Recent advance in the discovery of tyrosinase inhibitors from natural sources via separation methods

Tyrosinase (TYR) inhibitors are in great demand in the food, cosmetic and medical industrials due to their important roles. Therefore, the discovery of high-quality TYR inhibitors is always pursued. Natural products as one of the most important sources of bioactive compounds discovery have been increasingly used for TYR inhibitors screening. However, due to their complex compositions, it is still a great challenge to rapid screening and identification of biologically active components from them. In recent years, with the help of separation technologies and the affinity and intrinsic activity of target enzymes, two advanced approaches including affinity screening and inhibition profiling showed great promises for a successful screening of bioactive compounds from natural sources. This review summarises the recent progress of separation-based methods for TYR inhibitors screening, with an emphasis on the principle, application, advantage, and drawback of each method along with perspectives in the future development of these screening techniques and screened hit compounds.

Screening techniques for the identification of bioactive compounds in natural products

Natural products (NPs) have a long history of clinical use and are rich source of bioactive compounds. The development of tools and techniques for identifying and analyzing NP bioactive compounds to ensure their quality and discover new drugs is thus very important and still in demand. Screening techniques have proven highly useful for screening and analyzing active components in complex mixtures, which rely on cell culture, dialysis, ultrafiltration, chromatographic methods and target molecule immobilization, using biological targets to identify the active compounds. The recent progress in biological screening techniques in the field of natural products is reviewed here. This includes a review on the strategy and application of the screening methods, their detailed description and discussion of their existing limitations of the different models along with prospective in future development of screening techniques.

Screening for the bioactive constituents of traditional Chinese medicines—progress and challenges

The search for lead compounds from traditional Chinese medicines (TCMs) may be promising for new drug development.

An in vitro AChE inhibition assay combined with UF-HPLC-ESI-Q-TOF/MS approach for screening and characterizing of AChE inhibitors from roots of Coptis chinensis Franch

In this study, an in vitro acetylcholinesterase (AChE) inhibition assay based on microplate reader combined with ultrafiltration high performance liquid chromatography-electrospray quadrupole time of flight mass (UF-HPLC-ESI-Q-TOF/MS) was developed for the rapid screening and identification of acetylcholinesterase inhibitors (AChEI) from roots of Coptis chinensis Franch. Incubation conditions such as enzyme concentration, incubation time, incubation temperature and co-solvent was optimized so as to get better screening results. Five alkaloids including columbamine, jatrorrhizine, coptisine, palmatine and berberine were found with AChE inhibition activity in the 80% ethanol extract of C. chinensis Franch. The screened compounds were identified by HPLC-DAD-ESI-Q-TOF/MS compared with the reference stands and literatures. The screened results were verified by in vitro AChE inhibition assays, palmatine showed the best AChE inhibitory activities with IC50 values of 36.6μM among the five compounds. Results of the present study indicated that the combinative method using in vitro AChE inhibition assay and UF-HPLC-ESI-Q-TOF/MS could be widely applied for rapid screening and identification of AChEI from complex TCM extract.

Analysis of Bovine Serum Albumin Ligands fromPuerariae flosUsing Ultrafiltration Combined with HPLC-MS

Rapid screening techniques for identification of active compounds from natural products are important not only for clarification of the therapeutic material basis, but also for supplying suitable chemical markers for quality control. In the present study, ultrafiltration combined with high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed and conducted to screen and identify bovine serum albumin (BSA) bound ligands fromPuerariae flos. Fundamental parameters affecting the screening like incubation time, BSA concentration, pH, and temperature were studied and optimized. Under the optimum conditions, nine active compounds were identified by UV and MS data. The results indicated that this method was able to screen and identify BSA bound ligands form natural products without the need of preparative isolation techniques. Moreover, the method has more effective with easier operation procedures.

Simultaneous determination of geniposide, chlorogenic acid, crocin1, and rutin in crude and processed Fructus Gardeniae extracts by high performance liquid chromatography

Background:

Fructus Gardeniae, commonly used traditional Chinese medicine (TCM) called Zhizi in chinese, is derived from the dried fruit of Gardenia jasminoides Ellis of the Madder Family. To our knowledge, previously reported analytical methods were not developing for simultaneous determination of geniposide, chlorogenic acid, crocin1, and rutin in Fructus Gardeniae and its processed products of chaozheng pin (CZP) extracts.

Materials and Methods:

In this study, a HPLC method was developed for simultaneous determination four major active components in Fructus Gardeniae and its processed products.

Results:

The contents of geniposide, chlorogenic acid, crocin1, and rutin in Fructus Gardeniae samples analyzed were 2.492 - 4.242%, 0.162 - 0.407%, 0.417 -0.837%, and 0.116 - 0.251%, respectively.

Conclusion:

The developed method can be applied to the intrinsic quality control of Fructus Gardeniae.

Determination of 5-hydroxymethyl-2-furaldehyde of crude and processed Fructus Corni in freely moving rats using in vivo microdialysis sampling and liquid chromatography

BACKGROUND

Fructus Corni is derived from the dry ripe sarcocarp of Cornus officinalis Sieb. et Zucc. 5-hydroxymethyl-2-furaldehyde (5-HMF) is an important active composition of the Fructus Corni. However, there have been no reports on the concentration of 5-HMF in freely moving rats using microdialysis coupled with HPLC.

MATERIALS AND METHODS

The concentration of 5-HMF in free-moving rats after intra-gastric (i.g.) administration of the water extract of Fructus Corni and JZP was analyzed by microdialysis coupled with high-performance liquid chromatographic (HPLC).

RESULTS

Results demonstrated that the concentration of 5-HMF in microdialysate was 1.4951 μg/l, but higher in rat microdialysate after i.g. administration of the aqueous extract of JZP (5.2662 μg/l).

CONCLUSION

This method is proved to be rapid, accurate and simple. Real-time in vivo monitoring the concentration of 5-HMF provides the theoretical basis for further explaining the processing mechanism of Fructus Corni.

Screening, identification, and potential interaction of active compounds from Eucommia ulmodies leaves binding with bovine serum albumin

The aqueous extract of Eucommia ulmoides leaves has been commonly known as Du-zhong tea as a functional health food for the treatment of hypertension, hypercholesterolemia, and fatty liver. This study developed a centrifugal ultrafiltration-high-performance liquid chromatography (HPLC) method for screening and identification of bioactive compounds in E. ulmoides leaves binding with bovine serum albumin (BSA). Six active compounds were screened, isolated, and elucidated by their ultraviolet (UV), electrospray ionization-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR) data as geniposidic acid (1), caffeic acid (2), chlorogenic acid (3), quercetin-3-O-sambubioside (4), rutin (5), and isoquercitrin (6). The interaction between active compounds and BSA was investigated in the absence and presence of other compounds by quenching the intrinsic BSA fluorescence. The results indicated that the structures significantly affected the binding process. The values of binding constants for compounds 2-6 were in the range of 10(5)-10(6) mol L(-1), while geniposidic acid (1) hardly quenching the BSA intrinsic fluorescence. However, the quenching process of geniposidic acid was easily affected in the presence of other active compounds. The formation of the geniposidic acid-phenylpropanoid (flavonoid) complex could increase the binding affinity of geniposidic acid with BSA; however, the increased steric hindrance of the complex may make phenylpropanoid or flavonoid dissociate from BSA and then decrease their affinities.

Pharmacokinetic parameters of morroniside in iridoid glycosides of Fructus corni processing based on back-propagation neural network

CONTEXT

Fructus Corni is derived from the dry ripe sarcocarp of Cornus officinalis Sieb. et Zucc. (Cornaceae). Morroniside is an active constituent of Fructus Corni used in many traditional Chinese medicines (TCMs). This article describes a sensitive and specific assay for the quantitation of morroniside in rat plasma after oral administration of iridoid glycosides from Fructus Corni.

MATERIALS AND METHODS

In this article, back-propagation (BP) neural network method was fist developed for the prediction of pharmacokinetic (PK) parameters of morroniside in Fructus Corni.

RESULTS

The results show that mean square error (MSE) of neural network model with 11 hidden neurons and 90% training data is 0.092.

DISCUSSION AND CONCLUSION

This article provides a new method to calculate PK data, one do not need to figure out all the compartment parameters to acquire PK data of morroniside. Therefore, the BP neural network method would be useful for guiding the holistic PK study in consistence with the intrinsic theory and characteristics of TCM.

Anti-angiogenic, antinociceptive and anti-inflammatory activities of Lonicera japonica extract

This study aimed to elucidate some novel pharmacological activities of Lonicera japonica (Caprifoliaceae), which is widely used in Oriental folk medicine. The ethanolic extract of L. japonica (LJ) dose dependently inhibited chick chorioallantoic membrane angiogenesis. The antinociceptive activity of LJ was assessed using the acetic acid-induced constriction model in mice. LJ showed anti-inflammatory activity in two in-vivo models: the vascular permeability and air pouch models. LJ suppressed the production of nitric oxide via down-regulation of inducible nitric oxide synthase in lipopolysaccharide-stimulated RAW264.7 macrophage cells. However, LJ was unable to suppress induction of cyclooxygenase-2 in the stimulated macrophage cells. LJ decreased the reactive oxygen species level in the stimulated macrophage cells. In brief, the flowers of L. japonica possess potent anti-angiogenic and antinociceptive activities, in addition to anti-inflammatory activity, which partly supports its therapeutic efficacy.