Antitumor activity of chemical modified natural compounds

Search of new activity substances starting from chemotherapeutic agents, continously appears in international literature. Perhaps this search has been done more frequently in the field of anti-tumor chemotherapy on account of the unsuccess in saving advanced stage patients. The new point in this matter during the last decade was computer aid in planning more rational drugs. In near future "the accessibility of supercomputers and emergence of computer net systems, willopen new avenues to rational drug design" (Portoghese, P. S. J. Med. Chem. 1989, 32, 1). Unknown pharmacological active compounds synthetized by plants can be found even without this eletronic devices, as tradicional medicine has pointed out in many contries, and give rise to a new drug. These compounds used as found in nature or after chemical modifications have produced successful experimental medicaments as FAA, "flavone acetic acid" with good results as inibitors of slow growing animal tumors currently in preclinical evaluation for human treatment. In this lecture some international contributions in the field of chemical modified compounds as antineoplasic drugs will be examined, particularly those done by Brazilian researches.

Seleçäo por meio de células KB de substâncias e extratos potencialmente ativos em quimioterapia do câncer / Selection by means of KB cells of substances and extracts potentially active in cancer chemotherapy

Several synthetic, semi-synthetic and natural compounds as well extracts were screened for their growht inhibition activity on KB cells. The most active ones were naphthoquinones and derivatives of pyrido [4,3-b] carbazole alkaloids, with inhibition dose (ID50) < 4microng/ml. Of the crude extracts of several plants screened, Vellozia caput-ardeae showed to be the most active

Modificaçäo do método de DiPaolo & Moore para teste de novas substâncias anticâncer. Parte II: Emprego de células de tumor de Ehrlich nos testes in vitro e in vivo: estudo comparativo / Modification of Dipaolo & Moore-s method for screening new anticancer compounds. Parte II: Ehrlich tumor cells in vivo and in vitro tests: a comparative study

Para evitar o uso de grande número de animais necessários para triagem ou isolamento de novas drogas anticâncer, várias substâncias químicas e extratos vegetais foram testados pelo método de DiPaolo & Moore modificado a fim de comparar as respostas obtidas neste processo, que utiliza células do carcinoma de Ehrlich in vitro, com o método in vivo e que avalia a inibiçäo do crescimento do mesmo tumor inoculado em camundongos suíços. Os resultados indicam a possibilidade de se usar o método como pré-triagem de novas substâncias anticâncer e a superioridade do teste, sempre que estabelecida a equivalência com experimento animal, para isolamento de drogas potenciais existentes em sistema complexo como o extrato de plantas, levando-se em conta a economia de tempo e o número de animais utilizados