Extraction of phenolic compounds from the shells of pecan nuts with cytotoxic activity through apoptosis against the colon cancer cell line HT‐29

RIBAS, LUCAS EMANUEL; BARAVALLE, MARÍA EUGENIA; GASSER, FÁTIMA BELÉN; RENNA, MARÍA SOL; ADDONA, SILVINA; ORTEGA, HUGO HÉCTOR; SAVINO, GRACIELA HILDA; VAN DE VELDE, FRANCO; HEIN, GUSTAVO JUAN

JOURNAL OF FOOD SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021

0022-1147

The water extraction of phenolic compounds from two varieties(?Mahan? and ?Marameck?) of pecan nutshells (Carya illinoinensis) withoutand with sonication, varying the solvent/solid ratio (S), the pH, and the refluxingtime (t), was studied. Additionally, the in vitro cytotoxicity and the determinationof the cell death mechanism of the extracts against the colon cancer cellline HT-29 were investigated. The content of total phenolic compounds (TPC)of ?Marameck? nutshells resulted higher than for the ?Mahan? variety, and thepH increase resulted in higher TPC contents for both cultivars. The optimizedconditions for TPC extraction without and with sonication resulted: S = 33ml/g,pH = 12, and t = 9.6 min, and yielded ≈ 70 and 90 mg/g of TPC for ?Mahan? and?Marameck? nutshells, respectively. The optimized extracts of pecan nutshellswithout sonication from both cultivars presented similar cytotoxicity againstHT-29 colon cancer cells (IC50 ≈ 50 μg/ml), higher than for sonicated extracts(IC50 ≈ 88 and 138 μg/ml for ?Mahan? and ?Marameck,? respectively). Celldeath through apoptosis was the main mechanism of cell death induced by thenutshell extracts.Practical Application: The extraction of phenolic compounds (TPC) from theresidues of two varieties of pecan nutshells (?Mahan? and ?Marameck?) wasstudied. An optimal combination of variables within the pH range that minimizesthe solvent-to-solid ratio (S) and the time of refluxing (t), saving at the sametime, water and energy, was set up. The phenolic compound extracts obtainedfrom the residues of the pecan nuts exhibit cytotoxic effects against colon cancercells and could be of interest as an alternative treatment of different types ofcancer. Additionally, these extracts may be of importance to the food industry asthey can be used as antioxidant agents in food formulation. Also, the high levelsof anthocyanidins obtained fromthe pecan nut extracts after proanthocyanidins?strong acid hydrolysis can be purified and employed as natural red dyes.