Biological activities associated with tannins and flavonoids present in Hymenaea stigonocarpa and Hymenaea courbaril : A systematic review

The genus Hymenaea belongs to the Fabaceae family and has species distributed from Central America to South America in the Amazon. The wood of these species are widely used in civil construction, as well as the leaves, roots, sap and bark to treat inflammatory and respiratory diseases, infections, tumors and pain. This systematic review aimed to identify the biological activities associated with tannins and flavonoids in Hymenaea courbaril and Hymenaea stigonocarpa . Thus, research articles published between 2009 and 2019 that directly address this topic were searched using the following descriptors: Hymenaea AND flavonoids AND tannins AND biological activities AND medicinal plant, in PubMed Central, Web of Science, Scopus and Science Direct databases. The results obtained suggest that tannins and flavonoids are among the main compounds involved with potential antifungal and termiticidal effects, in addition to antioxidant, antibacterial, antidiarrheal, antiulcer, anti-inflammatory, myorelaxant, antiviral and larvicidal action for Aedes aegypti . The phytochemical diversity of these plants and the various biological activities help to expand scientific knowledge about these species, contributing to the eventual production of new products and/or new technologies. H. courbaril also presented promising results in a study, showing expressive muscle relaxant activity from extracts and fractions obtained from the stem bark. The ethanol extract and the ethyl acetate fraction (obtained from the methanol extract) at concentrations of 1000 µg/mL produced a myorelaxant effect on the trachea of rats, decreasing the contraction of muscle tissue caused by carbachol and potassium chloride, with relaxation of 43.7% and 52.5% for the ethanol extract and 95.2 and 100% for the ethyl acetate fraction, respectively. The best result presented by the ethyl acetate fraction may be related to the presence of flavonoids that are the majority in products extracted with this organic solvent. corroborating this information, this study identified the flavonoid astilbine from the ethyl acetate fraction, which in isolation demonstrated a myorelaxant effect of 49.8% at a concentration of 1000 µg/mL. The authors also report that the ethyl acetate fraction showed myorelaxant effects of 46.98% at the concentration of 300 µg/mL. The authors suggest that these results may be mainly linked to astilbine, since it presented approximately half of the value shown by the fraction in isolation (Bezerra et al., 2013). H. constituents for use in the manufacture of products to combat biodegradation caused by


Introduction
Brazil has an extensive territorial area with about 8.5 million square kilometers (Ahmad et al., 2017) and is the country with the greatest biodiversity in the world with approximately 46.000 known plant species in the country, which are distributed in six terrestrial biomes (Amazon Forest, Pantanal, Cerrado, Caatinga, Pampa and Atlantic Forest) (Garcez et al., 2016;Lima et al., 2018). The rich Brazilian biodiversity is a source of resources for the country, not only for the ecosystem services provided, but also for the opportunities that represent its conservation, sustainable use and genetic heritage (Maranhão et al., 2013;Nahdi et al., 2020;Vieira et al., 2015).
The Fabaceae family is one of the largest and most important botanical families due to the large number of plant species used as a source of food, medicinal (Muthu et al., 2012), ornamental, timber and forage suppliers (Lacerda et al., 2014), fibers (Pluempanupat et al., 2013), dyes, gums, resins (Çam & Hişil, 2010) and oils (Luiz & Dinheiro, 2008). It is composed of 19,327 species distributed in 727 genera (Alves et al., 2019). This family consists of trees, shrubs, lianas and herbs, and has a cosmopolitan distribution (Bezerra-Silva et al., 2015). Brazil has about 2.827 species distributed in 222 genera, of which 1.524 species and 16 genera are endemic (Yadav et al., 2018).
Among its genera is Hymenaea, considered predominantly neotropical and consisting of a total of 16 species, of which 13 are found in Brazil (Dimech et al., 2013;Maranhão et al., 2013). The species of this genus of greater economic and medicinal importance in the North, Northeast, Midwest and Southeast of Brazil are Hymenaea courbaril and Hymenaea stigonocarpa, popularly known as "jatobás", and are mainly found in cerrado vegetation (Oliveira et al., 2010;Veggi et al., 2014). These trees are widely used by the population in civil construction, ornamentation and mainly for curing or alleviating gastric, inflammatory, infectious and pulmonary diseases through their resin, fruit, sap, stem tea or stem bark (Bezerra-Silva et al., 2015;Maranhão et al., 2013;Santana et al., 2010).
Studies carried out with different parts (stem, roots and leaves) of Hymenaea species show that they have tannins, flavonoids, coumarins, amino acids and some carbohydrates in their composition (Oliveira de Veras et al., 2020;Oliveira et al., 2010;Veggi et al., 2014), which could explain the curative effects of this genus and its popular use (Boniface et al., 2017;Lacerda et al., 2014;Pinto et al., 2017).
Given the above, this study aims to identify in the literature biological activities associated with tannins and flavonoids present in the species Hymenaea courbaril and Hymenaea stigonocarpa through a systematic review, as these classes of compounds have outstanding antioxidant, antimicrobial, and gastroprotective activities, among others.

Data selection
The review process began after conducting the research and extracting the articles from the databases, applying previously defined inclusion and exclusion criteria (Table 1). Titles and abstracts were subsequently evaluated, in addition to eliminating duplicates found in the databases. This was followed by a thorough reading of the chosen works, with the articles which were not within the scope of this work being eliminated. The bibliographical references of the selected articles were also analyzed in order to find possible works that could be included in this research.

Data extraction
Based on reading the selected works, the information sought the following indicators: species, extraction methods, class of compounds present, isolated compounds and biological activities.

Results and Discussion
First, a total of 59 articles were found in the initial stage performed in the databases, but after reading the titles and abstracts according to the inclusion and exclusion criteria and eliminating repeated articles, 47 articles were discarded. Given the above, only 12 articles were used in the development of step 2. The texts were subsequently read in full and only 6 articles were used in the construction of the discussion. In addition, 4 articles obtained from the reference list of publications were added ( Figure 1). The ten articles selected after applying the methodological procedures were separated into different categories (Montana et al., 2019): Biological activities associated with Hymenaea stigonocarpa and Hymenaea courbaril (  (Bezerra et al., 2013;Dimech et al., 2013) Source: Prepared by the authors. Research, Society and Development, v. 11, n. 12, e174111234196, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v11i12.34196 8

Biological activities
Studies report that the Hymenaea genus mainly has tannins and flavonoids as major compounds in its phytochemical composition, however, other minor compounds are present in species of this genus, such as coumarins, amino acids and some carbohydrates (Oliveira de Veras et al., 2020;Oliveira et al., 2010). According to the studies found in this review, H. stigonocarpa and H. courbaril especially presented compounds belonging to the flavonoid and tannins class in their phytochemical composition (Bezerra-Silva et al., 2015;Maranhão et al., 2013;Veggi et al., 2014).
According to some authors, such activities are directly related to the presence of flavonoids such as astilbine, taxifolin, hultenin, 7-methoxycathequin and quercetin isolated from extracts, powder and flour obtained from these species (Cecílio et al., 2012;Dimech et al., 2013;Maranhão et al., 2013).
However, other authors discuss that the anti-inflammatory, antitermitic and antimicrobial activities, in addition to being associated with the flavonoids present in H. stigonocarpa , are also directly linked to the presence of tannins present in this specie (Bezerra et al., 2013;Dimech et al., 2013;Maranhão et al., 2013).

Antioxidant activity
The metabolic imbalance which often affects the body is associated with increased formation of free radicals, which promotes lipid peroxidation, characterized by a primary cytotoxicity that triggers a sequence of damage to cell membranes, which can cause flaccidity, lysis or apoptosis. Damage to DNA ribbons as well as collagen fibers and premature aging are also some effects caused by excess free radicals. Compounds with plant-based antioxidant activities are sought in a therapeutic or preventive way, since studies report that the action of natural antioxidants can inactivate these radicals and also repair the damage caused by them (Orsi et al., 2014;Rodrigues Orsi et al., 2012).
The mechanism by which antioxidant activity is triggered by plant extracts is complex, however, it is mainly attributed to the presence of phenolic compounds such as flavonoids, tannins and phenolic acids (Veggi et al., 2014). Such compounds play a fundamental role as an antioxidant due to the presence of aromatic hydroxyl groups, which eliminate free radicals through oxi-reduction reactions (Oliveira et al., 2010).
A species which has been gaining notoriety for presenting with antioxidant activity in some studies is Hymenaea courbaril L. var. stilbocarpa (Cecílio et al., 2012). Flavonoids and tannins with potential antioxidant action (C. Veggi et al., 2013;Martinez-Correa et al., 2012) were found in ethanol extracts obtained from its leaves, as presented in the study by Veggi et al., (2014). These authors identified the presence of tannins (1.8 mg/100 g of raw material) in H. courbaril, as well as the presence of procyanidins, both with antioxidant activity against the DPPH method, with an EC50 of 0.2 mg/cm 3 .
Another study with H. courbaril using ethanol extract obtained from the stem bark, as well as ethyl acetate and methanol fractions, revealed the presence of flavonoids, tannins and anthocyanins. The presence of the flavonoid astilbine was identified in the ethyl acetate fraction. However, compared to the antioxidant activity analyzed by the DPPH method, both the ethanol extract and the ethyl acetate and methanol fractions showed expressive antioxidant activity with EC50 of 3.07, 5.05 and 5.12 μg/mL, respectively (Bezerra et al., 2013).
The ethyl acetate extract obtained from the heartwood of H. stigonocarpa presented quercetin, 7-methoxycathequin, taxifolin and hultenin with antioxidant capacity in its composition according to the DPPH test, presenting an EC50 of 9.95, 30, 78, 54.85, 61.65 and 78.80 μg/mL, respectively. Quercetin showed the best result among the isolated compounds when compared to other flavonoid molecules. However, it is noteworthy that ethyl acetate extract showed better results when compared to the compounds alone. The study authors suggest that there is possibly a synergistic mechanism between the flavonoid molecules present in the extract, enhancing the antioxidant effect (Maranhão et al., 2013).
In another study, the methanol extract obtained from the heartwood of the H. stigonocarpa species also showed expressive antioxidant activity, with 91.00% of DPPH radical scavenging. The collaborators report that it was possible to observe the presence of phenolic compounds such as tannins and flavonoids in this extract, and to them, the antioxidant action verified in this study was linked (Oliveira et al., 2010).
H. stigonocarpa also showed antioxidant action which caused a decrease in lipid peroxidation against cell membranes in the brains of two-month-old male Wistar rats. In this study, the authors identified that the methanol extract of H. stigonocarpa (obtained from the stem bark) demonstrated in vitro EC50 of 5.25 μg/mL. According to the authors, the result obtained may be linked to the presence of flavonoid compounds, as well as the presence of tannins with antioxidant capacities (Rodrigues Orsi et al., 2012).
Another study using H. stigonocarpa found that the methanol extract obtained from the pulp of its fruit also presented flavonoids and tannins with potential antioxidant activity, attenuating lipid peroxidation in the membranes of neural cells in Wistar rats in a dose-dependent manner. The in vitro antioxidant action for this evaluation demonstrated the EC50 value of 27.33 μg/mL (Orsi et al., 2014).
All results obtained according to data found in scientific articles reinforce antioxidant action found in H. courbaril and H. stigonocarpa. These results demonstrate that these species have biotechnological potential for formulating products with therapeutic purposes for treating diseases such as cancer, diabetes, Parkinson's and Alzheimer's caused by oxidative stress (Rodrigues Orsi et al., 2012).

Antidiarrheal, gastroprotective, anti-inflammatory, myorelaxant and antiviral activities
Biological activities associated with the species H. courbaril and H. stigonocarpa were evidenced in the literature, justifying the ethnopharmacological use of these plants. Studies report that species like these are promising in terms of maintaining human health through the treatment of various diseases (Bezerra-Silva et al., 2015;Orsi et al., 2014). These studies also mention that the biological activities associated with these species are correlated with the classes of major compounds which compose the phytochemistry of these plants, such as flavonoids and tannins (Bezerra-Silva et al., 2015;Oliveira et al., 2010).
Contributing to the above information, a study using methanol extract obtained from the stem bark of H. stigonocarpa at doses of 100, 150 and 200 mg/kg produced an antidiarrheal effect in mice with percentages of 61, 50 and 53%, respectively.
In addition to this effect, the methanol extract also demonstrated gastroprotective effects at doses of 200 mg/kg. The authors report that this species has a promising profile for treating ulcers and digestive tract inflammation, however, other studies still need to be conducted (Rodrigues Orsi et al., 2012).
H. stigonocarpa also demonstrated anti-inflammatory effect from methanol extract (obtained from the fruit pulp flour).
In this study, the authors report that mice which were treated with 10% of the methanol extract of H. stigonocarpa, in addition to having the intestinal inflammatory process attenuated, gained weight. The authors point out that the mice showed a significant reduction in the extent of the intestinal lesion at the dose of 100 mg/kg, as well as attenuation of diarrheal conditions. The methanol extract at the concentration of 200 mg/kg showed an effect of reducing adhesion to adjacent organs, as well as decreasing malondialdehyde levels. However, it was possible to observe inhibition of myeloperoxidase activity at the concentration of 400 mg/kg. It was also observed that there was depletion in the glutathione and alkaline phosphatase levels in the colon at doses of 100, 200 and 400 mg/kg, indicating anti-inflammatory activity. The authors report that the results found may be linked to the flavonoids and condensed tannins found in the methanol extract (Orsi et al., 2014).
H. courbaril also presented promising results in a study, showing expressive muscle relaxant activity from extracts and fractions obtained from the stem bark. The ethanol extract and the ethyl acetate fraction (obtained from the methanol extract) at concentrations of 1000 µg/mL produced a myorelaxant effect on the trachea of rats, decreasing the contraction of muscle tissue caused by carbachol and potassium chloride, with relaxation of 43.7% and 52.5% for the ethanol extract and 95.2 and 100% for the ethyl acetate fraction, respectively. The best result presented by the ethyl acetate fraction may be related to the presence of flavonoids that are the majority in products extracted with this organic solvent. corroborating this information, this study identified the flavonoid astilbine from the ethyl acetate fraction, which in isolation demonstrated a myorelaxant effect of 49.8% at a concentration of 1000 µg/mL. The authors also report that the ethyl acetate fraction showed myorelaxant effects of 46.98% at the concentration of 300 µg/mL. The authors suggest that these results may be mainly linked to astilbine, since it presented approximately half of the value shown by the fraction in isolation (Bezerra et al., 2013).
A reduction in the cytopathic effect against rotavirus (one of the main causes of diarrhea in children and infants) was also evidenced from 500 µg/mL of ethanolic extract of H. courbaril (obtained from dehydrated leaves). According to the authors, the decrease in cytopathic effect caused by rotavirus in the MA-104 cell line (rhesus monkey kidneys) was mainly associated with the presence of flavonoid compounds, as well as the existence of tannins in its composition. The researchers of this study also discuss that one of the possible mechanisms by which this effect occurred may be due to the complexation of proteins vital to replicating the rotavirus (Cecílio et al., 2012).

H. stigonocarpa extracts and fractions obtained from the bark of this species showed a bactericidal effect against
Staphylococcus aureus (ATCC 33591), presenting minimum inhibitory concentration between 64 to 256 μg/mL. The bacteria showed structural changes after treatment, such as rupture of membranes and cell wall, leakage of materials into the cytoplasm, as well as molecular changes in nucleic acids, proteins and ribosomes. The authors also report that the presence of the flavonoid astilbine was identified in all samples, suggesting that it is the major compound present in the bark of H. stigonocarpa wood (Dimech et al., 2013).
A study using the milled heartwood of H. stigonocarpa, in addition to identifying the presence of flavonoids and tannins in its composition, also showed that this species presented natural resistance against the fungus Phanerochaete chrysosporium. In this study, the authors observed that the fungus, did not show mycelial growth when in contact with the ground heartwood of H. stigonocarpa. It is noteworthy that the microorganism used is one of those responsible for tree decay, degrading the main components of wood such as lignin and cellulose. According to the authors, the natural resistance presented by the milled heartwood of H. stigonocarpa may be mainly associated with the flavonoids found. These results suggest that H. stigonocarpa has antifungal potential, being able to treat plants with low durability to the attack of wood-reducing microorganisms (Oliveira et al., 2010).

Larvicide and antithermitic activities
Cyclohexane extract (obtained from H. stigonocarpa heartwood) at concentrations of 300 and 500 µg/mL showed larvicidal activity against Aedes aegypti mosquito larvae, the main vector of dengue, with 50% and 100% mortality of the larvae, respectively. The authors of this study report that the extract presented methoxylated flavonoids with possible larvicidal activities in its composition, which makes H. stigonocarpa a potential candidate to fight the dispersion of this dengue vector (Bezerra-Silva et al., 2015).
In addition to larvicidal activity, H. stigonocarpa also showed antithermitic activity through the cyclohexane extract (obtained from H. stigonocarpa heartwood) which was active against termites of the Nasutitermes corniger species, having Research, Society and Development, v. 11, n. 12, e174111234196, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v11i12.34196 median lethal concentration of 11.9 mg/mL, in 4 days . The authors report that the activity presented in this study may be correlated with the presence of methoxylated flavonoids in the cyclohexane extract. These researchers also report that methoxylated flavonoids, in addition to having antioxidant activity, can also interfere with the digestion of lignocellulose in termites, which could be one of the reasons why termites would avoid these wood species.
The ethyl acetate extract (obtained from H. stigonocarpa heartwood) also showed anti-termite activity against N. corniger species. As a result, the extract at the concentration of 100 mg/mL caused 70% termite death within 5 days. The authors report that the data suggest that the presence of four flavonoids (hultenin, taxifolin, quercetin and 7-methoxycathequin) in the composition of this extract was correlated with antithermitic activity. It is noteworthy that quercetin in isolation also demonstrated anti-termite activity, with 55% of termite death within 5 days. According to the researchers, no significant differences were detected between hultenin, taxifolin and 7-methoxycathequin for the outcome of termite death, which could lead to the understanding that quercetin may be the main flavonoid responsible for the antithermitic activity of the ethyl acetate extract of H. stigonocarpa (Maranhão et al., 2013).
The scarcity of studies involving H. courbaril and H. stigonocarpa is observed, in addition to the lack of phytochemical characterization of these species. being even more evident the lack of records of biological activities attributed to H. courbaril as illustrated in Figure 2.

Conclusion
In this review, it was possible to observe the biological activity presented by the species H. courbaril and H. stigonocarpa, with emphasis on flavonoids and tannins. Based on the number of articles available in the scientific literature, it can be observed that phytochemical studies with these plant species are scarce. Only the heartwood constituents of H. stigonocarpa have been studied with respect to their activity against xylophagous organisms (white-rot fungi and termites).

H. stigonocarpa
The results make these constituents candidates for use in the manufacture of products to combat biodegradation caused by either fungi or termites.
Thus, from the information presented on the species H. courbaril and H. stigonocarpa, it is possible to observe that they have economic and medicinal importance, however, very few has been explored. For this reason, further studies are needed to better understand the biological activity of these species.