Extract nested key from data structure

Extract nested key from data structure

I am fetching table on one site in my Rails app. This is the output I get
in variable @unsubscriber:
{
"total_count": 1,
"items": [{
"created_at": "Sun, 11 Aug 2013 08:07:22 GMT",
"tag": "*",
"id": "sdfsdfw12423535456",
"address": "xyz@abc.com"
}]
}
But I want just "address" in above string. I tried various ways but no
success. It may sound very basic, but can anyone please tell me how to do
it?