Some of the most used chemotherapeutic agents in oncological therapies are derived from natural substances, in particular from plants. These compounds can be extracted from various parts of plants, such as roots, leaves, flowers, or fruits, and are often recognized for their anti-cancer or antitumor properties. Some well-known examples of plant-derived chemotherapeutics include: Taxol extracted from the Pacific yew tree (Taxus brevifolia Nutt.) and another taxanes obtained from Taxus baccata L., Camptothecin extracted from happy tree (Camptotheca acuminata Decne.), Vinblastine and Vincristine extracted from the periwinkle plant (Catharanthus roseus (L.) G.Don) and more. In this study, the anti-leukemic activity of a plant widely distributed in Sardinia, the second-largest Italian island in the Mediterranean Sea, Vinca sardoa (Stearn) Pignatti, known as Sardinian periwinkle, was investigated. This species is known for its indole alkaloids, which exhibit a wide range of biological activities. Three extracts obtained from the aerial parts of plants cultivated in Italy, two from Iglesias (Sardinia) and one from Rome (Italy), were tested at different concentrations (1, 5, 10, and 15 mg/mL) on a B lymphoblast cell line (SUP-B15). Each extract demonstrated a good capacity to induce reductions in cell proliferation of up to 50%, and none of the concentrations exhibited cytotoxicity on normal cells.