Review on the Ethnopharmacological Use of Medicinal Plants and Their Anticancer Activity from Preclinical to Clinical Trial

Traditional medicine has played a key role in cancer treatment, particularly in developing countries where herbal remedies are extensively utilized. Ethnopharmacological knowledge has highlighted several medicinal plants traditionally used to treat cancers. However, only a fraction of these plants have undergone scientific evaluation to validate their anticancer potential. This review summarizes the ethnopharmacological use, preclinical studies, and clinical trial data of plant-derived compounds with anticancer properties. Preclinical investigations have demonstrated substantial cytotoxic activities of plant extracts and isolated fractions against various human cancer cell lines. For instance, extracts from Acokanthera schimperi, Clematis simensis, Euphorbia schimperiana, Kalanchoe petitiana , and Plumbago zeylanicum demonstrated potent activities across various cancer types, with IC50 values ranging between 0.086 and 6.37 μg/mL. Building on these preclinical findings, several plant-derived compounds have progressed to clinical trials. Curcumin from Curcuma longa is undergoing Phase II trial for advanced pancreatic cancer. Tea polyphenols and *indole-3-carbinol/3,3-diindolylmethane have shown efficacy in Phase II trials for multiple myeloma and breast cancer, respectively. Besides, epigallocatechin, lycopene, resveratrol (Polygonum, sulforaphane ( Brassica oleracea ), roscovitine/seliciclib, thymoquinone, piperine, Berberine and genistein are under Phase I–III trials. This review integrates ethnopharmacological knowledge, preclinical data, and clinical evidence, showing the key role of medicinal plants in anticancer drug discovery. While significant progress has been made, further studies are required to isolate, characterize, and elucidate the mechanisms of action of bioactive compounds. Bridging traditional medicine with contemporary research offers promising avenues for the development of novel chemotherapeutic and chemopreventive agents, advancing the fight against cancer.