In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In rodents , the effect of the beta - carboline derivative isopropyl - 6 - benzyloxy - 4 - methoxymethyl - beta - carboline - 3 - carboxylate ( abecarrnil ) , a new ligand for benzodiazepine receptors possessing anxiolytic and anticonvulsant properties , was evaluated on the function of central gamma - aminobutyric acid ( GABA ) A receptor complex , both in vitro and in vivo .
### Output Text:
In rodents , the effect of the <span class="chemical">beta - carboline</span> derivative <span class="chemical">isopropyl - 6 - benzyloxy - 4 - methoxymethyl - beta - carboline - 3 - carboxylate</span> ( <span class="chemical">abecarrnil</span> ) , a new ligand for <span class="chemical">benzodiazepine</span> receptors possessing anxiolytic and anticonvulsant properties , was evaluated on the function of central <span class="chemical">gamma - aminobutyric acid</span> ( <span class="chemical">GABA</span> ) A receptor complex , both in vitro and in vivo . 