Eugenia uniflora L . : potential uses as a bioactive plant

Arq. Inst. Biol., v.85, 1-9, e0752017, 2018 RESUMO: Os produtos naturais extraídos de plantas sempre exerceram papel importante na descoberta de substâncias bioativas. Este trabalho realizou uma revisão da literatura acerca das atividades biotivas da Eugenia uniflora L. (pitanga) como planta potencial em várias utilizações, podendo ser medicinal, antimicrobiana, antioxidante, inseticida e protetora. Foram encontrados trabalhos que comprovam a atividade antibacteriana do extrato de folhas de E. uniflora L. sobre Streptococcus, Staphylococcus aureus, Pseudomonas aeruginosa e Escherichia coli, além da presença de compostos antioxidantes, tais como fenólicos totais (antocianinas e flavonoides), a indução na proteção das plantas pelas fitoalexinas, bem como efeitos inseticida e anti-helmíntico pela utilização do seu extrato. Embora esses diferentes potenciais bioativos da pitangueira já tenham sido relatados, ainda são necessários mais estudos quanto à utilização de produtos naturais extraído de E. uniflora para o emprego em diferentes finalidades.


INTRODUCTION
Eugenia uniflora L., known as Surinam cherries, belongs to the family Myrtaceae, that has a wide diversity of plants, with 142 genera and 5,500 species (HEYWOOD et al., 2007;WILSON, 2011).Native to South America, the E. uniflora is widely distributed in Brazil, Argentina, Uruguay and Paraguay (CONSOLINI; SARUBBIO, 2002).This tree species can also be found in the southern United States, Caribbean islands, India, China, Egypt, Nigeria and Australia (WEYERSTAHL et al., 1988;KANAZAWA et al., 2000;BEZERRA et al., 2000).
As a plant with medicinal potential, the leaves and fruits of E. uniflora are known for their innumerable therapeutic properties.In Brazilian popular medicine, E. uniflora leaves and fruits have been widely used in the form of infusions to obtain exciting, antifebrile, antidiarrheal, antihypertensive and anti-rheumatic effects (AURICCHIO et al., 2007).CARVALHO (2006) also emphasizes that leaf tea or alcohol extract combats diarrhea, worm infestation, bronchitis, cough, fever, anxiety, and hypertension.
Research performed by SANTOS et al. (2015) evaluating the chemical composition of the essential oil obtained from young and mature leaves of E. uniflora from the city of Seropédica (Rio de Janeiro, Brazil), showed that leaf age influences the chemical composition and concentration of the substances present in the essential oil.The same authors verified the presence of sesquiterpenes, such as germacrone (35.59%), a substance found only in oil samples obtained from young leaves.Comparing this chemical composition with the essential oil samples extracted from the leaves of E. uniflora collected in Nigeria, it was found that the components and concentrations of the substances in the oil prove to be very complex.The percentage of the composition of essential oil constituents of the E. uniflora samples obtained from Nigeria were: atractylone (16.90%), curzerene (19.70%), selina-1,3,7-trien-8-one (17.80%), and furanodiene (9.60%) (SANTOS et al., 2015).COSTA et al. (2009) suggest that this difference in the composition and concentration of the substances in the oil can be determined by the edaphoclimatic conditions of each region.OGUNWANDE et al. (2005) andAMORIM et al. (2009) observed in their research that the hydroalcoholic extract of the leaves of E. uniflora diminishes the levels of the enzyme xanthine-oxidase linked to the appearance of gout.In addition, the hydroalcoholic extract of the leaves presents vaso-relaxing, antioxidant, antidiarrheal, hypotriglyceridemia, hypoglycemia, antibacterial property (OGUNWANDE et al., 2005;AMORIM et al., 2009) and antifungal actions (HOLETZ et al., 2002;VICTORIA et al., 2012).
The benefits attributed to E. uniflora are due to secondary metabolites endowed with potent antibacterial and antifungal activity in their leaves, including phenolic compounds such as flavonoids, terpenes, tannins, anthraquinones and essential oils (AMORIM et al., 2009).There is still limited information on the antiviral action of E. uniflora, although this activity has been also reported in other species of the genus Eugenia (SOOD et al., 2012).
In addition to antimicrobial properties, several plant species of the Myrtaceae family have been used as bioindicators of air quality (FURLAN et al., 2006;PINA;MORAES, 2007;ALVES et al., 2008).It has been also recommended the use of the E. uniflora tree for heterogeneous reforestation destined to the recomposition of degraded areas, of permanent preservation, aiming to provide food to avifauna (SCALON et al., 2001).
Due to the diversity of plants in Brazil, there are still few studies on the bioactive effects of the E. uniflora, being necessary more incentive, research and diffusion for adoption of the phytotherapic practice.The objective of this study was to make a bibliographical survey about the bioactive activities of E. uniflora, as a potential plant in the various uses, be it medicinal, antioxidant, insecticidal and protective.et al. (2016) showed in their study that the essential oil extracted from E. uniflora L. presented antimicrobial activity against six species of gram-positive bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus licheniformis, Bacillus subtilis, Enterococcus faecalis and Staphylococcus aureus (isolated number -10442), besides three species of gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and two species of fungi (Candida parapsilosis and Candida albicans).In this study, the species B. licheniformis was the most sensitive to E. uniflora essential oil, with minimal inhibitory concentration and minimum microbicide of 0.63 mg/mL.The authors also report that the biological activity of essential oils differs according to its geographical origin.Thus, they observed that samples of essential oils of Egyptian origin did not present significant antimicrobial activity under the tested microorganisms, except for the bacterium B. l icheniformis.On the other hand, they noticed antimicrobial activity of E. uniflora essential oil of Indian origin under gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Streptococcus faecalis and Staphylococcus albus).

SOBEH
Studies have shown that the extraction of E. uniflora essential oil from the same geographical origin may present different chemo-types for this species and that factors such as soil conditions, climate, seasonality and fertilization may influence the chemical composition and, consequently, the biological activity of essential oil (BASER; BUCHBAUER, 2010).
When testing the use of hydroalcoholic extracts of the green and mature fruit, as well as the infusion of the fresh E. uniflora leaf, OLIVEIRA et al. (2008) demonstrated the in vitro antibacterial activity of E. uniflora on Streptococcus bacterial strains.
NASCIMENTO ( 2013) also verified antibacterial activity of leaves and fruits (hydroalcoholic extract) of E. uniflora under strains of Staphylococcus aureus.The results showed in the disc diffusion test the formation of inhibition halos of 13 mm at concentrations of 100 and 50% for the hydroalcoholic extract of the leaves, confirming the antibacterial activity due to the formation of the halo being greater than 8 mm.For the hydroalcoholic extract of the fruits, there was the formation of inhibition halo only at the concentration of 100%.However, for the E. uniflora stem extract, at concentrations of 100, 50 and 25%, there was no inhibition halo formation.
When reviewing the bioactive effect of some plants, CATÃO et al. (2012) verified the medicinal effects of E. uniflora on gingival diseases caused by the agent Streptococcus mutans salivary in a group of 40 people aged 21 to 24 years, observing that the hydroalcoholic extract of the ripe E. uniflora fruit has similar efficacy to the dentifrice of Colgate Total 12 (Colgate-Palmolive, New York, United States) in the control group.
In the management of dairy cattle, two diseases have been the main causes of economic damages in the dairy activity: mastitis in milk matrices, caused by several microorganisms, being the most common agent Staphylococcus aureus; and diarrhea, considered one of the main causes of mortality in calves, caused mainly by the bacterium Escherichia coli.
When SILVA (2010) tested the antibacterial action of hydrometanolic extracts and essential oils of four species of plants (Eugenia uniflora, Baccharis dracunculifolia, Vernonia polyanthes and Matricaria chamomilla) on lineages of S. aureus and E. coli, he observed the effectiveness of extracts of E. uniflora and V. polyanthes on the two strains studied.For the S. aureus pathogen, extracts of E. uniflora and V. polyanthes had a minimum inhibitory concentration of 2.9 and 1.24 mg/mL, respectively.For the bacterial line E. coli, the extracts of E. uniflora and V. polyanthes had a minimum inhibitory concentration of 23.2 and 27.28 mg/mL, respectively.In relation to the oils, the most efficient were the essential oil of E. uniflora and rosemary of the field on S. aureus.
Another study verified the antimicrobial effect of E. uniflora crude extract in bacteria present in the water of a fish pond and bacteria present in the air.The authors observed that the crude ethanolic extract of E. uniflora presented an inhibitory action of 8% greater than the antibiotic amoxilin (positive control) for bacteria present in nursery water and 9% more efficient for bacteria present in the air (LORENZONI et al., 2012).HOLETZ et al. (2002) evaluated the antimicrobial activity of 13 medicinal plants of Brazil under bacteria and yeasts in vitro.Among the medicinal plants used, the authors showed that the crude hydroalcoholic extract of E. uniflora presented moderate antimicrobial activity for the bacteria Staphylococcus aureus and Escherichia coli with a minimum inhibitory concentration of 250 and 500 μg/mL, respectively.The same authors verified that, of the 13 evaluated plants, nine species (Psidium guajava, Eugenia uniflora, Punica granatum, Arctium lappa, Tanacetum vulgare, Mikania glomerata, Lippia alba, Piper regnellii, and Plantago major) presented antifungal activity under Candida krusei and Candida tropicalis, both with a minimum inhibitory concentration of 31.2 μg/mL, and moderate activity for Candida parapsilosis (125 μg/mL).AURICCHIO et al. (2007) demonstrated that E. uniflora extract has more expressive antimicrobial activity against Staphylococcus aureus, Salmonella choleraesuis and Pseudomonas aeruginosa.
It is noted that other species belonging to the genus Eugenia present bioactive compounds with antimicrobial activity in their composition.Studies by MAGINA et al. (2009) evaluated the antimicrobial activity of the essential oils of the leaves of Eugenia brasiliensis, Eugenia beaurepaireana and Eugenia umbelliflora under S. aureus, P. aeruginosa and E. coli.The results showed that the essential oils have antimicrobial activity that varied from moderate to strong, and they were more pronounced for E. umbelliflora and E. brasiliensis oils that strongly inhibited the growth of S. aureus with minimal inhibitory concentration of 119.2 and 156.2 μg/ mL, respectively.
Studies by THAMBI et al. (2013) evaluated in vitro the essential oil antimicrobial activity of E. uniflora (Myrtaceae) as gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Streptococcus faecalis and Staphylococcus albus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella aerogenes and Proteus vulgaris).The results showed that the oil has antimicrobial action against the four gram-positive microorganisms and is less active against gram-negative.G.S. Moura et al.CHAVASCO et al. (2014) evaluated the antimicrobial activity of raw extracts of leaves, fruits and seeds of Eugenia pyriformis Cambess (Myrtaceae).The authors showed that E. pyriformis leaf extract inhibited the growth of microorganisms Bacillus cereus, Bacillus subtilis, Enterococcus faecalis, Micrococcus luteus, Staphylococcus aureus, Enterobacter cloacae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhimurium, Serratia marcescens, Candida albicans and Saccharomyces cerevisiae, with the exception of Mycobacterium bovis and Mycobacterium tuberculosis.For the evaluation of E. pyriformis fruit extract, no activity was observed on the microorganisms P. mirabilis, E. coli, C. albicans, S. cerevisiae, M. bovis and M. tuberculosis, and the minimal inhibitory concentration results were between 12 and 50 mg/ mL.The authors also verified antimicrobial activity of the seed extract of the E. uniflora on 13 microorganisms of the 15 evaluated in the study.

Antioxidant action
Natural antioxidants, especially those of plant origin, have the potential protective effect on the human body against diseases associated with oxidative stress (ÖZEN et al., 2011), but also in nutraceuticals, bio-pharmaceutical and food industries (BRAITHWAITE et al., 2014;XIN et al., 2012) as preservatives.
Considering the pharmacological potential of leaf extract from E. uniflora, CUNHA et al. ( 2016) investigated the cytotoxicity and antioxidant activity of ethanolic extract of E. uniflora in human leukocytes and erythrocytes.The authors observed that the leaves of E. uniflora do not present cytotoxicity and genotoxicity to human cells at the concentrations tested (1-480 mg/mL).They also showed that the extract inhibited the free radical 2,2 diphenyl -1-picrilhydrazine (DPPH), in comparison with the ascorbic acid used as standard, suggesting that the chemical constituents in the plant extract reacted slowly with the DPPH radical, presenting antioxidant activity.The ethanolic extract of E. uniflora presented some polyphenolic compounds with high content, such as quercetin, quercitrin, isoquertin, luteolin and elagic acid, which may be at least partly responsible for its beneficial effects (CUNHA et al., 2016).BAGETTI (2009) andBAGETTI et al. (2011) analyzed the antioxidant capacity of the E. uniflora pulp (purple, red and orange) from Rio Grande do Sul, Brazil, and found that the orange pulps had a higher antioxidant effect than the red color pulps, and it was rich in carotenoids, while those of purple color presented a higher content of total phenolics, anthocyanins and high antioxidant activity, being considered as a source of bioactive compounds.According to MATSUMURA et al. (2000), these natural compounds present in the E. uniflora produce beneficial effects to the organism such as anti-inflammatory activity.SOBRAL-SOUZA et al. (2014) evaluated in vitro the antioxidant activity of E. uniflora and Psidium sobraleanum extracts by 2,2-diphenyl-1-picryl-hydrazila (DPPH) and thiobarbituric acid reactive substances (TBARS), besides quantifying phenols and flavonoids, demonstrating the protective effect of these compounds on heavy metals in cells of Escherichia coli and Candida albicans.The authors observed that the ethanolic extract of E. uniflora presented better antioxidant activity for the TBARS test with egg phospholipid, reducing the basal levels in the process of lipid peroxidation.
On the other hand, the hydroalcoholic extract of P. sobraleanum showed to be more efficient with significant inhibition in all the concentrations used, having as best result the concentrations of 40 and 10 μg/mL, when the oxidative stress was induced with the aid of iron sulphate II.For the evaluation of the protective effect, the authors concluded that the extracts, when in conjunction with iron II sulphate concentrations, did not present cytoprotective activity in vitro, and did not interfere in the bacterial strains survival profile (SOBRAL-SOUZA et al., 2014).HENTZE et al. (2004) point out that in most prokaryotic cells, as well as in eukaryotic cells, iron is an essential element for survival and propagation, presenting as a diverse group of hemoproteins involved in oxygen transport and storage, transfer of electrons and deoxyribonucleic acid (DNA) synthesis.
The total carotenoid and phenolic contents of the mature and semi-ripe E. uniflora fruits were determined spectrophotometrically.In mature purple cherry and in its film the anthocyanins, flavonols and total carotenoids were also determined.Phenolic compounds and total carotenoids in mature purple E. uniflora are found at higher levels than in red E. uniflora at the same maturation stage (LIMA et al., 2002).VICTORIA et al. (2012), in their study, verified the antioxidant activity of E. uniflora essential oil administered orally in rats, showing that there was reduction of lipid peroxidation in rat kidney and antioxidant activity.VELÁZQUEZ et al. (2003) carried out a study to prove the antioxidant properties of six plants used in popular medicine in Paraguay, including E. uniflora.In order to perform the experiment, the authors used rats that received the methanolic extract of aerial parts of the plants, in order to check the scavenger capacity of free radicals and their antioxidant activity.The results of the study led the authors to consider that the leaves of E. uniflora present high inhibitory activity of lipid peroxidation, superoxide ions and potent efficacy in the reduction of free radical 2,2 diphenyl -1-picrilhydrazine (DPPH).
Another study, carried out by LUZIA et al. ( 2010), confirmed that the E. uniflora seeds have high antioxidant potential.Using the ethanolic extract of E. uniflora seeds, the authors demonstrated values of maximum antioxidant activity and EC50 (concentration sufficient to obtain 50% of the maximum effect, estimated at 100%) of 92.15% and 30.72 mg.mL -1 , respectively.The phytochemical studies showed that the seeds had a high amount of total phenolic compounds.
According to OLIVEIRA et al. (2009), compounds with antioxidant action are known for their bioactive properties and include vitamins C and E, carotenoids, polyphenols, furanoids and thiols.E. uniflora is one of the fruits that have higher levels of total carotenoids (CAVALCANTE, 1991).

Plant protection effect
In recent years, the search for more sustainable alternatives in agricultural production has led many plant protection studies to evaluate the potential of medicinal plant derivatives in disease control, both for their direct effect on potential phytopathogens and for inducing defense mechanisms in plants (ITAKO et al., 2008;OOTANI et al., 2013).
The information on the effect of E. uniflora is still scarce in this sense.In one of the few studies, MAZARO et al. (2008) tested the potential of the E. uniflora plant on the induction of phytoalexins in soybean cotyledons (Glycine max).Besides the alcoholic extract, infusion, maceration and decoction were used.With the leaves of crocuses, it used the concentrations of 0.1; 1; 10 and 40%, in addition to essential oil.Water was used as control and chitosan (1%) as resistance inducer.The phytoalexins were able to induce phytoalexins in soybean cotyledons, responding to higher concentrations of the preparations.The essential oil presented a remarkable effect on the induction of phytoalexins, and it was superior to the other preparations.
MARQUES (2014) evaluated the potential of extracts and essential oil of E. uniflora in the control of Sclerotinia sclerotiorum, causal agent of the disease known as white mold.The author observed a direct inhibitory effect of E. uniflora derivatives on phytopathogen growth, as well as inhibition of necrosis formation in common bean leaves at 48 hours after inoculation.In addition, the inducing activity of the plantrelated proteins of the plants chitinases, β-1,3-glucanase, phenylalanine ammonia-lyase, peroxidases, and polyphenoloxidases was demonstrated, indicating the presence of bioactive molecules capable of reducing the severity of this disease in common bean.
The inducer effect of E. uniflora was demonstrated by XIN et al. (2012) in rice cultivation.The authors observed activity of linalool, a compound commonly found in essential oil of E. uniflora, as a defense inducer in rice in herbivory situations.
Studies by DOTTO et al. (2014) did not obtain promising results with hydroalcoholic extracts of E. uniflora leaves, marigold flowers (Calendula officinalis) and floral clove of India (Syzygium aromaticum) and Bordeaux syrup, applied in the strawberry preharvest on the induction of resistance to post-harvest diseases.

Insecticide action
Although pyrantharine derivatives have been reported with a potential bioactive effect on arthropods, research on their insecticidal action is still scarce.JUNG et al. (2013), in their work, evaluated the insecticidal activity of the Bordeaux syrup tree, in the concentration of alcoholic extract to 10%, noting a significant effect on the mortality of Atta laevigata Smith of 84.6% when compared with the control.SOUZA et al. (2008) evaluated the bioprospection of insecticidal substances native to the state of Mato Grosso do Sul, Brazil, analyzing the insecticidal effect of 10% Bordeaux syrup extract on adults of the weevil (Sitophilus zeamais), observing that on the fifth and tenth day after application of treatment there was mortality of adults around 20 and 30%, respectively.
A study by PEGORINI (2016), about different concentrations of E. uniflora essential oil (0, 0.25, 0.50, 0.75% 1.0, 1.25 and 1.5%) on larvae and adults of Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae) in vitro, observed that E. uniflora essential oil at 0.75% concentration caused 70.83% mortality in the larvae, not differing from the concentration of 1% that caused 50% mortality.For adults, there was no evidence of insecticidal action at the concentrations tested.

Anti-helminth effect
Worm infestation in sheep is one of the main causes of mortality, which causes high losses in sheep rearing in Brazil. HASSUM et al. (2013) found a promising result in the concentration of 200 mg.mL - of the E. uniflora extract, contributing to reduce the number of nematode larvae of the genus Trichostrongylus of gastrointestinal action to the species Haemonchus contortus, considered difficult to control by anthelmintic, available in the market.Therefore, the plant stands out as a bioactive plant with potential to be further researched and exploited.
OLIVEIRA (2003), studying the efficacy of different medicinal plants in the control of endoparasites of sheep, found that the combination of the plants Campomanesia guazumifolia (Camb.)Berg.+ Eugenia uniflora L. + Polygonum punctatum Ell., administered orally in sheep, showed efficacy in reducing the production of eggs of the super family Trichostrongyloidea of 63.52% and Strongyloides of 86.58% on the 14 th day after its application, thus contributing with lower levels of contamination in the pastures.It was also verified reduction of adult helminths of the genus Ostertagia, Trichostrongylus, Cooperia and Strongyloides.
Research by DIAS DE CASTRO (2014) verified the in vitro anthelmintic action of the aqueous and hydroalcoholic extract of E. uniflora on gastrointestinal nematodes of ruminants.The authors point out that the hydroalcoholic extract was more promising in inhibiting the hatchability of Haemonchus contortus (between 20.35 and 99.75%) when compared to aqueous extracts, in which inhibition of nematodes varied from 14.56 to 76.04%.With the objective of investigating compounds that are more effective in reducing the incidence of the protozoan belonging to the genus Leishmania, which causes cutaneous Leishmaniasis, RODRIGUES et al. (2013) investigated the potential of E. uniflora essential oil under the parasite forms of Leishmania, promastigote and amastigote, the mechanism of action and its cytotoxicity under these microorganisms.The authors concluded that essential oil extracted from the leaves of the E. uniflora, characterized by containing sesquiterpenes, has anti-Leishmania activity in both forms of the protozoan (amastigote and promastigote).In the determination of cytotoxicity, E. uniflora essential oil was 20 times more toxic for Leishmania amastigote forms than for phagocytic cells called macrophages.

Final considerations
There is still little information on the bioactive effects of E. uniflora in terms of plant protection and antifungal, antiviral and insecticidal activity.However, the results already obtained and the different properties and purposes of derivatives of this plant indicate its use potential and the importance regarding further studies on it.
G.S.Moura et al.