274
H. Schulz
plant in guatemala and mexico, shows similar signals at 2,196 cm
−1
. other species
of the genus Bidens are widely used in Chinese medicine, such as Bidens pilosa and
Bidens campylotheca. Several of them contain lipophilic polyacetylenes as well as
polyacetylene glucosides that are predominantly made responsible for the described
medicinal properties [115–117]. the distribution of polyacetylenes in the inflorescence of chamomile ( Matricaria chamomilla) has been also mapped by Raman
spectroscopy, integrating the wavenumber range between 2,148 and 2,234 cm
−1
[66,
108]. the authors were able to demonstrate that the polyacetylenes ( cis- and transspiroethers) are mainly present in the bottom of the flower heads.
9.3.6 Miscellaneous
A sensitive SERS Raman method was presented allowing to analyse cyanogenic
glycosides in plant tissue [118]. the individual spectra of the cyanogenic substances (linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin) were
registered using a Raman microscope equipped with a 532 nm laser. the authors
observed the signal of the cyanohydrin group at around 2,240 cm
−1
being influenced
by the nature of side groups in the molecule. In a similar way, the content of the
cyanogenic constituent amygdalin in bitter almond ( Prunus amygdalus) was investigated applying a standard addition series in which different amounts of the analyt
(0–700 nmol/mg) were added to ground sweet almond [119]. the best PLS regression model was developed on the vibrational band of the nitrile group (RmSECv:
13 nmol/mg; p: 0.937). Furthermore, the distribution of amygdalin in bitter almond
was investigated in situ applying Raman microscopy presenting highest amounts in
the epidermis. Stellacyanin, a copper-containing glyco-protein occurring in cucumber ( Cucumis sativus) has been characterised by Resonance Raman spectroscopy
[120]. In accordance with earlier Raman studies performed at the Japanese lacquer
tree Rhus vernicifera [121] the most intense signals in the stellacyanin spectrum
were detected in the range between 340 and 430 cm
−1
and assigned as Cu-S (cysteine) stretching modes.
the triterpene substance betulin, which is obtained from the outer bark of birch
tree, is well known for its broad range of biological properties such as anticancer,
antibacterial, anti-inflammatory, antifungal and antiviral activities. A complete vibrational assignment of all modes of betulin, based on dFt calculations, is presented by Fălămaş et al. [122]. Also, the individual calculated band positions are
compared with the measured Ft-Raman data proving that the theoretical model was
well computed. Furthermore, betulin and lupeol were successfully identified in a
natural extract of birch bark by means of Raman spectroscopy.
different Raman spectroscopic techniques were used to characterise the three
biologically active diterpenoic acids abietic acid, gibberellic acid and kaurenoic
acid [123]. Because conventional Raman spectroscopy was not suitable to detect
these substances exhibiting very low polarizability, uv-resonance and SERS Raman spectroscopy were applied. optimal signal sensitivity was achieved with
H. Schulz
plant in guatemala and mexico, shows similar signals at 2,196 cm
−1
. other species
of the genus Bidens are widely used in Chinese medicine, such as Bidens pilosa and
Bidens campylotheca. Several of them contain lipophilic polyacetylenes as well as
polyacetylene glucosides that are predominantly made responsible for the described
medicinal properties [115–117]. the distribution of polyacetylenes in the inflorescence of chamomile ( Matricaria chamomilla) has been also mapped by Raman
spectroscopy, integrating the wavenumber range between 2,148 and 2,234 cm
−1
[66,
108]. the authors were able to demonstrate that the polyacetylenes ( cis- and transspiroethers) are mainly present in the bottom of the flower heads.
9.3.6 Miscellaneous
A sensitive SERS Raman method was presented allowing to analyse cyanogenic
glycosides in plant tissue [118]. the individual spectra of the cyanogenic substances (linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin) were
registered using a Raman microscope equipped with a 532 nm laser. the authors
observed the signal of the cyanohydrin group at around 2,240 cm
−1
being influenced
by the nature of side groups in the molecule. In a similar way, the content of the
cyanogenic constituent amygdalin in bitter almond ( Prunus amygdalus) was investigated applying a standard addition series in which different amounts of the analyt
(0–700 nmol/mg) were added to ground sweet almond [119]. the best PLS regression model was developed on the vibrational band of the nitrile group (RmSECv:
13 nmol/mg; p: 0.937). Furthermore, the distribution of amygdalin in bitter almond
was investigated in situ applying Raman microscopy presenting highest amounts in
the epidermis. Stellacyanin, a copper-containing glyco-protein occurring in cucumber ( Cucumis sativus) has been characterised by Resonance Raman spectroscopy
[120]. In accordance with earlier Raman studies performed at the Japanese lacquer
tree Rhus vernicifera [121] the most intense signals in the stellacyanin spectrum
were detected in the range between 340 and 430 cm
−1
and assigned as Cu-S (cysteine) stretching modes.
the triterpene substance betulin, which is obtained from the outer bark of birch
tree, is well known for its broad range of biological properties such as anticancer,
antibacterial, anti-inflammatory, antifungal and antiviral activities. A complete vibrational assignment of all modes of betulin, based on dFt calculations, is presented by Fălămaş et al. [122]. Also, the individual calculated band positions are
compared with the measured Ft-Raman data proving that the theoretical model was
well computed. Furthermore, betulin and lupeol were successfully identified in a
natural extract of birch bark by means of Raman spectroscopy.
different Raman spectroscopic techniques were used to characterise the three
biologically active diterpenoic acids abietic acid, gibberellic acid and kaurenoic
acid [123]. Because conventional Raman spectroscopy was not suitable to detect
these substances exhibiting very low polarizability, uv-resonance and SERS Raman spectroscopy were applied. optimal signal sensitivity was achieved with