## 1 Introduction
### Antioxidant Activity
#### 1.1.1 Antioxidant Activity of Salvia Extracts--Chemical Models
In the same line, polar extracts of _Salvia amplexiaulis_[49] and _Salvia ringens_[50], both rich in kaempfer glycosides (298 to 636 mg/g extract and 120 to 465 mg/g extract, respectively), were suggested as good antioxidant agents, as estimated by DPPH\({}^{\bullet}\), ABTS\({}^{\bullet}\) and FRAP methods. Moreover, a methanolic extract of _Salvia syriaca_, with considerable amounts of ruin and rosmarinic acid, displayed a high DPPH\({}^{\bullet}\) scavenging activity, with the same magnitude of the standard solution 3.5-di-tert-butyl-4-hydroxytoluene (BHT; EC\({}_{50}\) values of 70 and 66 ug/mL, respectively) [51]. In addition, phenolic-rich extracts from different populations of _Salvia fruiticosa_[52] and aqueous and methanolic extracts of _Salvia cadmica_ from Turkey [53], were demonstrated to scavenge DPPH\({}^{\bullet}\) and ABTS\({}^{\bullet}\), and to reduce ferric ion as well. In these studies, rosmarinic acid was detected as the main compound, ranging from 20.6 to 41.9 mg/g extract [53]. In good agreement with these results, other _Salvia_ polar extracts, such as _S. amplexiaulis_[49], _Salvia halophila_[54], _Salvia virgata, Salvia persica, Salvia cereal_ and _Salvia reuterana_[40], were shown to inhibit \(\beta\)-carotene bleaching, in some cases with equal capacity to those of the standard compounds. Similarly, the potential of _Salvia_ species to inhibit lipid peroxidation, as estimated by TBARS assay, was reported for an ethyl acetate extract of _S. halophila_, which exerted an inhibitory ability similar to the commercial antioxidant BHT [54]. Moreover, among five solvent extracts from the aerial parts of _Salvia pachyphylla_, the ethyl acetate extract was the most active based on DPPH\({}^{\bullet}\) scavenging assay (EC\({}_{50}\) = 0.28 mg/ml) [55]. In addition, [PERSON] et al [56] reported the scavenging ability of six _Salvia_ species methanolic extracts as varying between 1 to 487.1 mg ascorbic acid equivalent /g dried extract, in the order: _Salvia hydrangea, Salvia macilenta \(>\) Salvia mulicalis, Salvia sclarea \(>\) Salvia xanthochelia_ and _Salvia llochacryla_[56]. Moreover, [PERSON] et al. [57] reported good antioxidant ability of ethanolic extracts of _S. sclarea_, as estimated through DPPH\({}^{\bullet}\) (EC\({}_{50}\) = 27.8 ug/mL) and inhibition of \(\beta\)-carotene (EC\({}_{50}\) = 19.1 ug/mL) methods. Likewise, methanolic extracts of _S. syriaca_ and _Salvia nervosa_ collected in Iran were shown to possess a scavenging ability towards DPPH\({}^{\bullet}\) similar to that of BHT [51; 58]. The authors found a good correlation between total phenolic compounds (TPC) and flavonoids (TFC), and their antioxidant activities, highlighting their richness in rosmarinic acid as well as quercetin and its glycosides. Other methanolic extracts of a collection of _Salvia_ species, including _Salvia eremophila, Salvia santolini, _S. memorosa_ and _Salvia atropatana_, were demonstrated to be good DPPH\({}^{\bullet}\) scavengers as well [16], and those of _S. sclarea_ and _S. memorosa_ were even claimed to be 1.4-2.2 times lower than those of BHT [40]. The high antioxidant potential of the two latter extracts was also attested to by other chemical in vitro tests, namely ORAC and ABTS [59]. Although less studied, aqueous extracts obtained from _Salvia_ plants have also been reported to be promising antioxidant agents. In this regard, an _S. officinalis_ decoction extract, rich in quinic acid, protocatechic acid, gallic acid and salvianolic acid, was shown to inhibit \(\beta\)-carotene bleaching with IC\({}_{50}\) values 2.7-fold higher than BHT [60]. In another study, our group demonstrated that the decoctions of _Salvia africana, Salvia officinalis 'lterterina', Salvia mexicana_[26] and _Salvia elegans_[27], had DPPH\({}^{\bullet}\) EC\({}_{50}\) values in the range of 6.6 \(\pm\) 0.7 and 10.7 \(\pm\) 2.1 ug/mL, with a potency of about half or the same order of ascorbic acid. Likewise, decoctions of _S. africana, S. officinalis 'lterina'_ and _S.