The Role of Ungeremine in the Growth-Inhibiting and Cytotoxic Effects of Lycorine: Evidence and Speculation*

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Abstract
The role of ungeremine (2), a natural metabolite of lycorine (1), in the growth-inhibitory and cytotoxic effects of 1 is evaluated. Ungeremine produced marked antibacterial action against ten bacterial isolates and significantly inhibited testicular metabolism in mice, and the growth and viability of S-180 tumour cells. Lycorine did not exhibit any noticeable inhibitory effect in these parameters. These findings suggest that the biological actions attributed to lycorine per se may be due, at least in part, to ungeremine, to which lycorine is converted under certain oxidising conditions. Where lycorine-ungermine conversion is not incipient, the growth-inhibitory and cytotoxic effects of lycorine may not manifest. Evidence is presented in support of this postulate. Additionally, plausible mechanisms of conversion of lycorine into ungeremine are appraised.