Antifungal amide from leaves of Piper hispidum

Amino acids L-phenylalanine and L-lysine involvement in trans and cis piperamides biosynthesis in two Piper species

Several Piper species accumulate piperamides as secondary metabolites, and although they have relevant biological importance, many details of their biosynthetic pathways have not yet been described experimentally. Experiments involving enzymatic reactions and labeled precursor feeding were performed using the species Piper tuberculatum and Piper arboreum. The activities of the phenylalanine ammonia lyase (PAL) enzymes, which are involved in the general phenylpropanoid pathway, were monitored by the conversion of the amino acid L-phenylalanine to cinnamic acid. The activity of the 4-hydroxylase (C4H) enzyme was also observed in P. tuberculatum by converting cinnamic acid to p-coumaric acid. L-[UL-14C]-phenylalanine was fed into the leaves of P. tuberculatum and incorporated into piperine (1), 4,5-dihydropiperine (2), fagaramide (4), trans-piplartine (7), and dihydropiplartine (9). In P. arboreum, it was only incorporated into the piperamide 4,5-dihydropiperiline (3). L-[UL-14C]-lysine was successfully incorporated into the 4,5-dihydropiperine piperidine group (2), dihydropyridinone, and trans- (7) and cis-piplartine (8). These data corroborate the proposal of mixed biosynthetic origin of piperamides with the aromatic moiety originating from cinnamic acid (shikimic acid pathway) and key amide construction with amino acids as precursors.

Polyketides, diketopiperazines and an isochromanone from the marine-derived fungal strain Fusarium graminearum FM1010 from Hawaii

The fungal strain Fusarium graminearum FM1010 was isolated from a shallow-water volcanic rock known as "live rock" at the Richardson's Beach, Hilo, Hawaii. Eleven specialised metabolites, including two undescribed diketopiperazines, three undescribed polyketides, and one undescribed isochromanone, along with five known fusarielin derivatives were obtained from F. graminearum FM1010. The structures of the six undescribed compounds were elucidated by extensive analysis of NMR spectroscopy, HRESIMS, chemical reactions, and electronic circular dichroism (ECD) data. Kaneoheoic acids G-I showed mild inhibitory activity against S. aureus with the MIC values in the range of 20-40 μg/mL when assayed in combination with chloramphenicol (half of the MIC, 1 μg/mL), an FDA approved antibiotic. Kaneoheoic acid I exhibited both anti-proliferative activity against ovarian cancer cell line A2780 and TNF-α induced NF-κB inhibitory activity with the IC₅₀ values of 18.52 and 15.86 μM, respectively.

Identification of Antifungal Compounds from Piper Plants Against Fusarium oxysporum: An Untargeted Metabolite Profiling-Based Approach

The phytopathogen Fusarium oxysporum produces considerable losses in economically important crops, making alternative control measures urgently required. Piper plants are widely distributed in tropical regions, and they are also known to produce metabolites with biological activity against infectious agents. As part of our continuous search for antifungals, 18 Piper-derived ethanolic extracts were evaluated by their in vitro effect on F oxysporum mycelial growth inhibition. The total content of phenol and flavonoid measurements and liquid chromatography-electrospray ionization-mass spectrometry analysis served as the chemical characterization of the investigated extracts. Piper pulchrum, Piper barcoense, and Piper tuberculatum exhibited the highest mycelial growth inhibition (>74%). The integration of chemical fingerprints and bioactivity datasets led to recognizing 4 bioactive candidates among extracts through single- Y orthogonal partial least squares regression and univariate statistics. These candidates were 2 amides (1,3), an alkyl lactone (2), and a prenylated benzoquinone (4), subsequently isolated and identified by nuclear magnetic resonance spectroscopy. These isolated compounds exhibited reasonable antifungal activity (IC50 < 50 µM). The findings indicated that the correlative association is advantageous for identifying bioactive metabolites within active extracts.

C-H Amidation and Amination of Arenes and Heteroarenes with Amide and Amine using Cu-MnO as a Reusable Catalyst under Mild Conditions

An atom-economical and efficient route for the direct amidation and amination of aryl C-H bonds using our synthesized recyclable heterogeneous Cu-MnO catalyst is reported here. The direct C-H amidation was carried out using a simple amide without any preactivated coupling partner, and simple air was used as the sole oxidant. The reaction proceeds very smoothly with a broad range of substrates containing numerous functional groups in very good to excellent yields. Direct C-H aminations with a secondary amine were carried out under base-, ligand-, and external oxidant-free conditions in very good to excellent yields in very mild conditions. Both the amidation and amination can be scaled up on a gram scale with similar yields. The major advantage is that our catalyst is recyclable and reused several times without any significant loss of reactivity.

Metabolomic approach of the antiprotozoal activity of medicinal Piper species used in Peruvian Amazon

ETHNOPHARMACOLOGICAL RELEVANCE

In the Peruvian Amazon as in the tropical countries of South America, the use of medicinal Piper species (cordoncillos) is common practice, particularly against symptoms of infection by protozoal parasites. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point of this work was a set of interviews of people living in six rural communities from the Peruvian Amazon (Alto Amazonas Province) about their uses of plants from Piper genus: one community of Amerindian native people (Shawi community) and five communities of mestizos. Infections caused by parasitic protozoa take a huge toll on public health in the Amazonian communities, who partly fight it using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help to identify new antiprotozoal compounds.

AIMS OF STUDY

To record and validate the use of medicinal Piper species by rural people of Alto Amazonas Province (Peru) and annotate active compounds using a correlation study and a data mining approach.

MATERIALS AND METHODS

Rural communities were interviewed about traditional medication against parasite infections with medicinal Piper species. Ethnopharmacological surveys were undertaken in five mestizo villages, namely: Nueva Arica, Shucushuyacu, Parinari, Lagunas and Esperanza, and one Shawi community (Balsapuerto village). All communities belong to the Alto Amazonas Province (Loreto region, Peru). Seventeen Piper species were collected according to their traditional use for the treatment of parasitic diseases, 35 extracts (leaves or leaves and stems) were tested in vitro on P. falciparum (3D7 chloroquine-sensitive strain and W2 chloroquine-resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Assessments were performed on HUVEC cells and RAW 264.7 macrophages. The annotation of active compounds was realized by metabolomic analysis and molecular networking approach.

RESULTS

Nine extracts were active (IC₅₀ ≤ 10 μg/mL) on 3D7 P. falciparum and only one on W2 P. falciparum, six on L. donovani (axenic and intramacrophagic amastigotes) and seven on Trypanosoma brucei gambiense. Only one extract was active on all three parasites (P. lineatum). After metabolomic analyses and annotation of compounds active on Leishmania, P. strigosum and P. pseudoarboreum were considered as potential sources of leishmanicidal compounds.

CONCLUSIONS

This ethnopharmacological study and the associated in vitro bioassays corroborated the relevance of use of Piper species in the Amazonian traditional medicine, especially in Peru. A series of Piper species with few previously available phytochemical data have good antiprotozoal activity and could be a starting point for subsequent promising work. Metabolomic approach appears to be a smart, quick but still limited methodology to identify compounds with high probability of biological activity.

Antibacterial kaneoheoic acids A-F from a Hawaiian fungus Fusarium sp. FM701

Alarming rate of resistance to the existing antibiotics exhibits the importance of developing new antibiotic molecules from relatively under explored sources as well as implementing alternative approaches like antibiotic adjuvants. Six previously undescribed fungal polyketides, kaneoheoic acids A-F (1-6) were isolated from a fungal strain Fusarium sp. FM701 which was collected from a muddy sample of Hawaiian beach. The structures of these six compounds were elucidated by spectroscopic interpretation, including HRESIMS and NMR, and electronic circular dichroism (ECD) analysis. All six compounds that were inactive when tested alone showed significant antibacterial activity against Staphylococcus aureus and Bacillus subtilis, in the range of 10-80 μg/mL when assayed in combination with either chloramphenicol (half of the MIC, 1 μg/mL), an FDA approved antibiotic or disulfiram (6 μg/mL), an established antibiotic adjuvant that augmented the activity of antibiotics.

1 H and 13 C NMR data, occurrence, biosynthesis, and biological activity of Piper amides

Alkamides are the major and characteristic chemical compounds of the plants belonging to the Piper genus. These compounds are responsible for the flavor of pepper spices and for its broad use in cuisine across many regions of the world. Humans are in contact every day with these substances, which additionally show a broad variety of pharmacological activities, making them an important research target. A large amount of NMR data for these natural products is dispersed throughout literature. Its organization will help those research groups interested in their identification and structural elucidation. This review summarizes the ¹ H and ¹³ C NMR data of 268 Piper amides in a systematic and orderly way, with a discussion on their biological activities, biosynthetic aspects, and NMR analysis of typical and relevant aspects of this information.

Synthesis of tetrazole derivatives bearing pyrrolidine scaffold and evaluation of their antifungal activity against Candida albicans

The increase of opportunistic fungal infections raises the need for design and synthesis of new antifungal agents. Taking into account that tetrazole derivatives exhibit antifungal activity, and some of them are in the phase of clinical trials, new tetrazole derivatives bearing pyrrolidine moiety were synthesized in order to present their action mode against C. albicans. The target compounds were obtained by N-alkylation of various 2-arylpyrrolidines with several 1-(3-chloropropyl)-5-aryl-2H-tetrazoles. Regardless of the substituents at tetrazole or pyrrolidine rings reactions took place in 48 h and with satisfactory yields ranging from 53 to 70%. We performed screen of the synthesized compounds to identify these nontoxic inhibiting the C. albicans planktonic and sessile cells, and conducted a series of follow up studies to examine the in vitro and in vivo activity of the most potent antifungals. The leading antifungal inhibitor: 2-{3-[2-(3-Methylphenyl)pyrrolidin-1-yl]propyl}-5-phenyl-2H-tetrazole (3aC) and the randomly selected ones: 5-phenyl-2-[3-(2-phenylpyrrolidin-1-yl)propyl]-2H-tetrazole (3aA), 5-(4-chlorophenyl)-2-{3-[2-(4-fluorophenyl)pyrrolidin-1-yl]propyl}-2H-tetrazole (3cD), and 5-(4-chlorophenyl)-2-{3-[2-(4-chlorophenyl)pyrrolidin-1-yl]propyl}-2H-tetrazole (3cE) showed little to no toxicity against the Vero cell line and Galleria mellonella. 3aC and 3aD, the most active against biofilm in vitro, demonstrated in vivo activity in the invertebrate model of disseminated candidiasis. Flow cytometry analysis showed that necrotic cell death was generated under 3aC due to its interactions with the fungal membrane; this confirmed by the mitochondrial damage (XTT assay) and reduced adhesion to the TR-146 cell line at 46.05 μM. Flow cytometry was used to directly measure the redox state of the treated cells with the fluorescent DCFH probe. Pro-necrotic tetrazole derivatives (3aA, 3aC, 3cD) are unable to induce ROS production in the C. albicans cells. Moreover, CLSM analyses revealed that the tetrazole derivatives (principally 3aC, 3aD, and 3aE) inhibit C. albicans' ability to neutralize macrophages; a more effective phagosomes organisation was observed. 3aC's and 3aD's activity reflected in an attenuation of virulence in disseminated candidiasis in vivo.

Synthesis and biological evaluation of (-)-kunstleramide and its derivatives

Stereoselective total synthesis of (-)-kunstleramide, a cytotoxic dienamide from the bark of Beilschmiedia kunstleri gamble, has been accomplished by using Keck's asymmetric allylation and Trost isomerization as key reactions. Application of the developed strategy for the synthesis of a series of amide analogues (8-22) was also reported. Furthermore, the synthesized compounds were evaluated for their in vitro anti-proliferative activities against human epithelial lung carcinoma (A549), human epithelial cervical cancer (HeLa), human breast adenocarcinoma (MCF7) and human neuroblastoma (IMR32) cell lines using the SRB assay. All the compounds show moderate anti-proliferative activity against all cell lines. Some of the piperazine derivatives (17-22) strongly inhibit the growth of breast cancer cells with IC50 values of 8-20 μM.

Antimicrobial effects of Piper hispidum extract, fractions and chalcones against Candida albicans and Staphylococcus aureus

Three chalcones, 2'-hydroxy-4,4',6'-trimethoxychalcone, 2'-hydroxy-4,4',6'-tetramethoxychalcone, and 3,2'-dihydroxy-4,4',6'-trimethoxychalcone, were isolated from the leaves of Piper hispidum in a bioguided fractionation of crude extract. The antimicrobial activity of crude extract of P. hispidum leaves was determined against bacteria Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus and yeasts Candida albicans, C. parapsilosis and C. tropicalis. Fractions and chalcones were tested against C. albicans and S. aureus. The checkerboard assay was performed to assess synergic interactions between extract and antifungal drugs, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction assay was used to evaluate anti-biofilm effects of extract. The extract was active against yeasts, S. aureus and B. subtilis with MIC values between 15.6 and 62.5μg/mL. Synergistic effects of extract associated with fluconazole and nystatin were observed against C. albicans, with fractional inhibitory concentration indices of 0.37 and 0.24, respectively. The extract was also effective against C. albicans and S. aureus biofilm cells at concentrations of 62.5 and 200μg/mL, respectively. Thus, P. hispidum may be a possible source of bioactive substances with antimicrobial properties.

Synthesis of β-arylated alkylamides via Pd-catalyzed one-pot installation of a directing group and C(sp(3))-H arylation

The synthesis of β-arylated alkylamides via alkyl C-H bond arylation has been realized by means of direct one-pot reactions of acyl chlorides, aryl iodides and 8-aminoquinoline. Depending on the structure of the starting materials, both single and double β-arylated alkylamides could be accessed.

Anti-nociceptive, anti-hyperalgesic and anti-arthritic activity of amides and extract obtained from Piper amalago in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Piper amalago (Piperaceae) has been used in folk medicine as an analgesic. This study aimed to evaluate the pharmacological effects of extract and pure amides obtained from P. amalago on pain to provide a pharmacological basis for their use in traditional medicine.

AIM OF THE STUDY

This study evaluated the anti-nociceptive, anti-hyperalgesic, anti-arthritic and anti-depressive activities of the ethanolic extract of P. amalago (EEPA) and the amides N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine (1) and N-[7-(3',4'-methylenedioxyphenyl)-2(E),4(E)-heptadienoyl] pyrrolidine (2) obtained from P. amalago in animal models.

MATERIALS AND METHODS

Mice treated daily with EEPA (100mg/kg, p.o.) were assayed for 20 days for knee edema (micrometer measurement), mechanical hyperalgesia (analgesiometer analysis), heat sensitivity and immobility (forced swim test) in the Complete Freund's Adjuvant (CFA) model. Cold (acetone test) and mechanical hyperalgesia (electronic von Frey analysis) responses were evaluated for 15 days in rats treated with oral EEPA (100mg/kg) in the spared nerve injury (SNI) model. Meanwhile, mice were evaluated for carrageenan-induced edema and mechanical hyperalgesia and for nociception using the formalin model after a single administration of EEPA (100mg/kg) or amides 1 and 2 (1mg/kg).

RESULTS

Amides (1) and (2) were detected and isolated from the EEPA. The EEPA inhibited mechanical hyperalgesia, knee edema, and heat hyperalgesia, but not depressive-like behavior, induced by the intraplantar injection of CFA. When evaluated in the SNI model, the EEPA inhibited mechanical and cold hyperalgesia. The EEPA, 1 and 2 prevented the mechanical hyperalgesia induced by carrageenan and the anti-nociceptive effects in both phases of formalin nociception. The EEPA did not induce alterations in the open field test.

CONCLUSION

The EEPA was effective for inhibition of pain and arthritic parameters but was not effective against depressive-like behavior; additionally, it did not alter locomotor activity. The amides obtained seemed to be the active component(s) present in the EEPA because they proved to be anti-nociceptive and anti-hyperalgesic in models of acute pain. Considering that few drugs are currently available for the treatment of chronic pain, especially neuropathic pain, the present results may have clinical relevance and open new possibilities for the development of new anti-hyperalgesic and anti-arthritic agents from P. amalago.

Recent advances in copper-catalyzed C-H bond amidation

Copper catalysis has been known as a powerful tool for its ubiquitous application in organic synthesis. One of the fundamental utilities of copper catalysis is in the C–N bond formation by using carbon sources and nitrogen functional groups such as amides. In this review, the recent progress in the amidation reactions employing copper-catalyzed C–H amidation is summarized.

Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action

Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in response between plants treated with sarmentine and herbicidal soaps such as pelargonic acid (nonanoic acid). However, little was known about the mechanism of action leading to the rapid desiccation of foliage treated by sarmentine. In cucumber cotyledon disc-assays, sarmentine induced rapid light-independent loss of membrane integrity at 100 μM or higher concentration, whereas 3 mM pelargonic acid was required for a similar effect. Sarmentine was between 10 and 30 times more active than pelargonic acid on wild mustard, velvetleaf, redroot pigweed and crabgrass. Additionally, the potency of 30 μM sarmentine was greatly stimulated by light, suggesting that this natural product may also interfere with photosynthetic processes. This was confirmed by observing a complete inhibition of photosynthetic electron transport at that concentration. Sarmentine also acted as an inhibitor of photosystem II (PSII) on isolated thylakoid membranes by competing for the binding site of plastoquinone. This can be attributed in part to structural similarities between herbicides like sarmentine and diuron. While this mechanism of action accounts for the light stimulation of the activity of sarmentine, it does not account for its ability to destabilize membranes in darkness. In this respect, sarmentine has some structural similarity to crotonoyl-CoA, the substrate of enoyl-ACP reductase, a key enzyme in the early steps of fatty acid synthesis. Inhibitors of this enzyme, such as triclosan, cause rapid loss of membrane integrity in the dark. Sarmentine inhibited the activity of enoyl-ACP reductase, with an I 50app of 18.3 μM. Therefore, the herbicidal activity of sarmentine appears to be a complex process associated with multiple mechanisms of action.

General base-tuned unorthodox synthesis of amides and ketoesters with water

We discovered a highly reactive λ³-hypervalent iodane species using an inorganic/organic base for the unorthodox synthesis of amides and ketoesters through grafting terminal alkynes. In contrast to the metal-catalyzed dehydrative approaches the in situ generated nonmetallic reagent efficiently created C–N/C–O and CO bonds with amines/alkynes and water at rt.

Diuretic and antilithiasic activities of ethanolic extract from Piper amalago (Piperaceae)

OBJECTIVE

Piper amalago is used in Brazilian folk medicine as diuretic and for the treatment of urinary calculus disease, although no scientific data have been described to support these effects. Thus, this study aims to evaluate the diuretic effects and antilithiatic activity of the ethanolic extract of P. amalago (EEPam).

MATERIALS AND METHODS

Ethanolic extracts of P. amalago (125, 250 and 500mg/kg) were orally administered in male Wistar rats (n=5) and urinary excretion was measured at intervals of up to 24h after administration. The antilithiasic effect of EEPam on calcium oxalate urolithiasis crystallization was examined in a turbidimetric model.

RESULTS

The oral administration of all doses of EEPam significantly increased urine output after 24h when compared to control group. Moreover, the application of EEPam, induced an inhibitory effect on calcium oxalate crystallization.

CONCLUSIONS

According to results, P. amalago extracts showed diuretic and natriuretic activity and antilithiasic effects.

In vitro schistosomicidal effects of aqueous and dichloromethane fractions from leaves and stems of Piper species and the isolation of an active amide from P. amalago L. (Piperaceae)

Dichloromethane and aqueous fractions from leaves and stems of Piper arboreum Aubl., P. aduncum L., P. amalago L., P. crassinervium H.B. & K., P. diospyrifolium Kunth, P. hispidum Sw. and P. xylosteoides (Kunth) Steud. were tested against adult worms of Schistosoma mansoni. The in vitro activity was evaluated in terms of mortality, number of separated worms and number of worms with reduced motor activity. Most dichloromethane fractions from all Piper species showed moderate schistosomicidal activity, but aqueous fractions were not active. The dichloromethane fraction of P. amalago leaves (at 100 μg/ml) showed the highest activity, resulting in worm mortality, the separation of worm pairs and reduced motor activity. Chromatographic fractionation of the dichloromethane fraction of P. amalago leaves led to the isolation of its major compound, which was also tested against adults of S. mansoni. The isolated piperamide N-[7-(3′,4′-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine, at 100 μm, resulted in the mortality of all adult worms after 24 h of incubation. The findings suggest that species of Piper are potential sources of schistosomicidal compounds.

Secondary metabolites from the phloem of Piper solmsianum (Piperaceae) in the honeydew of Edessa meditabunda

INTRODUCTION

The phytochemistry of species of the genus Piper has been studied extensively, including Piper solmsianum. However, no studies have addressed the phytochemistry of the sap content of Piper species.

OBJECTIVE

To evaluate the transferring of secondary compounds from the saps of P. solmsianum to the honeydew of Edessa meditabunda.

METHODOLOGY

The honeydew of E. meditabunda and saps of P. solmsianum were analysed by GC-MS, (1) H-NMR and LC-MS.

RESULTS

The lignan (-)-grandisin and the phenylpropanoid (E)-isoelemicin were detected in both saps of P. solmsianum and honeydew of E. meditabunda.

CONCLUSION

Analysis of honeydew secreted by the sap-sucking insect E. meditabunda indicated that (-)-grandisin and (E)-isoelemicin are absorbed from the phloem of Piper solmsianum.

Leishmanicidal activity of an alkenylphenol from Piper malacophyllum is related to plasma membrane disruption

Leishmaniasis and Chagas disease are parasitic protozoan infections that affect the poorest population in the world, causing high mortality and morbidity. As a result of highly toxic and long-duration treatments, novel, safe and more efficacious drugs are essential. In this work, the methanol (MeOH) extract from the leaves of Piper malacophyllum (Piperaceae) was fractioned to afford one alkenylphenol, which was characterized as 4-[(3'E)-decenyl]phenol (gibbilimbol B) by spectroscopic methods. Anti-protozoan in vitro assays demonstrated for the first time that Leishmania (L.) infantum chagasi was susceptible to gibbilimbol B, with an in vitro EC(50) of 23 μg/mL against axenic promastigotes and an EC(50) of 22 μg/mL against intracellular amastigotes. Gibbilimbol B was also tested for anti-trypanosomal activity (Trypanosoma cruzi) and showed an EC(50) value of 17 μg/mL against trypomastigotes. To evaluate the cytotoxic parameters, this alkenylphenol was tested in vitro against NCTC cells, showing a CC(50) of 59 μg/mL and absent hemolytic activity at the highest concentration of 75 μg/mL. Using the fluorescent probe SYTOX Green suggested that the alkenylphenol disrupted the Leishmania plasma membrane upon initial incubation. Further drug design studies aiming at derivatives could be a promising tool for the development of new therapeutic agents for leishmaniasis and Chagas disease.

First Total Synthesis of Two New Amide Alkaloids from Piper boehmeriaefolium

3-(3,4,5-Trimethoxyphenyl)propanoylpyrrole and 3-(3,5-dimethoxy-4-hydroxyphenyl)propanoylpyrrole, two new amide alkaloids, were prepared from 3,4,5-trimethoxybenzaldehyde via 3,4,5-trimethoxycinnamic acid and the corresponding dihydroacid. This route is simple and the reaction conditions are mild.

HPLC analysis of supercritical carbon dioxide and compressed propane extracts from Piper amalago L. with antileishmanial activity

Piper amalago L. leaves were extracted with supercritical carbon dioxide and compressed propane under different conditions, and with chloroform by the conventional maceration method. These methods were compared for the pyrrolidine alkaloid content. Supercritical carbon dioxide (SFE-CO₂) at 313 K and 12.55 MPa showed the highest selectivity for the main compound (600.53 mg/g of extract). A gradient high-performance liquid chromatography (HPLC) method was developed and validated to quantify the alkaloid N-[7-(3′,4′-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl]pyrrolidine (1) in the extracts. The HPLC method showed linearity, precision and accuracy, allowing the quantitative analysis of the alkaloid in all the samples. All the extracts were tested against the promastigote and intracellular amastigote forms of Leishmania amazonensis. The antileishmanial activity was evaluated in terms of inhibitory concentration for 50% of protozoa (IC₅₀). The cytotoxicity was also evaluated against J774A1 macrophages, and the cytotoxic concentrations for 50% of macrophages were obtained (CC₅₀). The SFE-CO₂ (313 K; 12.55 MPa) extract showed the highest antileishmanial activity with the following IC₅₀ values of 16 and 7 µg/mL against the promastigotes and intracellular amastigotes forms, respectively. The extract showed low cytotoxicity with a CC₅₀ value of 93 µg/mL.

Antifungal Compounds from Piper Species

This review documents chemical structures and antifungal activities of 68 compounds isolated from 22 Piper species of the plant family Piperaceae. These compounds include amides, flavonoids, prenylated benzoic acid derivatives, lignans, phenylpropanoids, butenolides, and cyclopentendiones. Some of them may serve as leads for potential pharmaceutical or agricultural fungicide development.

Secondary metabolites isolated from Piper chimonantifolium and their antifungal activity

In this study, the CH(2)Cl(2) extract from leaves of Piper chimonantifolium was subjected to several chromatographic separation procedures to afford one chromene (gaudichaudianic acid) as a major compound as well as two flavonoids (dihydrooroxylin and pinocembrin) and three steroids (sitosterol, sitosteryl palmitate and stigmasterol). The structures of all determined compounds were characterised by spectrometric analysis, mainly mass spectrometry and NMR, as well as their optical properties. This article describes the first phytochemical study of the leaves of P. chimonantifolium and an evaluation of the antifungal activity of its major compounds.

Cytotoxic amide alkaloids from Piper boehmeriaefolium

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.

Geranylation of benzoic acid derivatives by enzymatic extracts from Piper crassinervium (Piperaceae)

The ability to carry out geranylations on aromatic substrates using enzymatic extracts from the leaves of Piper crassinervium (Piperaceae) was evaluated. A literature analysis pointed out its importance as a source of prenylated bioactive molecules. The screening performed on aromatic acceptors (benzoic acids, phenols and phenylpropanoids) including geranyl diphosphate as prenyl donor, showed the biotransformation of the 3,4-dihydroxybenzoic acid by the crude extract, and the p-hydroxybenzoic acid by both the microsomal fraction and the crude extract, after treating leaves with glucose. The analysis of the products allowed the identification of C- and O-geranylated derivatives, and the protease (subtilisin and pepsin) inhibition performed on the O-geranylated compounds showed weak inhibition. Electrophoretic profiles indicated the presence of bands/spots among 56-58 kDa and pI 6-7, which are compatible with prenyltransferases. These findings show that P. crassinervium could be considered as a source of extracts with geranyltransferase activity to perform biotransformations on aromatic substrates.

Estrogenic and serotonergic butenolides from the leaves of Piper hispidum Swingle (Piperaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Our previous work has demonstrated that several plants in the Piperaceae family are commonly used by the Q'eqchi Maya of Livingston, Guatemala to treat amenorrhea, dysmenorrhea, and pain. Extracts of Piper hispidum Swingle (Piperaceae), bound to the estrogen (ER) and serotonin (5-HT7) receptors.

AIM OF THE STUDY

To investigate the estrogenic and serotonergic activities of Piper hispidum extracts in functionalized assays, identify the active chemical constituents in the leaf extract, and test these compounds as agonists or antagonists of ER and 5-HT7.

MATERIALS AND METHODS

The effects of the Piper hispidum leaf extracts were investigated in estrogen reporter gene and endogenous gene assays in MCF-7 cells to determine if the extracts acted as an estrogen agonist or antagonist. In addition, the active compounds were isolated using ER- and 5-HT7 receptor bioassay-guided fractionation. The structures of the purified compounds were identified using high-resolution LC-MS and NMR spectroscopic methods. The ER- and 5-HT7-agonist effects of the purified chemical constituents were tested in a 2ERE-reporter gene assay in MCF-7 cells and in serotonin binding and functionalized assays.

RESULTS

Three butenolides including one new compound (1) were isolated from the leaves of Piper hispidum, and their structures were determined. Compound 1 bound to the serotonin receptor 5-HT(7) with IC(50) values of 16.1 and 8.3 microM, respectively, and using GTP shift assays, Compound 1 was found to be a partial agonist of the 5-HT(7) receptor. The Piper hispidum leaf extracts, as well as Compounds 2 and 3 enhanced the expression of estrogen responsive reporter and endogenous genes in MCF-7 cells, demonstrating estrogen agonist effects.

CONCLUSIONS

Extracts of Piper hispidum act as agonists of the ER and 5-HT(7) receptors. Compound 1, a new natural product, identified as 9,10-methylenedioxy-5,6-Z-fadyenolide, was isolated as the 5-HT(7) agonist. Compounds 2 and 3 are reported for the first time in Piper hispidum, and identified as the estrogen agonists. No inhibition of CYP450 was observed for any of these compounds in concentrations up to 1 microM. These activities are consistent with the Q'eqchi traditional use of the plant for the treatment of disorders associated with the female reproductive cycle.

Molluscicidal and ovicidal activities of plant extracts of the Piperaceae on Biomphalaria glabrata (Say, 1818)

Schistosomiasis is a tropical disease caused by Schistosoma and occurs in 54 countries, mainly in South America, the Caribbean region, Africa and the eastern Mediterranean. Currently, 5 to 6 million Brazilian people are infected and 30,000 are under infection risk. Typical of poor regions, this disease is associated with the lack of basic sanitation and very frequently to the use of contaminated water in agriculture, housework and leisure. One of the most efficient methods of controlling the disease is application of molluscicides to eliminate or to reduce the population of the intermediate host snail Biomphalaria glabrata. Studies on molluscicidal activity of plant extracts have been stimulated by issues such as environmental preservation, high cost and recurrent resistance of snails to synthetic molluscicides. The aim of this study was to determine the molluscicide action of extracts from Piperaceae species on adult and embryonic stages of B. glabrata. Fifteen extracts from 13 Piperaceae species were obtained from stems, leaves and roots. Toxicity of extracts was evaluated against snails at two different concentrations (500 and 100 ppm) and those causing 100% mortality at 100 ppm concentration were selected to obtain the LC₉₀ (lethal concentration of 90% mortality). Piper aduncum, P. crassinervium, P. cuyabanum, P. diospyrifolium and P. hostmannianum gave 100% mortality of adult snails at concentrations ranging from 10 to 60 ppm. These extracts were also assayed on embryonic stages of B. glabrata and those from P. cuyabanum and P. hostmannianum showed 100% ovicidal action at 20 ppm.

In vitro antifungal activity of extracts and neolignans from Piper regnellii against dermatophytes

The present study was designated to evaluate the in vitro antidermatophyte activity of extracts from leaves of Piper regnellii as well as of the bioactivity-directed isolation of neolignans. The antifungal assay was performed by microdilution techniques. The hydroalcoholic extract of Piper regnellii leaves presented a strong activity against the dermatophyte fungi Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis and Microsporum gypseum with MICs of 15.62, 15.62, 15.62 and 62.5 microg/ml, respectively. On light microscopy and scanning electron microscopy of nail fragments not exposed to hydroalcoholic extract of Piper regnelli leaves, well-formed and extensive mycelial growth was seen. On nail fragments exposed to hydroalcoholic extract at concentrations more than 1.2mg/ml and then inoculated with spore suspension, growth was not seen. The hydroalcoholic extract was fractionated on silica gel in to nine fractions. The active chloroform fraction was lyophilized and chromatographed by column chromatography on silica gel. Structures were established by comparison with literature data and identified as eupomatenoid-3 and eupomatenoid-5. The pure compounds showed strong activity on Trichophyton rubrum with MIC of 50 and 6.2 microg/ml, respectively. Comparing the activity of the active chloroform fraction obtained from hydroalcoholic crude extract with that of isolated compound eupomatenoid-5, it is clear that this showed the same results against Trichophyton rubrum. The results showed that the plant could be explored for possible antifungal agents and provides preliminary scientific validation for the traditional medicinal use of this plant.

Trypanocidal tetrahydrofuran lignans from Peperomia blanda

Five tetrahydrofuran lignans and two known flavones were isolated from the aerial parts of Peperomia blanda. The structures of the isolated lignans were elucidated by interpretation of their spectroscopic data, including by gHMQC and gHMBC. The relative and absolute configurations of the isolates were determined from NOESY interactions and optical properties, respectively. Four of the lignans were diastereomeric whilst one was of mixed biosynthetic origin. All but one of the lignans exhibited high in vitro trypanocidal activity when assayed against epimastigotes of Trypanosoma cruzi strain Y.

Antifungal amides from Piper scutifolium and Piper hoffmanseggianum

Chromatographic fractionation of a dichloromethane extract from the leaves of Piper scutifolium yielded two new isobutyl amides, scutifoliamide A ( 1) and scutifoliamide B ( 2), together with the known compounds piperolactam C ( 3), piperovatine ( 4), piperlonguminine ( 5), corcovadine ( 6), isopiperlonguminine ( 7), and isocorcovadine ( 8). From the dichloromethane extract from the leaves of P. hoffmannseggianum two new isobutyl amides, hoffmannseggiamide A ( 9) and hoffmannseggiamide B ( 10), were obtained together with the known compounds isopiperlonguminine ( 7) and isocorcovadine ( 8), sitosterol, and stigmasterol. The structures of the new compounds were established on the basis of spectroscopic data analysis. The inhibitory activity of compounds 1-10 against the growth of the fungi Cladosporium sphaerospermum and C. cladosporioides was determined by bioautography.

Evaluation of the leishmanicidal activity of plants used by Peruvian Chayahuita ethnic group

AIM OF THE STUDY

A total of 27 ethanolic plant extracts from 27 species were screened for leishmanicidal activity in vitro against Leishmania amazonensis. Most of the selected species (19) are traditionally used by the Chayahuitas, an Amazonian Peruvian ethnic group, to treat skin affections and/or leishmaniasis.

MATERIAL AND METHODS

A colorimetric method based on the reduction of tetrazolium salt (MTT) was used to measure the viability of Leishmania amazonensis promastigote and amastigote stages.

RESULTS AND CONCLUSIONS

Only the leaves of two species of the Piperaceae family (Piper hispidum Sw., and Piper strigosum Trel.) showed good leishmanicidal activities (IC(50)<10 microg/ml against amastigotes). Roots of Tabernaemontana sananho Ruiz & Pav. (Apocynaceae), together with bark of Vismia tomentosa Ruiz & Pav. (Clusiaceae), fruits of Solanum straminifolium var straminifolium Jacq. (Solanaceae), and stems of Zamia lindenii Regel ex André (Cycadaceae) showed low activity against amastigote stage (IC(50) around 50 microg/ml). Of those only Tabernaemontana sananho displayed also good activity on promastigotes (IC(50)<10 microg/ml). Results are discussed herein, in relation with the traditional use of the plants and compared with other data from the relevant literature.

Toxicity of extracts and isobutyl amides from Piper tuberculatum: potent compounds with potential for the control of the velvetbean caterpillar, Anticarsia gemmatalis

The isobutyl amides pellitorine (compound 1) and 4,5-dihydropiperlonguminine (compound 2) were extracted from the seeds of Piper tuberculatum Jacq. (Piperaceae) in yields of 6.10 and 4.45% respectively. The acute toxicities to the velvetbean caterpillar, Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae), of extracts of seeds, leaves and stems of P. tuberculatum, and of compounds 1 and 2, were evaluated by means of contact bioassays. The extracts caused 80% mortality when doses higher than 800.00 microg insect(-1) of extract of seeds, leaves and stems were administered to the velvetbean caterpillars. Compounds 1 and 2 showed 100% mortality at doses of 200 and 700 microg insect(-1) respectively. The LD(50) and LD(90) values were respectively 31.3 and 104.5 microg insect(-1) for compound 1, and 122.3 and 381.0 microg insect(-1) for compound 2. The potential value of extracts and amides derived from P. tuberculatum as efficient insecticides against velvetbean caterpillars is discussed.

Chemistry and evolution of the Piperaceae

The chemistry of members of the family Piperaceae is of great interest owing to the variety of biological properties displayed. A survey of structural diversity and bioactivity reveals that groups of species specialize in the production of amides, phenylpropanoids, lignans and neolignans, benzoic acids and chromenes, alkaloids, polyketides, and a plethora of compounds of mixed biosynthetic origin. Bioassays againstCladosporium cladosporioidesandC. sphaerospermunhave resulted in the characterization of various amides, prenylated phenolic compounds, and polyketides as potential classes of antifungal agents. Studies on the developmental process in seedlings ofPiper solmsianumhave shown that phenylpropanoid are produced instead of the tetrahydrofuran lignans found in adult plants. In suspension cultures ofP. cernuumandP. crassinervium, phenylethylamines and alkamides predominate, whereas in the adult plants prenylpropanoids and prenylated benzoic acids are the respective major compound classes. Knowledge of the chemistry, bioactivity, and ecology of Piperaceae species provides preliminary clues for an overall interpretation of the possible role and occurrence of major classes of compounds.

Chromenes of polyketide origin from Peperomia villipetiola

An extract of leaves and stems of Peperomia villipetiola has been found to contain myristicin (3-methoxy-4,5-methylenedioxy-allylbenzene) and seven chromenes, whose structures are methyl 5-hydroxy-7-methyl-2,2-dimethyl-2H-1-chromene-6-carboxylate (1), methyl 5-methoxy-7-methyl-2,2-dimethyl-2H-1-chromene-8-carboxylate (2), methyl 7-hydroxy-5-methyl-2,2-dimethyl-2H-1-chromene-6-carboxylate (3), methyl 7-methoxy-5-methyl-2,2-dimethyl-2H-1-chromene-6-carboxylate (4), 5-methanol-7-hydroxy-2,2-dimethyl-2H-1-chromene-6-carboxylic acid (5), 5-methanol-7-methoxy-2,2-dimethyl-2H-1-chromene-6-carboxylic acid (6), and methyl 5-acetoxymethanol-7-hydroxy-2,2-dimethyl-2H-1-chromene-6-carboxylate (7). A biosynthetic rationale for 1-7 suggests that orsellinic acid may be a common intermediate. The anti-fungal activities of the chromenes were measured bioautographically against Cladosporium cladosporioides and Cladosporium sphaerospermum: compounds 6 and 7 were found to be the most active.

Haloxylines A and B, Antifungal and Cholinesterase Inhibiting Piperidine Alkaloids from Haloxylon salicornicum

Haloxylines A (1) and B (2), new piperidine alkaloids, have been isolated from the chloroform soluble fraction of Haloxylon salicornicum and their structures elucidated by spectroscopic techniques including 2D-NMR. Both the compounds displayed antifungal and cholinesterase enzymes inhibitory potentials.

Benzoic acid derivatives from Piper species and their fungitoxic activity against Cladosporium cladosporioides and C. sphaerospermum

Piper crassinervium, P. aduncum, P. hostmannianum, and P. gaudichaudianum contain the new benzoic acid derivatives crassinervic acid (1), aduncumene (8), hostmaniane (18), and gaudichaudianic acid (20), respectively, as major secondary metabolites. Additionally, 19 known compounds such as benzoic acids, chromenes, and flavonoids were isolated and identified. The antifungal activity of these compounds was evaluated by bioautographic TLC assay against Cladosporium cladosporioides and C. sphaerospermum.

A new method of synthesis and Antibacterial activity evaluation of piper amides

Several natural piper amides and their mimics were synthesized by developing a new strategy of amide formation. The piper amides were tested against both gram +ve and gram -ve bacterial strains and found that they are particularly more active against Staphylococcus aureus and Chromobacterium violaceum strains.