# Brazilian Propolis: Nature's Liquid Gold with Anti-Inflammatory and Anticancer Potential
## 4 Secondary Metabolites of Brazilian Propolis  
Brazilian propolis is renowned for its great diversity of colours, chemical composition and bioactive properties depending on the geographic region and plant sources. The most well-known types include green, red, and brown propolis, each linked to specific botanical origins. Apart from those, yellow and black propolis have been reported to occur in some regions, though they are less studied [14]. Green propolis mainly originates from _Baccharis dracunculifolia_ DC. and is rich in artemillin C, a key bioactive compound. Red propolis, derived from _Dalbergia ecastophyllum_ (L.) [PERSON] and _Symphonia globulifera_ ([PERSON]), is recognised for its high content of isoflavoids and polyprenylated benzophenones. Brown propolis has a more complex composition, often containing terpen, flavonoids, and phenolic acids, and is derived from _Araucaria angustifolia_ ([PERSON].) [PERSON], _Pinus_ spp., and _Eucalyptus_ spp. Yellow and black propolis have also been identified in certain regions of Brazil, however, they are less studied, and their unique chemical profiles are still being explored. These colour variations reflect differences in plant resins collected by bees, which has an impact on the biological activity and commercial value of each type. The diversity of Brazilian propolis makes it a powerful natural product with numerous medicinal and industrial applications. Literature data indicate that green propolis is particularly rich in prenylated phenolic compounds that are largely responsible for its well-documented biological effects. The most characteristic compound of green propolis is artemillin C, whose presence has been demonstrated by [PERSON], [PERSON] et al., and [PERSON] et al. This type of propolis also contains baccharin, caffeic acid, chlorogenic acid, culifolin, kaempfer, kaempfer, and \(p\)-coumaric acid [36; 37; 38; 39]. As for Brazilian red propolis, the most abundant bioactive constituents identified by [PERSON] et al. were formontein, isoliquiritigenin, pinocbarn, biochanin A, luteolin, quercetin, pinobanksin, daidzein, liquiritigenin and rutin. Other researchers have also identified the presence of formonentin, vesittol, neovestitol, and cinnamic acid derivatives [40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53]. The last well-identified type of Brazilian propolis is brown propolis which, according to [PERSON] et al., contains compounds such as caffeic acid phenethyl ester (CAPE), kaempfer, chrysgin, quercetin, apigenin, ferulic acid, pinochemrin, galangin, vanillic acid and \(p\)-coumaric acid. Also, when studying the components of this natural product, [PERSON] membogurski observed the presence of 5-O-E-caffeoylquinic acid, naringenin, drupanin and baccharin, among others [44]. Apart from the bioactive compounds described above, Brazilian propolis contains a variety of volatile oils, the composition of which varies depending on the regional flora. The main volatile compound identified in Brazilian green propolis is meridolol. [PERSON] et al. also found carvacrol, acetophenone, spathulenol, (E)-nerolidol and \(\beta\)-caryophyllene in the green variant [54]. Additionally, [PERSON] et al. identified the allyl ester of 3-prenylcinnamic acid and spathulenol [55]. Brazilian red propolis is rich in phenylpropanoids, including elemicin and methyleugenol [56]. In brown propolis, volatile compounds, such as acetophenone, nerolidol and spathulenol, have been identified as major constituents [57]. The volatile oil of southeastern brown propolis contains 1,8-cyncol, terpinen-4-ol and various sesquiterpenes [54]. These volatile oils exhibit a wide range of beneficial biological properties. Brazilian propolis is an extremely rich treasure trove of bioactive compounds that vary according to type (green, red or brown) and contribute to its potent biological activity extensively utilised by humans in many different ways.