SERS study of different configurations of pharmaceutical and natural product molecules ginsenoside Rg3 under the interaction with human serum albumin on simple self-assembled substrate

Rapid SERS Detection of Thiol-Containing Natural Products in Culturing Complex

Thiol-containing natural products possess a wide range of bioactivities. The burst of synthetic biology technology facilitates the discovery of new thiol-containing active ingredients. Herein, we report a sensitive, quick, and robust surface-enhanced Raman scattering technology for specific and multiplex detection of thiol-containing compounds without purification requirements and also indicating the thiols with different chemical environments. Using this platform, we successfully demonstrated the simultaneous detection of thiol-containing compounds from as low as 1 μM of analytes spiked in complex culture matrices.

Stereoisomers of Saponins in Panax notoginseng (Sanqi): A Review

Panax notoginseng (Sanqi), a traditional Chinese medical drug which has been applied to medical use for over four centuries, contains high content of dammarane-type tetracyclic triterpenoid saponins. A number of stereoisomeric dammarane-type saponins exist in this precious herb, and some are particularly regarded as “biomarkers” in processed notoginseng. Contemporary researches have indicated that some saponin stereoisomers may show stereospecific pharmacological activities, such as anti-tumor, antioxidative, anti-photoaging, anti-inflammatory, antidiabetic, and neuro-protective activities, as well as stereoselective effects on ion channel current regulation, cardiovascular system, and immune system. The current review provides a comprehensive overview of chemical compositions of raw and processed P. notoginseng with a particular emphasis on saponin stereoisomers. Besides, the pharmacological and pharmacokinetic researches, as well as determination and biotechnological preparation methods of stereoisomeric saponins in notoginseng are discussed extensively.

Based on SERS conformational studies of ginsenoside Rb1 and its metabolites before and after combined with human serum albumin

Surface-enhanced Raman scattering (SERS) and fluorescence spectroscopy were employed to probe the interaction of the pharmaceutical and natural product molecules, ginsenoside Rb1, Rd, Rg3 and compound K (CK), with human serum albumin (HSA). Normal Raman spectra of these four ginsenosides were obtained from solid powder on glass slide. Based on the unsplit peak at 1445 cm(-1), the stacking modes of ginsenoside Rb1, Rd, Rg3 and CK were quite similar, when the deconvolution of alkyl chain was not occurred. SERS spectra of ginsenoside Rb1, Rd, Rg3 and CK were obtained from a colloidal silver surface on a self-assembled SERS substrate, the most enhanced modes were those with certain motions perpendicular to the metal surface, such as C24C25 stretch and CH out-of-plane bending from alkyl chain. The SERS spectra were used to predict similar perpendicular orientation of flexible alkyl chain and parallel orientation of carbocyclic rings on Ag colloid particles. Therefore, when combined with HSA, the transformations of four ginsenosides still exhibit similar, although in different binding cavities in subdomain IIA and IIIA by making the methyls at C26 and C27 perpendicular plugging into the hydrophobic site of HSA, while the aglycone and glucose nearby are perpendicularly exposed outside to fit other suitable active targeting sites.

Comparative binding mechanism of lupeol compounds with plasma proteins and its pharmacological importance

Binding of lupeol compounds with plasma proteins.