Pharmaceutical properties of ‘ sucupira ’ ( Pterodon spp . )

The plant of the genus Pterodon (Fabaceae, Leguminosae), commonly known as ‘sucupira’ or ‘faveira’, are disseminated throughout the central region of Brazil and has frequently been used in popular medicine for its anti-rheumatic, analgesic, and anti-inflammatory properties. In recent years, interest in these plants has increased considerably. The biological effects of different phytoextracts and pure metabolites have been investigated in several experimental models in vivo and in vitro. The literature describes flavonoids, triterpene and steroids, while one paper presented studies with proteins isolated from the genus. This review provides an overview of phytochemical and pharmacological research in Pterodon, showing the main chemical compounds studied to date, and focusing on the relationship between these molecules and their biological activity. Furthermore, this study paves the way for more in-depth investigation, isolation and characterization of the molecules of this plant genus.


INTRODUCTION
The broad biodiversity within Brazil's territory places the country in a strategic position to develop rational and sustained exploration of new metabolites with therapeutic value.Brazil's landmass covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these habitats.The plant chemical diversity is also driven by these forces, in an attempt to best adapt the plant to suit the particular abiotic stresses, fauna, and microbes that coexist in the environment.Certain areas of vegetation, such as the Amazonian Forest, Atlantic Forest, Cerrado (Brazilian Savanna), and Caatinga, are rich in biodiversity and are therefore of great interest for the discovery of natural compounds with biological activity against diseases (Basso et al., 2005).
The vegetal genus Pterodon spp., belonging to the Fabaceae (= Leguminosae)/ Faboideae subfamily, is popularly known in Brazil as 'sucupira branca' or 'faveira' and comprises four native species: Pterodon abruptus Benth., Pterodon apparicioi Pedersoli., Pterodon polygalaeflorus Benth. and, Pterodon emarginatus Vogel. (synonym Pterodon pubescens Benth.).Interestingly, the species Pterodon emarginatus and Pterodon pubescens are in fact the same plant species.In 1862 this plant was classified as Pterodon pubescens by Bentham, but Vogel subsequently demonstrated that it was in fact the same plant species as that of Pterodon emarginatus.The species now bears the official name of Pterodon emarginatus Vogel.Unfortunately, it is commonly misidentified as being two distinct species (Carvalho, 2004).
In general, these species are native aromatic trees reaching 5-10 m in height distributed throughout the central region of Brazil (Goiás, Minas Gerais and São Paulo) (Oliveira, Paiva, 2005;Dutra et al., 2008a).These trees frequently grow in the Brazilian Cerrado and in transitional areas approaching the Paraná River basin's semi-deciduous forest.Despite their slow growth, these species are important in mixed reforestations designed to recover degraded areas (Oliveira, Paiva, 2005), due to their tolerance for direct sunlight and low soil fertility.
In mature seeds of some species, such as Pterodon emarginatus (Vogel), a distinguishing characteristic is the frequent presence of phenolic compounds in the integuments.Tests on these compounds have demonstrated their contribution to great hardness, low water permeability and high resistance to pathogen attack (Suárez, Engleman, 1980).Also, in mature seeds, the embryo show fleshy cotyledons, with accumulated lipid and protein reserves.
Although the 'sucupira' seeds are commercially available at the medicinal flora market and are widely used in domestic medicine for their anti-rheumatic (Sabino et al., 1999b;Coelho et al., 2004), analgesic (Coelho et al., 2005) and anti-inflammatory (Carvalho et al., 1999;Dutra et al., 2009) properties, only a small number of papers have described the various flavonoids, amino-containing, triterpene, steroid, and others secondary compounds present in the Pterodon genus.In addition, to the best of our knowledge, there is only one report available in the literature showing studies with proteins isolated from this genus, a 5 kDa α-amylase inhibitor reported by Silva et al. (2007).In this review, we have described the main chemical compounds studied to date and focused on establishing a relationship between these molecules and their biological activity.The Tables I to V summarize the main molecules published in the literature.

Biological properties
The active metabolites were isolated at the same time that the medicinal properties were investigated.In folk medicine, wine infusions from Pterodon genus seeds are used in the treatment of rheumatoid arthritis, an autoimmune disease characterized by chronic inflamed joints and exacerbated functions of macrophages and T and B  et al., 2008).Sabino et al. (1999b) and Coelho et al. (2004) have demonstrated the antiarthritic effect of hydro-alcoholic extract of P. pubescens seeds using the collagen-induced arthritis model (Table I).Also, these researchers have presented studies in vitro and in vivo demonstrating that acute administration of even extremely high doses of the oil of P. pubescens seeds are non-mutagenic, non-toxic, and non-cytotoxic to human peripheral blood mononuclear cells (PBMNCs) (Sabino et al., 1999a).In subsequent work, sub-acute toxic effects were not observed with hydro-alcoholic extract in studies of hematological, histopathological, clinical, and biochemical parameters in arthritic mice, according to studies of Coelho et al. (2001).Further analysis revealed the anti-inflammatory (Silva et al., 2004) and anti-nociceptive effects of ethanolic extracts of P. pubescens seeds, confirming the rationale behind the use of this plant in popular medicine to treat pain disorders (Coelho et al., 2005) (Table I).
The investigations on the pharmacological properties of 'sucupira' surpass those of its anti-inflammatory and anti-rheumatic activities.Dutra et al. (2008b) studied the total phenolic content and antioxidant activity of seeds of P. emarginatus (Table II).The phenolic constituents found  Mahajan, Monteiro, 1972;1973;Fascio et al., 1975;Arriaga et al., 2000 Mors et al., 1967 in vegetables have attracted considerable attention because of their antioxidant activity.The antioxidant activities of phenolics are mainly due to their redox properties, which allow them to act as reducing agents, hydrogen donors, and singlet oxygen quenchers.They have a metal chelation potential and play an important role in the adsorption or neutralization of free radicals.Buthanolic and methanolic fractions of the P. emarginatus seeds demonstrated a marked scavenging effect on DPPH radical (2,2-diphenyl-2-picrylhydrazyl hydrate).
Other studies have demonstrated the potential trypanocidal effect of the oleaginous ethanolic extract of P. pubescens seeds and its fractions (Menna-Barreto et al., 2008) (Table II).Trypanosoma cruzi is the causative agent of Chagas' disease, the parasitic infection that remains one of the leading causes of heart diseases in Latin America.Current treatment options for this disease involve two nitroheterocyclic compounds that present low efficacy and severe side effects.It is hoped that antiparasitic therapeutic agents can be identified from the plants through screening efforts aimed at discovering new molecules such as natural products, proteins and, peptides with recognized biological activity (Araújo et al., 2005;Hansen et al., 2007).
Also in the area of parasitic diseases, a group of Brazilian researchers demonstrated that the P. pubescens fruit essential oil inhibited the penetration of the cercaries of Schistosoma mansoni (Dos Santos-Filho et al., 1972, 1987;Katz et al., 1993).One of the compounds identified as a component of this oil was the 14,15-epoxigeranylgeraniol (3), a molecule isolated by Mors et al. (1967), and shown to be effective as a chemoprophyloactic agent in schistosomiasis.Mahajan and Monteiro (1973) also investigated the anti-cercaria action of P. pubescens while the other three species were studied by Fascio et al. (1975) (Table II).Almeida, Gottlieb, 1975;Braz Filho et al., 1971;Marques et al., 1998 Pa: Pterodon apparicioi; Ppo: Pterodon polygalaeflorus; Ppu: Pterodon pubescens Further biological activity data was presented by Neto (1973) during his doctoral research.He demonstrated that the oil obtained from P. pubescens seeds presented significant in vitro antimicrobial activity (Table II).
From the P. polygalaeflorus species, the diterpene 6α-7β-dihydroxyvouacapan-17β-oate was demonstrated to have an anti-inflammatory activity in the paw edema produced by carrageenin (Nunan et al., 1982) and, in subsequent studies, showed an important anti-nociceptive activity (Duarte et al., 1996) (Table I).The ethanolic extract from seeds showed significant larvicidal activity against the Aedes aegypti mosquito (De Omena et al., 2006) (Table II) and the hydro-alcoholic extract was the most active bronchodilator among those plants widely used in north-eastern Brazil for respiratory tract diseases (Leal et al., 2000) (Table I).

Toxicology
A paper written by Sabino et al. (1999a) presented a study in which the oil of P. pubescens seeds (PpSO) was tested for acute toxicity, mutagenic activity and cytotoxicity against human peripheral blood mononuclear cells (PBMNC).The study provided data to classify PpSO as non-cytotoxic to PBMNC, non-mutagenic and, nontoxic after acute administration, since the PpSO doses tested were significantly higher than those used by the population.
Also, the clastogenicity of 'sucupira oil' extracted from P. pubescens was tested in vivo on wistar rat bone marrow cells.Metaphase analysis showed that the compound did not induce a significant increase in the frequencies of chromosomal aberrations (Dias et al., 1995).

CONCLUSION
The broad biodiversity in Brazil places the country in a strategic position in the development and rational exploitation of new metabolites with therapeutic value.Areas of vegetation such as the Central Cerrado are rich in species of value in the search for natural compounds with activity against many diseases.The chemical characterization of these compounds, the determination of their mechanism of action and, the study of biological activities in vitro and in vivo, have yielded important information about the natural compounds and their derivatives.
The aim of this review was to present the studies involving the genus Pterodon and its natural compounds, with the goal of encouraging further investigation of these plants.The isolation and characterization of new molecules, and their correlation with new biological tests, provides fertile ground for the development of drugs for a large number of diseases.

TABLE I -
Biological activities in vivo of Pterodon spp.plant extracts/vouacapan derivative BE: buthanolic extract; EE: ethanolic extract; EO: essential oil; HAE: hydro-alcoholic extract; HE: hexanic extract; ME: methanolic extract; OEP: oleaginous extract mon member of the dihydroflavonol group (41).Details of these molecules are shown in Table

TABLE III -
Structure of the diterpenes based on molecule I, identified from the Pterodon genus

TABLE IV -
Structure of the diterpenes based on molecule II, identified from the Pterodon genus

TABLE V -
Structure of the isoflavones based on molecule III, identified from the Pterodon genus