Effect of pretazettine and viva-natural, a dietary seaweed extract, on spontaneous AKR leukemia in comparison with standard drugs.

Antileukemic activity of pretazettine hydrochloride (PTZ: a narcissus alkaloid) and Viva-Natural (a seaweed extract) has been confirmed against spontaneous AKR T cell leukemia in mice containing 20% of advanced leukemia. The activity of both agents has been compared with selected standard cytotoxic drugs, vincristine (VCR), methotrexate (MTX), 6-thioguanine (6-TG), and adriamycin (ADR), and immunomodulators, pyran copolymer (MVE-2), isoprinosine, levamisole and tilorone. PTZ activity seems to be superior (90% increase in life span, ILS) to those of MTX (71% ILS), 6-TG (60%), and ADR (49%), and inferior to VCR (114% ILS). Viva-Natural has been found to be the only immunomodulator (61%) active against AKR T cell leukemia, while all standard immunomodulators tested were not active. Combination treatment of PTZ with VCR, or 6-TG, or ADR, or Viva-Natural were synergistic, but combination of PTZ with MTX was not beneficial. PTZ or VCR has been found to be therapeutically very effective (323 or 347% ILS, respectively) against mice in advanced stage of leukemia, and induced complete clinical remissions. Also, PTZ has been found to reverse the leukemia-enhancing effect of ciclosporin in AKR mice at preleukemic stage.