Independently of its origin (natural or artificial) these chiral molecules (namely, their enantiomers) may have different biological activity. This can be illustrated by means of the following examples:
The enantiomers of limonene, both formed naturally, smell differently. One of the enantiomers (S)-limonene smells of lemon while its mirror image compound (R)-limonene smells of oranges. We distinguish between these two enantiomers because our nasal receptors are also made up of chiral molecules that recognise the difference.