# Comparison of the Biological Potential and Chemical Composition of Brazilian and Mexican Propolis
## 3 Discussion
### Propolis: Color, Botanical Sources, and Chemical Composition  
The coloration of propolis will depend on the plant's origin and its ecosystem since bees collect substances from plants. For example, the Brazilian green propolis is derived mainly from the species _Baccharis dracunculifolia_. On the other hand, in the Gulf Region of Mexico, the majority of propolis found is from the green variety, unlike the northern region, where the ecosystem is more desertic than the other regions, and mesquite _(Prosopis laevigata)_ is a predominant vegetable source [29]. Each plant species has its secondary metabolites responsible for its biological activities, and propolis contains the metabolites of the plant that will define its biological activity. In Mexico, the most remarkable locations with diversity of tropical vegetation are in the Gulf and Pacific coasts of the country; for this reason, a diversity of propolis colors is seen (chestnut-green, red, yellow-red, dark yellow, dun, or black) [28]. In Brazil, the classification of propolis by color is strongly associated with its botanical source [30]. [PERSON] et al. [31] classified propolis samples collected in the country (except the north region) into 12 groups, according to the appearance and color of the extracts. Subsequently, a new propolis variation was found in hives along the coast and mangroves in northeastern Brazil, which was classified as group 13, standing for red propolis [32]. In the southern region of Brazil, five types of propolis were described according to the classification of color (yellow, light brown, dark brown, greenish-brown, and reddish brown). In the northeast region, 6 were described (greenish-brown, dark brown, yellow, and red), and in the southeast region one type of propolis was described as green (or greenish-brown). It is noteworthy that these regions have diverse and varied ecosystems (Figure 1a), so although the name of the color may be similar, the composition of propolis is different mainly due to the different botanical sources. Propolis is a complex mixture, and more than 300 chemical moieties have been identified [33]. According to the verified articles (Tables S1 and S2 of supplementary material) [33], Brazilian and Mexican propolis composition analyses found many shared compounds, even considering different geographic regions, ecosystems, and types (color differences) [34; 35; 36; 37; 38; 39; 40; 41; 42; 43]. Many of these chemical compounds stand out for their biological activity, for example, phenolic acids, phenolic acid esters, flavonoids, terpenoids, luteolin, galantine, trans ferulic acid, caffe acid, chrysin, pinobanksin 5-methyl ether, quercetin, apigenin, kaempfer, naringenin, rutin, catechulin, p-cumaric, pinobanksin, pinocembrin, and pinobanksin 3-acetate, and many others [21; 25; 26; 27; 28; 29; 30; 31; 32]. On the other hand, some compounds that are considered propolis-type markers, such as in propolis from Brazil, are are appicillin C (3,5-diphenyl-4-hydroxycinnamic acid) for green propolis [44; 45; 46; 47] and formonetin (3-hydroxy-8-9-dimethoxyprocarpan) for red propolis [32; 48; 49; 50]. These chemical markers described for each propolis are physiologically associated with the main botanical source. The primary source of green propolis is wild rosmary (alcerim do campo--_Baccharis dracunculifolia_) and rabo-de-bugic or marmelo-do-mangue (_Dalbergaic castapallyulum_ (L) [PERSON]), with 35.68% of artemisinin C [51], while the red propolis presents 67.59% formonentin in its chemical composition [49; 50]. In the case of brown propolis, its composition varies according to several botanical sources (Eucalyptus, _Mimosa caesalpiniaefolia, Mimosa scabrella_, Cecropia, Anacardiaceae, Asteraceae, Citrus, Cocos and Poaceae, Populus), without a specific marker described [52; 53].