This document discusses structure-activity relationships (SAR) and quantitative structure-activity relationships (QSAR). SAR involves analyzing how changes to a molecule's structure affect its biological activity. QSAR establishes a mathematical relationship between biological activity and a molecule's geometric and chemical characteristics. SAR identifies important functional groups for binding through systematic structural modifications. QSAR analysis can be 2D, considering factors like those in Hansch analysis or Free-Wilson analysis, or 3D, considering steric and electrostatic values as well as hydrogen bonding abilities as in Comparative Molecular Field Analysis or Comparative Molecular Similarity Index Analysis.

1. Presented by
Mr. Bharat Kumar
17mph202
Guided by
Dr. Vivek Vyas
Assistant professor
Department of Pharmacology,
Institute of Pharmacy,
Nirma university, Ahmedabad
SAR / QSAR

2. Definition
SAR (Structure activity relationship)
 The analysis of the dependence of biological effects of a chemical upon its
molecular structure.
 Molecular structure and biological activity are correlated by observing the results
of systematic structural modification on defined biological endpoints.
QSAR (Quantitative structure activity relationship)
 A QSAR is a mathematical relationship between a biological activity of a
molecular system and its geometric and chemical characteristics.

4. SAR / QSAR
“SAR is a qualitative not a quantitative relationship”

5. Structure Activity Relationship (SAR)
Aim - Identify which functional groups are important for binding and/or activity
Method
 Alter, remove or mask a functional group
 Test the analogue for activity
 Modifications may disrupt binding by electronic / steric effects
 Easiest analogues to make are those made from lead compound
 Possible modifications may depend on other groups present
 Some analogues may have to be made by a full synthesis (e.g. replacing an aromatic
ring with a cyclohexane ring)
 Allows identification of important groups involved in binding

6. QSAR (Quantitative structure activity relationship)
 2D analysis – In this two types
 Hansch analysis –
 Free-Wilson Analysis -

7. QSAR (Quantitative structure activity relationship)
 3D analysis
 Comparative Molecular Field Analysis (CoMFA) - It provide
a. Steric values
b. Electrostatic values
 Comparative Molecular Similarity Index Analysis (CoMSIA) -
It provide steric and electrostatic values and consider
1. H - bond donor
2. H - bond acceptor
3. Hydrophobic field