**Author details**

thought to be elastase inhibitors. Apratoxins such as Apratoxin-a from *Lyngbya majuscule* is another metabolites biosynthesized from a hybrid NRPS-PKS pathway. It is cytotoxic due its

**Species of cyanobacteria Bioactive compound Biological activity References** *Spirulina platensis* Spirulan Antiviral [38]

*Lyngbya majuscule* Apratoxins Anticancer [23] *Nostoc commune* Nostodione Antifungal [38]

*Anabaena circinalis* Anatoxin-a Anti-Inflammatory [11, 38] *Fischerella muscicola* Fischerellin Antifungal [11]

**Table 4.** Potential applications of cyanobacterial natural products in pharmaceutical and cosmetics industry.

γ-linolenic acid Precursor to prostaglandins [39] Phycocyanin Cosmetic colourants [1]

Carotenoids Antioxidant [36] MAAs Sunscreen [40]

Scytonemin Anti-inflammatory, Anti-proliferation [41]

Antibacterial metabolites produced by cyanobacteria are effective against gram negative and gram positive bacteria. In the age of antibacterial resistance, new drugs are essential to combat bacterial infections. The hapalindole-type class of indole alkaloids has been found to pos-

Secondary metabolites can be used as natural ingredients in the cosmetics industry. Uses include the photoprotective MAAs in sunscreens to protect the skin from harmful UVR. Pigments such as carotenoids and phycobiliproteins could be used as natural colourants but also as antioxidants to protect the skin from damage caused by UV exposure [11]. Other potential uses for cyanobacterial secondary metabolites include their use in the nutra-

Cyanobacteria have a long evolutionary history and have adapted to deal with natural and anthropogenic stress. The morphological, biochemical and physiological diversity of cyanobacteria gives rise to the vast amount of secondary metabolites produced all with their own specific functions that aid in the organism's survival. These secondary metabolites can also be utilised in drug discovery as lead compounds due to their complex structures and varied bioactivities. New natural products can be identified through biosynthetic pathway analysis using genomic data with around 208 cyanobacterial genomes sequences publically available [12]. Although extensive research has been conducted on cyanobacterial secondary metabolites

ability to induce G1-phase cell cycle arrest and apoptosis [42].

sess antimicrobial (bacteria, fungi) and antialgal activity [16].

ceutical and agricultural industry [11, 43].

32 Secondary Metabolites - Sources and Applications

**5. Conclusion**

Bethan Kultschar and Carole Llewellyn\*

\*Address all correspondence to: c.a.llewellyn@swansea.ac.uk

Department of Biosciences, Swansea University, Swansea, Wales, UK
