Pectins having a combination of unexpectedly high molecular weights and low degrees of methylation have been isolated from Aloe vera plants, are superior gel pectins for forming calcium cross-lined gels. Such pectins can be obtained by extracting homogenized Aloe Vera plants or portions thereof. These pectins can be used to prepare pharmaceutical compositions comprising pharmacological agents for application to animals and humans, so as to provide controlled release of the pharmacological agent.