# A Comprehensive Review of Stingless Bee Products:
## 2 Stingless Bee Honey
### Antioxidant Properties
#### 2.1.1 Phenolic and Flavonoid Compounds  
Phenolics are a heterogenic group of compounds developed by the secondary metabolism of plants, and they can be divided into two groups: flavonoids and non-flavonoids. Flavonoids are also known as phenolic acids, and their derivatives are flavanols, flavanones, and flavones. Examples of non-flavonoids are stilbenes, tannins, and lignins [32]. According to [PERSON] et al. [33], both flavonoids and many other phenolic components have been reported for their effectiveness as antioxidants, anticancer, antibacterial, and cardioprotective agents; anti-inflammation; and promoting the immune system. According to [PERSON] et al. [34], stingless bee honey is reported to have higher phenolic content compared to European honeybee honey, which is due to the stingless bee being smaller, thus enabling it to collect nectar from different species of flowers. Furthermore, [PERSON] et al. [35] stated that while building and sealing the hive, stingless bees combine their salivary secretion from the abdomen glands and beeswax; thus, the phytochemical composition of the honey could be attributed to the phytochemicals in the cerumen. However, the phenolic composition of stingless bee honey varies according to floral and geographical origin and the preference of each bee species during foraging [36].  
In recent years, reports of individual phenolic compounds found in stingless bee honey have been scarce. Table 2 summarises individual phenolic compounds from Malaysian,Brazilian, and Cuban stingless bee honey. According to the Malaysian Standards [16], good-quality stingless bee honey is characterised by the presence of benzoic acid, phenylpropanoic acid, 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, vanillic acid, protocatechuic acid, and \(p\)-coumaric acid. Referring to Table 2, almost all reported stingless bee honey complies with the Malaysian Standards, which consist of \(p\)-coumaric acid, protocatechuic acid, vanillic acid, and 4-hydroxybenzoic acid [31, 35, 36, 37, 38, 39]. However, one species of stingless bee honey--_Melipona scutellaris_ ([PERSON], 1811), from Brazil--does not contain any phenolic compounds that match the Malaysian Standards and thus does not qualify as good-quality honey in Malaysia [39].  
The most abundant phenolic compounds discovered in the 12 species of stingless bee honey listed in Table 2 are \(p\)-coumaric acid and naringenin, followed by salicylic acid, protocatechuic acid, caffeic acid, taxifolin, aromadendrin, and quercetin. According to [PERSON] et al. [40], the phenolic acid ratio is usually higher than that of flavonoids in honey. The author also stated that gallic acid, caffeic acid, \(p\)-coumaric acid, and sinapic acid are proven to be easily absorbed by the human intestine despite the differences in kinetic efficacy. Reports on the detection of \(p\)-coumaric acid were discovered in honey of the _Heterotrigona itama_[31, 39], _Scapotrigona bipuncatta_[36, 38], _Trigona hypogea_[36], _Tetragonisca angustula_[36, 38], _Tetragonisca angustula_[36, 38], _Tetragona clavipes_[36, 38], _Melipona marginata_[36, 38], _Melipona quadriscata_[35, 36, 38], _Melipona quadricista_[35, 36, 38], _Melipona bicolor_[35, 38], _Melipona mondury_[38], and _Melipona rufventris mondory_ species [38]. Next, also one of the most abundant chemical compounds found in stingless bee honey, naringenin has been found in _Heterotrigona itama_[39], _Scapotrigona bipuncatta_[35, 36, 38], _Trigona hypogea_[36], _Tetragonisca angustula_[36, 38], _Tetragona clavipes_[36, 38], _Melipona marginata_[38], _Melipona quadriscata_[38], _Melipona bicolor_[38], _Melipona mondury_[38], and _Melipona rufventris mondory_ species [38]. As shown in Table 2, the presence of quercetin was reported in the honey of eight stingless be species, namely, _Scapotrigona bipuncatta_[35, 36], _Melipona marginata_[35, 36], _Tetragonisca angustula_[36, 38], _Melipona quadriscata_[35, 36, 38], _Melipona bicolor_[35], and _Heterotrigona itama_[39].