## 3 Honey Phenolic Fraction and Bioactive Compounds  
Phenolic compounds are recognised as responsible for the widely investigated antioxidant properties of honey, as indicated by a positive correlation with the water- and lipid-soluble antioxidants capacity [46]. Their content is derived from its floral origin (both if it is single-origin or multifocal) and contributes to honey's colour [48]. A significant correlation (r = 0.6, n = 36, \(p\) < 0.001) was confirmed by [PERSON] et al., with Irish dark honeys showing higher total phenolic content (TPC) [49]. Interestingly, the same study has also revealed that phenolic compounds were found to be significantly more abundant in Irish urban honeys than in rural samples. More specifically, in this study, Irish heather honey showed comparable chemical composition to Manuka honey (MH) with regard to its TPC (68.16 \(\pm\) 2.73 and 62.43 \(\pm\) 10.03 mg GAE/100 g, respectively, where GAE stands for gallic acid equivalents). A TPC of 88.7 mg GAE/100 g and a lipid-soluble antioxidants capacity of 60.7 mg TE (Trolox equivalents)/100 g represented the highest values among the Estonian honeys analysed by [PERSON] et al., and they were both registered in heather honey, which was also the darkest sample, with the most red tones [46]. Noticeable levels of total phenolics were also confirmed by [PERSON] et al. [42] for heather honey from Nordic countries. This highlights the potential of heather honey for biomedical applications, considering that honey antioxidant activity is correlated to the beneficial effects of honey on various health issues [50] and to the antibacterial efficacy [42]. Similar TPC values for Manuka honey to those observed by [PERSON] et al. have been also measured by [PERSON] et al. (72.1 \(\pm\) 2 and 75.4 \(\pm\) 0.8 mg GAE/100 g), but in this case, they were shown to be significantly higher than other unifloral honey from traditional Indian medicinal plants such as tulsi plant (_Ocinum tenuiforum_ L) and alfalfa (_Medicago sativa_), respectively 50.6 \(\pm\) 2.7 and 18.3 \(\pm\) 0.3 mg GAE/100 g [48]. Moreover, additional factors may act independently or jointly with the honey phenolics, leading to an additive or synergistic (potentiated) effect. As such, further investigations on the medicinal effect of alternative honey varieties to Manuka honey could still disclose a high therapeutic power. The variety of phenolic and structurally related compounds observed in honey is determined mainly by the floral origin and the geographical collocation. Some examples are listed here and shown in Table 1 merely to offer a brief (but by no means exhaustive) illustration of the diverse assortment of phenolics measured in the latest published characterisation of different honey varieties. The honey phenolic fraction can include benzoic acids such as syringe acid, its aldehyde syringaldehyde, and its ester methylsyringate. The latter has been detected in Manuka honey [51; 52], Iranian unifloral honeys such as Persian rose, hawthorn, and thyme [51], and also identified as a biomarker of asphodel honey [53; 54]. Gallic acid was the most concentrated phenolic acid quantified in strawberry tree honey, accounting for 54.44% of the phenolic acid content, which was followed by 4-hydroxybenzoic acid and caffeic acid [55]. Homogentisic acid has been identified in peculiarly high concentrations in strawberry tree honey [54], of which it represents,together with abscisic acid derivatives, a specific marker of botanical origin [56; 57]. Ellagic acid, typically found in raspberry honey, was also detected in lingonberry honey by [PERSON] et al. [42]. Phenyllactic acid and p-HBA (para-hydroxybenzoic acid) were the benzoic acids found in the highest concentration in honeys from Iran [51]. Cinnamic acid has been detected in chestnut honey [58] and is typically found in high concentrations in heather honey, together with myricetin and abscisic acid derivatives [46]. Coumaric acid is the most represented cinnamic acid derivative in buckwheat honey [42].