INTRODUCTION

Ugni molinae Turcz. known as "Multilla", "Murta", "Mutilla", 'Myrtle berry'', ''Chilean cranberry'' or ''Chilean guava'', is a deciduous wild growing shrub that belongs to the Myrtaceae family. Henceforth, this berry will be referred as murta. It grows in the southern regions in the coastal mountains of Chile, the Andean Mountain foothills, and also in some regions of Argentina and Bolivia (^{Hauser et al., 2014}; ^{Alfaro et al., 2014}). Murta berries can be consumed during the summer as fresh fruits or used to produce jam, syrup, desserts and liquor (^{Seguel et al., 2000}). In Chile, even before the arrival of the Spaniards in 1536, the indigenous population of the area used this fruit as part of their diet and for the production of alcoholic beverages (^{Barreau et al., 2016}). As dried fruits, murta can be used in food preparations or herbal infusions (^{Puente-Díaz et al., 2013}; ^{Rodríguez et al., 2014}).

Apart from its nutritional properties, murta fruit and leaves have been used for a long time as a medicinal plant by Chilean indigenous peoples, such as Mapuche, Puelche and Pehuenche, who used leave infusions to treat dysentery (^{Hauser et al., 2014}) and urinary tract infections. Murta berries have also been used for its astringent and stimulant properties (^{Schreckinger et al., 2010}). Some animal studies have revealed analgesic, antiaging and anti-inflammatory properties in leaves of Ugni molinae (^{Delporte et al., 2007}). The beneficial properties of extracts obtained from murta are partly due to the presence of different phenolic compounds (^{Romaní et al., 1999}). Murta berries have a rich and diversified composition of bioactive compounds with health-promoting properties that have been intensively studied (^{Rodríguez et al., 2014}). The relatively high content of polyphenolic compounds found in murta berries could be used as a new potential source of antioxidants (^{Puente-Díaz et al., 2013}). In addition, these berries can be considered as an important source of vitamins, minerals and dietary fiber (^{Ah-Hen et al., 2013}).

Due to an increase in the commercial value of murta in the domestic market, the Chilean Institute of Agricultural Research (INIA) developed a program in 1996 aimed at studying the domestication of this species, consisting of the collection of wild germplasm and the development of protocols for the regeneration and multiplication of plants, including the evaluation of the agronomic potential of these fruits (^{Seguel et al., 2000}; ^{Alfaro et al., 2013}). INIA researchers carried out the molecular characterization of the wild germplasm collected in order to study the genetic diversity of this species, so as to complete its phenotypic and agronomic characterization (Alfaro et al., 2013). This review article covers the most important aspects of murta (Ugni molinae) berry including the composition and biological activities.

BOTANICAL BACKGROUND

Murta is an aromatic species belonging to the Myrtaceae family that typically dwells near the coastal and pre-Andean mountains of South America. It can also grow in subtropical regions, such as the Juan Fernández Island, but it can even grow in relatively desolate areas, such as sites of old lava flows, which indicates that it is a versatile plant (^{Schreckinger et al., 2010}; ^{Retamales et al., 2014}). Some specimens of murta are also found in western Argentina, and certain regions of Bolivia (^{Scheuermann et al., 2008}).

In Chile, murta grows in an area between southern Talca (Maule Region) (34°41'-36°33' S) and Palena (Coyhaique Region) (43°15'-43°45' s) (Fig. 1C). It is known as "murta" in the zones of Valdivia and Chiloé, as "murtilla" in Concepción surroundings and as "uñi" by Mapuche people

(^{Fredes, 2009}; ^{Retamales et al., 2014}).

This species was identified and classified for the first time by Western botanists in 1844 (^{Rubilar et al., 2006}). There are two new murta plant varieties grown in Chile, named as South pearl-INIA and Red pearl-INIA (^{Ah-Hen et al., 2013}). Different ecotypes of this plant develop a variety of fruit colors including soft green, yellow, fuchsia (purplish), light and dark red (^{Scheuermann et al., 2008}).

Murta is a wild rounded shrub (Fig. 1A) reaching up to 2 meters high. The plant has opposite leaves of about 1.7 cm long, which are generally ovoid and pointed. The plant produces a small globoid berry (Fig. 1B) that develops on a seasonal basis from March to May (^{Alfaro et al., 2014}). Fruit equatorial diameter ranges from 0.71-1.31 cm (Alfaro et al., 2013), while weight ranges from 0.25 and 0.40 g The number of seeds per fruit varies greatly depending on the region in which the plant grows, with an average of 16.08 ± 10 seeds per fruit (^{Torres et al., 1999}).

The characteristic aroma of murta berries may be described as fruity, combining the sweetness of a strawberry (Fragaria * ananassa ) with the pungency of a guava (Psidium guajava L.), and the texture of a dried blueberry (Vaccinium corymbosum L. ) with floral note due to volatile compounds similar to those found in many aromatic tropical and traditional fruits widely consumed around the world (^{Ah-Hen et al., 2013}).

COMPOSITIONAL CHARACTERIZATION

Many factors affect the physicochemical properties of murta berries, including cultivar/ genotype, altitude, environmental conditions (climate, light, temperature, soil type and other conditions), etc. (^{Alfaro et al., 2013}). There is an apparent hybridization in murta, which has given rise to the generation of numerous ecotypes. This suggests the existence of a high variability in the physicochemical parameters of the fruit (^{Torres et al., 1999}). Moreover, the stage of maturity that affects the overall nutritive quality of murta berries also depends on the agro-ecological zone where the plants grow. Ripening lasts from mid-February to mid-March in the Maule Region (34°41'-36°33' S); from March to April in the Araucanía Region (location 37°35'-39°37' S); and from April to May in the Los Lagos Region (location 40^e15'-44^e14' S), especially in Chiloé Island (Fig. 1C) (Torres et al., 1999).

The nutritional composition of murta berries is shown in Table 1. Sugars are among the most important compounds that determine fruit quality. During the early period of berry growth, the fruit accumulates sucrose (^{Conde et al., 2007}). However, glucose and fructose content increase with ripening. At the ripeness stage, the fruit produces a disaccharide (sucrose) and it is transformed into molecules of two monosaccharides (glucose and fructose), increasing its sugar concentration. The highest soluble solid content (10-27°Brix) was found in the berries grown in Region del Maule (Chile) and this berries contain a high amount of dietary fiber (20.0%) (^{González, 2009}).

Fig. 1 (A) Murta shrub; (B) Murta (Ugni molinae) berries. 

Another important component of murta is pectin, which is a valuable functional food ingredient widely used as gelling, emulsifying and stabilizing agent. Nowadays, its high content of pectin (0.32-1.14%) allows preparing jam, jellies, infusions and liquor from this fruit. A fraction of this pectin is of high molecular weight, low neutral sugar content, and high degree of methoxylation, which increases the potential use of murta berries (^{Taboada et al., 2010}). There are only a few reports regarding the content of vitamins and minerals in murta fruit. ^{Moraga (2008}) found that murta berries contain 4.53-12.55 mg of vitamin C (Vit. C) in 100 g of fresh berries., while ^{Merino (2002}) and ^{Schmidt-Hebbel (1990}) found calcium, phosphorus and potassium in murta berries.

The content of vitamin C in murta is very low but it influences on the acceptance and palatability of this fruit on consumers, since it has a high antioxidant power, which becomes protective of tissues and cells of our body that are helpful for development of strong connective tissues and provides protection to the immune system against attacks of some pathogenic microorganisms, among others (^{Iqbal et al., 2004}). More than 85% of Vit. C in human diets is supplied by fruits and vegetables (^{Davey et al., 2000}; ^{Lee and Kader, 2000}) like the berries.

Calcium (Ca) is an essential mineral for human health, partaking in the biological functions of several tissues (musculoskeletal, nervous and cardiac system, bones and teeth, and parathyroid gland). In addition, Ca may act as a cofactor in enzyme reactions (fatty acid oxidation, mitochondrial carrier for ATP, etc.) and it is involved in the maintenance of the mineral homeostasis and physiological performance in general (^{Morgan, 2008}). Phosphorus (P) is closely related to Calcium homeostasis and also related to bone and teeth formation and the majority of the metabolic actions in the body, including kidney functioning, cell growth and the contraction of the heart muscle (^{Renkema et al., 2008}). Potassium (K) plays a role in the maintenance of the balance of the physical fluid system and assisting nerve functions through its role in the transmittance of nerve impulses. It is also related to heart activity muscle contraction (^{Lambert et al., 2008}). Unfortunately,thereis still no information about the mineral content of murta.

Table 1 Compositional characterization of murta. 

Finally, murta seed oil is rich in linoleic acid. The composition of the fatty acids present in the seed oil has a high degree of unsaturation. It has a high content of linoleic acid but it does not contain linolenic acid (^{Torres et al., 1999}), which means that these seeds could be a potentially good source of edible oil and may become a dietary supplement of good quality.

BIOACTIVE COMPOUNDS

The chemical composition of murta varies depending on climatic conditions during growth. Extreme climate conditions promote polyphenol synthesis (^{Schreckinger et al., 2010}). The phytochemical composition of murta includes a wide variety of phenolic compounds in the leaves and fruits as well as pentacyclic triterpene acids (alphotolic, corosolic, and asiatic acid) in the leaves (Table 2). Phenolic compounds are categorized into classes depending on their structure, and subcategorized within each class according to the number and position of the hydroxyl group and the presence of other substituents (^{Jimenez-Garcia et al., 2013}).

The main phenolic compounds in berries are flavonoids (anthocyanins, flavonols, flavanols), condensed and hydrolyzable tannins, stilbenoids (resveratrol), and phenolic acids. A study conducted by ^{Alfaro et al. (2014}) showed that the phenolic compounds in murta fruit possess antioxidant and antimicrobial activity.

Besides, there are 24 volatile compounds of the murta fruit aroma that have been elucidated, of which the major components are methyl 2-methyl butanoate, ethyl butanoate, ethyl 2-methyl butanoate, methyl hexanoate, ethyl hexanoate, methylbenzoate, and ethyl benzoate are (^{Schreckinger et al., 2010}).

Anthocyanins

Anthocyanins are a group of red, purple, violet and blue water soluble polyphenolic plant pigments widely distributed in berry fruits, which can act as antioxidants or free radical scavengers, thus preventing oxidative stress (^{Gorinstein et al., 2013}; ^{Brito et al., 2014}) and cardiovascular disease risk (^{Junqueira-Gongalves et al., 2015}). Anthocyanins are also of technological interest due to their impact on the sensorial characteristics of food products.

Table 2 Some polyphenolic compounds reported in murta. 

Anthocyanins in murta berry fruits were accurately detected and identified using HPLC with UV-visible detection and high resolution time of flight mass spectrometry (HR-ToF-MS). The anthocyanins identified in the berries were mainly 3-O-glycoside conjugates and their derivatives (^{Brito et al., 2014}). In addition ^{Rubilar et al. (2011}) identified cyanidin-3-glucoside and peonidin-3-O-glucoside. Cyanidin-3-glucoside and peonidin-3-glucoside reach a total concentration of about 1 |jmol g^-1 of dry matter (^{Ruiz, 2008}).

Other phenolic compounds

Murta berries also have high contents of other phenolic compounds, but these levels are lower than those of anthocyins. The content of flavonols composition has been the subject of many studies. The amount of flavonols observed in murta fruit is two times higher than those in maqui (Aristotelia chilensis) and calafate (Berberís microphylla) fruits, being quercetin derivatives the most abundant flavonol (^{Ruiz et al., 2010}). ^{Shene et al. (2009}) reported myricetin glucoside, quercetin glucoside, quercetin glucuronide and quercetin dirhamnoside in a 50% water/ethanol murtilla fruit extract (^{Alfaro et al., 2014}). Twelve flavonol compounds have been identified in murta berries (Table 2). The highest amounts of these compounds correspond to caffeic acid-3-glucoside, quercetin-3-glucoside and quercetin. ^{Peña-Cerda et al. (2016}) identified 92 phenolic compounds in murta leaves and reported that gallic acid, myricetin, and quercetin were the most abundant ones.

Caffeic acid is one of the most common phenolic acids in fruits and grains. It is also present in dietary supplements for human consumption. Some glycosylated derivatives of caffeic acid are responsible for different biological activities, such as suppression of humoral and cellular immunity (^{Junqueira-Gongalves et al., 2015}).

Quercetin is one of the most abundant flavonols in the human diet and it has both chemical and biological properties (^{Junqueira-Gongalves et al., 2015}).. In recent times, many of its benefits for health have been confirmed, including protection against various forms of cancer, cardiovascular diseases and neurodegenerative diseases (Junqueira-Gongalves et al., 2015). Studies have shown that quercetin also exhibits anti-inflammatory, antibacterial and relaxing muscle activities (^{Erlund, 2004}). Furthermore, this compound has been described as a potent competitive inhibitor of certain cytochromes P450 enzymes and sulfotransferases (^{Harbone and Williams, 2000}; Junqueira-Gongalves et al., 2015), a potent anticancer agent in human studies (^{Shih-Li et al., 2006}) and a strong antioxidant that can contribute to the prevention of atherosclerosis (Junqueira-Gongalves et al., 2015). In addition, it has been demonstrated that it reduces the carcinogenic activity of several cooked food mutagens, enhances the anti-proliferative activity of anticancer agents, and inhibits the growth of tumor cells (Junqueira-Gongalves et al., 2015).

Other minor bioactive compounds in murta berries were rutin, gallic acid, quercitin, luteolin, kaempferol, kaempferol-3-glucoside, luteolin-3-glucoside, p-coumaric acid and myricetin. Kaempferol is considered as a powerful antioxidant, with beneficial effects that include anti-tumor, anti-inflammatory, and anti-ulcer activity (^{Junqueira-Gongalves et al., 2015}). Quercitin and rutin have shown strong antioxidant and antibacterial effects, which may protect the cells of the colon (Junqueira-Gongalves et al., 2015). In addition, there is evidence that quercitin decreases phototoxicity of hypericin and fagopyrin, which are substances found in St. John's wort (Hypericum perforatum L.) and buckwheat (Fagopyrum esculentum Moench), respectively (Junqueira-Gongalves et al., 2015).

Previous works have shown that murta leaf extracts contain hydroxybenzoic acids, flavan-3-ols, glycosylated flavonols (^{Rubilar et al., 2006}) and triterpene acids (^{Aguirre et al., 2006}). The analgesic properties of murta infusions are associated with both flavonoid glucosides and triterpenoids (^{Delporte et al., 2007}). Rubilar et al. (2011) have conducted an analysis of leaf extracts of this berry, describing hydrobenzoic acid derivatives, quercetin dirhamnoside and myricetin rhamnoside as the main compounds, and several others that were not identified.

Triterpenoids

The phytochemical composition of murta leaves includes pentacyclic triterpene acids, such as alphotolic, corosolic, ursolic and asiatic acids (^{Schreckinger et al., 2010}). Triterpene acids present in murta leaves possess a potent anti-inflammatory activity, which is similar to that of synthetic non-steroidal anti-inflammatory drugs. Several recent reports on the topical anti-inflammatory activities of plant extracts have related the anti-inflammatory properties of plant extracts with the presence of triterpenoids, and more specifically to the very widespread and relatively abundant ursolic acid (^{Banno et al., 2004}; Banno et al., 2005; ^{Aguirre et al. 2006}).

In the last fifteen years, interest in pentacyclic triterpenoids has revived. ^{Aguirre et al, (2006}) have contributed to the knowledge that several 2a-hydroxy pentacyclic triterpene acids present in murta leaves have an interesting topical anti-inflammatory activity. ^{Wen et al. (2008}) stated that pentacyclic triterpenoids represent a new class of glycogen phosphorylase "a" (GPa) inhibitors, an enzyme that has a fundamental role in the release of glucose into the bloodstream through the glycogenolysis (Aguirre et al., 2006).

AROMA AND VOLATILE COMPOUNDS

Berries are receiving considerable attention in the aroma industry because of their flavor and aroma, which are frequently considered as exotic and stimulate consumption worldwide. Table 3 shows the concentration of the different volatile compounds identified in fresh murta fuit. ^{Schreckinger et al. (2010}) found that the main components in the aroma of murta fruit were methyl 2-methyl butanoate, ethyl butanoate, ethyl 2-methyl butanoate, methyl hexanoate, ethyl hexanoate, methylbenzoate, and ethyl benzoate. ^{Scheuermann et al. (2008}) and Schreckinger et al. (2010) reported t methyl 2-methyl butanoate, ethyl butanoate, methyl pentanoate, ethyl 2-methyl butanoate, methyl hexanoate, a-pinene, ethyl hexanoate, 1,8-cineole, D-limonene and methyl benzoate as common volatile constituents in different ecotypes of the plant (Table 3). Furthermore, Scheuermann et al. (2008) identified twenty four volatile aromatics in the murta fruits; these compounds were absorbed onto a Porapak Q column, where the filling material is a porous polymer of copolymers of ethyl vinybenzene and divinylbenzene, they reported the major volatile constituent is methyl hexanoate (97.2-250.5 |jg kg^-1 fresh weight), and is found in different ecotypes of murta.

The murta aroma is considered a mixture of tropical and traditional aroma constituents (^{Scheuermann et al., 2008}). Some volatile compounds, such as butyl acetate, ethyl 2-methyl butanoate, ethyl hexanoate, hexyl acetate methyl octanoate, ethyl benzoate, limonene and benzaldehyde, are present in the aroma of traditional fruits like apple, apricot, peach and pear. Nevertheless, a study conducted by Scheuermann et al. (2008) showed that there are other aroma compounds, such as ethyl 2-methyl propanoate, methyl and ethyl pentanoate, ethyl (2E)-but-2-enoate, ethyl 2-methyl butanoate, ethyl 3-methyl butanoate, methyl and ethyl benzoate, which are present in the aroma of tropical fruits like pitanga (Eugenia uniflora L.), umbu-caja (Spondias citherea), camucamu (Myrciaria dubia), araca-boi (Eugenia stipitata), cupuacu (Theobroma grandiflorum), murici (Byrsonima crassifolia L., Rich), cashew apple (Anacardium occidentale L.) and mango (Mangifera indica).

Table 3 Aroma volatile compounds released from four ecotypes of murta fruit (^{Scheuermann et al., 2008}). 

ANTIOXIDANT CAPACITY ASSESSEMENT

Nowadays, several scientific studies have demonstrated that regular intake of berries would reduce the risk of development and/or progression of several chronic diseases, including cardiovascular diseases, neurodegenerative, and certain forms of cancer (^{Seeram, 2008}; ^{Basu et al., 2010}). Nevertheless, there are few studies on native South American berries. A wide variety of methods has been applied to the study of the radical-scavenging activity, and the antioxidant activity of murta berries. Table 4 summarizes the different values obtained using different methods. The ABTS (2,2'-azino-bis(3- ethylbenzthiazoline-6-sulphonic acid) method resulted in higher values than DPPH (2, 2-diphenylpicrylhydrazyl) assay (^{Augusto et al. 2014}). The obtained antioxidant and oxygen radical absorbance capacity of fresh murta berries are 2.4-45.6 and 1.3-16.2 mmol Trolox equivalent (TE) 100 g^-1 dried matter, respectively (^{Rodriguez et al., 2014}).

The antioxidant activity of murta is also greater than that observed in Chilean maqui and calafate berries (^{Alfaro et al., 2014}). The potential of these berries is very promising; therefore, special attention should be given to their study by researchers and agro-entrepreneurs.

Phenolic compounds act as exogenous antioxidant systems, composed of molecules mainly from the diet, and are proposed to protect against oxidative damage by oxygen-derived free radicals and reactive oxygen species (ROS) (^{Lambert et al., 2008}). The ROS are involved in the mechanism that contributes to endothelial dysfunction and other metabolic disorders (^{Foncea et al., 2000}). Therefore, the antioxidant capacity of natural phenolic compounds could reverse these damages. The molecular mechanisms of the antioxidant property of phenols and flavonoids have not yet been fully elucidated, and are still a matter of considerable debate. However, it has been suggested that the ability of these compounds to partition in cell membranes and the resulting restriction on their fluidity could critically hinder the diffusion of the ROS, thereby decreasing the kinetics of free radical reactions (^{Arora et al., 2000}).

The high antioxidant capacity of berries is the most widely studied attribute among the biological properties of the fruit (^{Skrovankova et al., 2015}). In fact, one of the ways through which the harmful effects of oxidative stress can be prevented and counteracted is the daily consumption of natural antioxidants, like those of murta.

The antioxidant activity of bioactive constituents of murta berries has been assessed by in vitro assays measuring the ability to reduce and trap free radicals; their potential as antioxidant is usually measured by comparing it to that of a reference substance, usually Trolox (trade name of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, derivative of vitamin E) (^{Paredes-López et al., 2010}). A great diversity of methods has been applied to study both the radical-scavenging activity as well as the antioxidant activity of berry phenolic compounds, resulting in great differences in the outcome (^{Heinonen, 2007}). The antioxidant capacity of murta has been studied using some assays like oxygen radical absorbance capacity (ORAC) method, ferric-reducing/ antioxidant power (FRAP) method, and 2, 2-diphenylpicrylhydrazyl (DPPH) (^{Peña-Cerda et al., 2016}), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS+), among others (Paredes-López et al., 2010).

Table 4 Antioxidant capacity of murta. 

The ORAC assay has been used in the analysis of pure substances, mixture of natural antioxidants and also in biological tissues. Free radicals, which are highly reactive species, can cause chain reactions, and also oxidative damage to biological macromolecules. These reactions are generated during cellular respiration, giving rise to radicals, such as hydroxyl (OH') and superoxide (O₂'^-) (^{Dontha, 2016}). Antioxidants are the main organic defense against these species, and include enzymes such as catalase, and non-enzymatic compounds such as vitamin E, C, β-carotene, bilirubin, glutathione, which are generally consumed in the diet or as supplements. To know the level of circulating antioxidants, it is necessary to have a number of methods to establish radical trapping antioxidant capacity. Most of these methods determine antioxidants that are water-soluble. These include ORAC assays for measuring both the time and percentage of damage caused by the free radical (AAPH') to a fluorescent protein (R-ficoeritrina), manifesting its integrity in fluorescence intensity (Avello and Pastene, 2004). The highest ORAC values of fruits range from 10.0-25.0 mmol TE 100 g^-1 fresh weight, including murta (^{Speisky et al., 2012}).

DPPH is a rapid, inexpensive, convenient, and an accurate method to evaluate antioxidant activity. DPPH solutions have a violet color, and the delocalized unpaired electron is responsible for the strong absorption. Reduction reactions can be seen as decolorization. Results can be expressed as EC₅₀ (concentration of antioxidant that reduces 50% of the DPPH radical) or percentage of decolorization. The DPPH is a long-lived radical, and it is likely that the antioxidant response of biologically relevant antioxidants is different from that with the DPPH radical (^{Celli et al., 2014}).

The FRAP assay was introduced by ^{Benzie and Strain (1996}) and is based on a change in the oxidation state of iron under low pH. The pH 3.6 required for this analysis improves iron insolubility, although it could also decrease the ionization potential of some compounds needed for the electron transfer reaction. In general, antioxidant capacity measured by FRAP is poorly correlated to other assays, such as DPPH and ORAC (^{Celli et al., 2014}). Ultimately, the antioxidant activity in murta fruits has been related to high polyphenol levels (^{Alfaro et al., 2013}). High levels of flavonoids like flavan-3-ols (e.g. catechin and epicatechin), along with the anthocyanins cyanidin-3-glucoside and peonidin- 3-glucoside could be responsible for the high antioxidant activity observed in murta berry (Alfaro et al., 2013).

HEALTH BENEFITS

Murta fruit is known to relieve circulation disorders and increase visual acuity, especially at night. Furthermore, mastication of fresh fruit without skin is useful to treat conditions of the mouth, such as thrush and stomatitis (^{Suwalsky and Avello, 2014}).

Information from tradition coincides with the results of preliminary phytochemical studies, since polyphenolic compounds, such as flavonoids and tannins, have astringent and potentially antioxidant activity (Avello and Pastene, 2004; ^{Arancibia-Radich et al., 2016}). Murta possesses a complex blend of polyphenols with a wide distribution of molecular weights. Altogether, gallic tannins can be hydrolyzed to gallic acid, which partnered with flavonoids and catechins, contributing significantly to raise the antioxidant capacity of the plasma (Avello and

Pastene, 2004).

The antimicrobial and insecticide activities of vegetables are important in defending the plant itself and the projection of an applicable use against pathogens in various areas. For example, in the search for new antimicrobial drugs in the conservation of various products and as allelochemicals (non-nutritional secondary metabolites produced by living organisms) (^{Avello et al., 2009}).

Murta is a species that is not a usual target for pathogens. The plant possesses mechanisms highly effective including secondary metabolites, such as phenolics and saponin glycosides defense, which are not part of the defensive shackles of species, conferring an innate protection (^{Avello et al., 2009}). Therefore, murta leaf and berry extracts have shown a strong topical anti-inflammatory activity in mice due to the presence of several pentacyclic triterpene acids, including the 2-a-hydroxy derivatives alphitolic, asiatic, and corosolic acids (^{Aguirre et al., 2006}; ^{Schreckinger et al., 2010}; ^{Arancibia-Radich et al., 2016}).

It is known that polyphenols and many other natural antioxidants (vitamins, carotenoids and other endogenous constituents) may promote a better health. These antioxidants are capable of fulfilling a number of functional roles, acting as free radical scavengers, peroxide decomposers, singlet and triplet oxygen quenchers, enzyme inhibitors and synergists (^{Alfaro et al., 2013}). Polyphenolic compounds are known to be useful in formulating nutritional or medicinal supplements for the treatment of several diseases. An important activity of polyphenols is the inhibition of digestive enzymes, especially carbohydrate-hydrolyzing enzymes such as R-amylase and R-glucosidase. Inhibitors of these enzymes are able to retard carbohydrate digestion, thus causing a reduction in glucose absorption rate. Effective R-amylase and R-glucosidase polyphenol-type inhibitors from natural resources have been reported to be useful in reducing postprandial hyperglycemia (Rubilar

et al., 2006).

Recent studies have focused on the phenolic composition of murta leaf extracts, where this extracts were particularly active in preventing the growth of Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae bacteria (^{Aguirre et al., 2006}; ^{Schreckinger et al., 2010}).

Murta dry leaf extracts have also shown a nematicidal effect against the rot-knot nematode Meloidogyne hapla (Table 5), among other species (^{Schreckinger et al., 2010}).

Table 5 Biological activities of fruits and leaves of murta 

Besides, the effect of two different extractive solvents (water and 50/50 ethanol/water) on the growth of bacterium strains isolated from fecal samples was evaluated in vitro using disk diffusion tests. Isolates of sensitive gut bacteria were characterized through the partial sequence of 16S rDNA gene and enzymatic profiles. Finally, to relate sensitivity to the extracts and enzymatic capability, the profiles were compared to those of lactic acid bacteria that were found to be resistant to murta extracts in a previous study (^{Shene et al., 2009}). According to Shene et al. (2012) the average antimicrobial activity of penicillin was higher than that of the extracts. In general, the extracts and gentamicine exerted a similar antimicrobial activity. Murta extracts showed variable antimicrobial activity depending on both the strain and the solvent used for the extraction. The 50/50 ethanol/water extract exerted, in general, a higher antimicrobial activity than that of the water extract (Shene et al., 2012).

CONCLUSIONS

Murta (Ugni molinae Turcz.) is not a widely-known Chilean native species, but it has one of the richest sources of phenolic compounds with broad biological activities. This review has shown that murta berries and leaves have a rich and diversified composition of bioactive compounds, mainly phenolic compounds, where the main compounds found in berries and leaves are flavonoids (anthocyanins, flavonols, flavanols), condensed and hydrolyzable tannins, stilbenoids (resveratrol), and phenolic acids.

Moreover, most of the health attributes have been related to the phenolic compounds, therefore, murta leaf and berry extracts have proven to have shown a strong topical anti-inflammatory activity, antimicrobial activity, an analgesic affect and have strong antioxidant activity.

The properties given by bioactive compounds coming from murta offer many opportunities for their use in food industry. Most of the health attributes have been related to the phenolic compounds, but other components, such as terpenes, may also result in health benefits. Finally, further studies are needed to understand the beneficial effects reported to date.