The main goal of this Thesis was the investigation of GABAA-receptor modulators, based on the natural product valerenic acid. Therefore, variation of three different structural features should - through chemical modification and subsequent pharmacological investigation- determine the influence of these modifications on efficacy and selectivity. Each modification made, represents a chapter within this thesis. The first chapter contains the derivatization of the carboxylic acid function. It was crucial to study the pharmacological effects exhibited by the chemical properties of the only polar (heteroatomic) group. Therefore, this functionality was transformed into various esters and amides, to investigate the role of hydrogen acceptor or hydrogendonor interactions. Through 17 synthesized acid-derivatives (including the carboxylic acid bioisostere tetrazole) it could be proven, that a hydrogen donor interaction is crucial for the observed pharmacological effect. Furthermore the role of both exocyclic methyl substituents, attached on the indanyl core, was investigated in terms of efficacy and selectivity. This was accomplished through appropriate substitution of each methyl group via alkyl- respectively alkenyl residues of different size. As a result, methyl substitution in 7-position seems to be crucial for both efficacy and selectivity, as each modification led to severe loss of both pharmacological parameters. Furthermore, it could be demonstrated, that at maximum an ethyl substituent is tolerated for the vinylogous substituent in 3-position, as each larger modification significantly lowered efficacy and selectivity at the GABAA-receptor. Finally, synthetic limitaions of the published valerenic acid total synthesis in terms of modularity could be illustrated. Therefore, a slightly different synthetic approach was developed to enable structural variations - especially in 7-position- yet not accessible through published syntheses. As a result, a more economical and versatile alternative synthesis for valerenic acid derivatives was developed within this thesis.