Suqin Sun

Fourier transform mid-infrared (MIR) and near-infrared (NIR) spectroscopy for rapid quality assessment of Chinese medicine preparation Honghua Oil

Honghua Oil (HHO), a traditional Chinese medicine (TCM) oil preparation, is a mixture of several plant essential oils. In this text, the extended ranges of Fourier transform mid-infrared (FT-MIR) and near infrared (FT-NIR) were recorded for 48 commercially available HHOs of different batches from nine manufacturers. The qualitative and quantitative analysis of three marker components, alpha-pinene, methyl salicylate and eugenol, in different HHO products were performed rapidly by the two vibrational spectroscopic methods, i.e. MIR with horizontal attenuated total reflection (HATR) accessory and NIR with direct sampling technique, followed by partial least squares (PLS) regression treatment of the set of spectra obtained. The results indicated that it was successful to identify alpha-pinene, methyl salicylate and eugenol in all of the samples by simple inspection of the MIR-HATR spectra. Both PLS models established with MIR-HATR and NIR spectral data using gas chromatography (GC) peak areas as calibration reference showed a good linear correlation for each of all three target substances in HHO samples. The above spectroscopic techniques may be the promising methods for the rapid quality assessment/quality control (QA/QC) of TCM oil preparations.

Excess Infrared Absorption Spectroscopy and Its Applications in the Studies of Hydrogen Bonds in Alcohol-Containing Binary Mixtures

Excess infrared (IR) absorption spectroscopy, a new concept brought forward by applying the idea of excess thermodynamic functions to infrared spectroscopy, is shown to be a potential method to study hydrogen bonds. It can be applied to enhance spectral resolution of complexed IR bands, to evaluate nonideality of liquid mixtures, and to estimate selective molecular interactions. The sign of the excess infrared absorption coefficient is also of importance in providing information on molecular interactions. The results demonstrate that excess infrared absorption spectroscopy can unveil new information on hydrogen bonding in condensed phases.

Discrimination of Fritillary according to geographical origin with Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

Fritillaria is a traditional Chinese herbal medicine for eliminating phlegm and relieving a cough with a long history in China and some other Asian countries. The objective of this study is to develop a nondestructive and accurate method to discriminate Fritillaria of different geographical origins, which is a troublesome work by existing analytical methods. We conducted a systematic study on five kinds of Fritillaria by Fourier transform infrared spectroscopy, second derivative infrared spectroscopy, and two-dimensional (2D) correlation infrared spectroscopy under thermal perturbation. Because Fritillaria consist of a large amount of starch, the conventional IR spectra of different Fritillaria only have very limited spectral feature differences. Based on these differences, we can separate different Fritillaria to a limited extent, but this method was deemed not very practical. The second derivative IR spectra of Fritillaria could enhance spectrum resolution, amplify the differences between the IR spectra of different Fritillaria, and provide some dissimilarity in their starch content, when compared with the spectrum of pure starch. Finally, we applied thermal perturbation to Fritillaria and analyzed the resulting spectra by the 2D correlation method to distinguish different Fritillaria easily and clearly. The distinction of very similar Fritillaria was possible because the spectral resolution was greatly enhanced by the 2D correlation spectroscopy. In addition, with the dynamic information of molecular structure provided by 2D correlation IR spectra, we studied the differences in the stability of active components of Fritillaria. The differences embodied mainly on the intensity ratio of the auto-peak at 985 cm(-1) and other auto-peaks. The 2D correlation IR spectroscopy (2D IR) of Fritillaria can be a new and powerful method to discriminate Fritillaria.

Study of Thermal Melting Behavior of Microbial Polyhydroxyalkanoate Using Two-Dimensional Fourier Transform Infrared Correlation Spectroscopy

The molecular level premelting process of purified biosynthesized polyester poly(hydroxybutyrate-co-hydroxyvalerate) or P(HB-co-HV) (20.4% HV) was investigated by two-dimensional Fourier transform infrared (2D FT-IR) correlation spectroscopy. Intensity variations and band shifts in the characteristic spectral regions for C=O groups (1710–1770 cm−1), C-H groups (2910–3010 cm−1), and C-O-C groups (1220–1310 cm−1) were selected for a detailed study of the thermally induced phase transition of the copolymer. The 2D correlation approach successfully demonstrated that a fully amorphous liquid-like structure was formed following the disappearance of the crystals in the sample, by going through an intermediate state related to the lost conformation of the highly ordered and helical polyester main chain.

Pharmacokinetic comparisons of two different combinations of Shaoyao-Gancao Decoction in rats: Competing mechanisms between paeoniflorin and glycyrrhetinic acid

ETHNOPHARMACOLOGICAL RELEVANCE Shaoyao-Gancao Decoction (SGD), a well-known traditional Chinese medicine prescription, is a combination of Radix Paeoniae Alba (Paeonia lactiflora Pall, root) and Glycyrrhizae uralensis (Glycyrrhiza uralensis Fisch., root and rhizome, honeyed) for spasmolysis and emergency pain relief. Paeoniflorin (PF) and glycyrrhetinic acid (GA) are two typical active components of SGD for pain relief. AIM OF THE STUDY To study comparative pharmacokinetics of ten bioactive compounds in SGDs with two different combinations of RP and GU, and therefore to investigate the herb-herb interaction mechanisms of Shaoyao-Gancao Decoction for better spasmolysis and emergency pain relief in rats. MATERIALS AND METHODS Herbal IR macro-fingerprinting was implemented to provide the full chemical fingerprints of RP, GU and SGD decoctions and to investigate the variation rule of the full chemical profile of SGDs with various combinations of RP and GU. A specifically developed HPLC-MS/MS assay coupled with protein precipitation method was employed to determine the plasma concentrations of the ten analytes. Male Wistar rats were orally administered with SGD1 (RP:GU, 1:1 (w/w)) and SGD2 ((RP:GU, 4:1 (w/w)) equivalent to 9.5 g/kg body weight of GU. RESULTS Full chemical fingerprints of RP, GU and SGDs with various combinations of RP and GU were provided in the form of IR macro-fingerprints. Except for liquiritin, there were statistically significant differences (p<0.05 or p<0.01) of these analytes between SGD1 and SGD2 in in vivo pharmacokinetic study. Compared with the results when oral administrated with SGD1, six glycosides (PF, albiflorin, oxypaeoniflorin, isoliquiritin, ononin, and glycyrrhizin) exhibited higher systematic exposure levels (AUC0-t) and slower elimination rates (CL) whereas two glycones (GA and isoliquiritigenin) were the reverse when administrated with SGD2. CONCLUSIONS Increasing the amount of RP attenuated the inhibitory effect of GA via competing being consumed by intestinal bacteria (or β-glucosidase) to reduce the conversion amount of glycyrrhizin to GA and subsequently to afford significantly higher bioavailability and longer efficacy of PF, glycyrrhizin, albiflorin, oxypaeoniflorin, isoliquiritin, and ononin, leading to better spasmolysis and emergency pain relief.

Quantitative Classification of Two-Dimensional Correlation Spectra

Two-dimensional (2D) correlation spectroscopy, which takes advantage of the apparent enhancement of spectral resolution, is known to be useful in qualitative discrimination of seemingly similar samples. The possibility of quantitative classification of 2D correlation spectra is even more desirable. Two useful parameters, namely Euclidian distance and correlation coefficient between 2D correlation spectra, are introduced for this purpose. Dry and sweet red wine samples are used to demonstrate the utility of these parameters. The distances between the 2D infrared (IR) spectra of sweet and dry red wines are roughly proportional to the differences of sugar contents in them. The result shows that the two parameters are useful measures for the quantitative evaluation of the similarity among the samples and their corresponding 2D correlation spectra.

Study on similar traditional Chinese medicines Cornu Cervi Pantotrichum, Cornu Cervi and Cornu Cervi Degelatinatum by FT-IR and 2D-IR correlation spectroscopy

As complicated mixture systems, traditional Chinese medicines (TCM) are very difficult to identify and discriminate, especially for the drug samples have the same source. Therefore, finding a rapid and effective identification method for the similar TCM is the most pressing task in TCM research. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative spectra and two-dimensional correlation infrared spectroscopy (2D-IR), were applied to studying and identifying three very similar traditional Chinese animal drugs Cornu Cervi Pantotrichum (CCP), Cornu Cervi (CC) and Cornu Cervi Degelatinatum (CCD). On the basis of the different FT-IR and 2D-IR spectra ratios of amide I bands, amide II bands and Ca(3)(PO(4))(2), three similar animal drugs of the same source were successfully identified and discriminated. Then the FT-IR spectra data of total 30 samples, comprising 10 samples each of above three drugs, were obtained and analyzed with the soft independent modeling of class analogy (SIMCA) pattern recognition technique. The result showed that the three kinds of drug samples located in three different clusters separately. As a result, it was demonstrated that the macroscopic IR fingerprint method could discriminate the three similar TCM, CCP, CC and CCD, rapidly, effectively and non-destructively.

Rapid discrimination of Herba Cistanches by multi-step infrared macro-fingerprinting combined with soft independent modeling of class analogy (SIMCA)

Herba Cistanche, an important Chinese herbal medicine, has common four species, Cistanche deserticola (CD), Cistanche tubulosa (CT), Cistanche salsa (CS) and Cistanche sinensis (CSN) which have been frequent mixed used. To clarify the sources of Herba Cistanches and ensure the clinical efficacy and safety, a method combing IR macro-fingerprinting with statistical pattern recognition was developed to analyze and discriminate the four species of Herba Cistanche. By comparing FT-IR, second derivative spectral fingerprints via group-peak matching, the similarity to CD and total saccharides (TS) followed an increasing sequence, CTCSN>CS>CD. Characteristic fingerprints of their 2D-IR correlation spectra in 1750-1000 cm(-1) have confirmed the above findings in a more intuitive way. In terms of sources for phenylethanoid glycosides (PhGs), CT can be an ideal alternative species. However, in terms of using them as a whole, more pharmacological study should be conducted due to the different ratios of their chemical constituents, which is also applicable to CSN and CS. Moreover, the four species (179 samples) has been objectively classified by SIMCA based on IR macro-fingerprints.

Data-driven signal-resolving approaches of infrared spectra to explore the macroscopic and microscopic spatial distribution of organic and inorganic compounds in plant

The nondestructive and label-free infrared (IR) spectroscopy is a direct tool to characterize the spatial distribution of organic and inorganic compounds in plant. Since plant samples are usually complex mixtures, signal-resolving methods are necessary to find the spectral features of compounds of interest in the signal-overlapped IR spectra. In this research, two approaches using existing data-driven signal-resolving methods are proposed to interpret the IR spectra of plant samples. If the number of spectra is small, “tri-step identification” can enhance the spectral resolution to separate and identify the overlapped bands. First, the envelope bands of the original spectrum are interpreted according to the spectra–structure correlations. Then the spectrum is differentiated to resolve the underlying peaks in each envelope band. Finally, two-dimensional correlation spectroscopy is used to enhance the spectral resolution further. For a large number of spectra, “tri-step decomposition” can resolve the spectra by multivariate methods to obtain the structural and semi-quantitative information about the chemical components. Principal component analysis is used first to explore the existing signal types without any prior knowledge. Then the spectra are decomposed by self-modeling curve resolution methods to estimate the spectra and contents of significant chemical components. At last, targeted methods such as partial least squares target can explore the content profiles of specific components sensitively. As an example, the macroscopic and microscopic distribution of eugenol and calcium oxalate in the bud of clove is studied.

Monitoring all-trans-retinoic acid-induced differentiation of human acute promyelocytic leukemia NB4 cells by Fourier-transform infrared spectroscopy.

Monitoring all- trans- retinoic acid-induced differentiation of human acute promyelocytic leukemia NB 4 cells by Fourier-transform infrared spectroscopy