Structure-activity relationship (saR)is the relationship between chemical structure and pharmacological activity for a series of compounds Lead compound is a compound that has a desirable biological activity with therapeutic relevance, but typically has some shortcoming that is likely to be overcome through the development of analogs• Structure-activity relationship (SAR) is the relationship between chemical structure and pharmacological activity for a series of compounds. • Lead compound is a compound that has a desirable biological activity with therapeutic relevance, but typically has some shortcoming that is likely to be overcome through the development of analogs