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- Cholesterol transporter proteins in HepG2 cells can be modulated by phenolic compounds present in Opuntia ficus-indica aqueous solutionsPublication . RESSAISSI, Asma; ATTIA, Nebil; Pacheco, Rita; Fale, Pedro; Serralheiro, Maria LuisaIncreased blood cholesterol is a risk factor for atherosclerotic cardiovascular disease. This study tested the hypothesis that phenolic compounds can modulate the level of cholesterol transporters including Niemann-Pick C1-like 1 (NPC1L1) and ATP-binding cassette transporters in liver cells. HepG2 cells, used as a model of hepatocytes, showed a decrease in the abundance of cholesterol transporters comparatively to the control when treated with the Opuntia ficus-indica's cladodes decoction. The decrease was between 13-70%, 25-60%, 9-60% and 23-60% for NPC1L1, ABCA1, ABCG5 and ABCG8 transporters, respectively, when using between 0.15 and 0.35 mg/mL of decoction in the culture medium. FTIR analysis showed changes in the amount of RNA, which may be the cause of the decrease in the level of several proteins. These in vitro results pave the way to a molecular explanation for the decoction of cladodes effect on cholesterol levels as it reduced the membrane cholesterol transporter proteins, NPC1L1, ABCG5/ABCG8 and ABCA1, in HepG2 cells.
- Serum albumin modulates the bioactivity of rosmarinic acidPublication . Brito, Elsa; Silva, André; Fale, Pedro; Pacheco, Rita; Serralheiro, António; Haris, Parvez I.; Ascensão, Lia; Serralheiro, Maria LuisaRosmarinic acid (RA) is a phenolic compound with biological activity. The objective of the present study was to investigate whether this compound kept its biological activity in the presence of proteins. For this purpose, bovine serum albumin (BSA) was used as a model protein, and the capacity of the RA to inhibit acetylcholinesterase (AChE) and affect antioxidant activity was evaluated in the absence and presence of BSA. A mixture of phenolic compounds containing RA, obtained from a medicinal plant was added to this study. The AChE inhibitory activity of RA was reduced by *57% in the presence of BSA, while the antioxidant activity increased. These results lead to the investigation of the effect of RA on the BSA structure using Fourier transform infrared spectroscopy (FTIR). At 37 C and higher temperatures, RA caused a decrease in the temperature modifications onthe proteinstructure. Furthermore, FTIR and native-gel analysis revealed that protein aggregation/ precipitation, induced bytemperature, wasreduced in thepresence of RA. The novelty of the present work resides in thestudy of the enzyme inhibitory activity and antioxidant capacity of polyphenols, such as RA, in the presence of a protein. The findings highlight the need to consider the presence of proteins when assessing biological activities of polyphenols in vitro and that enzyme inhibitory activity may be decreased, while the antioxidant capacity remains or even increases.