first antibiotic discovered penicillin isolated mold ''penicillium'' penicillin related beta lactams work inhibiting dd transpeptidase enzyme required bacteria cross link peptidoglycan form cell wall several natural product drugs target tubulin component cytoskeleton include tubulin polymerization inhibitor colchicine isolated ''colchicum autumnale'' autumn crocus flowering plant used treat gout ref name pmid ref colchicine biosynthesized amino acids phenylalanine tryptophan paclitaxel contrast tubulin polymerization stabilizer used chemotherapeutic drug
Natural science Chemistry Natural product chemistry