THE DIGESTIBILITY AND UTILIZATION OF SOME POLY- SACCHARIDE CARBOHYDRATES DERIVED FROM

LICHENS AND MARINE ALGX

BY T. SAIKI. (From the Skeff~kt Labmutory of Physiologica Chemistry, Yate University.)

(Received for publication, July r9, 1906.)

During the last few years increased attention has been directed to the employment of a number of peculiar food materials hitherto restricted in use to a few countries. The most familiar of the products are furnished by the alga: and lichens, while some underground storage organs of flowering plants aft‘ord the unusual compounds of the inulin type. A recent publication of the Bureau of Fisheries1 has pointed out that while marine plants are extensively utilized in France, Ireland, Scotland, and other European countries, in the East Indies, in China, and elsewhere, in no other country are such products relatively and actually so important or utilized in such a large variety of ways as in Japan. The products enter extensively into the dietary of the Japanese; and since all of the important prepara- tions can be made from plants easily available in the United States, it has lately been suggested that they ought to find a ready use in dietetic ways in this country.2 This refers espe- cially to several groups of plant products characterized by their content of types of carbohydrates differing notably from those which constitute the staple nutrients of our diet.

Carrageen, or Irish moss, dulse, laver, and vegetable gelatin, vegetable isinglass or agar-agar, are the most familiar seaweed preparations. Iceland moss represents the lichen products; while the familiar inulin-yielding plants are the edible Jerusa- lem artichoke (Hcliunthus tuberosus) and the Japanese Stachys

1 H. M. Smith, “The Seaweed Industries of Japan,” Bull. of the Bureau of Fisheries, xxiv, p. 133, rgoq. For the edible algae and lichens used by the Hawaiians, cf. Setcheil, Univ. of Calif, Pub., Botany, ii, p. 91, 1905 @mu).

1 H. M. Richards, Science, xxi, p. 895, rgog; also H. M. Smith, lot. cit., p. r6g.

251

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

252 Utilization of Polysaccharide Carbohydrates

afi+zis,i together with the non-edible roots of Inula helesium, Dahlia variabilis, and Lappa minor from which inulin itself is isolated.2 In Japan the most widely used edible products furnished by marine algae are nori, kanten, kombu, and wakame. A description of these products together with detailed informa- tion regarding their manufacture and commercial uses has been published by the Bureau of Fisheries.3 Their chemical compo- sition has not been the subject of adequate investigation until quite recently. Quantitative determinations of the so-called proximate principles were available, but these give a most im- perfect and, as we shall see, often misleading conception of the real chemical make-up and nutritive value of such products.4 In the commercial marine algae, starch and the simpler sugars are rarely found. Mannose and mannite may be present; but the materials are primarily characterized by a number of inter- esting and scarcely investigated polysaccharides which yield dextrose, galactose, mannose, pentose, and methyl pentose on hydration with acids. In addition to this, cellulose also occurs. The fungi and lichens contain similar compounds, chitosan- the polysaccharide yielding glucosamin-occurring in addition as a constituent of the cell wall. To these peculiar carbohydrates the inulin and related compounds obtained from the Corn- pus&z, and the xylose-yielding xylan or wood-gum may be added for consideration here.

It is well recognized at present that the only carbohydrates directly available in intermediary metabolism are the simple monosaccharides, particularly the six-carbon sugars. If other

1 Cf. v. Noorden. Von Leyden’s Handbuch der Erncihrungstherapie, ii, p. 227.

2 Cf. Dean, Amer. Chem. Jown., xxxii, p. 69, r904. 1 Bull. of the Bweau of Fisheries, xxiv, p. 133, 1904. References to the

literature on these products will also be found in this bulletin. Cf. also K. Yendo, Uses of Mar&e Alga in Japan. Postelsia, 1901.

4 The most valuable data bearing on the composition of the algae, lichens, and fungi will be found reviewed by Czapek, Biochemie der Pfkan.een, i, 1905. On algae, cf. also Koenig and Bettels, Zeitschr. f. Uttterstuhung d. Nahrwzgs- M. GenussmitteZ, ~905, p. 487; on lichens, cf. Ulander, Untersuchungen fiber die Kohlenhydrate der Flechten, Disserta- tion, Gbttingen, 1905; Wander and Tollens, Ber. d. deutsch. chew Gesellsch., xxxix, p. 401, 1906, where reference to the literature, especially to papers by Tollens and his pupils, will be found.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki 253

soluble carbohydrates are introduced parenterally into the cir- culation without previous passage through the alimentary tract, i. e. without digestive hydrolysis, most of them are speedily eliminated in large part by the kidneys precisely like some foreign substance. This is true of inulin and the soluble lichenA carbohydrate isolichenin, as well as the more common carbo- hydrates: glycogen, dextrin, soluble starch or saccharose.1 From this it appears that the polysaccharides must be subjected to preliminary cleavage into “physiological ” sugars before they can become readily available in nutrition. One naturally in- quires, therefore, whether and to what extent the animal organism is equipped for appropriate digestion of the complex carbohydrates to which reference has been made above.

The growing evidence of the specificity of enzymes, exemplified pay excelleltce in such individual carbohydrate enzymes as sucrases, lactases, amylases, etc., at once suggests that mannan, ,galactan, xylan, pentosan,. and all the other complex polysac- charides may require special enzymes for their conversion into assimilable sugars. The experience of Professor Mendel and his collaborators has already brought evidence in this direction. The polysaccharide inulin, apparently so closely related to the readily digested starches, dextrins, and glycogen, and differing only as does “levulan ” from “ dextran, ” is not hydrolyzed by the ordinary alimentary enzymes. Neither amylolytically active saliva, pancreatic juice, intestinal extracts nor the vegetable preparation “ Taka-diastase ” from Eurotiztm oryate transform it at all into reducing sugar.2 It is, however, readily converted into levulose by acid of the strength of the gastric juice at 37O C., even when proteid is present. In accord with the failure of inulin to be digested, Sandmeyer recovered over half of the quantity fed to diabetic dogs in the fseces. Similarly Mendel and Nakaseko” failed to get conclusive evidence of glycogen formation in rabbits after inulin feeding, although an accumula-

1 Cf. Mendel and Mitchell, Amer. Jown. oj Physiol., xiv, p. 139, 1905. 1 Amer. Jowm. of Physiol., ii, p, xvii, 1898; Richaud, Compt. rend. de la

SOL de biol., Xii, p. 4x6,1900; Bierry and Portier, ibid, p. 423; Bierry, ibid,, lix, p. 256, 1905; Weinland, Zeitschr. f . Biol., xlvii, p. 286 (footnote), ‘905.

* Sandmeyer, Zektschr. f. Biol., xxxi, p. 12, 1894. 4 Nakaseko, Amer. Journ. of Physiol., iv, p. 246, ~901.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

254 Utilization of Polysaccharide Carbohydrates

tion is easily procured by using the derived levulose.1 Inulin is readily converted into soluble sugar by the enzyme inulase (found in fungi such as Aspergillus and Perticilium) which in turn does not digest starch, although it inverts cane-sugar.2

The lichens, formed by the symbiosis of algae and fungi, furnish a variety of carbohydrates. The most familiar example is the Iceland moss (Cetruriu is&dica), which has already been the subject of investigation in this laboratory.3 It is composed largely of soluble polysaccharides and yields two characteristic products: lichenin and isolichenin; the latter soluble in water at ordinary temperatures, the former separating in gelatinous form like starch paste. Ulander and Tollens have found that various more common species of lichen differ in respect to the occurrence of these characteristic carbohydrates which are extracted by hot water and gelatinize on cooling. Thus Cet- rariu, Evernia prunastri, Usnea barbafa, afford the similar carbohydrates lichenin, evernin, and usnin; whereas Cladonia ran&e&a, Stereocaulon pascale, Peltigra aphtosa, and Corn&~- la&a aculeata yield no such polysaccharides. In all the lichens, however, other insoluble polysaccharide residues (mannan, gala&an, pentosan, and methyl pentosan) are present in abund- ance, together with some cellulose. The chemical nature of lichenin has been the subject of controversy; but the evidence that it is a “ dcxtran” rather than a galactan now seems convincingq5

It is reported that lichens, especially Cetraria isla?zdica, have found wide use as articles of diet.6 The inhabitants of Iceland, Norway, and Sweden mixed Iceland moss with various cereals and mashed potatoes, from which an “uncommonly palatable and healthful bread was prepared.” Sir John Franklin and his

* Professor von Noorden lately informed Professor Mendel that he has ceased to recommend the use of inulin-containing foods to diabetic patients. Cf. v. Leyden’s Handbuch der Embhrungsfherapie, ii, p. 221.

2 Dean, Bet. Gus.. xxxv, p. 24, 1903. * Brown, Amer. Journ. of Physiol., i, p. 455, 1898.

4 Ber. ct. deutsch. chew Gesellsch., xxxix, p. 401, 1906; cf. also Mfiller, Zeifschr. f. physiol. Chem., XIV, p. 278, 1905.

8 Cf. Brown, Zoc. cit.; Wander and Tollens, Zoc. cit.; Miiller, ZOG. cit. The galactan nature of lichenin was advanced by Escombe, Zeifschr. f. physiol. Chem., xxii, p. 295, 1897.

6 Schneider, A Text-book of Lichenology, 1897, p. 23.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki 255

companions made use of this lichen during their Arctic voyages. It has especially been recommended as an article of diet for con- valescents. Other genera reported to be used as food by Polar navigators are Umbilicaria and Gyrophora, referred to under the name of Tripe-de-roche or Rock tripe.1 In view of these facts the digestibility of the specific carbohydrates becomes of con- siderable interest. Brown2 found, in this laboratory, that ordinary amylolytic enzymes, as well as hydrochloric acid of o .3- o. 5 per cent. strength have no noticeable effect on lichenin ; and iso- lichenin was at most converted into a dcxtrin-like form, without production of sugars. These observations have been confirmed in our experiments reported below. In accord with this Brown failed to induce glycogen formation in rabbits by feeding lichenin.

With respect to the digestibility of the more insoluble types of carbohydrates found in the lichens and alga: our knowledge is most limited. Schulze and Castor03 have been unable to demon- strate any digestion of hemicelluloses by means of ptyalin, pancreatin, diastase, or “Taka-diastase”; and the existence of enzymes capable of hydrolyzing pentose-polysaccharides in the alimentary tract of man and the higher animals is most uncer- tain4 Pentosans are apparently utilized far better in the alimentary tract of herbivora than in carnivora. To what extent non-enzymatic fermentative processes contribute to this cannot yet be said. Doubtless the cytases and other plant enzymes themselves aid in such utilization.s The attempts to obtain evidence of cytases in mammals have for the most part failed, According to Slowtzoff 6 the carbohydrate enzymes of the alimentary tract do not act upon xylan. It is slowly attacked by the acid gastric juice and poorly absorbed. Mannans (salep extract) are likewise not hydrolyzed by animal amyIases,f and Weinlands has been unable to induce the formation of manna-

* Smith, Dictionary of Popular Names of Economic Plants, 1882, p. 418. 2 LOG. cit.; cf. also Berg, Jahresb. d. Chem., 1873, p. 845. 8 Zeitschr. f. physiol. Chem., xxxvii, p. 50, 19oa. 4 Cf. Neuberg, Ergeb. d. Physiol., iii, I, p. 421, rgoq.

. 5 Cf. Bergmann, Skand. Arch. f. Physiol., xviii, p. 119, rgo6. 6 &&chr. f . physiol. Chem., xxxiv, p. 181, 1901. t Cf. Gatin, Corn@. rend. de la sot. de biol., Iviii, p. 847, 1905. I Zeiischr. f. Biol., xlvii, p. 280, 1905.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

256 Utilization of Polysaccharide Carbohydrates

nases in dogs by appropriate feeding. In lower forms, however, cytases and xylanases are reported to 0ccur.l In plants these polysaccharide enzymes doubtless arise. Finally the value of unusual sugars such as pentoses, mannose, glucosamin, etc., in nutrition is not yet satisfactorily established; accordingly they deserve little recommendation as actual nutrients2 It is inter- esting, therefore, to find the following comment in Schneider’s Lichenology : “In general it may be stated that lichens were used as an article of diet only in case of famine or in those coun- tries where cereals are not abundant, principally because all lichens contain a bitter principle which is very disagreeable to the taste and difficult to remove and which has a deleterious effect upon the digestive tract, producing a form of intestinal inflammation. ” (p. 23).

EXPERIMENTS.

We have made a study of the digestibility of a nutiber of typical products, viz. :

I. Extracts of Cefraria kslundica (Iceland moss) containing lichenin. 2. Extracts of Chondrw crispzcs (Irish moss), containing a gelatinizing

carbohydrate. 3. Japanese kombu (konbu).~ Under this name the Japanese recog-

nize several kinds of standard foods prepared from Luminuri- crcece. especially L. japonica. It is ordinarily cooked with soups

or served as a vegetable, The carbohydrates which it yields by acid hydrolysis are glucose, fructose, pentose, and methyl pentose.

4. Japanese wakame. From UIzdaria pinnatifida. This alga yields d-galactose in addition to the sugars just mentioned. Alaria escul&a is similarly used by the Scotch and Irish.

5. Japanese nori (Asakusanori). Prepared from various species of Porphyra and sold in thin, paper-like sheets. It yields espo- cially i-galactose and d-mannose.

6. Agar-agar (kanten). This familiar product is prepared from the

1 Cf. Biedermann and Moritz, Arch. f. d. gcs. Physiol., lxxiii, p. 236, 1898; Seilliere, CompL rend. de la JOG. & biol., lviii, p. ao, 1905; Pacant, ibid, p. 29; v. Fiirth, Vergl. &em. Physiol., pp. 190, 226.

2 Cf. Neuberg, lot. cit. (pentosans and pentoses); Bial, Berl. klin. wochelrschr., 1905; Ewald, Festschrift, (glucosamin).

8 The modes of preparation of this and the other Japanese seaweed products are described in the Bweau of Fisheries Bulletin, No. 562; also by K Yendo, Postelsia, 1901. The data regarding the carbohydrates are taken from Koenig and Bettels, lot. cit., p. 457.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T, Saiki

hot-water extracts of various species of Gelidium and differs somewhat according to its origin. It yields galactose and pen- tose, the gala&an forming about one-third of the dry substance; pentosans about 3.5 per cent.; cellulose, o. 5 per cent.

BEAKER DIGESTIONS. Methods. Two preparations of agar- agar were used in the form of a I per cent. jelly. The other products were used in .finely cornminuted form after being boiled with hot water and suspended therein. The enzyme prepara- tions included (a) filtered human saliva, (b) pancreatic juice collected from dogs after injections of secretin, (c) alcoholic (20 per cent.) extracts of dog’s pancreas, (d) chloroform-water extracts of dog’s and pig’s intestine, (e) malt diastase, (f) Taka- diastase (Parke, Davis, & Co.), (g) inulase, prepared from Aspergillus niger.1 The digestive mixtures, preserved with toluene were kept at a constant temperature of 40~ C. and tested after twenty hours, and again at the end of three days, for reducing sugars with Fehling’s solution. Whenever the reaction was positive a second test for osazones was made with phenyl- hydrazine. In every case a control trial was carried out under the same conditions with boiled enzyme extracts; the latter experiments were uniformly negative. The trials were often repeated and the numerous protocols need not be recorded here. The results are summarized below:

Ryulin. The amylolytic power of the saliva used was always pre- viously established with starch paste. The digestion tubes contained the following proportions :

Product used . . . . . . . . . . . . . . . . . . . zoc.c.(oraogm.) Saliva... . . . . . . . . . . . . . . . . . . , . . .I0 c.c. Toluene.... . . . . . . . . . . . . . . . . . . . . 3drops.

The results of the trials were uniformly negative. Occasionally minute traces of reduced copper precipitate were obtained in the tests after three days’ digestion. This was, however, not a constant result. Osazones were never obtained.

Pancreatic Amykzse. The tests were made with amylolytically active enzyme solutions. The pancreatic juice was used in proportion of 1.5 or a C.C. to IO C.C. of the carbohydrate material; or 20 C.C. of the latter were mixed with IO C.C. of the pancreatic extracts. The results were negative in every case.

Itieslinat Extract. This contained very active invertin. It was used

‘For this preparation, active on inulin, I am indebted to Dr. A. L. Dean. For the method of preparation see Dean, Bat. Gas., xxxv, p. 26,

x903-

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

258 Utilization of Polysaccharide Carbohydrates

in the proportion of IO cc. to 20 cc. of the carbohydrate mixtures. The results were all negative.

Vegetable Amylases. With malt d’ t ras ase no digestion whatever was obtained in many trials. With Taka-diastase (from Eurofium oryzae) the carbohydrate extracts of Iceland moss and Irish moss gave sugar tests after 20 hours’ digestion. Usually crystalline osazones could be obtained. The other preparations were not hydrolyzed. Strong solu- tions of the enzyme were used.

Znulase. The results obtained with this enzyme were comparable with those just reported for vegetable amylases. They suggest interesting questions regarding the specificity of enzymes, especially those of vege- table origin. A specimen protocol is tabulated below:

Digestion Mixture at 40’ C. (Toluene, 3 drops.)

--

1 % agar, 20 gm. + 2%inulase sol., 1 c.c. Jceland moss, 20 C.C. “ ‘I Irish moss, 20 “ “ ‘I fgiklagnori, 20 “ I‘ ,‘

20 I‘ “ (‘ Wakamk, I‘ Tnulin, 2”; “

“ I‘ ‘I I‘

Reduction Test with Fehling’s Solution.

After 20 hrs.

-

After 3 days

- + -I-

trace? “

;1

Hydrolysis by Dilute Acid. In order to simulate conditions prevailing in the alimentary tract the extracts were subjected to o. 4 per cent. hydrochloric acid at 40“ C. for 20 hours. Traces only of reducing com- pounds could be produced by this process, quite,in contrast with the behavior of inulin, for example, towards acid gastric juice. No definite osazone tests could be obtained. Agar-agar was subjected to the action of dilute acid, then washed to neutral reaction and tested with saliva and diastase. The digestibility was only slightly facilitated by this mild preliminary hydrolytic treatment.

Bacferial Digestion. The action of three cultures of Bacillus coli communis 1 on culture material containing cornminuted sea-weed or lichen carbohydrates was investigated. Witte’s “peptone” (I per cent.) was adbed, the mixtures sterilized, inoculated, and Fehling’s test tried at thaend of the third and seventh days, with negative results. In one series, Liebig’s extract of meat was also added to the extent of I per cent. With one of the cultures slight gas production was regularly noted in the media with agar-agar, Cetraria and Chow&w.

UTILIZATION EXPERIMENTS. PZa?z. The preceding artificial

r For these I am indebted to Professor 1,. F. Rettger.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki

digestion experiments gave little promise of a successful utili- zation of the lichen- and alga-carbohydrates in the animal b0dy.l Nutrition experiments undertaken to test this point have verified the deduction made. In addition to a standard, easily digested diet, various preparations were fed to dogs or ingested by the author, and the carbohydrate content of the corresponding farces compared with what the normal control diet alone afforded. The method applied for the quantitative determination consisted in boiling 3 grams of dried f=ces with $120 C.C. of 2 per cent. hydrochloric acid for 2 hours. The mixture was then cooled, neutralized, filtered, and made up to 200 cc. In this fluid reducing sugar was determined by Allihn’s gravimetric method, the cuprous oxide being filtered on a Gooch crucible and weighed as cupric oxide. The length of time selected for the acid hydrolysis was decided upon after a preliminary experiment in which various products used for feeding were boiled with 2 per cent. hydrochloric acid and samples removed at intervals for the estimation of sugar. The data are given below:

Materials Used (1 gm. substance -t 100 cc. 2 per cent.

HCI).

Agar-agar (Japanese) Agar-agar (sou:ce unknzwn) Agar-agar A ;;aazF (recovered from fseces)* ag Nori Kombu Cetraria islandica, dried, Chondrus crispus, dried,

Su ar Formed (Estimated as 8, extrose) after Boiling.

1 hour. 3 hours per cent. per cent -__-

64.1 49.5 62.6 54.0 60.1

~ ---

47.6 47.3 34.9

20:1 2E 13.0 26.9 21.5

48.2 46.8 67.6 74.4

----

. ! ‘. 1 _’ -

5 hours. per cent. ---_

46.3 45.3 44.2 32.4 13.2 23.2 28.8 44.2 74.1

* The lower figures obtained with this are undoubtedly due to the high ash content of the (impure) preparation.

Feeding Trials. I. A small dog was fed on a daily diet of 300 gms. of meat. On two days 350 C.C. and ago cc. respectively of an extract of Chondrus cvis~us, containing I per cent. of dry substance and estimated after analysis to yield a total of 4.5 gms. sugar, were fed with the meat. The farces of this two-day period were marked off by feeding finely _-..-.-__.-_ -

1 It is stated in Thorp’s Dictionary of Applied Chemistry that agar-agar is used to make a paste not eaten by insects.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

260 Utilization of Polysaccharide Carbohydrates

ground cork. A comparison of the composition of the air-dry freces with a sample of both previous and subsequent days was made. -_--..- -- -___

I Sugaro~yF~~e~lysis I

Air-dry Freces per Day.

Fore-period No reduction test Chondrus-period After-period

2.7 grams (12.2 ye) Trace only

3 grams. 11 “

41 ”

No reducing compound was found in the urine. The effect of the Chondrus polysaccharides is evident in the increased quantity of farces as well as the undecomposed carbohydrate present. In this connection it is interesting to note that in unpublished experiments conducted under Professor Mendel’s guidance, Mr. Courten failed to induce glycogen formation in rabbits after liberal feeding with Chondrus carbohydrates.

II. A small dog received a mixed diet of meat, milk, bread, and cracker meal. On one day IO gms. of agar-agar were added in the form of jelly. The farces were marked off as well as possible with lamp-black and analyzed as in Experiment I. The carbohydrate content (as sugar) was as follows:

Fore-period, 2 days. . . . . . . . . . . . ,18 peI;(cent.

After-period. . . . . . . . . . . . . . . A ar-period. 1 day.. . . . . . . , . . : 3.:

“ 1

III. A small dog was fed with meat. On two days an extract of C&aria islandica containing s per cent. of solids was added in quantities of 292 cc. and 300 cc. respectively. The carbohydrate content was estimated as equivalent to 6.3 gms. of dextrose. The feces of the lichen- feeding period were marked off by giving very fine quartz sand at the beginning of the feeding and cork at the start of the after-period. No reducing compound was found in the urine. The composition of the feces is given below:

I Composition of the Preces.

Diet. 1 Wei$$air- 1 Carbohydrate, as Dextrose.

-_-.-~-.-_-----_-..~r

*These freces belong to the Cetraria feeding period.

1 These fzces doubtless still enclosed some agar-agar, owing to the diniculty of exact separation.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki

IV. Experiments on a man weighing 53 kilos. This individual (T. S.) is unusually free from intestinal disturbances of any sort. The faces in all the trials were marked off with lamp-black. On a very liberal mixed diet, including vegetables like corn, the dry freces contained as much as 7 per cent. of carbohydrate, calculated as dextrose. The results of successive two-day periods on a mixed diet kept approximately comparable follow :

--_--- -- -j-.~_- Farces.

Food.

_-- --_ .-

Weight. Carbohydrate, as Dextrose. ----

Fresh. Grams. iYl22.

i

Grams. Per cent.

-_--- -_--. .- ---

Usual diet -t 20 gm. agar-agar in jelly form 317

Usual diet, alone 120 El 18.0 6.7

Usual diet + 10 gm. agar-agar 317 43 17.2

__.. .---___-.-__--- -... .-.--.--. .--- ~~~~.- ~_._.._

Since the agar-agar used yielded over 50 per cent. of reducing carbohydrates it will be noted that the utilization of the poly- saccharides was very imperfect. The effect on the total mass of faxes passed is also very marked. The agar easily retains water in the alimentary residues and prevents the formation of dry, hard, faecal masses which readily induce constipation. This property of the agar, together with its failure to dissolve readily by digestion or fermentative change has led Professor Mendel to suggest its use in appropriate cases of chronic constipation, with very satisfactory results. The same suggestion has lately been advanced by Schmidt,1 without experimental evidence of the kind here presented.

The results of another series of observations extending over eighteen days are summarized below. The jndividual periods each covered two days, the faxes being marked off correspond- ingly with lamp-black. The daily diet, selected in accord with the subject’s preference, consisted uniformly of

1 Miinch. med. Wochmtschr., 1905, p. rg7o.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

262 Utilization of Polysaccharide Carbohydrates

Beef steak, 513 grams. Bread, 500-600 grams. Sugar, 40 grams. Butter, 31 grams. Three eggs. Two apples.

In alternate periods the algae preparations were added in boiled form, the quantity being distributed through the three meals. Nitrogen estimations were made by the Kjeldahl- Gunning method.

UTILIZATION EXPERIMENTS ON MAN.

T

7OlUlIIl C.C.

:zi

1315 1030

1570 1600

:aEi

1530 1615

:ts

EE

:%

1495 1420

:pecifit :ravlt]

mro- gal.

--

:P ‘G

-.

_-.

- Weight.

Fe&%. __-_ -.

Nitrogen. -I- Carbohydrate (as Dextrose).

Moist :rams

;ir-dr, .ir-dry Lir-dr

hams. Per

_...

4.1 0.0

3.6 7.7

4.0 7.0

4.4 8.0

4.3 8.3

3.4 8.0

4.7 8.0

3.9 9.6

2.0 1.8 is

Jr-dr, ham:

62

\ir-dry Per

cent. _---._

14.4

46

70

65

1.6

4.8

1.4

52 0.1

43 0.1

59

A$ar-a$?~, 1: 8;r”. 20.3 24.8 t 313 8.8

:x2 i2:; i 222 0.7

wakame, 31 p. E:6” 1 321 3.4

NOTIC NOTE 2:: 1

275 0.7

Asak~~anori. 8 gv:. XI:: 1 207 trace

NOTE 23.4 NOfl.2 22.3 I

171 trace

KoFbu, ;i $f”. 2%:: 1 234 2.5

NOIX 23.4 NOtE 24.8 t

168 trace

Raw “Italian”Chest- nuts (Castanea)

.a ‘I “ 1;: pf”. Zf:f

233 76 63

-_-- -_-.- _- -

The experiment with unboiled chestnuts was added to ascer- tain the effect of raw starch on the composition of the faeccs in comparison with algae carbohydrates. The results indicate the relative indigestibility of starch offered in this form.

Character of the Unabsorbed Carbohydrates ilz the Faxes. In the experiments with agar-agar an attempt was made to recover

4.2

0.1

18.9 3.2

--

Urine. T

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki

the unused material where a considerable quantity of farces was available. They were extracted with hot water and the extracts precipitated with alcohol. The precipitate was redissolved in hot water and allowed to gelatinize on cooling. The pieces of solid jelly were soaked in water to remove soIuble salts and other carbohydrates, then redissolved in hot water and again pre- cipitated with alcohol. The products were characteristic in respect to solubility and gelatinizing power; but as the analysis (p. 259) shows, they were still relatively impure. Normal f=ces failed to give any agar-like carbohydrate.

CONCLUSIONS. A survey of the protocols indicates the poor utilization of the Japanese preparations---a result which our pre- liminary studies on digestibility lead one to anticipate. The polysaccharide carbohydrates of such products as we have ex- amined are scarcely attacked by familiar alimentary enzymes or profoundly altered by such bacterial processes as they might be expected to become subject to in the digestive tract of man. It is an interesting observation that some of the enzymes of plant origin seem to be somewhat more effective in liberating sugars from these polysaccharides. The exhaustive review of Japanese nutrition investigations recently published by Professor Oshimal contains references to several studies on the utilization of the nutrients of dietaries rich in algae food preparations. The compilation of one hundred and twenty-five nutrition investi- gations on Japanese shows the following average coefficients of digestibility (p. 54):

.--..-.~~-~~ ---. _____ Utilization of

Kind of Food. Protein.

Per cent. Carbohydrate.

Per cent. ----- ----

Ordinary mixed diet Vegetable mixed diet

In contrast with these figures are the results obtained in trials with alga: as food (p. 194.) :

1 U. S. Dept. of Agric., Ofice of Exper. Stations, Bull. No. i59, 1905.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

264 Utilization of Polysaccharide Carbohydrate

Coefficient of Digestibility.

Dried Marine Algae. Carboh

z drates, Including

rude Fibre. Crude Fibre.

Ecklonia bicyclis Lim+uria sp.

UIopleryx pinnaiifida

36.2 17.8 75.2 65.3 55.0 65.4 72.8 I 2.8

-I I -

Such experiences warn us against the extravagant claims for some of the modern food products manufactured from marine algae.’ As food accessories they doubtless have a deserved place and they may well serve uses quite apart from any nutrient functions. But at the present time they can scarcely be rated as effective foodstuffs. It has been claimed that some of the species rich in nitrogen, e. g., Porphyra, are particularly valuable because of their content of proteid. The latter is, however, merely calculated on the basis of the nitrogen content. The experience gained in the case of the mushrooms where, according to MendelF the nitrogen is largely in the form of unavailable non-proteid compounds, has indicated what erroneous inferences may be drawn regarding the nutritive values of plant substances rich in nitrogen. Until more is known regarding the character of the nitrogenous constituents of the algae, it seems best to reserve judgment on this point. The number of alga: sus- ceptible of being prepared in palatable ways is doubtless very large; perhaps it is after all not without significance that in this country they have not found favor in competition with an abundance of wholesome and more distinctly nutritive food materials.

SUMMARY.

Experiments with a variety of alga and lichen preparations containing a large proportion of poly$accharide carbohydrates

1 Some of these preparations are sold as substitutes for animal gelatin. One widely used agar product which we have examined contains the statement on the package: “Its food value is more than double that of an equal weight of eggs or beef-steak. ”

namer. Joum. of Physiot., i, p. 225, 1898.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. Saiki

indicated that the latter were not readily transformed to sugar by carbohydrate-digesting enzymes of animal origin and scarcely more readily ‘by vegetable enzymes or bacteria. Corresponding with this, the digestibility and availability of such products in the alimentary tract were found to be very imperfect in both man and animals. The results of these investigations should be applied in criticism of the claims made for some of the “food preparations” rich in indigestible carbohydrates, and many food materials more properly rated as “food accessories. ” Inci- dentally the basis for certain therapeutic uses of sea-weed. preparations has been indicated

I desire to acknowledge the help and criticism of Professor Mendel, who suggested this study to me.

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from

T. SaikiMARINE ALGÆ

DERIVED FROM LICHENS AND POLYSACCHARIDE CARBOHYDRATES

UTILIZATION OF SOME THE DIGESTIBILITY AND

1906, 2:251-265.J. Biol. Chem. 

  http://www.jbc.org/content/2/3/251.citation

Access the most updated version of this article at

 Alerts:

  When a correction for this article is posted• 

When this article is cited• 

alerts to choose from all of JBC's e-mailClick here

  #ref-list-1

http://www.jbc.org/content/2/3/251.citation.full.htmlaccessed free atThis article cites 0 references, 0 of which can be

by guest on May 29, 2018

http://ww

w.jbc.org/

Dow

nloaded from