Antimicrobial, antioxidant and anticancer activities of Laurencia catarinensis , Laurencia majuscula and Padina pavonica extracts

The antimicrobial, antioxidant, and anticancer activities of ethanolic extract of <i>Laurencia catarinensis, L. majuscula and Padina pavonica</i> were determined. The highest antibacterial activity; 23.40 ± 0.58 mm (00.98 µg/ml) and 22.60 ± 2.10 mm (03.90 µg/ml) were obtained against <i>Klebsiella pneumonia</i> by <i>Laurencia catarinensis</i> and <i>Padina pavonica</i>, respectively. However, <i>Padina pavonica</i> showed excellent antibacterial activity against <i>Bacillus subtilis</i> (21.7 ± 1.5 mm; 1.95 µg/ml), <i>Staphylococcus aureus</i> (21.7 ± 0.58 mm; 1.95 µg/ml), <i>Streptococcus pyogenes</i> (20.7 ± 1.2 mm; 1.95 µg/ml) and <i>Acinetobacter baumannii</i> (20.1 ± 1.2 mm; 3.9 µg/ml). Moreover, the highest antifungal activity; 24.7 ± 2.0 mm (0.98 µg/ml), 23.7 ± 1.5 mm (0.98 µg/ml), 23.6 ± 1.5 mm (0.98 µg/ml) was obtained by <i>Padina pavonica</i> against <i>Candida tropicalis</i>, <i>C. albicans</i> and <i>Aspergillus fumigatus</i>, respectively. The algal extracts showed DPPH radical scavenging activity in a concentration-dependent manner with maximum scavenging activity (77.6%, IC₅₀ = 5.59 µg/ml and 77.07%, IC₅₀ = 14.3 µg/ml) was provided by <i>Padina pavonica</i> and <i>Laurenica majuscula</i>, respectively. The <i>in vitro</i> antitumor activity revealed that the IC₅₀ values of <i>Padina pavonica</i> were 58.9, 115.0, 54.5, 59.0, 101.0, 101.0, and 97.6 µg/ml; <i>Laurencia catarinensis</i> were 55.2, 96.8, 104.0, 78.7, 117.0, 217.0, 169.0 µg/ml; and <i>Laurencia. majuscula</i> were 115.0, 221.0, 225.0, 200.0, 338.0, 242.0, and 189.0 µg/ml; respectively against A-549 (Lung carcinoma), Caco-2 (Intestinal carcinoma), HCT-116 (Colon carcinoma), Hela (Cervical carcinoma), HEp-2 (Larynx carcinoma), HepG-2 (Hepatocellular carcinoma), and MCF-7 (Breast carcinoma) cell lines.