In Brazil, plants of the genus Byrsonima (Malpighiaceae) represent a rich source of catechin and epicatechin derivatives and are used in folk medicine for the treatment of gastric ulcers, inflammation, skin infections, fever and asthma. They are popularly known as “murici-vermelho” or “murici-cascudo” and grow wild in the cerrado (savannah-like) vegetation of Brazil. Byrsonima species have been scientifically proven to possess several pharmacological properties, such as antiulcerogenic, mutagenic and antimicrobial activity .
The results of this study demonstrate an absence of any mutagenic activity in leaf extracts of B. verbascifolia, B. correifolia, B. fagifolia and B. intermedia, at all the concentrations tested on the four S. typhimurium strains, since the number of revertant colonies observed on each test plate was less than twice that in the negative control . However, B. coccolobifolia extract doubled the number of revertant colonies in strain TA98, both in the presence and in the absence of metabolic activation, suggesting an ability to cause frameshift mutations, before and even after being metabolized. In strain TA97a, the dose–response for B. coccolobifolia went up to a mutagenicity ratio of 1.9, giving evidence of mutagenicity. B. ligustrifolia also doubled the number of revertant colonies in strain TA98 in the absence of metabolic activation and can be considered an inducer of frameshift mutations.
In a previous study, we showed that a MeOH extract of B. crassa exhibited mutagenic activity in the Ames test. The following compounds were isolated from the acetate fraction: quercetin-3-O-β-D-galactopyranoside, quercetin-3-O-α-L-arabinopyranoside, amentoflavone, methyl gallate and (+)-catechin. Among these, only amentoflavone exhibited positive mutagenicity. Therefore, this compound contributes to the mutagenic activity observed in the MeOH extract .
In another study, MeOH, hydromethanol and chloroform extracts of B. intermedia were assessed for mutagenicity by the Ames test and mutagenic activity was not positively identified, in any extract, but the MeOH extract showed signs of mutagenicity to the strains TA98 (+S9,-S9) and TA100 (-S9). The values of the MR were close to 2, and the dose–response effect was significant. Phytochemical analysis of the MeOH extract furnished (+)-catechin, (-)-epicatechin, quercetin-3-O-β-D-galactopyranoside, methyl gallate, gallic acid, quercetin-3-O-α-L-arabinopyranoside, amentoflavone, quercetin, quercetin-3-O-(2”-O-galloyl)- β -galactopyranoside and quercetin-3-O-(2”-O-galloyl)- α -arabinopyranoside .
Comparing the compounds in the MeOH extracts of B. intermedia with those from B. crassa , similar profiles were observed, but a difference was seen in the flavonol concentration and the difference in the amentoflavone content explained the results obtained. In B. crassa, mutagenic activity was observed and the main compound of the extract responsible for this effect was amentoflavone . In B. intermedia, this biflavonol is also present, but in smaller amounts, explaining the signs of mutagenic activity obtained in the assays with Salmonella .
Quercetin is a compound that is always present in Byrsonima extracts [4–6]. It is a flavonoid known for its mutagenic potential. Resende et al.  showed that quercetin is highly mutagenic in TA98, TA100 and TA102. This compound has been observed to induce a mutation ratio of 20.4, suggesting that quercetin contributes to the mutagenic potential of this genus.
For the hydroalcoholic extract of B. intermedia and B. fagifolia, the results obtained here are also similar to results described for the MeOH extract [5, 17]. This fact suggests that the MeOH and hydroalcoholic extracts are similar in composition.
The detection of genotoxicity is highly advisable, so as to avoid the risk of genotoxic exposure to mutagens and carcinogens. However, some genotoxic compounds cannot be completely avoided because they are air pollutants, or some might be ingested as food contaminants. Also, some therapeutic drugs belong to an important group of genotoxic compounds. Antimutagenicity studies have been developed to diminish the risk in the event of genotoxic exposure . There have been several reports in the literature, that medicinal plants or fruit juices have components such as polyphenols, vitamins, chlorophylls, terpenes and unknown organic compounds, which are described as antimutagens and perhaps anticarcinogens .
In the present study, the B. verbascifolia and B. correifolia extracts acted as strong antimutagens against NPD, with inhibition up to 48% and 51% of induced revertants, respectively. B. fagifolia and B. intermedia were moderately antimutagenic, and their percentages of inhibition reached 36% and 30%. These extracts were able to prevent frameshift mutations.
When combined with MMC, none of the extracts could be considered antimutagenic, although B. correifolia extract reduced significantly the number of revertants at several doses.
Against AFB1, B. verbascifolia and B. correifolia extracts performed as strong antimutagens, reaching inhibition levels of 91% and 80% of revertants, respectively. It should be emphasized that when the concentration of the B. verbascifolia extract was varied, the inhibition remained at 91%, which reinforces its strongly protective potential. B. fagifolia and B. intermedia were moderately antimutagenic in these tests, reaching 36% and 32% inhibition, respectively. This demonstrates the potential of these extracts to be used as protective agents against indirect mutagens, which require metabolic activation.
Against B[a]P, all the extracts showed strong antimutagenicity and may be able to prevent frameshift mutations. B. verbascifolia reached a level of inhibition of 82%, B. correifolia 83%, B. fagifolia 76% and B. intermedia 77%. It should be emphasized that even when the concentration of the B. correifolia extract was varied, the percentages of inhibition remained very close to each other (at 82-83%), confirming its protective potential.
In previous studies, no mutagenic activity was observed in MeOH and chloroform extracts of B. basiloba, however, both extracts showed antimutagenic activity. The highest inhibition level (89%) was obtained with the MeOH extract, in the strain TA100 in the presence of AFB1. Phytochemical analysis of these extracts revealed the presence of n-alkanes, lupeol, ursolic and oleanolic acid, (+)-catechin, quercetin-3-O-α-L-arabinopyranoside, gallic acid, methyl gallate, amentoflavone, quercetin, quercetin-3-O-(2”-O-galloyl)-β-D-galactopyranoside, and quercetin-3-O-(2”-O-galloyl)-α-L-arabinopyranoside .
Rinaldo et al.  demonstrated that in MeOH extracts and aqueous infusions from the leaves of five Byrsonima species, only in B. coccolobifolia was it not possible to observe the presence of catechins and epicatechins. In the other four species analyzed, it was found that the MeOH extracts showed larger amounts of catechins than the infusions, per gram of leaves. B. basiloba showed the highest concentration of catechin diastereomers, followed by B. verbascifolia, B. crassa and B. intermedia.
The results of this study are in agreement with those in the above mentioned research. B. verbascifolia and B. intermedia did not exhibit mutagenic activity, nor did B. basiloba , but all of them were antimutagenic and showed high concentrations of catechins , suggesting that catechins are important in antimutagenic activity. This point is corroborated by a study that claims that catechins are already known for their antimutagenic and cancer preventive properties [20, 21].
The phytochemistry of all species analyzed to date in the genus Byrsonima is similar; we suggest that all species possess amentoflavone and quercetin, but in varied amounts. Probably, B. coccolobifolia and B. ligustrifolia possess higher concentrations of amentoflavone or quercetin, because they were mutagenic, but all the other species studied here probably possess a lower concentration of these flavonoids.
Although the mutagenic biflavonoid amentoflavone was present in the non-mutagenic B. basiloba, the amount of this compound found in the MeOH extract (1.79 mg/g of MeOH extract) was much smaller than that found in the (mutagenic) B. crassa (17.04 mg/g of MeOH extract) and B. intermedia (13.70 mg/g of MeOH extract) extracts, which showed weak signs of mutagenicity in an earlier study [5, 6].
Finally, we have to emphasize the excellent chemopreventive ability of these extracts, especially with respect to compounds that require metabolic activation. All extracts evaluated were considered strongly antimutagenic against at least one of the tested mutagens.
The careful study of medicinal plants should be encouraged, because while many beneficial properties are confirmed or discovered, as shown here, some species may pose risks to users.