Gallnuts: A Potential Treasure in Anticancer Drug Discovery.

In the discovery of more potent and selective anticancer drugs, the research continually expands and explores new bioactive metabolites coming from different natural sources. Gallnuts are a group of very special natural products formed through parasitic interaction between plants and insects. Though it has been traditionally used as a source of drugs for the treatment of cancerous diseases in traditional and folk medicinal systems through centuries, the anticancer properties of gallnuts are barely systematically reviewed. To evidence the traditional uses and phytochemicals and pharmacological mechanisms in anticancer aspects of gallnuts, a literature review was performed. The systematic review approach consisted of searching web-based scientific databases including PubMed, Web of Science, and Science Direct. The keywords for searching include gallnut, Galla Chinensis, , , , nutgall, gall oak, , and galla turcica. Two reviewers extracted papers independently to remove the papers unrelated to the anticancer properties of gallnuts. Patents, abstracts, case reports, and abstracts in symposium and congress were excluded. As a result, 14 articles were eligible to be evaluated. It is primarily evident that gallnuts contain a number of bioactive metabolites, which account for anticancer activities. The phytochemical and pharmacological studies reviewed strongly underpin a fundamental understanding of anticancer properties for gallnuts (Galla Chinensis and Galla Turcica) and support their ongoing clinical uses in China. The further bioactive compounds screening and evaluation, pharmacological investigation, and clinical trials are expected to progress gallnut-based development to finally transform the wild medicinal gallnuts to the valuable authorized anticancer drugs.