1.5.2.Natural products from marine organisms Spongouridine(3)and spongothymidine(4)23 were known to be the first bioactive nucleotide compounds to be isolated from the Carribean sponge Cryptotheca crypta in 1950's.These compounds were potent anticancer and antiviral agents.Some of the marine organisms lead a sedentary lifestyle,and thereby synthesize several complex and extremely potent chemicals for their defense from predators.20 The potential of these chemicals can be utilized to treat various ailments, especially cancer.Discodermolide(5),isolated from the marine sponge Discodermia dissoluta,is one such example which has a similar mode of action when compared to that of paclitaxel and possesses a strong anticancer activity.Infact,a combination therapy of the above two drugs has led to reduced tumor growth in certain cancers.24 H HN o- -0 HO HN 0 OH OH Spongouridine(3) Spongothymidine(4倒 Discodermolide (5) 1.5.3.Natural products from microorganisms. The discovery of penicillin in 1929 opened the gates for microorganisms as a source of potential drug candidates.Since then, a large number of microorganisms were screened for drug discovery which led to the discovery of antibacterial agents like cephalosporins-1.5.2. Natural products from marine organisms: Spongouridine (3) and spongothymidine (4) 23 were known to be the first bioactive nucleotide compounds to be isolated from the Carribean sponge Cryptotheca crypta in 1950’s. These compounds were potent anticancer and antiviral agents. Some of the marine organisms lead a sedentary lifestyle, and thereby synthesize several complex and extremely potent chemicals for their defense from predators.20 The potential of these chemicals can be utilized to treat various ailments, especially cancer. Discodermolide (5), isolated from the marine sponge Discodermia dissoluta, is one such example which has a similar mode of action when compared to that of paclitaxel and possesses a strong anticancer activity. Infact, a combination therapy of the above two drugs has led to reduced tumor growth in certain cancers.24 O OH HO N HN O O Spongouridine (3) HO O OH HO N HN O O Spongothymidine (4) HO O O H2N OH OH OH O HO O Discodermolide (5) 1.5.3. Natural products from microorganisms: The discovery of penicillin in 1929 opened the gates for microorganisms as a source of potential drug candidates. Since then, a large number of microorganisms were screened for drug discovery which led to the discovery of antibacterial agents like cephalosporins-