Inhibition of CpLIP2 Lipase Hydrolytic Activity by Four Flavonols (Galangin, Kaempferol, Quercetin, Myricetin) Compared to Orlistat and Their Binding Mechanisms Studied by Quenching of Fluorescence

Abstract

The inhibition of recombinant CpLIP2 lipase/acyltransferase from Candida parapsiolosis was considered a key model for novel antifungal drug discovery and a potential therapeutic target for candidiasis. Lipases have identified recently as potent virulence factors in C. parapsilosis and some other yeasts. The inhibition effects of orlistat and four flavonols (galangin, kaempferol, quercetin and myricetin) characterized by an increasing degree of hydroxylation in B-ring, were investigated using ethyl oleate hydrolysis as the model reaction. Orlistat and kaempferol (14 µM) strongly inhibited CpLIP2 catalytic activity within 1 min of pre-incubation, by 90% and 80%, respectively. The relative potency of flavonols as inhibitors was: kaempferol > quercetin > myricetin > galangin. The results suggested that orlistat bound to the catalytic site while kaempferol interacted with W294 on the protein lid. A static mechanism of interactions between flavonols and CpLIP2 lipase was confirmed by fluorescence quenching analyses, indicating that the interactions were mainly driven by hydrophobic bonds and electrostatic forces. From the Lehrer equation, fractions of tryptophan accessibility to the quencher were evaluated, and a relationship with the calculated number of binding sites was suggested.

Interactions between Phosphatidylcholine and Kaempferol or Myristicin: Langmuir Monolayers and Microelectrophoretic Studies

“…Myricetin is the most potent inhibitor among flavanols. The results obtained for myricetin confirm the relationship between its structure and function, and the number and position of the OH group on the ring [ 20 ]. Myricetin has also been identified as the most potent inhibitor (of the 16 important flavonoids) of mammalian DNA polymerases and human topoisomerases in in vitro studies [ 21 ].…”

Cytotoxic, Antioxidant, and Enzyme Inhibitory Properties of the Traditional Medicinal Plant Matthiola incana (L.) R. Br.

“…There is only one study in which M. incana seeds, rich in linolenic acid oil (55–65%), reduced cholesterol levels and increased omega-3 fatty acid levels in the plasma of rats [ 41 ]. However, the phytochemical composition cannot be compared to M. incana aerial parts, as this extract is particularly rich in polyphenols; among flavonoids detected in this extract, kaempferol, naringenin, and luteolin were found to inhibit α-GLU [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. Kaempferol was also able to inhibit lipase [ 47 ].…”

Protein binding of 4-hydroxybenzoic acid and 4-hydroxy-3-methoxybenzoic acid to human serum albumin and their anti-proliferation on doxorubicin-sensitive and doxorubicin-resistant leukemia cells

“…Binding constants and number of binding sites were calculated by using equation, Eq. (2) [ [19] , [20] , [21] ] that is shown here. Where; n was the number of binding sites per HSA.…”

“…In these current studies, the Stern-Volmer equation, Eq. (1) was used to analyze the fluorescence quenching of HSA [ [19] , [20] , [21] ] that is shown below. Where; F 0 and F were the steady-state fluorescence intensities of HSA at 342 nm in the absence and in the presence of samples, respectively.…”