linalool is found in two enantiomeric forms in essential oils.
The (R)-(-) linalool is the
linalool found in lavandin, lavender, bergamot, clary sage, myrtle,
neroli,bitter orange petitgrain, basil,
while the (S)-(+)- linalool is found in coriander and
cardamom oil. (Ref BL)
The biological effects(activity) is directly related to the
chirality of a compound in question.
The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom. The term chiral in general is used to describe an object that is not superposable on its mirror image. In chemistry, chirality usually refers to molecules. Two mirror images of a chiral molecule are called enantiomers or optical isomers. Pairs of enantiomers are often designated as "right-" and "left-handed".
Enantiomers of each other often show different chemical reactions with
other substances that are also enantiomers. Since many molecules in the
bodies of living beings are enantiomers themselves, there is often a
marked difference in the effects of two enantiomers on living beings. In
for example, often only one of a drug's enantiomers is responsible for
the desired effects, while the other enantiomer is less
active, inactive, or sometimes even responsible for adverse effects (unwanted side-effects).