In the earlier tests 16 parts of starch converted by 1 part of the ferment was the value found. These results are in close agreement with values reported by Sherman (Jour. Am. Chem. Soc., xxxii, 1073) for a sample of recent purchase. He found a conversion of 51 parts of starch to the colorless end-point in thirty minutes for one sample, while for another he found 66 parts, in the same time. It will be noted that our time limit is ten minutes. It is worthy of note that for a perfectly fresh and specially prepared sample furnished by Dr. Takamine, a conversion of 278 parts in thirty minutes was found by Sherman. Taking the time into consideration, it will be seen that the results are about the same for the market samples as those found by us and much lower than claimed, as well as much lower than for other makes of similar products. The difference in the behavior of fresh specially prepared Taka-Diastase and the market sample is very clearly shown. No one questions the fact that fresh laboratory samples of Taka-Diastase may show a moderate converting power on starch. But we have to deal with the activity of market samples only, and Sherman’s work and our own show the low digesting power of the product as physicians may secure it on the market.
The marked difference in activity between perfectly fresh and ordinary market samples of Taka-Diastase is very clearly shown also in a recent paper published by Wohlgemuth.[24] In the digestion of starch paste to the “dextrin” stage Wohlgemuth found in the commercial sample a strength approximately a hundred times less than that observed in a fresh sample sent him by Dr. Takamine.
Wohlgemuth’s results were obtained by a method not essentially different from ours, with this difference, however, that he digested through 24 hours in the cases reported, and carried the reaction to the “dextrin” stage only, in place of to a colorless end-point. Making the proper reductions, it is evident that the actual values found by him for the market samples bought in Germany are not greater than those reported by us.
The reference to the work of Sherman is made because, in a following paper in the same journal, he recommends the use of salt as an activator in finding the strength of certain diastase preparations. It is well known that dialyzed diastase preparations and starch of highest purity have but slight action on each other; a little salt increases the activity greatly, and also increases the activity of commercial diastase preparations. These facts Sherman utilizes in working out a method for valuation of commercial diastases. The facts were well known to us at the time of our former report, but it was not thought best to depart from the general method which had been in use by all analysts following the general scheme of Roberts. Quite recently, I. Bang has published a paper on the investigation of diastase (Biochem. Ztschr., xxxii, 417) in which he studies the behavior of sodium chlorid and other salts on the rapidity of starch conversion, and finds that a much smaller amount of salt than Sherman recommends brings the maximum increase.
The method employed in our former tests is a good comparative method, and this is all that may be claimed at present for any method. By adding salt to our starch solution the activity of Panase and other ferments is likewise greatly increased. For Panase, a preparation possessing rather high starch-converting power, we have recently found an increase of about 30 per cent. in the converting power, with salt present. Working to loss of blue color, merely, it is possible in this way to get a higher value than that claimed by the manufacturer. There is no practical gain in using the salt for our purpose as the methods are at best arbitrary, and the results only comparative.
Taking all the facts into consideration, it is recommended that the rejection of Taka-Diastase and Liquid Taka-Diastase be allowed to stand and that, in view of their extensive exploitation, this report be authorized for publication so that physicians may know the facts.
This report was referred to Parke, Davis & Co., and they made the following reply:
“The report submitted in your letter of the 23d is, we contend, erroneous and unjust: first, to our Liquid Taka-Diastase, because over three years ago we changed our formula, reducing the alcohol from 18 per cent. to 10 per cent., increasing the glycerin and thus prolonging greatly the period of activity.
“As for our regular Taka-Diastase, our claim is and has been for years simply that Taka-Diastase will digest or hydrolyze 150 times its weight of starch in ten minutes, under proper conditions. We do not claim, we do not permit our representatives to claim, that Taka-Diastase will completely transform starch, to the colorless end-point, into sugars. Taka-Diastase is used to supplement a deficiency of ptyalin and converts the starch into soluble material with great rapidity, thus giving the gastric fluid immediate access to the proteids.
“If in the enclosed labels the word ‘digest’ were replaced with the word ‘liquefy,’ the claim could not be assailed by the most carping critic. To save any possible question, we shall therefore make this change in our label, having it read: ‘Taka-Diastase will liquefy 150 times its weight of starch in ten minutes, under proper conditions.’ Is there the slightest question in your mind that this statement as just quoted is entirely correct and entirely supported by clinical experience?