Coumarins represent one of the most active classes of compound possessing a wide spectrum of biological activity such as anti-HIV, anticoagulant, antimicrobial, antioxidant, and anti-inflammatory, agents. Although most of the existing natural coumarins have been isolated from higher plants, some of them have been discovered in microorganisms, for example, aminocoumarin antibiotics: novobiocin, coumermycin A1, and chlorobiocin (produced by the actinomycete Streptomyces niveus). Coumarins can be synthesized by the Perkin reaction, Pechmann reaction or by Knoevenagel condensation and recently,...