Spent espresso coffee grounds as a source of anti-proliferative and antioxidant compounds

Disposal of spent espresso coffee grounds (SCG) is costly and leads to the loss of bioactive compounds that could be fractionated, in several applications. This work aimed to investigate phenolic profile, tocopherols, and antioxidant and anti-proliferative activities of SCGs ethanolic extracts from coffee powders differing in coffee provenience and composition (arabica/robusta). Tyrosol, detected for the first time in SCGs, was the most abundant phenolic measured (121-1084 mg/kg in the extract), along with 4-hydroxybenzoic acid and vanillin (885-1813 and 340-1103 mg/kg, respectively). Extract derived from 100% robusta from Guatemala (S7-R) showed the highest alpha- to beta-tocopherol ratio of 1.2 and the highest antioxidant potential as evidenced by RACI and GAS values of -0.43 and 0.20, respectively. Moreover, S7-R showed a promising anti-proliferative activity toward human lung carcinoma cells (A549), with IC50 value of 61.2 mu g/mL comparable to that given by the positive control vinblastine (IC50 value of 67.3 mu g/mL).