# Pharmacological and Cosmeceutical Potential of Seaweed Beach-Casts of Macaronesia
## 3 Results and Discussion
### Antigaging Activity
#### 3.4.1 Chelating and Antioxidant Activities  
None of the extracts exhibited ferric chelating or \(\beta\)-carotene bleaching activity at the maximum concentration tested (250 \(\mu\)g/mL).  
Regarding the antioxidant activity, five extracts (1.E, 1.M, 2.E, 2.M and 11.E) scavenged the DPPH radical by more than 50% at 250 \(\mu\)g/mL, with two of them (1.E and 2E) surpassing 80%. For these five samples, the IC\({}_{50}\) values were calculated (Figure 5 and Table S3 Supplementary Material). The most active extract (2.E) was 9.57-fold less active than Trolox (IC\({}_{50}\) values of 69.4 \(\mu\)g/mL vs. 7.25 \(\mu\)g/mL), followed by 1E with IC\({}_{50}\) of 81.57 (11.2-fold less active than Trolox), while the other exhibit very low activity. The fractionation of the extracts revealed seven fractions with IC\({}_{50}\) values below 229.06 \(\mu\)g/mL, four of which were the most promising with IC\({}_{50}\) values between 50.25 \(\mu\)g/mL and 71.70 \(\mu\)g/mL (Figure 5 and Table S3 Supplementary Material). It should be noted that the 2.M extract being only the third most active, it gave rise to the two most active fractions, about 2.5 times more active than the original extract.  
The ABTS test also reflects the antioxidant capacity of the samples, being a more sensitive method than the DPPH method, since the neutralization of the ABTS radical can occur by transferring a hydrogen atom or an electron [62]. The ABTS test yielded more interesting results, with eight extracts capable of inhibiting more than 50% of the radicals at 250 \(\mu\)g/mL. To these extracts the IC\({}_{50}\) values ranging from 6.21 \(\mu\)g/mL to 242.78 \(\mu\)g/mL (Figure 6, Table S3 Supplementary Material). The most active extracts were, like in the DPPH method, 1.E and 2.E, with IC\({}_{50}\) values 2.31 and 2.68-fold higher than the activity of Trolox (2.68 \(\mu\)g/mL for the ABTS assay), respectively. The fractionation of the extracts gave rise to 12 active fractions (IC\({}_{50}\) values ranging from 8.89 \(\mu\)g/mL to 185.04 \(\mu\)g/mL) (Figure 6, Table S3 Supplementary Material) but none of the fractions exhibited higher activity than the reference compound Trolox. Additionally, with only one exception, no fraction was more active than the extract that gave rise to it, which seems to suggest a synergistic effect between the constituents of the extract with antioxidant action, which is lost when fractioned. The exception mentioned above is 2.M.4 (IC\({}_{50}\) = 9.57 \(\mu\)g/mL) a fraction 2.6 times more active than the original extract 2.M (IC\({}_{50}\) = 24.66 \(\mu\)g/mL).  
Figure 5: IC\({}_{50}\) values of DPPH scavenging activity by the extracts (light bars) and fractions thereof (dark bars). Trolox was used as reference.  
From the antioxidant activity point of view, three extracts (1.E, 1.M, 2.E) and three fractions (1.E.3, 1.M.2 and 2.M.4) seem very good antioxidants products, which is not completely surprising considering the species compositions of most of the beach-casts, mainly composed of brown and red algae, rich in antioxidant molecules, such as pigments [63], phlorotannins [64], sulfated polysaccharides [65] and sterols [66], among others.  
The antioxidant samples found here can act as reactive oxygen species (ROS) scavengers and in this way contributing to the protection of cellular structures such as proteins and lipids, and to a lower activation of extracellular matrix (ECM) degrading enzymes, since the ROS play an important role on the activation of matrix metalloproteinases that degrade ECM, namely collagenases [61].