Leung's Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics

and other drugs, followed by boiling or steam-
ing and then drying. The resulting product
therefore cannot be compared directly with
the American orEuropean productor any other
unprocessed product (JIANGSU;NANJING;WANG).

COMMERCIAL PREPARATIONS

Crude and extracts. Strengths (seeglossary)of
extracts are expressed in weight-to-weight

ratios. Crude was formerly official in U.S.P.

(1850–1936) and N.F. (1942).

Regulatory Status. Subject of a negative Ger-

man therapeutic monograph, due to toxicity

that can occur within the therapeutic dose

(includingvomiting,dizziness,musclespasms,

hypothermia, paralysis of respiratory system,

and rhythmic heart disorders) (BLUMENTHAL1).

REFERENCES

See the General References forBLUMENTHAL1;BRUNETON;CLAUS;DER MARDEROSIAN AND BEUTLER;
FARNSWORTH3;FERNALD;FOGARTY;FROHNE AND PFANDER;GOSSELIN;GRIEVE;GUPTA;JIANGSU;KARRER;
MARTINDALE;MCGUFFIN1&2;MERCK;NANJING;SAX;WANG.

1. G. de la Fuente et al.,Heterocycles, 27 ,
   1109 (1980).


2. E. Arlandini et al.,J. Nat. Prod., 50 , 937
   (1987).


3. H. Hikino et al.,J. Nat. Prod., 47 , 190 (1984).


4. A. Crema,Arch. Ital. Sci. Farmacol., 7 ,
   119 (1957).


5. N. G. Bisset,J. Ethnopharmacol., 4 , 247
   (1981).
   6. M. Murayama et al.,J. Pharm. Pharm-
   acol., 35 , 135 (1991).
   7. P. G. Xiao and K. J. Chen.Phytother. Res.,
   1 , 2, 5 (1987).
   8. J. L. Hartwell,Lloydia, 34 , 103 (1971).
   9. M. Kimura et al.,Jpn. J. Pharmacol., 48 ,
   290 (1988).

AGAR

Source:Red algae, includingGelidium carti-
lagineum (L.) Gaill., Gelidium amansii
Lamour.,Gracilariaconfervoides(L.)Grev.,
otherGelidiumandGracilariaspecies as
well as species of the generaPterocladia,
Ahnfeltia,Acanthopeltis,andSuhria.

Common/vernacular names:Agar-agar, gelosa,
gelose, layor carang, and vegetable gelatin; also,
Chinese gelatin, colle du Japon, Japanese
gelatin, and Japanese isinglass.

GENERAL DESCRIPTION

Agar is the dried hydrophilic, colloidal extract
of various red algae (Class Rhodophyceae);

the more commonly used red algae areGeli-

dium cartilagineum (L.) Gaill., Gelidium

amansii Lamour., Gracilaria confervoides

(L.) Grev., other Gelidium andGracilaria

species as well as species of the genera

Pterocladia, Ahnfeltia, Acanthopeltis, and

Suhria. Agar is extracted from the algae by

boiling them in water at a neutral or slightly

acidic pH. The hot liquor is filtered and on

cooling forms a gel that is purified by freezing

and thawing followed by drying.

The major agar producer has been and still

is Japan. Other producing countries include

the United States, Spain, Portugal, Chile,

Taiwan, Korea, Morocco, New Zealand,

Australia, Argentina, and Mexico.

Agar is insoluble in cold water but readily

soluble up to 5% in boiling water. The

solution (sol) on cooling to 35–40C forms

Agar 9