Abstract
The new pentacyclic triterpene 11β-hydroxypristimerin (1), along with the known metabolites pristimerin (2), 6-oxopristimerol (3) and vitideasin (4), were isolated from a Salacia crassifolia root wood extract, following a bioassay-guided fractionation approach. Both the extract and the purified triterpenes displayed pronounced cytotoxic activity against human cancer cell lines. The NCI-60 cell line screen revealed that compound 2 was the most active, with a mean GI50 of 0.17 μM, while compound 1 had a mean GI50 of 8.7 μM. A COMPARE analysis of the screening results showed that pristimerin is likely to be the main compound responsible for the cytotoxic activity of the extract (mean GI50 of 0.3 μg·mL−1). A targeted search for pristimerin and related derivatives using LC-MS/MS revealed the presence of pristimerin (2) and 6-oxopristimerol (3) in all Celastraceae species examined and in all plant parts tested, while vitideasin (4) was only detected in the genus Salacia.
Highlights
Anticancer drugs derived from plants such as vinblastine, vincristine, etoposide, teniposide, paclitaxel (Taxol® ), docetaxel, topotecan and irinotecan continue to have significant therapeutic value [1]; cancer remains a leading cause of death worldwide
Previous phytochemical investigations of the hexane extract of the leaves of S. crassifolia led to the isolation of friedelanes [4], commonly found in the leaves of Celastraceae species, and known as precursors of quinone methide triterpenoids found in the roots of these species [5,6]
In our search for new cytotoxic agents, the hexane extract of S. crassifolia root wood was selected by preliminary high-throughput screening of Cerrado plant extracts, tested at 10 μg·mL−1 in eight cancer cell lines: Colo205 and KM12, A498 and U031, HEP3B and SKHEP
Summary
Anticancer drugs derived from plants such as vinblastine, vincristine, etoposide, teniposide, paclitaxel (Taxol® ), docetaxel, topotecan and irinotecan continue to have significant therapeutic value [1]; cancer remains a leading cause of death worldwide. Celastraceae, popularly known as Bacupari-do-Cerrado, has been used by traditional communities to treat cancer [3]. It is a tree from the Cerrado biome adapted to the region’s dry climate with a well-developed root system. This species is cultivated for its edible fruit, used as an ornamental plant, and used for reforestation and restoration of degraded. Previous phytochemical investigations of the hexane extract of the leaves of S. crassifolia led to the isolation of friedelanes [4], commonly found in the leaves of Celastraceae species, and known as precursors of quinone methide triterpenoids found in the roots of these species [5,6]. We report the bioassay-guided isolation and structure elucidation of compounds 1–4 and their cytotoxic activity
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