b. illustrates the number of occurrences and the percentage of occurrences in the reviewed publications for each database. For Scopus, the most frequent keyword is "antioxidant activity" found in 6 documents, followed by "secondary metabolites" (5), "cytotoxicity" (4), and "DPPH" (3). The remaining keywords are found in less than three publications. In the case of WoS the most commonly used words were "secondary metabolites" present in 6 publications, followed by "polyphenols" with 4 after "antioxidant activity" and "essential oil" with 2. The reminder keywords are present in two or less publications.