Abstract
Three new acylated anthocyanidin 3-rutinoside-5-glucosides were isolated from the violet-blue flowers of Saintpaulia ‘Thamires’ ( Saintpaulia sp.) along with a known flavone glycoside. Three new acetylated anthocyanins were determined to be 3- O -[6- O -(4- O -(acetyl)-α-rhamnopyranosyl)-β-glucopyranoside]-5- O -(β-glucopyranoside)s of malvidin (pigment 1), peonidin (pigment 2), and pelargonidin (pigment 3) by chemical and spectroscopic methods. HPLC analysis revealed that malvidin 3- O -acetylrutinoside-5- O -glucoside existed as a dominant pigment in the violet-blue flowers. Moreover, the isolated flavone was identified to be apigenin 4′- O -β-glucuronopyranoside (pigment 4). On the visible absorption spectral curves of fresh violet-blue petals and in their crude extracts in pH 5.0 buffer solution, two characteristic absorption maxima at 547 and 577 nm, with a shoulder near 620 nm, were observed. In contrast, the absorption curves of malvidin 3- O -acetylrutinoside-5- O -glucoside and its deacyl anthocyanin exhibited only one maximum at 535 nm in pH 5.0 buffer solution, and its color was violet and soon fell into decay. However, by addition of apigenin 4′- O -glucuronide, the color of malvidin 3- O -acetylrutinoside-5- O -glucoside changed from violet to violet-blue, similar to that of the fresh flower in pH 5.0 buffer solution. The absorption curve of its violet-blue solution exhibited two similar absorption maxima at 547 and 577 nm, with a shoulder near 620 nm. These results suggest that intermolecular copigmentation between malvidin 3- O -acetylrutinoside-5- O -glucoside and apigenin 4′- O -glucuronide may be responsible for the violet-blue flower color of S . ‘Thamires’.
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Claims 9
Claim · model-written summary
Three new acylated anthocyanins were isolated from Saintpaulia flowers.
Verbatim
e0“Three new acylated anthocyanidin 3-rutinoside-5-glucosides were isolated from the violet-blue flowers of Saintpaulia ‘Thamires’ ( Saintpaulia sp.)”
Claim · model-written summary
The new anthocyanins were characterized as derivatives of malvidin, peonidin and pelargonidin.
Verbatim
e0“Three new acetylated anthocyanins were determined to be 3- O -[6- O -(4- O -(acetyl)-α-rhamnopyranosyl)-β-glucopyranoside]-5- O -(β-glucopyranoside)s of malvidin (pigment 1), peonidin (pigment 2), and pelargonidin (pigment 3)”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
Malvidin acetylrutinoside glucoside was the dominant pigment in the violet-blue flowers.
Verbatim
e0“malvidin 3- O -acetylrutinoside-5- O -glucoside existed as a dominant pigment in the violet-blue flowers”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
The isolated flavone was identified as apigenin glucuronopyranoside.
Verbatim
e0“the isolated flavone was identified to be apigenin 4′- O -β-glucuronopyranoside (pigment 4)”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
Fresh violet-blue petals and crude extracts showed maxima at 547 and 577 nm and a shoulder near 620 nm.
Verbatim
e0“two characteristic absorption maxima at 547 and 577 nm, with a shoulder near 620 nm, were observed”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
The isolated malvidin pigment and its deacylated form had one absorption maximum at 535 nm.
Verbatim
e0“the absorption curves of malvidin 3- O -acetylrutinoside-5- O -glucoside and its deacyl anthocyanin exhibited only one maximum at 535 nm in pH 5.0 buffer solution”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
Addition of apigenin glucuronide changed malvidin pigment color from violet to violet-blue.
Verbatim
e0“by addition of apigenin 4′- O -glucuronide, the color of malvidin 3- O -acetylrutinoside-5- O -glucoside changed from violet to violet-blue”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
The violet-blue pigment solution showed two maxima at 547 and 577 nm and a shoulder near 620 nm.
Verbatim
e0“The absorption curve of its violet-blue solution exhibited two similar absorption maxima at 547 and 577 nm, with a shoulder near 620 nm”
t0“Saintpaulia ‘Thamires’”
Claim · model-written summary
The authors propose that intermolecular copigmentation produces the violet-blue flower color.
Verbatim
e0“intermolecular copigmentation between malvidin 3- O -acetylrutinoside-5- O -glucoside and apigenin 4′- O -glucuronide may be responsible for the violet-blue flower color of S . ‘Thamires’”