Glycine can be a specific precursor of the Cgvl0 unit (I) of ajmaline (11), and probably of reserpine (111), and may be a fundamental precursor for this unit in alkaloids.RECENTLY we reported that glycine could be specifically incorporated into the C,-,, unit as it occurs in the isoquinoline alkaloid cephaeline in Cephaelis acuminata, but that it was a poor precursor of fl-sitosterol in the same plant.lS2 At the same time it was confirmed that while acetic acid acts as a normal precursor of /%sitosterol, it is neither significantly nor specifically incorporated into cephaeline.2 We now present evidence that glycine is also specifically incorporated into this same C,,,, unit as it occurs in indole alkaloids found in RazLwoZfa seypentina, and hence that it may be a universal precursor of this unit.

The biosynthesis of hydrastine and of berberinewas investigated by administering radioactive glucose, phenylalanine, tyrosine, and dopamine to Hydrastis canadensis L. Both hydrastine and berberine were found to be specifically derived from two molecules of tyrosine. The ratio of incorporation of the two molecules of radiotyrosine into hydrastine was not unity, and varied with time. Dopamine was also incorporated into hydrastine without randomization, but only one molecule was utilized. These results, which are consistent with the classical hypothesis and disprove the prephenic acid hypothesis of biogenesis, provide direct evidence for some of the steps in the biosynthetic pathway by which hydrastine and berberine are formed in the plant. INTRODUCTIOS

The biosynthesis of hydrastine and of berberinewas investigated by administering radioactive glucose, phenylalanine, tyrosine, and dopamine to Hydrastis canadensis L. Both hydrastine and berberine were found to be specifically derived from two molecules of tyrosine. The ratio of incorporation of the two molecules of radiotyrosine into hydrastine was not unity, and varied with time. Dopamine was also incorporated into hydrastine without randomization, but only one molecule was utilized. These results, which are consistent with the classical hypothesis and disprove the prephenic acid hypothesis of biogenesis, provide direct evidence for some of the steps in the biosynthetic pathway by which hydrastine and berberine are formed in the plant. INTRODUCTIOS

No abstract

The rate of photochemical degradation of aqueous solutions of picloram under ultraviolet light was measured by five different methods of analysis. These were chosen to assay the loss of picloram, dechlorination, alteration or loss of the aromatic amino group, loss of aromaticity, and decarboxylation. The initial rate and mean rate of reaction were determined in each case, and their relationship to each other was used to assess the significance of that particular reaction to the overall degradation of picloram and its early degradation products. Results suggest that dechlorination is the major photochemical process, with decarboxylation, loss of aromaticity, and deamination all being significant subsequent reactions.