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An immuno-modulator fraction (Alva) extracted from an endemic plant, in the south of Madagascar, the Aloe vahombe, significantly protects mice against bacterial, parasitic and fungal infections. Wishing to verify whether the fraction Alva was active in tumour reduction, we studied its effect on the development of experimental fibrosarcoma and melanoma in mice by intravenous and intracutaneous injections and injections directly into the tumour of the immunostimulant fraction. We have observed cures, only in the case of the McC3-1 tumour but it is encouraging to note that under different experimental conditions the rate of growth of tumours in animals which were treated is slower than in those not treated. The Alva fraction is a substance which is hydrosoluble, thermostabile, having a molecular weight exceeding 30 000 and is a polysaccharide. The predominant sugars are glucose and mannose in 3:1 ratio. Preliminary studies of its action seem to indicate that the Alva fraction acts upon non-specific response and could possibly stimulate the phagocyte activity of the peritoneal macrophagus.

When the mice are given a hypodermic infection of unrefined Vahombe extract, the Aloe called Vahombe is a liliaceous plant growing in the South of Madagascar, they are protected against the infection caused by the Klebsiella, a pneumonia vector to man, giving rise to an experimental septicaemia in the mouse. Neither bactericide nor bacteriostatic activity has been detected yet about Aloe extract. The anti-infectious activity is proportional to the dose of extract injected, the protecting power is the greatest when the mice have been treated with Aloe, two or three days previously to the infection due to Klebsiella pneumoniae. We have determined the LD50 (Lethal dose 50) for the check batches (non-treated mice) and for the batches of protected mice. We were able to show that the previous injection developed the resistance to infection, multiplied from thirtyfold to a hundrefold. We have tackled the purification of the substance--made soluble after lyophilisation of the crude extract--by means of filtration with Sephadex G50. It would be the first time, for all we know, that a substance endowed with organism. At present we are proceeding with the purification of the active principle and contemplating trying the protective power upon virus infections as well as upon cancerous or parasitic ones.