calcium oxalate. Two major glyco sidi active principles, sennoside A and
B, are present along with free an thraquinones. At low doses, the tannin exerts as tringen effect and relieves diarrhoea;
at higher doses anthraquinones stimu lat laxative effect and relieve constipa tion (Natural Medicines Comprehen siv Database, 2007.)
There are three main types of rhu barbs—Chinese Indian or Himalayan,
and Rhapontic.
The Chinese rhubarb consists of the
rhizomes and roots of Rheum palma tu and R. officinale.
The Indian rhubarb consists of dried
rhizomes of R. emodi and R. web bianum rhizomes and roots of R.
moorcroftianum and R. spicforme are
also reported to be mixed with the
drug. R. rhaponticum is the Rhapontic
rhubarb.
Rheum moorcroftianum Royle (the
Himalayas at altitudes of 3,000—
5,200 m., chiefly in Garhwal and Ku R maon) possesses properties similar to
those of R. emodi and the roots are
mixed with the latter.
Rheum spicforme Royle (drier
ranges of Kumaon and Sikkim at alti tude of 2,700—4,800 m.) also possess e purgative properties. The rhizomes
and roots are mixed up with Himalayan
rhubarb.
Rheum webbianum Royle (the west er and central Himalayas at altitudes
of 3,000—5,000 m.) is the source of
Himalayan rhubarb.
Rheum palmatum is esteemed as
the best type of (Chinese) rhubarb.
Two new stilbene glycosides, 4’-O-
methylpiceid and rhapontin, isolat e
