Amides from Piper brachystachyum and Piper retrofractum

Three unsaturated amides, designated brachystamides-C, D and E have been characterised from Piper brachystachyum Wall. Brachystamide-C, shown to be N-isobutyl-15-(3',4'-methylenedioxyphenyl)-2E,4E,13E-pentadecatrienamide, was unusual in having a non-conjugated double bond. Piper retrofractum Vahl. yielded retrofractamide-D, which has been fully characterised.     

Bioactive aristolactams from Piper umbellatum

Four alkaloids named piperumbellactams A-D (1-4) were isolated from branches of Piper umbellatum together with known N-hydroxyaristolam II (5), N-p-coumaroyl tyramine (6), 4-nerolidylcatechol (7), N-trans-feruloyltyramine, E-3-(3,4-dihydroxyphenyl)-N-2-[4-hydroxyphenylethyl]-2-propenamide, beta-amyrin, friedelin, apigenin 8-C-neohesperidoside, acacetin 6-C-beta-d-glucopyranoside, beta-sitosterol, its 3-O-beta-d-glucopyranoside and its 3-O-beta-d-[6'-dodecanoyl]-glucopyranoside. Glycosidase inhibition, antioxidant and antifungal activities of these compounds were evaluated. Compounds 1-3 showed moderate alpha-glucosidase enzyme inhibition with IC50 values 98.07+/-0.44, 43.80+/-0.56 and 29.64+/-0.46, respectively. In DPPH radical scavenging assay, compounds 2, 3 and 6 showed potent inhibitory activity while compounds 4, 5 and 7 showed potent antifungal activity.     

Alkamides from the fruits of Piper longum and Piper nigrum displaying potent cell adhesion inhibition

Eight alkamides 1-8 were isolated by bioassay-guided isolation of EtOH extracts of the fruits of Piper longum and Piper nigum (Piperaceae). Their structures were elucidated by spectroscopic analysis ((1)H, (13)C NMR, and ESI-MS) as follows: guineensine (1), retrofracamide C (2), (2E,4Z,8E)-N-[9-(3,4-methylenedioxyphenyl)-2,4,8-nonatrienoyl]piperidine (3), pipernonaline (4), piperrolein B (5), piperchabamide D (6), pellitorin (7), and dehydropipernonaline (8). Their compounds 3-5, 7, and 8 inhibited potently the direct binding between sICAM-1 and LFA-1 of THP-1 cells in a dose-dependent manner, with IC(50) values of 10.7, 8.8, 13.4, 13.5, and 6.0 microg/mL, respectively.     

Antifungal flavanones and prenylated hydroquinones from Piper crassinervium Kunth

Bioactivity-guided fractionation of the EtOAc extract from leaves of Piper crassinervium yielded three prenylated hydroquinones together with two known flavanones naringenin and sakuranetin. Their structures were determined by means of spectroscopic analysis (NMR, IR, UV and MS) including two-dimensional NMR spectroscopy experiments (1H-1H COSY, HMQC, HMBC and NOESY). The antifungal activity was determined by direct bioautography against Cladosporium cladosporioides and C. sphaerospermum.     

Activity-guided isolation of antiplasmodial dihydrochalcones and flavanones from Piper hostmannianum var. berbicense

The bioassay-guided purification of an n-hexane extract from the leaves of Piper hostmannianum var. berbicense led to the isolation of four monoterpene or prenyl-substituted dihydrochalcones (1a, 1b, 2, 3) as well as the known compounds 2',6'-dihydroxy-4'-methoxydihydrochalcone (4), linderatone (5), strobopinin (6), adunctin E (7) and (-)-methyllinderatin (8). Their structures were established on the basis of NMR and X-ray analysis. (-)-Methyllinderatin, linderatone and 2',6'-dihydroxy-4'-methoxydihydrochalcone exhibited the most potent antiplasmodial activity with IC50 values of 5.64, 10.33 and 12.69 microM, respectively against both chloroquine-sensitive and resistant strains of Plasmodium falciparum (F32,FcB1). The activity of (-)-methyllinderatin was confirmed in vivo against Plasmodium vinckei petteri in mice (80% of reduction of parasitemia) at a dose of 20 mg/kg/day.     

Indole alkoloids from Nauclea officinalis with weak antimalarial activity

Five indole alkaloids (naucleofficines A-E) were isolated from the stems (with bark) of Nauclea officinalis: (E)-2-(1-beta-d-glucopyranosyloxybut-2-en-2-yl)-3-(hydroxymethyl)-6,7-dihydro-indolo[2,3-a]quinolizin-4(12H)-one (1), (E)-1-propenyl-12-beta-d-glucopyranosyloxy-2,7,8-trihydro-indolo[2,3-a]pyran[3,4-g]quinolizin-4,5(13H)-dione (2), (E)-2-(1-hydroxybut-2-en-2-yl)-11-beta-d-glucopyranosyloxy-6,7-dihydro-indolo[2,3-a]quinolizin-4(12H)-one (3), (E)-1-propenyl-4-hydroxy-2,4a,7,8,13b,14,14a-hepthydro-(4alpha,4abeta,13balpha,14abeta)indolo[2,3-a]pyran[3,4-g]quinolizin-5(13H)-one (4) and 1-(1-hydroxyethyl)-10-hydroxy-7,8-dihydro-indolo[2,3-a]pirydine[3,4-g]quinolizin-5(13H)-one (10-hydroxyangustoline) (5), together with two known compounds, naucleidinal (6) and angustoline (7). All of the structures of the seven compounds above were elucidated by spectroscopic methods including use of 1D- and 2D-NMR spectroscopic analyses. Compounds 2 and 3 are rare examples of monoterpene indole alkaloids with a glucopyranosyloxy group attached to position C-12. In vitro activity screening of the above seven compounds showed weak to moderate inhibitory activity against Plasmodium falciparum.     

Trypanocidal tetrahydrofuran lignans from inflorescences of Piper solmsianum

In addition to sitosterol, syringaldehyde, 3,4,5-trimethoxybenzoic acid, isoelemicin and grandisin, two new tetrahydrofuran lignans were isolated from Piper solmsianun and characterized as rel-(7R,8R,7'R,8'R)-3',4'-methylenedioxy-3,4,5,5'-tetramethoxy-7,7'-epoxylignan and rel-(7R,8R,7'R,8'R)-3,4,3',4'-dimethylenedioxy-5,5'-dimethoxy-7,7'-epoxylignan on the basis of spectroscopic data, including 2D NMR spectrometric techniques. Their in vitro activity were determined against the trypomastigote form of Trypanossoma cruzi.     

Piperidine alkaloids from Piper methysticum

Pipermethystine (1), 3alpha,4alpha-epoxy-5beta-pipermethystine (2) and awaine (3) were isolated from the aerial parts of kava (Piper methysticum G. Forster, Piperaceae) and identified by HRMS and NMR spectroscopic analysis. 1 was concentrated in the stem peelings and leaves. 2 and 3 are new alkaloids with 2 found only in cv. Isa among the 11 cultivars examined, and 3 occurred primarily in young leaves of all cultivars. The stem peelings have been used in recent years as a source of kavalactones in kava dietary supplement industry. Quantitative aspects of these piperidine alkaloids in P. methysticum and their potential activities on human physiology are discussed.     

Chromenes from Peperomia serpens (Sw.) Loudon (Piperaceae)

Chromatographic separation of the CH2Cl2 extract from leaves of Peperomia serpens yielded two chromenes [5-hydroxy-8-(3',7'-dimethylocta-2',6'-dienyl)-2,2,7-trimethyl-2H-1-chromene (1) and 5-hydroxy-8-(3'-methyl-2'-butenyl)-2,2,7-trimethyl-2H-1-chromene-6-carboxylic acid (2)], besides the known chromene [methyl 5-hydroxy-2,2,7-trimethyl-2H-1-chromene-6-carboxylate (3)] and the flavonoid, dihydrooroxylin (4). Their structural elucidation were achieved by spectroscopic analyses. The antifungal activities of the CH2Cl2 extract and the isolated chromenes were measured bioautographically against Cladosporium cladosporioides and C. sphaerospermum, when it was found that the crude extract showed higher activity as compared to the pure compounds.     

Kavalactones from Piper methysticum, and their 13C NMR spectroscopic analyses

The kavalactone, 11-methoxy-5,6-dihydroyangonin, and eight previously reported analogs along with four other aromatic compounds were isolated from the root extracts of Piper methysticum (Kava Kava). Their structural elucidations were made by 1H and 13C NMR spectroscopic assignments using COSY, HMBC and HMQC experiments.     

Antiparasitic activity of prenylated benzoic acid derivatives from Piper species

Fractionation of dichloromethane extracts from the leaves of Piper heterophyllum and P. aduncum afforded three prenylated hydroxybenzoic acids, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid, 3-[(2E,6E,10E)-11-carboxy-13-hydroxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl]-4,5-dihydroxybenzoic acid and 3-[(2E,6E,10E)-11-carboxy-14-hydroxy-3,7,15-trimethyl-2,6,10,15-hexadecatetraenyl]-4,5-dihydroxybenzoic acid, along with the known compounds, 4,5-dihydroxy-3-(E,E,E-11-formyl-3,7,15-trimethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid (arieianal), 3,4-dihydroxy-5-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 4-hydroxy-3-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid, 4-hydroxy-3-(3,7-dimethyl-2,6-octadienyl)benzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid. Their structures were elucidated on the basis of spectroscopic data, including homo- and heteronuclear correlation NMR experiments (COSY, HSQC and HMBC) and comparison with data reported in the literature. Riguera ester reactions and optical rotation measurements established the compounds as racemates. The antiparasitic activity of the compounds were tested against three strains of Leishmania spp., Trypanosoma cruzi and Plasmodium falciparum. The results showed that 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid exhibited potent and selective activity against L. braziliensis (IC₅₀ 6.5 μg/ml), higher that pentamidine used as control. Moreover, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl- 2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid showed moderate antiplasmodial (IC₅₀ 3.2 μg/ml) and trypanocidal (16.5 μg/ml) activities, respectively.     

Variability in essential-oil composition of Piper marginatum sensu lato

This paper contains data on the chemical composition of the essential oils of 22 leaf samples of Piper marginatum Jacq. collected in different areas and ecosystems of the brazilian Amazon, as well as an overview of the available literature. The species presents a large synonymy based on their different leaf characteristics and distinct scents where some of them smell like anise or very close compounds. By GC, GC/MS, and cluster analysis, we identified seven chemotypes for the leaf oils. The main components found in chemotype I were safrole (1) and 3,4-(methylenedioxy)propiophenone (2). The chemotype II was dominated by 3,4-(methylenedioxy)propiophenone (2) and p-mentha-1(7),8-diene (10). The major compounds identified in chemotype III were 3,4-(methylenedioxy)propiophenone (2), myristicin (3), (E)-beta-ocimene (11), and gamma-terpinene (12). In the chemotype IV, the principal constituents were beta-caryophyllene (13), alpha-copaene (14), and 3,4-(methylenedioxy)propiophenone (2). The chemotype V was dominated by (E)-isoosmorhizole (6), (E)-anethole (8), and isoosmorhizole (7). The main compounds found in the chemotype VI were 2-methoxy-4,5-(methylenedioxy)propiophenone (4), methoxy-4,5-(methylenedioxy)propiophenone isomer 5, and (E)-isoosmorhizole (6). The major constituents in chemotype VII were beta-caryophyllene (13), bicyclogermacrene (15), and (E)-asarone (9).     

Anti-protozoal and plasmodial FabI enzyme inhibiting metabolites of Scrophularia lepidota roots

The ethanolic root extract of Scrophularia lepidota, an endemic plant of the Turkish flora, has been investigated for its anti-protozoal and inhibitory effect towards plasmodial enoyl-ACP reductase (FabI), a key enzyme of fatty acid biosynthesis in Plasmodium falciparum. Chromatographic separation of the extract yielded 10 iridoids (1-10), two of which are new, and a known phenylethanoid glycoside (11). The structures of the new compounds were determined as 3,4-dihydro-methylcatalpol (8) and 6-O-[4'-O-trans-(3,4-dimethoxycinnamoyl)-alpha-L-rhamnopyranosyl]aucubin (scrolepidoside, 9) by spectroscopic means. The remaining metabolites were characterized as catalpol (1), 6-O-methylcatalpol (2), aucubin (3), 6-O-alpha-L-rhamnopyranosyl-aucubin (sinuatol, 4), 6-O-beta-D-xylopyranosylaucubin (5), ajugol (6), ajugoside (7), an iridoid-related aglycone (10) and angoroside C (11). Nine isolates were active against Leishmania donovani, with the new compound 9 being most potent (IC50 6.1 microg/ml). Except for 4, all pure compounds revealed some trypanocidal potential against Trypanosoma brucei rhodesiense (IC50 values 29.3-73.0 microg/ml). Only compound 10 showed moderate anti-plasmodial (IC50 40.6 microg/ml) and FabI enzyme inhibitory activity (IC50 100 microg/ml). 10 is the second natural product inhibiting the fatty acid biosynthesis of Plasmodium falciparum.     

Chemosystematic investigations of irregular diterpenes in Anisotome and related New Zealand Apiaceae

A chemosystematic HPLC-UV and HPLC-MS investigation of New Zealand members of the Apiaceae was performed. Diterpenes were identified and quantified in methanolic extracts from subaerial parts of 28 taxa and 54 samples of Aciphylla, Anisotome, Apium, Gingidia, Lignocarpa, Oreomyrrhis, and Scandia. Six diterpenes (1-2, 4-7) and four polyacetylenes (8-11) were identified. The known compounds were the diterpenes anisotomenoic acid 1, anisotomene-1-ol 2, 16-acetoxyanisotomenoic acid 4 and anisotomene-1,12-diol 5; and the polyacetylenes falcarinol 8, falcarindiol 9, (+)-9(Z),17-octadecadiene-12,14-diyne-1,11,16-triol 10, and (+)-9(Z),17-octadecadiene-12,14-diyne-1,11,16-triol 1-acetate 11. New irregular diterpenes 13,14-dihydroanisotom-12E-ene-1,14-diol 6 and 14-methoxy-13,14-dihydroanisotom-12E-ene-1-ol 7 were isolated from A. haastii. Isomers of the new semi-synthetic diterpene 16-hydroxyanisotomenoic acid 3 were detected in extracts of Anisitone flexuosa. Structure elucidation was performed by HR mass spectrometry and 1D and 2D NMR spectroscopy. In crude extracts, compounds were identified by their HPLC retention times and their on-line HPLC-UV and MS spectra. Anisotomene diterpenes occurred in eight out of 16 species of the genus Anisotome, but were not detected in any of the other genera. In contrast, polyacetylenes were present in all the genera investigated.     

Insecticidal activity of synthetic amides on Spodoptera frugiperda

The phytochemistry of the genus Piper (Piperaceae) has been widely studied due to the biological properties of amides from these plants. In this work, we have synthesized and evaluated the toxic effect of 11 amides against the fall armyworm Spodoptera frugiperda larvae. The naturally occurring piperine was also evaluated. The most active amide was N-[3-(3',4'-methylenedioxyphenyl)-2-(E)-propenoyl]piperidine with a LD50 of 1.07 microg mg(-1) larvae. This amide was also evaluated by ingestion.     

Geranyl chalcone derivatives with antifungal and radical scavenging properties from the leaves of Artocarpus nobilis

Antifungal activity guided fractionation of the n-butanol extract from the methanol extract of the leaves of Artocarpus nobilis furnished 2',4',4-trihydroxy-3'-geranylchalcone (1), 2 ',4',4-trihydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (2), 2',4',4-trihydroxy-3'-[2-hydroxy-7-methyl-3-methylene-6-octaenyl]chalcone (3), 2',3,4,4'-tetrahydroxy-3'-geranylchalcone (4), 2',3,4,4'-tetrahydroxy-3'-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]chalcone (5). The chalcones 3 and 5 are new natural products whereas 1 and 2 are reported first time from the family Moraceae. All these compounds showed good fungicidal activity against Cladosporium cladosporioides and high radical scavenging activity towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical in TLC bio-autography method.     

Antimalarial xanthones from Calophyllum caledonicum and Garcinia vieillardii

The antimalarial activity of 22 xanthones against chloroquino-resistant strains of Plasmodium falciparum was evaluated. Natural caloxanthone C (1), demethylcalabaxanthone (2), calothwaitesixanthone (3), calozeyloxanthone (4), dombakinaxanthone (5), macluraxanthone (6), and 6-deoxy-gamma-mangostin (7) were isolated from Calophyllum caledonicum. 1,6-dihydroxyxanthone (8), pancixanthone A (9), isocudraniaxanthone B (10), isocudraniaxanthone A (11), 2-deprenylrheediaxanthone B (12) and 1,4,5-trihydroxyxanthone (13) were isolated from Garcinia vieillardii. Moreover, synthetic compounds (14-22) are analogues or intermediates of xanthones purified from Calophyllum caledonicum (Oger J.M., Morel C., Helesbeux J.J., Litaudon M., Seraphin D., Dartiguelongue C., Larcher G., Richomme P., Duval O. 2003. First 2-Hydroxy-3-Methylbut-3-Enyl substituted xanthones isolated from Plants: structure elucidation, synthesis and antifungal activity. Natural Product Research 17(3), 195-199; Helesbeux J.J., Duval O., Dartiguelongue C., Seraphin D., Oger J.M., Richomme P., 2004. Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors. Tetrahedron 60(10), 2293-2300). The relationship between antimalarial activity and molecular structure of xanthones has also been explored. The most potent xanthones (2), (3) and (7) (IC50 = c.a. 1.0 microg/mL) are 1,3,7 trioxygenated and prenylated on the positions 2 and 8.     

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.     

Anti-HBV active constituents from Piper longum

In the screening search for Hepatitis B virus inhibitory agents from medicinal plants, the ethanol extract of Piper longum Linn. was found to possess superior anti-HBV activity in vitro. Bioassay-guided fractionation coupled with repeated purification resulted in the isolation of four new compounds, involving two new glycosides longumosides A (1) and B (2) and two new amide alkaloids erythro-1-[1-oxo-9(3,4-methylenedioxyphenyl)-8,9-dihydroxy-2E-nonenyl]-piperidine (3), threo-1-[1-oxo-9(3,4-methylenedioxyphenyl)-8,9-dihydroxy-2E-nonenyl]-piperidine (4), as well as two compounds 3β,4α-dihydroxy-2-piperidinone (5), 5,6-dihydro-2(1H)-pyridinone (6) from natural source for the first time. The structures of the four new compounds were determined by extensive analyses of the MS, IR, 1D and 2D NMR data. Besides, the compounds 2–6, together with the known compounds 7–11 obtained previously, were assayed for their anti-HBV activity by using Hep G 2.2.15 cell line in vitro. Results suggested the compound piperine (7) possessed remarkable inhibitory HBV activity, against the secretion of hepatitis B virus surface antigen (HBsAg) and hepatitis B virus e antigen (HBeAg) with the Selectivity Index (SI) values of 15.7 and 16.8, respectively.     

Geranyl flavonoids from the leaves of Artocarpus altilis

Five geranyl dihydrochalcones, 1-(2,4-dihydroxyphenyl)-3-{4-hydroxy-6,6,9-trimethyl-6a,7,8,10a-tetrahydro-6H-dibenzo[b,d]pyran-5-yl}-1-propanone (2), 1-(2,4-dihydroxyphenyl)-3-[3,4-dihydro-3,8-dihydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (4), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(3,4-epoxy-4-methyl-1-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (5), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-hydroxy-4-methyl-2-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (8), and 2-[6-hydroxy-3,7-dimethylocta-2(E),7-dienyl]-2',3,4,4'-tetrahydroxydihydrochalcone (9), along with four known geranyl flavonoids (1, 3, 6, 7), were isolated from the leaves of Artocarpus altilis. Their structures were established by spectroscopic means and by comparison with the literature values. Compounds 2, 4, and 9 exhibited moderate cytotoxicity against SPC-A-1, SW-480, and SMMC-7721 human cancer cells.