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By means of four murine models, the authors demonstrated in vivo that 1,4-benzoquinone guanylhydrazone thiosemicarbazone (1), which is known to be antimicrobially active, and its hydrochloride (2) exert an antineoplastic effect. In leukaemia P 388 and leukaemia L 1210 both compounds had a curative action already after four oral administrations. The "cured" animals were resistant or cross-resistant to further transmissions of leukaemia. The resistance was transmissible by splenocytes.

A series of carbonyl derivatives of tilorone was synthetized by reaction with appropriate amino compounds, mainly hydrazines and hydrazides. The condensation products obtained were tested for cancerostatic activity against the murine leucaemia L 1210 and the Walker carcinosarcoma of the rat. Only three of the substances under investigation (1a, 5, 13) proved active against the Walker carcinosarcoma, one of which (5) being comparable to tilorone. No activity against L 1210 was observed, even tilorone exerted no effect. The reduction in activity against the Walker carcinosarcoma which resulted from the carbonyl substitution might be caused by a decrease in the ability to intercalate into DNA.

Eight of fifteen Fluorenone-Azomethines without alkylating function have been found effective against the leukemia L 1210. Little modifications concerning the structure of the compounds caused loss of effectiveness. It seems remarkably that one corresponding derivative with a nitrogen mustard group (4) was ineffective. Correlations between chemical structure and biological effect have not yet been found.

Lambdamycin-producing strains were detected by means of the BIP test method. The isolation technique and the physicochemical and biological properties of lambdamycin, an antibiotic produced by Streptomyces glaucoachromogenes, are described. Lambdamycin is a yellow-green pigment of the chromoglycoside type. Digitalose and fucose are the sugar components. The physicochemical properties of lambdamycin resemble those of chartreusin. However, the known biological activity is different. The antibiotic can be isolated from culture filtrates and from the mycelium by extraction with lower aliphatic alcohols. It can be purified by gel filtration methods. Lambdamycin displays antimicrobial activity, particularly against grampositive bacteria. Strains which produce enzymes inactivating different commercial antibiotics are also inhibited. Moreover, lambdamycin shows antiviral activity, as well as cancerostatic and ergotropic action in vitro and in vivo. The acute LD50 of lambdamycin in mice after 21 days was greater than 125 mg/kg when administered intraperitoneally.

Violamycin B, an antibiotic-complex, inhibited the growth of Sarcoma 180 in a well defined manner. The products Violamycin A, BII, and BI obtained by gelfiltration, were tested against the lymphoid Leukemia L1210. The results showed an increase of the toxicity and, simultaneously, a decrease of the antineoplastic effect, depending on the number of the sugar-components.

Compounds of a special azomethine type have been tested on their activity against concanavalin A and phytohemagglutinine P mediated agglutination of leukemia L 1210 cells. With exception of two compounds possessing a bis-(beta-hydroxyethyl) amino group at the phenyl moiety in para-position to the azomethine group all substances considerable inhibited agglutination of L 1210 cells. In vitro active concentrations are also obtained in animal experiments at least for a short time at the site of injection (i.p.) The importance of cellular reactions for effectivity in vivo is discussed.

The action of many psychotropic drugs on the adenylate cyclase system and its role in the regulation of tumour cell division justify the expectance that potentially psychotropic 1-benzopyrano[4,3-b]-1,5-benzodiazepine derivatives (3a,b and 6a,b) will also exert a cancerostatic effect. The synthesis of 6,6a,7,8,13,13a-hexahydro-1-benzopyrano[4,3-b]-1,5-benzodiazepines (4a and b) and their separation into the antileukaemic (L 1210) cis-forms and the inefficacious trans-forms are described. The cis-form 5a, unlike the trans-form 6a, stimulated the adenylate cyclase system.

Lambdamycin, a chromoglycoside antibiotic like chartreusin was found to be very active against leukemias L 1210 and P 388 and moderate effective against melanoma B 16 and Lewis lung carcinoma of mice. It was nearly without any effect when tested on Walker 256 carcinoma of rats. The effectiveness of lambdamycin was compared with that of cyclophosphamide, 5-fluorouracil and 6-mercaptopurine.