The effect of light on the production of Heimia alkaloids

Alkaloid extracts obtained from light- and dark-grown shoot cultures of Heimia salicifolia were partially fractionated and semi-quantitatively analysed for phenyl- and biphenylquinolizidine alkaloids. The concentrations of the two structural types of alkaloids in extracts of shoots grown with illumination increase over a 4 week culture period. In extracts obtained from shoots grown in darkness for 4 weeks, however, we observed substantial decreases in the concentrations of both the phenyl- and biphenylquinolizidine alkaloids. We observed that growth in the dark for periods of up to 9 weeks resulted in a further reduction in the levels of biphenyl alkaloids relative to those of the phenylquinolizidinols.