There is a continuous need for antibiotics, mainly with new mechanisms of action, since infectious diseases represent the second major cause of death in the world and bacteria resistance levels are high. This review describes the contribution of microbial natural products for the development of the major antibiotic classes, the mechanisms of action of current antibiotics, some modern approaches involving genetic tools for the discovery and development of new antibiotics from microbial products and antibiotics in clinical trials.

O Ageratum conyzoides, vegetal conhecido popularmente no Brasil é constituído por várias substâncias químicas, dentre elas os flavonóides, aos quais já foi atribuída a atividade antitumoral. Neste estudo foi avaliado o efeito das frações clorofórmica e metanólica do extrato AcOEt das folhas sobre o crescimento do tumor de Ehrlich. Foi constatado que o tratamento com as frações metanólicas, nas doses de 50 mg/kg de peso foi eficaz, inibindo o crescimento tumoral. A porcentagem de inibição para a fração metanólica estabilizada foi de 69,84% e de 68,25% para a fração metanólica não estabilizada. Estudos posteriores se fazem necessários para esclarecer quais os mecanismos envolvidos nesta inibição do crescimento tumoral.

Ageratum conyzoides, a popular vegetal in Brazil, is composed by many chemical compounds, including flavonoids, and antitumoral activity has been attributed to it. In this assay the effect of chloroform and methanol fractions from EtOAc extract of the leaves on the growth of the Ehrlich tumor was evaluated. Under our experimental conditions we have observed that the treatment with methanol fractions, under the dosage of 50 mg/kg was efficient on inhibiting the tumoral growth. There was an inhibition percentage of 69.84% to the stabilized methanol fraction and 68.25% to the non-stabilized fraction. Further studies are necessary to clarify which mechanisms are involved in the inhibition of the tumoral growth.