberulum (Benth.) Maxim. Their structures were elucidated by analysis of spectroscopic data involving NMR, IR, UV, and HRESIMS data. Calculated and experimental ECD was used to confirm the configuration of compound 1. Compounds 14, 16, and 17 exhibited relatively positive DPPH radical scavenging activities, with corresponding EC50 of 10.23, 24.12, and 21.83 µM, respectively. In addition, compound 5 inhibited LPS-induced NO production in BV-2 microglia with an IC50 value of 18.05 µM.

Piplartine-Inspired 3,4,5-Trimethoxycinnamates: Trypanocidal, Mechanism of Action, and In Silico Evaluation.

Chagas disease (CD) is one of the main neglected tropical diseases that promote relevant socioeconomic impacts in several countries. The therapeutic options for the treatment of CD are limited, and parasite resistance has been reported. Piplartine is a phenylpropanoid imide that has diverse biological activities, including trypanocidal action. Thus, the objective of the present work was to prepare a collection of thirteen esters analogous to piplartine (1-13) and evaluate their trypanocidal activity against Trypanosoma cruzi. Of the tested analogues, compound 11 ((E)-furan-2-ylmethyl 3-(3,4,5-trimethoxyphenyl)acrylate) showed good activity with IC50 values = 28.21 ± 5.34 µM and 47.02 ± 8.70 µM, against the epimastigote and trypomastigote forms, respectively. In addition, it showed a high rate of selectivity to the parasite. The trypanocidal mechanism of action occurs through the induction of oxidative stress and mitochondrial damage. In addition, scanning electron microscopy showed the formation of pores and leakage of cytoplasmic content. Molecular docking indicated that 11 probably produces a trypanocidal effect through a multi-target mechanism, including affinity with proteins CRK1, MPK13, GSK3B, AKR, UCE-1, and UCE-2, which are important for the survival of the parasite. Therefore, the results suggest chemical characteristics that can serve for the development of new trypanocidal prototypes for researching drugs against Chagas disease.

The antinociceptive and anti-inflammatory potential and pharmacokinetic study of significant alkamides ingredients from Asarum Linn.

ETHNOPHARMACOLOGICAL RELEVANCE: Asari Radix et Rhizoma (ARR), including 3 major plants of genus Asarum Linn, A. heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag., A. sieboldii Miq. f. sieboldii and A. sieboldii Miq f. seoulense (Nakai) C. Y. Cheng et C. S. Yang, is one of the most important traditional herbal medicine in Asia with tremendous pharmacological activities. For a long time, researchers focus attention on studing asarinin and essential oils, the indicating ingredients of ARR, but paid less attention to another characteristic component, alkamides. The role of alkamides in the major efficacy of ARR medication remains to be elucidated. AIM OF THE STUDY: This study aims to investigate the contribution of alkamides in the efficacy of ARR according to the evaluation of antinociceptive and anti-inflammatory effects and in vivo pharmacokinetics processes. MATERIALS AND METHODS: For pharmacodynamic study, the analgesic and anti-inflammatory effects of alkamides-enriched fraction (ARRA) were comparatively evaluated by writhing test, hot plate test, and ear swelling test in mice after oral administration. For pharmacokinetic study, an UHPLC-MS/MS method was developed for the simultaneous determination of N-isobutyl-2E,4E,8Z,10Z/E-dodecatetraenamide (DDA) and other 6 major characteristic ingredients of ARR in rat plasma. The analytical method was validated and successfully applied to the pharmacokinetic study of ARR extract and DDA. RESULTS: Pharmacodynamic study show that the ARR and ARRA can significantly inhibit the writhing times of mice caused by acetic acid administration, increase the pain threshold of thermal stimulation, and inhibit xylene treated ear swelling degree by reduce PGE2 and TNF-α levels in the inflamed tissue. For pharmacokinetic study, the pharmacokinetic parameters of Vd/F and CL/F after intravenous administration in rats of DDA are 63.94 ± 32.12 L/kg and 0.33 ± 0.06 L/min/kg, respectively. The plasma drug concentration declined with the T1/2 value of 2.25 ± 0.96 h, and the MRT0-∞ was 2.23 ± 1.02 h. The absolute bioavailability of DDA after oral administration was calculated as 10.73%. DDA, methyleugenol, and asarinin have relatively high AUC0-∞ values when the ethanol and water extract of ARR is orally administered. CONCLUSIONS: ARRA is a kind of active ingredients with potential analgesic and anti-inflammatory effects that played a significant role in the major efficacy of ARR. DDA, the major compound of ARRA, has a high level of exposure in vivo, which could be is suitable for the pharmacokinetic marker or new quality marker of ARR.

Cytotoxic alkaloids from the root of Zanthoxylum paracanthum (mildbr) Kokwaro.

Chemical investigation of the root of Zanthoxylum paracanthum afforded 1 new alkamide derivative, (2E,4E)-6-oxo-N-isobutyldeca-2,4-dienamide (1) together with 10 known congeners including one phenolic amide (2), four benzophenanthridines (3 - 6), three indolonaphthyridines (7 - 9) and two lignans (10 and 11). Their structures were elucidated by a combination of spectroscopic and spectrometric data. Using resazurin reduction assay, the crude extract (10 µg/mL) and isolates (10 µM) were screened for their cytotoxic activities against the drug-sensitive (CCRF-CEM) leukemia cell line and its multidrug-resistant counterpart (CEM/ADR5000). Compounds 3, 4 and 6 showed cytotoxicity against CCRF-CEM with IC50 values of 2.00 ± 0.33, 2.31 ± 0.20 and 0.11 ± 0.04 µM, respectively. Only compound 6 exhibited strong cytotoxic activity against CEM/ADR5000 with an IC50 value of 2.34 ± 0.34 µM in comparison with the standard drug doxorubicin which showed IC50 values of 0.01 ± 0.14 (CCRF-CEM) and 26.78 ± 3.30 µM (CEM/ADR5000).

In vitro antileishmanial and immunomodulatory activities of the synthetic analogue riparin E.

Leishmaniases are infectious diseases caused by protozoa of the genus Leishmania, that may have different clinical manifestations. First line drugs used in the treatment of leishmaniosis are high costly, and are very aggressive requiring medical monitoring. Thus new therapeutic alternatives are needed and, in this context, natural products have been considered as a source of new antileishmania agents. Riparins are alkamides found in the unripe fruits of Aniba riparia. Several biological activities are described for this group of compounds, such as antimicrobial and antiparasitic potential. The objective of this work was to evaluate the anti-leishmania activity riparin E (Rip-E) in vitro, against promastigotes and internalized amastigotes of Leishmania amazonensis. Rip-E was able to inhibit promastigote cell growth (IC50 4.7 µg/ml) and to reduce the percentage of macrophages infected with amastigotes, reducing its infectivity (survival index) (IC50 1.3 µg/ml). The cytotoxicity against BALB/c murine macrophages was also assessed (CC50 50.6 µg/ml) and the selectivity index was 38.9. Rip-E also demonstrated immunomodulatory activity, evidenced by the increase of the phagocytic capacity and lysosomal activity. However, Rip-E did not affect directly the production of nitric oxide. These results suggest that Rip-E has antileishmania potential, by both its direct inhibitory effect and its ability to activate macrophages.

Isolation and synthesis of a new benzylated alkamide from the roots of Lepidium meyenii.

A new benzylated alkamide, N-(3,4-dimethoxybenzyl)-9Z-oleamide (1), along with two known ones (2 and 3) were isolated from the roots of Lepidium meyenii collected from Lijiang, Yunnan Province of China. Their structures were elucidated by extensive spectroscopic analyses and the new compound further confirmed by a one-step synthesis. All the isolated alkamides were evaluated for their cytotoxicity against five human cancer cell lines. However, no significant activities were detected at concentrations up to 40 µM.

Alkamides from Anacyclus pyrethrum L. and Their in Vitro Antiprotozoal Activity.

In our ongoing study to evaluate the antiprotozoal activity of alkamides from Asteraceae, a dichloromethane extract from the roots of Anacycluspyrethrum L. showed a moderate in vitro activity against the NF54 strain of Plasmodium falciparum and against Leishmaniadonovani (amastigotes, MHOM/ET/67/L82 strain). Seven pure alkamides and a mixture of two further alkamides were isolated by column chromatography followed by preparative high performance liquid chromatography. The alkamides were identified by mass- and NMR-spectroscopic methods as tetradeca-2E,4E-dien-8,10-diynoic acid isobutylamide (anacycline, 1), deca-2E,4E-dienoic acid isobutylamide (pellitorine, 2), deca-2E,4E,9-trienoic acid isobutylamide (3), deca-2E,4E-dienoic acid 2-phenylethylamide (4), undeca-2E,4E-dien-8,10-diynoic acid isopentylamide (5), tetradeca-2E,4E,12Z-trien-8,10-diynoic acid isobutylamide (6), and dodeca-2E,4E-dien acid 4-hydroxy-2-phenylethylamide (7). Two compounds-undeca-2E,4E-dien-8,10-diynoic acid 2-phenylethylamide (8) and deca-2E,4E-dienoic acid 4-hydroxy-2-phenylethylamide (9)-were isolated as an inseparable mixture (1:4). Compounds 3, 4, and 5 were isolated from Anacycluspyrethrum L. for the first time. While compounds 4 and 5 were previously known from the genus Achillea, compound 3 is a new natural product, to the best of our knowledge. All isolated alkamides were tested in vitro for antiprotozoal activity against Plasmodium falciparum, Trypanosomabruceirhodesiense, Trypanosomacruzi, and Leishmaniadonovani and for cytotoxicity against L6 rat skeletal myoblasts.

A New Alkamide with an Endoperoxide Structure from Acmella ciliata (Asteraceae) and Its in Vitro Antiplasmodial Activity.

From the aerial parts of Acmella ciliata (H.B.K.) Cassini (basionym Spilanthes ciliata Kunth; Asteraceae), three alkamides were isolated and identified by mass- and NMR spectroscopic methods as (2E,6E,8E)-N-isobutyl-2,6,8-decatrienamide (spilanthol, (1)), N-(2-phenethyl)-2E-en-6,8-nonadiynamide (2) and (2E,7Z)-6,9-endoperoxy-N-isobutyl-2,7-decadienamide (3). While 1 and 2 are known alkamides, compound 3 has not been described until now. It was found that the unusual cyclic peroxide 3 exists as a racemate of both enantiomers of each alkamide; the 6,9-cis- as well as the 6,9-trans-configured diastereomers, the former represents the major, the latter the minor constituent of the mixture. In vitro tests for activity against the human pathogenic parasites Trypanosoma brucei rhodesiense and Plasmodium falciparum revealed that 1 and 3 possess activity against the NF54 strain of the latter (IC50 values of 4.5 and 5.1 µM, respectively) while 2 was almost inactive. Compound 3 was also tested against multiresistant P. falciparum K1 and was found to be even more active against this parasite strain (IC50 = 2.1 µM) with considerable selectivity (IC50 against L6 rat skeletal myoblasts = 168 µM).

Effects of synthetic alkamides on Arabidopsis fatty acid amide hydrolase activity and plant development.

Alkamides and N-acylethanolamines (NAEs) are bioactive, amide-linked lipids that influence plant development. Alkamides are restricted to several families of higher plants and some fungi, whereas NAEs are widespread signaling molecules in both plants and animals. Fatty acid amide hydrolase (FAAH) has been described as a key contributor to NAE hydrolysis; however, no enzyme has been associated with alkamide degradation in plants. Herein reported is synthesis of 12 compounds structurally similar to a naturally occurring alkamide (N-isobutyl-(2E,6Z,8E)decatrienamide or affinin) with different acyl compositions more similar to plant NAEs and various amino alkyl head groups. These "hybrid" synthetic alkamides were tested for activity toward recombinant Arabidopsis FAAH and for their effects on plant development (i.e., cotyledon expansion and primary root length). A substantial increase in FAAH activity was discovered toward NAEs in vitro in the presence of some of these synthetic alkamides, such as N-ethyllauroylamide (4). This "enhancement" effect was found to be due, at least in part, to relief from product inhibition of FAAH by ethanolamine, and not due to an alteration in the oligomerization state of the FAAH enzyme. For several of these alkamides, an inhibition of seedling growth was observed with greater results in FAAH knockouts and less in FAAH over-expressing plants, suggesting that these alkamides could be hydrolyzed by FAAH in planta. The tight regulation of NAE levels in vivo appears to be important for proper seedling establishment, and as such, some of these synthetic alkamides may be useful pharmacological tools to manipulate the effects of NAEs in situ.

N-trans-feruloyltyramine and flavonol glycosides from the leaves of Solanum sordidum

Chemical investigation of the leaves of Solanum sordidum Sendtn., Solanaceae, resulted in the isolation and identification of sitosterol, stigmasterol, 3β-O-β-glycopyranosyl stigmasterol, 3β-O-β-glycopyranosyl sitosterol, kaempferol-3-O-α-rhamnopyranosyl-(1-6)-α-glycopyranoside, rutin, and N-trans-feruloyltyramine. The structures of these compounds were established by analysis of 1D and 2D NMR spectrometric data and comparison with data in the literature. The evaluation of antioxidant activity showed an IC50 of 159.5 ppm for the chloroformic fraction and IC50 of 77.5 ppm for the hydromethanolic fraction.