Abstract
Seaweeds or marine macroalgae are the oldest members of the plant kingdom, with a history extending back many hundreds of millions of years. Based on photosynthetic pigments, marine macroalgae can be classified into three groups, namely green algae commonly known as Chlorophyta, brown algae or Phaeophyta, and red algae also called Rhodophyta. In response to different kinds of environmental stress, marine algae develop defense strategies resulting in a significant level of structural chemical diversity, from different metabolic pathways. In this review a brief description of the most important seaweed compounds and their bioactivities are presented in this study. Seaweeds contain minerals, amino acids, proteins, fatty acids, lipids, polysaccharides, dietary fibers, vitamins, and various secondary metabolites, such as phenols, alkaloids, terpenes, and pigments. Many of these constituents possess high economic values and can be extracted to obtain antioxidative, anti-inflammatory, anticancer, antimicrobial, antifungal, antiviral, anti-obesity, antidiabetic, and antihypertensive products. Therefore, a new trend to isolate and identify bioactive compounds and constituents from marine algae has emerged.