Activity-guided isolation of antileishmanial compounds from Piper hispidum
Graphical abstract
. One new amide (1) as well as two known chalcones (2, 3) and one known flavanone (4) were isolated from P. hispidum leaves. Their structures were established by spectroscopic methods. The results showed that the known chalcone exhibited the most potent antileishmanial activity with an IC50 of 0.8 μM (amphotericin B: IC50 = 0.2 μM).
Highlights
► We investigated the activity-guided isolation of antileishmanial compounds from Piper hispidum.► A new amide compound has been isolated, together with three known compounds.► The known chalcone displayed the most potent antileishmanial activity.
Introduction
Leishmaniasis is a group of prevalent diseases caused by protozoan parasites belonging to the genus Leishmania extended over Africa, Asia, Europe, North and South America. An estimated 12 million people are infected worldwide in 88 countries with an annual incidence of about 2–3 million (Chava et al., 2005, Murray et al., 2005). The clinical manifestations may range from single cutaneous lesions to a fatal visceral form. Leishmaniasis is a serious problem for public health in the world, especially in tropical and subtropical regions where the parasites have developed resistance to current drugs. In the absence of effective vaccines, chemotherapy still plays a critical role in treating this disease. It relies on multiple parenteral injections with pentavalent antimonials that are considerably toxic (Guerin et al., 2002) and prone to induce resistance. Second-line drugs, such as amphotericin B, produce strong collateral effects, are costly for the majority of the populations in affected countries, and have restricted therapeutic spectra in different clinical forms of leishmaniasis (Davis et al., 2004). Recently, miltefosine has been shown to be active by oral route against Bolivian mucosal leishmaniasis (Soto et al., 2007) but its efficacy remains to be determined against other types of leishmaniasis (Murray et al., 2005, Yardley et al., 2005, Perez-Victoria et al., 2003).
Therefore, the search for novel, effective, and safe drugs for the treatment of these diseases is essential for the control and prevention of leishmaniasis. One of the main opportunities is through the discovery of new antiparasitic agents from natural origins (Ioset, 2008). The genus Piper (Piperaceae), widely distributed in the tropical and subtropical regions of the world, is a pantropical group with nearly 2000 species, constituting an important element of mountain and lowland forests (Quijano-Abril et al., 2006). Phytochemical investigations of Piper species (Parmar et al., 1997) has reported the isolation of several classes of antiprotozoal compounds such as alkaloids (Rukachaisirikul et al., 2004), flavanones (Portet et al., 2007), chalcones and dihydrochalcones (Torres-Santos et al., 1999, Hermoso et al., 2003, Flores et al., 2007, Jenett-Siems et al., 1999), lignans (Cabanillas et al., 2010, Ma et al., 1991), neolignans (Luize et al., 2006). In South American traditional Pharmacopeias, the leaves of Piper hispidum Sw. and P. elongatum Vahl are used as poultices for healing wounds and to treat the symptoms of cutaneous leishmaniasis “Uta” (Estevez et al., 2007), and the leaves of P. aduncum L. are used for inflammation, and as antiseptic (Orjala et al., 1994).
As part of our studies to uncover antileishmanial agents from the Peruvian biodiversity and provide scientific grounds for the ethnomedicinal use of P. hispidum, we carried out an activity-guided fractionation of P. hispidum against amastigote forms of Leishmania amazonensis in vitro. This extract exhibited interesting activity against axenic amastigotes of L. amazonensis, with an IC50 of 6.3 μg/ml.
Section snippets
Results and discussion
The bioassay-guided fractionation of the ethanolic extract of P. hispidum leaves (IC50 = 6.3 μg/ml) against L. amazonensis axenic amastigotes yielded a methanolic fraction (IC50 = 5.1 μg/ml), from which a new compound (1) and three known compounds, including two chalcones (2, 3) and one flavanone (4) were isolated by column chromatography. The structures of compounds 1–4 were elucidated on the basis of spectroscopic data, including homo- and heteronuclear correlation NMR experiments (COSY, HSQC and
General experimental procedures
The UV spectra were recorded on Specord 205 spectrometer. IR spectroscopy was performed on a FT-IR Parabon Perkin Elmer spectrophotometer. The structures of the isolated compounds were identified by nuclear magnetic resonance (NMR; Bruker Avance 500 equipped with a TBI z-gradient 5 mm probe), 1H NMR (500 MHz), 13C NMR (125 MHz), and 2D NMR analysis in CDCl3; NMR experiments were performed at 298 K using standard pulse sequences. Chemical shifts (d) are given in ppm relative to TMS with coupling
Acknowledgements
We thank Dr. Nicolas Fabre from the University of Toulouse, France, as well as the Department of Chemistry of the Pontificia Universidad Católica del Perú, for assistance in obtaining 1H, 13C NMR and MS spectra.
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2023, Studies in Natural Products ChemistryMetabolomic approach of the antiprotozoal activity of medicinal Piper species used in Peruvian Amazon
2021, Journal of EthnopharmacologyCitation Excerpt :It consists of four genera (Piper, Peperomia, Zippelia and Verhuellia) (Quijano-Abril et al., 2006), with Piper and Peperomia genera being the most represented (Dyer and Palmer, 2004; Salehi et al., 2019; Vásquez-Ocmín et al., 2017). Piper species are classically used in Latino-American traditional medicine for the treatment of fever and protozoal diseases (Durant-Archibold et al., 2018; Rojas Cardozo et al., 2014; Ruiz et al., 2011), however fragmented information is still not sufficient to make a comprehensive inventory of the species used for this purpose. The Piper genus contains about 2000 species, many of them being dominant in their native habitat (Islam et al., 2020).
A comprehensive review of chalcone derivatives as antileishmanial agents
2018, European Journal of Medicinal ChemistryCitation Excerpt :DMC showed effectiveness and selectivity against intracellular L. amazonensis amastigotes with ED50 of 24 μg/mL [20]. In a bioassay-guided fractionation of the ethanolic extract of Piper hispidum collected from Peru, two chalcones derivatives (2-hydroxy-3,4,6-trimethoxychalcone, 3 and cardamomin - 2,4-dihydroxy-6-methoxychalcone, 4) were isolated and tested against axenic amastigotes [18]. Compound 3 exhibited the best activity with an IC50 of 0.8 μM, followed by 4 with an IC50 of 8 μM.
The chemotherapeutic potential of chalcones against leishmaniases: a review
2018, International Journal of Antimicrobial AgentsCitation Excerpt :Two more chalcones, 9 and 10 (Fig. 4) that strongly inhibited the in vitro growth of amastigotes of L. amazonenis (IC50 = 0.25 and 2.23 µg/mL, respectively), were isolated from the ethanol leaf extract of Piper hispidum by bioassay-guided fractionation. However, both compounds were mildly toxic to macrophages [29]. Chalcones 11 and 12 (Fig. 5) were isolated alongside other phenolic compounds from Psorothamnus polydenius whole plant methanol extract.
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