Wr. Cullen et Di. Hettipathirana, THE EFFECT OF ARSENICALS ON ALKALOID PRODUCTION BY CELL-SUSPENSION CULTURES OF CATHARANTHUS-ROSEUS, Applied organometallic chemistry, 7(7), 1993, pp. 477-486
The effect of arsenic compounds on indole alkaloid production by cell
suspension cultures of Catharanthus roseus was investigated. The analy
sis of indole alkaloids was achieved by using thermospray liquid chrom
atography-mass spectrometry (LC MS) which facilitated the rapid screen
ing of alkaloid composition in cultures treated with different arsenic
als at different times in their growth cycle. Treatment with dimethyla
rsinate (DMA), a non-selective herbicide, has a drastic inhibitory eff
ect on alkaloid production although it is the least toxic arsenical to
growth. Tryptamine, an early precursor in the biosynthesis of indole
alkaloids, accumulates in cells treated with DMA, indicating that the
initial step of condensation of tryptamine with secologanin is inhibit
ed. Treatment with DMA during the early stationary phase of culture gr
owth enhances the accumulation of some alkaloids, although some, such
as catharanthine, are suppressed. The arsenicals arsenate and methylar
sonate (MMA) have an inhibitory effect on alkaloid production when app
lied during the early growth stages. In contrast to MMA and DMA, arsen
ate has a stimulatory effect on catharanthine production when introduc
ed to the culture during its early stationary phase. Thus the changes
in the pattern of alkaloid accumulation on addition of arsenicals are
dependent on the arsenic species and its concentration, as well as the
time of application. This variable response indicates that each arsen
ical has a distinct mode of action on the secondary metabolic pathways
of C. roseus.