Cytotoxic Effect of Methanol Extracts and Partitions of Two Mexican Desert Plants against the Murine Lymphoma L5178Y-R

Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study aims to investigate the cytotoxic activity of these plants against a murine lymphoma. Soxhlet extraction of dried and powdered plant material was performed with methanol. Also, a further partitioning of these methanolic extracts with hexane and ethyl acetate was achieved. The in vitro cytotoxic activity against the murine lymphoma L5178Y-R cell line was assessed via the colorimetric MTT assay. The methanol extract from P. marginatus exhibited high cytotoxic activity (up to 94%) at concentrations ranging from 3.9 to 500 μg/mL;however, hexane and ethyl acetate partitions from this methanolic extract showed lower but significant (p < 0.05) concentration-dependent cytotoxicity (hexane partition up to 94% at 500 μg/mL;ethyl acetate partition up to 94% at 65.5 μg/mL). The methanolic extract and partitions derived from I. sonorae also showed significant (p < 0.05) and concentration-dependent cytotoxicity against L5178Y-R cells at concentrations ranging from 7.81 to 500 μg/mL (methanolic extract up to 63% at 500 μg/mL;hexane partition up to 76% at 250 μg/mL;ethyl acetate partition up to 73% at 500 μg/mL). These results demonstrate that the methanol extracts and partitions from P. marginatus and I. sonorae possess significant cytotoxic activity against the murine lymphoma L5178Y-R and validate the ethnobotanical use of these plants for the treatment of diseases consistent with cancer symptomatology. Previous scientific reports describe the isolation of isoquinoline alkaloids of P. marginatus as well as cucurbitacins from I. sonorae, phytochemicals that could be responsible for their observed cytotoxic activity in this research. The direct extraction with methanol of medicinal plants allows extracting of both high and low-polarity compounds, contrary to the simple extraction with water that only allows obtaining compounds of high polarity. The subsequent partition of the methanol extract with a solvent of low polarity (hexane) and another of medium polarity (ethyl acetate) allows making a preliminary fractionation of the bioactive molecules present in the plant that will facilitate the bioguided chromatographic isolation of the pure compounds responsible for the biological activity of the plant.