A fructose anhydride from the leaves of the barley plant.

IN determining the sugar content of a cold water extract of dried barley leaves, it was found that the estimate of total sugar was considerably higher if hydrolysis was effected by heating with N/5 sulphuric acid in a boiling water-bath for 10 min., than if treatment with 0-1 % invertase was employed. The sample of invertase was obtained from the British Drug Houses and under the conditions employed inversion of sucrose was complete. In one experiment the value for total sugar obtained after acid hydrolysis was 2-72% of the fresh weight of the leaves, whilst after enzymic hydrolysis it was only 1-33 %. Separate estimates of fructose and glucose showed that the excess of reducing sugar resulting from the acid treatment was almost entirely fructose. These observations led to an attempt to isolate a fructose anhydride from the leaves. It has long been known that fructose anhydrides occur in cereals [Miintz, 1878] and in bulbs [Wallach, 1886]. More recentlytheir presence in the Gramineae has been reported by de Cugnac [1931], and by Kizel and Kretovitsch [1934], and their constitution has been discussed by Challinor et al. [1934] and by Schlubach and Koenig [1934]. The presence of these compounds in the barley grain was recorded by Tanret [1891], and in the stems and leaf sheaths of the barley plant by Colin [1925] and Belval [1924; 1933]. As far as can be ascertained their presence in the leaf lamina has not hitherto been demonstrated, in fact both Colin [1925] and de Cugnac [1931] state that these compounds do not invade the leaf parenchyma, although they have been found in the leaves of the iris [Augem, 1928], and of the yucca [Schlubach and Florsheim, 1931].1 The barley leaves from which a fructose anhydride has now been isolated were detached from plants which had received a full manurial treatment. The seeds were sown on 3. iv. 33, and the collection of leaves was made 10-11 weeks later, when the ears were emerging from their sheaths. Subsequent work has shown that it is unlikely that fructose anhydrides accumulate in the leaves before this stage of the plant's development. Preparation of materialfor water extraction. Green leaves (7 kg.) were detached from the plants at the stage described above and plunged into boiling 95% alcohol in such quantity that the final alcohol concentration was 75-80%. After extracting under a reflux condenser for 5-6 hours, the alcoholic extract was poured off and the residual leaf material dried at 80}90o. It was then ground to a powder and again extracted with 95% alcohol for 4 hours and dried at 95°. The product, a straw-coloured powder, was now free from sugars, waxes and green pigments and constituted 60% of the total dry weight of the leaves.