UCOSIDES

=Salicin=, C_{13}H_{18}O_{7} (glucose+saligenin, or _o_-oxy benzyl alcohol)
is found in the bark, leaves, and flowers of most species of willow, the
proportion present depending upon the season of the year, and the sex of
the tree. It is used as a remedy against fevers and rheumatism, causing
less digestive disturbances than the salicylic acid which is the oxidation
product of saligenin and which is sometimes used as a remedy for
rheumatism.

=Coniferin=, C_{16}H_{22}O_{8} (glucose and coniferyl alcohol), is found in
the bark of fir trees. The coniferyl alcohol obtained from coniferin by
hydrolysis can be easily oxidized to _vanillin_, and is, therefore, the
source for the artificial flavoring extract used as a substitute for the
true extract of the vanilla bean.

=Populin=, C_{20}H_{22}O_{8} (glucose+saligenin+benzoic acid), found in the
bark of poplar trees, is used in medicine as an antipyretic. It can be
hydrolyzed, by a special enzyme, into salicin and benzoic acid.

The structure of the two typical closed-ring alcohols which are present in
these glucosides is indicated by the following formulas;

Coniferyl alcohol
Saligenin
CH=CH.CH_{2}OH
/\ /\
/ \ / \
| |CH_{2}OH | |
| |OX | |OCH_{3}
\ / \ /
\/ \/
OX

THE ALDEHYDE GLUCOSIDES

=Salinigrin=, C_{13}H_{16}O_{7} (glucose and _m_-oxy benzaldehyde), is
found in the bark of one species of willow (_Salix discolor_). Its isomer,
known as _helicin_ (glucose and _o_-oxy benzaldehyde, or salicylic
aldehyde), does not occur naturally in any plant, but is easily produced
artificially by the gentle oxidation of salicin. Their relationships are
shown on the following formulas;

Salicin Helicin Salinigrin

/\ /\ /\
/ \ / \ / \
| |CH_{2}OH | |CHO | |CHO
| |OX | |OX | |
\ / \ / \ /
\/ \/