Binding of Clitoria ternatea L. flower extract with α-amylase simultaneously monitored at two wavelengths using a photon streaming time-resolved fluorescence approach

Abstract

The binding of an extract from the flowers of Clitoria ternatea L. to the digestive enzyme amylase was investigated. This extract is a mixture of flavonoids, including anthocyanins, and has been previously shown to inhibit the activity this enzyme. This has implications for modulating starch digestion. Since the extract contains a mixture of flavonoids, including anthocyanins, in order to investigate the kinetics, we made use of time-resolved fluorescence to simultaneously monitor two different emission bands emanating from the extract. This measurement was enabled by the use of a "photon streaming" approach and changes in fluorescence lifetime and intensity were used to follow the interaction. A longer wavelength band (655 nm) was ascribed to anthocyanins in the mixture and these were observed to bind at a rate an order of magnitude slower than other flavonoids present in the extract, monitored at a shorter wavelength (485 nm). Changes in the fluorescence emission of the extract upon binding were further assessed by the use of decay associated spectra.Highlights  Clitoria ternatea L extract inhibits α-amylase activity  Binding monitored using time-resolved fluorescence  Photon streaming enables simultaneous two wavelength data acquisition  Anthocyanins bind ~10 times slower than other flavonoids ACCEPTED MANUSCRIPT

Fluorescent Products of Anthocyanidin and Anthocyanin Oxidation

“…25 Fluorescence centered at 655 nm (for an excitation wavelength of 392 nm) of Clitoria ternatea L. flower extracts has been ascribed to anthocyanins. 26 Anthocyanin fluorescence at 602−662 nm was employed to study the subcellular localization of anthocyanins using fluorescence lifetime microscopy. 27 Anthocyanins were found to interfere with the fluorometric determination of chlorophyll when excited with blue light (470 nm).…”

“…Fluorescence emission when excited at 390 nm was observed to allow for differentiation between cyanidin-containing anthocyanins, showing a fluorescence peak at 520 nm, from peonidin-containing anthocyanins, emitting fluorescence with a maximum at 610 nm . Fluorescence centered at 655 nm (for an excitation wavelength of 392 nm) of Clitoria ternatea L. flower extracts has been ascribed to anthocyanins . Anthocyanin fluorescence at 602–662 nm was employed to study the subcellular localization of anthocyanins using fluorescence lifetime microscopy .…”

Phenolic content and potential bioactivity of apple juice as affected by thermal and ultrasound pasteurization

“…A methodology similar to that previously applied to the binding of butterfly pea extract to BSA was employed. 29 In order to excite the extract a longer wavelength (378 nm) was selected, as using a shorter wavelength light (e.g. <295 nm) would also excite fluorescent amino acids in the HSA (notably tyrosine and tryptophan) as well as the extract (Figure 2).…”

Combining Natural Ingredients to Optimise Antioxidant Content in Brewing Herbal Drinks

“…Previous research on green tea that has been carried out by other researchers includes in vivo and in vitro and hypoglycemic testing [1], testing with targeted and untargeted metabolomics [2], to recover tea antioxidants [3], for metabolomics testing with other characteristics [4,5,6]. Meanwhile, research on the butterfly pea flower has been carried out several decades previously and can be traced, namely the effect of butterfly pea flower on free radical hemolysis and oxidative damage [7], phenolic, antioxidant, and color testing [8], amylase binding [9], in vitro testing of antidiabetic properties. and antioxidant [10], anti-obesity metabolomics [11], and antidiabetic properties [12], and research [13] on the bioactive components of butterfly pea flower which showed antioxidant, antihemolytic and antihypertensive effects, inhibiting the activity of α-amylase and αglucosidase and reducing LDL cholesterol and DNA induced oxidation.…”