Essential Oil from Piper aduncum: Chemical Analysis, Antimicrobial Assessment, and Literature Review

UHPLC-HRMS/MS Chemical Fingerprinting of the Bioactive Partition from Cultivated Piper aduncum L

Piper aduncum L. is widely distributed in tropical regions and the ethnobotanical uses of this species encompass medicinal applications for the treatment of respiratory, antimicrobial, and gynecological diseases. Chemical studies reveal a diverse array of secondary metabolites, including terpenes, flavonoids, and prenylated compounds. Extracts from P. aduncum have shown antibacterial, antifungal, and larvicidal activities. Our study explores the activity of extracts and partitions against Mycobacterium tuberculosis H37Rv, as well as the chemical diversity of the bioactive partition. This marks the first investigation of the bioactive partition of P. aduncum from agroecological cultivation. The ethyl acetate partition from the ethanolic leaf extract (PAEPL) was found to be the most active. PAEPL was subjected to column chromatography using Sephadex LH-20 and the obtained fractions were analyzed using UHPLC-HRMS/MS. The MS/MS data from the fractions were submitted to the online GNPS platform for the generation of the molecular network, which displayed 1714 nodes and 167 clusters. Compounds were identified via manual inspection and different libraries, allowing the annotation of 83 compounds, including flavonoids, benzoic acid derivatives, glycosides, free fatty acids, and glycerol-esterified fatty acids. This study provides the first chemical fingerprint of an antimycobacterial sample from P. aduncum cultivated in an agroecological system.

Evaluation of molluscicidal activity on Biomphalaria glabrata (Say, 1818) and phytochemical characterization of hydroalcoholic extract of leaves of Ricinus communis L. (EUPHORBIACEAE)

Schistosomiasis is a parasitic infection of great prevalence worldwide, affecting 250 million people in 78 countries. Faced with this problem, studies that seek to analyze molluscicidal activity from plant extracts have stood out. The present work aimed to obtain the phytochemical characterization and investigate the molluscicidal activity in the hydroalcoholic extract of Ricinus communis leaves on Biomphalaria glabrata. The hydroalcoholic extract was prepared by macerated with solvent ethanol P.A 96%, followed by filtration and concentration in rotary evaporator. Next, five groups of snails with 10 animals each, one being the negative control group, were submitted to treatments with four concentrations of 25, 50, 75 and 100 mg/L of hydroalcoholic extract of R. communis. The parameters mortality, physiological and behavioral aspects of mollusks were analyzed during 96h. The chemical characterization of the extract was performed by high-performance liquid chromatography coupled to mass spectrometry (LC-MS). Chemical characterization revealed the presence of tannins, flavonoids and ricinin alkaloid, but under the conditions analyzed, the presence of saponins was not observed. There was no significant molluscicidal activity of the extract. However, a greater influence was observed in the diet, in addition to the motility and physiological state of the snails (alteration of cephalopodal mass and oviposition). The toxicity test was performed with Artemia salina and no toxicity was observed for this microcrustacean. It is expected that the results obtained contribute to the fight against the expansion of schistosomiasis and that they make room for other studies that investigate the molluscicidal action of plant extracts.

Piper aduncum Essential Oil Rich in Dillapiole: Development of Hydrogel-Thickened Nanoemulsion and Nanostructured Lipid Carrier Intended for Skin Delivery

The essential oil extracted from the leaves of Piper aduncum, an aromatic plant from the Amazon region, is rich in dillapiole and presents anti-inflammatory activity. In this study, nanoemulsions (NE) and nanostructured lipid carriers (NLC), which are biocompatible nanostructured systems of a lipid nature, were prepared by high-pressure homogenization for the yet unexplored skin delivery of dillapiole. The addition of hydroxyethylcellulose produced hydrogel-thickened NE or NLC in view to improving the viscosity and skin adherence of the nanoformulations. Formulations were characterized with respect to dillapiole content, droplet size, polydispersity index, zeta potential, morphology, rheological behavior, bioadhesion, skin permeation profile, and in vitro irritancy (HET-CAM). The formulations developed presented spherical, homogeneous nanometric particle size (around 130 nm), narrow polydispersity index (<0.3), and negative zeta potential (around −40 mV). Dillapiole content was slightly lower in NLC compared to NE since the production process involves heating. The hydrogels containing nanocarriers showed pseudoplastic behavior with bioadhesive characteristics. The developed formulations exhibited a controlled release profile, dillapiole delivery up to the dermis, the layer of interest for anti-inflammatory potential, and low irritant potential in the chorioallantoic membrane (HET-CAM). Both hydrogels-thickened NE and NLC seemed to be promising formulations for skin delivery of Piper aduncum essential oil.

Essential Oils from Colombian Plants: Antiviral Potential against Dengue Virus Based on Chemical Composition, In Vitro and In Silico Analyses

Currently, there are no therapies to prevent severe dengue disease. Essential oils (EOs) can serve as primary sources for research and the discovery of phytomedicines for alternative therapy. Fourteen EOs samples were obtained by distillation from six plants used in Colombian folk medicine. GC/MS analysis identified 125 terpenes. Cytopathic effect (CPE) reduction assays revealed differences in antiviral activity. EOs of Lippia alba, citral chemotype and carvone-rich fraction; Lippia origanoides, phellandrene chemotype; and Turnera diffusa, exhibited strong antiviral activity (IC50: 29 to 82 µg/mL; SI: 5.5 to 14.3). EOs of Piper aduncum, Ocimum basilicum, and L. origanoides, carvacrol, and thymol chemotypes, exhibited weak antiviral activity (32 to 53% DENV-CPE reduction at 100 µg/mL; SI > 5.0). Cluster and one-way ANOVA analyses suggest that the strong antiviral activity of EOs could be attributed to increased amounts of non-phenolic oxygenated monoterpenes and sesquiterpene hydrocarbons. Docking analyses (AutoDock Vina) predicted binding affinity between the DENV-2 E protein and terpenes: twenty sesquiterpene hydrocarbons (−8.73 to −6.91 kcal/mol), eight oxygenated monoterpenes (−7.52 to −6.98 kcal/mol), and seven monoterpene hydrocarbons (−7.60 to −6.99 kcal/mol). This study reports for the first time differences in the antiviral activity of EOs against DENV, corresponding to their composition of monoterpenes and sesquiterpenes.

Machine Learning Analysis of Essential Oils from Cuban Plants: Potential Activity against Protozoa Parasites

Essential oils (EOs) are a mixture of chemical compounds with a long history of use in food, cosmetics, perfumes, agricultural and pharmaceuticals industries. The main object of this study was to find chemical patterns between 45 EOs and antiprotozoal activity (antiplasmodial, antileishmanial and antitrypanosomal), using different machine learning algorithms. In the analyses, 45 samples of EOs were included, using unsupervised Self-Organizing Maps (SOM) and supervised Random Forest (RF) methodologies. In the generated map, the hit rate was higher than 70% and the results demonstrate that it is possible find chemical patterns using a supervised and unsupervised machine learning approach. A total of 20 compounds were identified (19 are terpenes and one sulfur-containing compound), which was compared with literature reports. These models can be used to investigate and screen for bioactivity of EOs that have antiprotozoal activity more effectively and with less time and financial cost.

Antifungal Activity against Fusarium oxysporum of Botanical End-Products: An Integration of Chemical Composition and Antifungal Activity Datasets to Identify Antifungal Bioactives

Plants produce various compounds as defensive barriers to naturally control fungal diseases. Among them, vascular wilt caused by Fusarium oxysporum is one of the most destructive diseases in crops, causing relevant economic losses. The application of synthetic fungicides is the most used management for this disease. However, this kind of method also involves adverse environmental impacts. Therefore, alternative methods are continuously being developed as a strategy to be involved in integrated pest management programs. Thus, as part of our research on antifungals of plant origin, a group of botanical extracts was assessed for the respective inhibitory effect on mycelium and conidia of F. oxysporum. Mycelial growth inhibition was measured in 12-well plates containing amended semi-solid medium, whereas conidial susceptibility was determined through microdilution. The identification of the bioactive compounds among test extracts was performed using an indirect approach, consisting of the integration of chemical composition and antifungal activity datasets through single-Y orthogonal partial least squares (OPLS) regression. Results showed that Piper aduncum extract was the most potent mycelial growth inhibitor whereas P. elongatum exhibited the best effect on conidia susceptibility. The active compounds identified through statistical integration and subsequent isolation were piperaduncin C, asebogenin and (-)-methyllinderatin. These findings indicated that the integrative, indirect approach is useful for the identification of bioactive metabolites from botanical extracts to be further used as biological protective agents against this phytopathogen.

Bioactive Essential Oils from Cuban Plants: An Inspiration to Drug Development

Aromatic plants and essential oils are important agents as complementary and alternative medicines in many cultures and geographical locations. In this review, a literature search on essential oils from Cuba, their chemical compositions, and their pharmacological properties was carried out. Out of 171 published scientific articles on essential oils of Cuban plants, a total of 31 documents, focused on both chemical composition and pharmacological properties, were considered for this review. In general, an increase in articles published in the last decade was noted, particularly in recognized international journals in English. Myrtaceae and Piperaceae were the most representative families collected in the occidental area of the country. Leaves and aerial parts were predominantly used, while a wide and variable number of components were identified, including terpenes, aliphatic derivatives, sulfur-containing compounds, phenylpropanoids, alkaloids and amine-type compounds. Finally, different biological activities were reported such as antiprotozoal, antibacterial, antifungal, cytotoxic, anthelmintic, larvicidal and insecticidal. In conclusion, we encourage further studies that would promote the use of essential oils from Cuban plants in new pharmaceutical products.

Brito L, Figueiredo MR, Soeiro MDNC. In Vitro Phenotypic Activity and In Silico Analysis of Natural Products from Brazilian Biodiversity on Trypanosoma cruzi

Chagas disease (CD) affects more than 6 million people worldwide. The available treatment is far from ideal, creating a demand for new alternative therapies. Botanical diversity provides a wide range of novel potential therapeutic scaffolds. Presently, our aim was to evaluate the mammalian host toxicity and anti-Trypanosoma cruzi activity of botanic natural products including extracts, fractions and purified compounds obtained from Brazilian flora. In this study, 36 samples of extracts and fractions and eight pure compounds obtained from seven plant species were evaluated. The fraction dichloromethane from Aureliana fasciculata var. fasciculata (AFfPD) and the crude extract of Piper tectoniifolium (PTFrE) showed promising trypanosomicidal activity. AFfPD and PTFrE presented EC50 values 10.7 ± 2.8 μg/mL and 12.85 ± 1.52 μg/mL against intracellular forms (Tulahuen strain), respectively. Additionally, both were active upon bloodstream trypomastigotes (Y strain), exhibiting EC50 2.2 ± 1.0 μg/mL and 38.8 ± 2.1 μg/mL for AFfPD and PTFrE, respectively. Importantly, AFfPD is about five-fold more potent than Benznidazole (Bz), the reference drug for CD, also reaching lower EC90 value (7.92 ± 2.2 μg/mL) as compared to Bz (23.3 ± 0.6 μg/mL). Besides, anti-parasitic effect of eight purified botanic substances was also investigated. Aurelianolide A and B (compounds 1 and 2) from A. fasciculata and compound 8 from P. tuberculatum displayed the best trypanosomicidal effect. Compounds 1, 2 and 8 showed EC50 of 4.6 ± 1.3 μM, 1.6 ± 0.4 μM and 8.1 ± 0.9 μM, respectively against intracellular forms. In addition, in silico analysis of these three biomolecules was performed to predict parameters of absorption, distribution, metabolism and excretion. The studied compounds presented similar ADMET profile as Bz, without presenting mutagenicity and hepatotoxicity aspects as predicted for Bz. Our findings indicate that these natural products have promising anti-T. cruzi effect and may represent new scaffolds for future lead optimization.

Comprehensive Utilization of Immature Honey Pomelo Fruit for the Production of Value-Added Compounds Using Novel Continuous Phase Transition Extraction Technology

Simple Summary

For the first time, this study investigated the extraction of bioactive substances with different polarities from immature honey pomelo fruit (IPF), a by-product of pomelo planting processing that causes resource waste and environmental pollution, using novel continuous phase transition extraction technology (CPTE). The results showed that CPTE was suitable for extracting essential oil, naringin, and pectin in sequence according to their polarities. The naringin extraction process was optimized by the response surface methodology, resulting in an extract ratio up to 99.47%. Moreover, the pectin extracted from IPF by CPTE showed better quality compared to commercial counterparts, as evidenced by lower protein and ash contents and higher white value. Together, these results suggested that CPTE could be a promising technology to improve the application value of IPF. For instance, the extracted bioactive components can be utilized as nutraceutical food ingredients. The scientific insights from this study will contribute to the development of functional food ingredients and comprehensive utilization of farming by-products.

Abstract

The immature honey pomelo fruit (IPF) is a huge agro-industrial by-product generated during pomelo planting. Although IPF is rich in nutrients, more than 95% of IPF is discarded annually, which causes resource waste and a serious environmental problem. Here, we report a novel continuous phase transition extraction technology (CPTE) to improve the comprehensive utilization of IPF by sequentially generating high value products and solve pollution problems related to their disposal. First, essential oil was successively extracted by CPTE at a yield of 1.12 ± 0.36%, in which 43 species were identified. Second, naringin extraction parameters were optimized using the response surface methodology (RSM), resulting in a maximum extraction rate of 99.47 ± 0.15%. Finally, pectin was extracted at a yield of 20.23 ± 0.66%, which is similar to the contents of commercial pectin. In conclusion, this study suggested that IPF was an excellent potential substrate for the production of value-added components by CPTE.

Potential of Piper spp. as a source of new compounds for the leishmaniases treatment

Current treatment guidelines for leishmaniasis is based on chemotherapy with drugs that show a set of limitations such as high cost, toxicity, difficult route of administration, and lack of efficacy in endemic areas. In this context, phytopharmaceutical products and herbal medicines emerge as promising alternatives for developing new treatment against leishmaniasis. This review discusses the perspectives of leishmaniasis treatment based on natural products and phytotherapy highlighting the Piper genus, especially P. aduncun and P. mollicomum Kunth covering the period of 1998 to 2020. Leishmanicidal activity of pure compounds of Piper spp. [3-(3,4,5-trimethoxyphenyl) propanoic acid, 3-chlorosintenpyridone, 2'-hydroxy-3',4',6'-trimethoxy-chalcone, cardamonin, conocarpan, cubebin, eupomatenoid, flavokavain B, ( +)-(7R,8S)-epoxy-5,6-didehydrokavain, N-[7-(3',4'-methylenedioxypheny l-2(E),4(E)-heptadienoyl-pyrrolidine, N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl-pyrrolidine, piperovatine, pellitorine, and piplartine (piperlongumine)] were proved against the promastigote and amastigote forms of parasite related with cutaneous (L. (L.) amazonensis, L. (V.) braziliensis, and L. (V.) guyanensis) and visceral (L. (L.) donovani, L. (L.) chagasi, and L. (L.) infantum). We also discussed the perspective of leishmaniasis treatment, considering the potential synergism between different promising species of Piper, presenting some interesting interaction possibilities for future studies between plants. Finally, the necessary steps for technological development of phytomedicines and herbal medicines with the desirable quality requirements for medicines are highlighted. The data presented here highlight the use of Piper spp. as source of pharmacological compounds that can lead to effective, safe, and inexpensive treatments for leishmaniasis.

Piper aduncum essential oil: a promising insecticide, acaricide and antiparasitic. A review

Several studies have assessed the potential of essential oils as substitutes for synthetic pesticides, in order to counter insect resistance to commercial pesticides. Piper aduncum L. is a very common shrub in the Amazon Rainforest and in other subtropical areas. The objective of this review was to analyse the existing information on P. aduncum essential oil as a raw material for new bioproducts for sustainable pest disease management. With this review, we collected and critically analysed 59 papers, representing all the studies that aimed to evaluate the essential oil properties of this species as an insecticide, acaricide and antiparasitic. The chemical composition differs depending on the origin, although phenylpropanoid dillapiole is the most cited component, followed by myristicin, 1,8-cineole and β-ocimene. Between the acaricidal, antiparasitic and synergistic activities, the insecticidal effects are highly promising, with optimal results against the malaria vector Aedes aegypti, with an LC50 that ranges between 57 and 200μg/mL. Acaricidal activity has mainly been reported against Tetranychus urticae, showing an LC50 that ranges between 5.83 and 7.17μg/mL. Antiparasitic activity has predominately been found on Leishmania amazonensis, and antipromastigote activity has been found to be between 23.8 and 25.9μg/mL. Concerning the synergistic effect between dillapiole and synthetic insecticides, four studies on Spodoptera frugiperda found promising results with cypermethrin. In this review, we highlighted the potential of P. aduncum essential oil as a biopesticide, also focusing on the lack of information about applied research. We also provide suggestions for future investigations.

Piper capitarianum essential oil: a promising insecticidal agent for the management of Aedes aegypti and Aedes albopictus

Mosquitoes are responsible for serious public health problems worldwide, and as such, Aedes aegypti and Aedes albopictus are important vectors in the transmission of dengue, chikungunya, and Zika in Brazil and other countries of the world. Due to growing resistance to chemical insecticides among populations of vectors, environmentally friendly strategies for vector management are receiving ever more attention. Essential oils (EOs) extracted from plants have activities against insects with multiple mechanisms of action. These mechanisms hinder the development of resistance, and have the advantages of being less toxicity and biodegradable. Thus, the present study aimed to evaluate the chemical composition of the EOs obtained from Piper capitarianum Yunck, as well as evaluating their insecticidal potential against Aedes aegypti and A. albopictus, and their toxicity in relation to Artemia salina. The yields of the EOs extracted from the leaves, stems, and inflorescences of P. capitarianum were 1.2%, 0.9%, and 0.6%, respectively, and their main constituents were trans-caryophyllene (20.0%), α-humulene (10.2%), β-myrcene (10.5%), α-selinene (7.2%), and linalool (6.0%). The EO from the inflorescences was the most active against A. aegypti and A. albopictus, and exhibited the respective larvicidal (LC₅₀ = 87.6 μg/mL and 76.1 μg/mL) and adulticide activities (LC₅₀ = 126.2 μg/mL and 124.5 μg/mL). This EO was also the most active in the inhibition of AChE, since it presented an IC₅₀ value of 14.2 μg/mL. Its larvicidal effect was observed under optical and scanning electron microscopy. Additionally, non-toxic effects against A. salina were observed. Docking modeling of trans-caryophyllene and α-humulene on sterol carrier protein-2 (SCP-2) suggests that both molecules have affinity with the active site of the enzyme, which indicates a possible mechanism of action. Therefore, the essential oil of P. capitarianum may be used in the development of new insecticide targets for the control of A. aegypti and A. albopictus in the Amazonian environment.

Gas chromatography coupled to mass spectrometry (GC-MS) characterization and evaluation of antibacterial bioactivities of the essential oils from Piper arboreum Aubl., Piper aduncum L. e Piper gaudichaudianum Kunth

The objective of this study was to determine the chemical profile and to evaluate the antibacterial activity of the essential oils of Piper species and modulation of the antibiotic activity, using the microdilution method to determine the minimum inhibitory concentration. The chemical components were characterized by gas chromatography coupled to mass spectrometry, which revealed β-copaen-4-α-ol (31.38%), spathulenol (25.92%), and germacrene B (21.53%) as major constituents of the essential oils of Piper arboreum, Piper aduncum, and Piper gaudichaudianum, respectively. The essential oils analyzed in this study did not present a clinically relevant activity against standard and multiresistant Escherichia coli. However, in the case of multiresistant Staphylococcus aureus, there was a significant activity, corroborating with reports in the literature, where Gram-positive bacteria are more susceptible to antimicrobial activity. The essential oils modulated the effect of the antibiotics norfloxacin and gentamicin, having on the latter greater modulating effect; however, for erythromycin, no statistically significant effect was observed. In conclusion, the results obtained in this study demonstrated that the essential oils of the analyzed Piper species present an inhibitory effect against S. aureus and modulate antibiotic activity, most of which presents synergistic activity.

Effect of the essential oils from Piper sp. and blue led lights in the enhancement of the antibiotic activity of drugs against mdr bacterial strains

The indiscriminate use of antibiotics has made bacterial resistance an important public health problem, since many antibiotics have become ineffective. Phototherapy can be considered an alternative to reduce the abusive use of antimicrobials, thus impacting microbial resistance. The objective of this study was to determine the chemical profile and to evaluate the effect of blue LED lights on the antibacterial activity of essential oils from Piper species, as well as their aminoglycoside antibiotic activity modulation using the microdilution method to determine the Minimum Inhibitory Concentration (MIC). The antibiotic activity modulating effect of these oils was also determined using the broth microdilution method with 96-well plates which were exposed to LED light for 20 min. Chemical components were characterized by gas chromatography coupled to mass spectrometry, revealing β-copaen-4-α-ol, germacrene A and germacrene B as major essential oil constituents for Piper arboreum (OEPar), Piper aduncum (OEPad) and Piper gaudichaudianum (OEPg), respectively. OEPar obtained a MIC of 512 μg/mL against Staphylococcus aureus and a MIC ≥ 1024 μg/mL against Escherichia coli. OEPad and OEPg showed MIC values ≥ 1024 μg/mL against the utilized strains. The essential oils modulated the effect of the antibiotics amikacin and gentamicin, with this effect being potentiated when exposed to blue LED. The blue LED light in the absence of the essential oil also showed an ability to modulate aminoglycoside antibiotic activity in this study, presenting mostly synergistic effects. In conclusion, the results obtained in this study demonstrate that photodynamic therapy using blue LED light interferes with the antibacterial action of P. arboreum, P. aduncum and P. gaudichaudianum essential oils and aminoglycoside antibiotic activity.

Bigger Data Approach to Analysis of Essential Oils and Their Antifungal Activity against Aspergillus niger, Candida albicans, and Cryptococcus neoformans

With increasing drug resistance and the poor state of current antifungals, the need for new antifungals is urgent and growing. Therefore, we tested a variety of essential oils for antifungal activity. We report the minimum inhibitory concentrations (MIC) values for a common set of 82 essential oils against Aspergillus niger, Candida albicans, and Cryptococcus neoformans. Generally, narrow-spectrum activity was found. However, C. neoformans was much more susceptible to inhibition by essential oils with over one-third of those tested having MIC values below 160 ppm. GC-MS analysis showed the essential oils to be chemically diverse, yet, the potentially active major constituents typically fell into a few general categories (i.e., terpenes, terpenoids, terpenols). While essential oils remain a rich source of potential antifungals, focus should shift to prioritizing activity from novel compounds outside the commonalities reported here, instead of simply identifying antifungal activity. Further, capitalizing on bigger data approaches can provide significant returns in expediting the identification of active components.

Chemical Composition, Antimicrobial and Antiparasitic Screening of the Essential Oil from Phania matricarioides (Spreng.) Griseb

Essential oils (EOs) have gained increasing attention due to their pharmacological effectiveness, and they also constitute some of the most popular natural products. In this study, we present the chemical characterization of the EO from Phania matricarioides and the in vitro activity/selectivity against a wide panel of bacteria, fungi and parasitic protozoa. Forty-five compounds were identified in the studied EO, of which lavandulyl acetate (40.1%) and thymyl isobutyrate (13.9%) were the major components. The EO did not inhibit bacterial or fungal growth at the maximum concentration tested (64 µg/mL), although it displayed activity on all evaluated protozoa (IC₅₀ values ranging from 2.2 to 56.6 µg/mL). In parallel, the EO demonstrated a noteworthy cytotoxic activity against peritoneal macrophages (CC₅₀ values of 28.0 µg/mL). The most sensitive microorganism was Trypanosoma cruzi, which had a superior activity (IC₅₀ = 2.2 µg/mL) and selectivity (SI = 13) in respect to other parasitic protozoa and the reference drug (p < 0.05). Further in vivo studies are needed to evaluate the potential use of this EO and the main compounds as antitrypanosomal agents. To our knowledge, this is the first report of chemical characterization and antimicrobial assessment of the EO from P. matricarioides.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications

Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Ethnomedical uses and pharmacological activities of most prevalent species of genus Piper in Panama: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Piperaceae is the fifth largest family of plants in Panama. This review focuses on the ethnomedical uses of the most prevalent Panamanian species and biological activities of their extracts and/or constituents both in Panama and worldwide. Many species have a plethora of ethnomedical uses such as antibacterial, antifungal, anti-inflammatory, anticancer, antidiabetic, anti-Helicobacter pylori, antiulcer, antiprotozoal, estrogenic, insecticidal, local anesthetic, diuretic, and for women's health conditions.

AIM OF THE REVIEW

The aim of this review is to compile all ethnomedical uses of most prevalent species of Piper in Panama, and their extracts or phytoconstituents worldwide, through a complete literature search, so that it may allow selection of potential unexplored Piper species for future research and development of phytotherapeuticals for important ailments.

METHODOLOGY

This review conducted a thorough search in books and databases such as Google Scholar, PubMed, Sci-Finder, Scopus, ACS publications, Science Direct, and Reaxys (Elsevier), until October of 2017. The information provided in this review is based on peer-reviewed papers only in English. The key words used to search were: "Piper", "Piperaceae", "Panama", "Pharmacological activity", "Chemistry," "Toxicity," and "Clinical studies". Scientific names of the plants were validated through www.tropicos.org. Potential full-texts of eligible papers, irrespective of database, were identified. Study selection and data extraction were conducted by one author (AIS) and confirmed by others (MPG, ADA). The extracted data were summarized in tabular form and a narrative description was used to provide a summary of updated information.

RESULTS

The ethnomedical uses of most prevalent 23 Panamanian species of Piper both in Panama as well in the world are provided. Of these species only Piper arboreum, Piper auritum, Piper cordulatum, Piper hispidum, Piper dariense, Piper multiplinervium and Piper umbellatum have ethnomedical uses in Panama. Some of the uses are by native Amerindians of Panama. These include ailments such as liver pains, common colds, skin infections, insecticidal, as a bath to alleviate colds, snakebites, different types of pains, skin ailments, wound healing, rheumatism, women's health, antipyretic, and anti-inflammatory. Other Panamanian species are widely used in many countries of the world. Of all the Piper species, P. aduncum has the most ethnomedical uses. Panamanian uses are different from the ones in other countries. A total of 61 compounds present in Piper species reported in this review have shown a variety of biological activities in vitro. These compounds belong to different chemical types, such as chromenes, amides, alkaloids, benzopyrans, benzoates, essential oils, pyrrolidines, flavokaines, chalcones, methylenedioxy propiophenones, cinnamates, monoterpenes, sesquiterpenes, phenols, among others. From this review it is evident that extracts and pure compounds isolated from Piper species have shown a wide array of mainly in vitro activity and some ethnomedical uses may be correlated with their activities reported.

CONCLUSIONS

Plants of this genus have provided bioactive species, both from crude extracts and pure compounds thus substantiating their efficacy in traditional medicine. In vivo and toxicological studies are still limited, but the results of different activities of Piper reported point out the great potential of these species for obtaining bioactive principles that may be useful in treating diseases. However, a thorough investigation of Piper species relating to chemistry, in vivo pharmacological activities, with emphasis on their mechanism of action, safety and efficacy and toxicity is warranted.

Essential Oils from Neotropical Piper Species and Their Biological Activities

The Piper genus is the most representative of the Piperaceae reaching around 2000 species distributed in the pantropical region. In the Neotropics, its species are represented by herbs, shrubs, and lianas, which are used in traditional medicine to prepare teas and infusions. Its essential oils (EOs) present high yield and are chemically constituted by complex mixtures or the predominance of main volatile constituents. The chemical composition of Piper EOs displays interspecific or intraspecific variations, according to the site of collection or seasonality. The main volatile compounds identified in Piper EOs are monoterpenes hydrocarbons, oxygenated monoterpenoids, sesquiterpene hydrocarbons, oxygenated sesquiterpenoids and large amounts of phenylpropanoids. In this review, we are reporting the biological potential of Piper EOs from the Neotropical region. There are many reports of Piper EOs as antimicrobial agents (fungi and bacteria), antiprotozoal (Leishmania spp., Plasmodium spp., and Trypanosoma spp.), acetylcholinesterase inhibitor, antinociceptive, anti-inflammatory and cytotoxic activity against different tumor cells lines (breast, leukemia, melanoma, gastric, among others). These studies can contribute to the rational and economic exploration of Piper species, once they have been identified as potent natural and alternative sources to treat human diseases.