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On the Preparation of a Concentrated Source of the Heat-Labile Vitamin B, Free from Contamination with the Heat-Stable Factor G^*

(From the Department of Anatomy, University of California, Berkeley.)

To judge from our results with 25 per cent alcohol, an efficient extractive of both the heat-labile and heat-stable, water-soluble vitamins, the heat-stable factor is in low concentration in the outer layers of the rice kernel and decreases further in abundance in the inner layers, whereas the heat-labile factor is in high concentration in the rice outer layers and decreases only slightly in the inner layers. Clay activated by the 25 per cent alcoholic extract furnishes an excellent source of vitamin B free from the heat-stable factor.

When the syrup resulting from concentration of a 25 per cent alcohol extract is treated with 95 per cent alcohol so that the resulting concentration is 90 per cent, most of the heatstable factor is removed; nevertheless, large losses in the heat-labile factor are produced in this way. When the final concentration is 80 per cent these losses are much reduced, though unfortunately somewhat more heatstable vitamin is present. In the case of the rice polish, so little of the heatstable factor is initially present that fractionation with the 80 per cent alcohol yields an extract almost free of the heat-stable factor and very rich in vitamin B. Finally, adsorption with clay appears more selective for the heat-labile vitamin and thus the last traces of the heat-stable factor are left behind. Though we have not succeeded, as have some investigators, in approximating quantitative removal of anti-neuritic B from clays by means of barium hydroxide, the feeding of these clays has given us an adequate and, indeed, very high dosage of anti-neuritic B with assured absence of the heat-stable factor.

Manuscript received 24 April 1930.