Phytochemistry and pharmacology of natural prenylated flavonoids.

Prenylated flavonoids are a special kind of flavonoid derivative possessing one or more prenyl groups in the parent nucleus of the flavonoid. The presence of the prenyl side chain enriched the structural diversity of flavonoids and increased their bioactivity and bioavailability. Prenylated flavonoids show a wide range of biological activities, such as anti-cancer, anti-inflammatory, neuroprotective, anti-diabetic, anti-obesity, cardioprotective effects, and anti-osteoclastogenic activities. In recent years, many compounds with significant activity have been discovered with the continuous excavation of the medicinal value of prenylated flavonoids, and have attracted the extensive attention of pharmacologists. This review summarizes recent progress on research into natural active prenylated flavonoids to promote new discoveries of their medicinal value.

Cucurbitane-type triterpenoids from the fruits of Citrullus colocynthis.

A phytochemical investigation of the fruits of Citrullus colocynthis resulted in the isolation of 21 structurally diverse cucurbitane triterpenoids, including 9 previously undescribed ones, colocynins A-I (1-9). Their absolute configurations were elucidated by means of quantum chemical electronic circular dichroism (ECD) calculations, CD exciton chirality method, and single-crystal X-ray crystallography. Colocynins A-C (1-3) represent the first examples of nonanorcucurbitane-type triterpenoids. An anti-acetylcholinesterase activity assay showed that 6, 10, 13, 18, and 20 exhibited inhibitory activities, with IC50 values ranging from 5.0 to 21.7 µM. In addition, 18 and 21 showed significant cytotoxicity against PACA, A431, and HepG2 cells, with IC50 values ranging from 0.042 to 0.60 and 3.6-14.4 µM, respectively.

In silico screening of off-line comprehensive two-dimensional counter-current chromatography with liquid chromatography for four saponins isolation.

Being restrained by the limited peak capacity, one-dimensional chromatography usually leads to an unsatisfactory separation with low purity of compounds in a complex mixture. To obtain more highly pure targets for standard reference and to discover new substances for structural elucidation, two-dimensional chromatography is more and more prevalent in many fields. As few metrics on assessment of the preparative capability of two-dimensional chromatographic separations are reported, a methodology of in silico screening of various two-dimensional chromatographic separations with a minimal number of experiments was demonstrated in this work, which was based on three descriptors including the occupation rate of peaks and system homogeneity of a two-dimensional separation space, and the minimal distance of all nearest-neighbor distances of peaks. Combining the advantages of counter-current chromatography and liquid chromatography, we elaborated the methodology by employing off-line comprehensive two-dimensional counter-current chromatography with liquid chromatography to be in silico screened for separation of four saponins from Panax notoginseng at an analytical scale to simulate the case of preparative scale transfer. The predictive results were presented by two-dimensional contour plots and verified by experiments. The result showed that the experimental results were in general accord with the predictive results.

[Definitive screening design combined with design space for optimizing purification process of Scutellariae Radix extract].

In the pharmacopoeia, many process parameters for the purification process of Scutellariae Radix are unclear. In this study, deterministic screening design combined with design space method was used to optimize the purification process of Scutellariae Radix extract. Nine method parameters such as mass fraction of solution(X_1), first acid precipitation pH(X_2) and first holding time(X_3) in the purification process were firstly studied by definitive screening design. The yield of baicalin was defined as the evaluation index. A stepwise regression method was used then to build quantitative models between evaluation index and method parameters and the three most critical impact parameters were determined. Probability-based design space was calculated and successfully verified with the experimental error simulation method. Finally, the second standing temperature, the first standing temperature and the pH value of the second acid precipitation were determined as the three most critical method parameters. The recommended operating space was as follows: the second standing temperature 5-7 ℃, the first standing temperature 13-15 ℃, and the pH of the second acid precipitation 1.5-1.7. Within this operating space, the baicalin yield in the purification process was over 80%, and the probability of reaching the standard was over 0.96. In this study, we optimized the effect of various parameters for the purification process of the Scutellariae Radix extract in the pharmacopoeia on the yield of baicalin and provided a reference for industrial production of the exact of Scutellariae Radix.

An Off-Line DPPH-GC-MS Coupling Countercurrent Chromatography Method for Screening, Identification, and Separation of Antioxidant Compounds in Essential Oil.

Essential oils are an important source of natural antioxidants and multiple methods have been established for evaluation of their overall antioxidant activity, however, the antioxidant activities of their compounds are less investigated. In the present study, the hyphenation of 2,2'-diphenyl-1-picrylhydrazyl (DPPH)-gas chromatography (GC)-mass spectrometry (MS) offline and high-speed countercurrent chromatography (HSCCC) is established for efficient screening, identification, and isolation of antioxidants from essential oils and applied to the essential oil of Curcuma wenyujin Y.H. Chen et C. Ling. Five compounds are preliminarily screened as antioxidants using DPPH-GC according to the reduction of GC peak areas of each compound after reaction with DPPH and then identified as eucalyptol (7.66%), camphor (2.34%), δ-elemene (1.15%), ß-elemene (7.10%), and curzerene (15.77%) using GC-MS. Moreover, these five compounds are isolated by HSCCC using two solvent systems, n-hexane-acetonitrile-ethanol (5:3:2, v/v) and n-hexane-acetonitrile-acetone (4:3:1, v/v), and subjected to DPPH scavenging assay. Camphor, δ-elemene, and ß-elemene show weak DPPH scavenging activity, while curzerene and eucalyptol show moderate DPPH scavenging activity. Notably, a significant synergistic effect on DPPH scavenging is found between curzerene and eucalyptol. The result demonstrated that off-line DPPH-GC-MS coupling CCC is an efficient method for screening, identification, and separation of antioxidant compounds in essential oil.

[Overview on hypoglycemic active constituents of traditional Chinese medicine based on insulin receptor signaling pathway].

Insulin resistance,as the main link in the pathogenesis of type 2 diabetes mellitus( T2 DM),runs through the whole process of occurrence and development of T2 DM and is closely related to the insulin receptor signaling pathway. Insulin stimulation causes autophosphorylation of the insulin receptor( IR),which then activates tyrosine phosphorylation of insulin receptor substrate( IRS).Phosphorylation of IRS can induce and activate phosphatidylinositol 3-kinase( PI3 K),subsequently activate downstream 3-phosphoinositide-dependent protease 1( PDK1) and Akt/PKB,and finally promote expression and translocation of glucose transporter 4 to increase glucose uptake of insulin-sensitive tissues and alleviate insulin resistance. Currently,oral hypoglycemic agents for clinical treatment of T2 DM have different side effects on the human body. Traditional Chinese medicine not only has a wide range of sources and abundant types,but also has comprehensive multi-component,multi-link and multi-target effects,showing unique advantages in the treatment of diabetes. In recent years,more and more researchers at home and abroad pay attention to the active ingredients in traditional Chinese medicine for alleviating insulin resistance. In this paper,we would summarize the active hypoglycemic ingredients of traditional Chinese medicine associated with the insulin receptor signaling pathway,which may provide some theoretical guidance for the development of traditional Chinese medicine in the treatment of diabetes.

Chiral Separations by Countercurrent Chromatography.

Chiral separations by countercurrent chromatography are mainly divided into two types: homogeneous chiral selector addition and interfacial chiral ligand exchange. In this chapter, we describe two methods for the enantioseparation of phenylsuccinic acid and α-hydroxy acids by high-speed countercurrent chromatography using hydroxypropyl-ß-cyclodextrin and N-n-dodecyl-L-proline as chiral selectors for both above mentioned modes.

[Effects of hypericum perforatum extract on the immunogenic myocardial fibrosis in mice and its mechanism].

OBJECTIVE: To study the effects of hypericum perforatum extract (HPE) on myocardial fibrosis of the experimental autoimmune myocarditis (MFEAM) in mice. METHODS: MFEAM model of immunosuppressive mouse was established by porcine cardiac myosin. The mice in the MFEAM model group were randomly divided into: MFEAM model group (n=14), HPE 100 mg/kg group (n=13), HPE 40 mg/kg group (n=13) and captopril (Cap) 50 mg/kg control group (n=13). Drug in each group was dissolved in 0.4 ml of physiological saline each time, and administered by intragastric administration twice a day for 60 days; the normal control group (n=10) and the MFEAM model group was given normal saline at the same volume and course of treatment as above described way. The ratio of heart weight and spleen weight to body weight were calculated, the general conditions of mice were observed. The contents of procollagen I N-terminal peptide(PINP), procollagen III N-terminal peptide (PIIINP) and TGF-ß1 in serum of mice were detected. The degree of myocardial fibrosis (MF) and collagen volume fraction (CVF)were measured under the microscope by Masson staining. The protein expression of TGF-ß1 was detected by Western blot. RESULTS: The serum levels of TGF-ß1, PINP and PIIINP in the model group were higher than those in the normal group significantly (P＜0.05 or P＜0.01). Meanwhile , the levels of MF and CVF were increased, and the protein expression of myocardial TGF-ß1 was up-regulated. However, the serum levels of PINP, PIIINP and TGF-ß1 in HPE40 mg/kg, HPE 100 mg/kg and Cap treated-groups were decreased significantly. HPE and Cap could improve or decrease the MF level and CVF of the MFEAM model mice, and down-regulated the expression of TGF-ß1 protein in different degrees. Compared with the MFEAM model group, the difference was significant (P＜0.05 or P＜0.01). CONCLUSION: HPE has a therapeutic effect on MF, which may be related to its reduction of collagen deposition and inhibition of TGF-ß1 signaling pathway.

Coumarins from Edgeworthia chrysantha.

A new coumarin, edgeworic acid (1), was isolated from the flower buds of Edgeworthia chrysantha, together with the five known coumarins umbelliferone (2), 5,7-dimethoxycoumarin (3), daphnoretin (4), edgeworoside C (5), and edgeworoside A (6). Their structures were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences (1H-1H COSY, HSQC and HMBC), in combination with acetylation reactions.

A new furolactone-type lignan from Lycium chinense.

The phytochemical investigation of extracts from the root barks of Lycium chinense yielded a new furolactone-type lignan, lyciumin (1). Its structure and absolute configurations were established on the basis of spectral data, particularly by the use of 1D NMR, 2D shift-correlated NMR pulse sequences ((1)H-(1)H COSY, HSQC, HMBC and ROESY) and CD spectra.

Norlignans from Asparagus cochinchinensis.

A new norlignan glycoside, named iso-agatharesinoside (2), and its aglycone, iso-agatharesinol (1), were isolated from the tuberous roots of Asparagus cochinchinensis. Their structures were established on the basis of spectral data, particularly by the use of 1D NMR and several 2D shift-correlated NMR pulse sequences (1H-1H COSY, HSQC, HMBC and ROESY).

Two phthalide dimers from the radix of Angelica sinensis.

The phytochemical investigation of extracts from the radix of Angelica sinensis yielded a new phthalide dimer, 3,3'Z-6.7',7.6'-diligustilide, along with a known dimer, levistolide A. Their structures were established on the basis of spectral data, particularly using 1D-NMR and several 2D shift-correlated NMR pulse sequences (¹H-¹H COSY, HSQC, HMBC and NOESY).

[Studies on optimal extraction conditions of flavonoid from the flowers of Edgeworthia chrysantha].

OBJECTIVE: To study the optimum extraction process of the total flavonoids from the flowers of Edgeworthia chrysantha Lindl. METHODS: The effect of the concentration of ethanol, extraction time and ratio of material to liquid on the total flavonoid contents were investigated by the orthonogal test with the content of tiliroside as the chemical reference. RESULTS: The optimum extraction condition was established as follows: the concentration of ethanol 75%, extraction time 1. 5 hours and the ratio of material to liquid 1:9. CONCLUSION: The method is simple and feasible, and is the optimum extraction process of the total flavonoids from flowers of Edgeworthia Chrysantha Lindl.