▎ 摘　　要

NOVELTY - A graphene base comprises a nanographene planar structure having a size of 1-10 nm and a thickness of 0.34-3.4 nm. USE - Graphene base is used in pharmaceutical composition, and for preparing medicaments for treating and/or preventing diseases e.g. cancer or diseases-related to excessive topoisomerase I and/or topoisomerase II activity. The cancer is at least one chosen from colon cancer, breast cancer, gastric cancer, lung cancer, colorectal cancer, pancreatic cancer, ovarian cancer, prostate cancer, kidney cancer, liver cancer, brain cancer, melanoma, multiple myeloma, chronic myeloid leukemia, hematological tumors, and lymphoma (all claimed). ADVANTAGE - The graphene base is easy to synthesize, and has a simple structure and precise targeting function for the major groove of nuclear DNA, high-efficiency inhibitory activity against topoisomerase I and II and higher anticancer activity than chemotherapeutic drugs. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) preparation of graphene base, which involves subjecting julolidine as a precursor to a one-step reaction in an alcoholic solvent in the presence of a catalyst at a reaction temperature of 100-300 degrees C for 0.05-24 hours. The catalyst is an organic acid and/or its anhydride and/or a phosphorus-containing compound; (2) method for inhibiting topoisomerase I and/or topoisomerase II, which involves contacting the graphene base with a cell to inhibit topoisomerase I and/or topoisomerase II; and (3) method for treating and/or preventing diseases, which involves administering the graphene base.