K Yu
Waters Corporation
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Publication
Featured researches published by K Yu.
Analytica Chimica Acta | 2014
Michael D. Jones; Bharathi Avula; Yan-Hong Wang; Lu Lu; Jianping Zhao; Cristina Avonto; Giorgis Isaac; Larry R. Meeker; K Yu; Cristina Legido-Quigley; Norman W. Smith; Ikhlas A. Khan
Roman and German chamomile are widely used throughout the world. Chamomiles contain a wide variety of active constituents including sesquiterpene lactones. Various extraction techniques were performed on these two types of chamomile. A packed-column supercritical fluid chromatography-mass spectrometry method was designed for the identification of sesquiterpenes and other constituents from chamomile extracts with no derivatization step prior to analysis. Mass spectrometry detection was achieved by using electrospray ionization. All of the compounds of interest were separated within 15 min. The chamomile extracts were analyzed and compared for similarities and distinct differences. Multivariate statistical analysis including principal component analysis and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to differentiate between the chamomile samples. German chamomile samples confirmed the presence of cis- and trans-tonghaosu, chrysosplenols, apigenin diglucoside whereas Roman chamomile samples confirmed the presence of apigenin, nobilin, 1,10-epioxynobilin, and hydroxyisonobilin.
Journal of the Brazilian Chemical Society | 2016
J Yuk; Dhavalkumar N. Patel; Giorgis Isaac; Kerri Smith; M Wrona; Hernando J. Olivos; K Yu
The chemical profiles of four ginseng roots samples from three species of ginseng (Panax quinquefolius, Panax ginseng and Panax notoginseng) and two commercial ginseng products containing P. quinquefolius and red P. ginseng were compared using ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC/QTOF-MS). Principal component analysis allowed a holistic approach in showing distinct chemical differences between the three ginseng species and correct classification of the two commercial products to their respective species. Further investigation of the chemical profile variations yielded ten main markers that were distinct for the three species. This study shows the potential of chemical profiling for the classification of complex natural product samples, such as ginseng, and application to commercial products sold in the market. This methodology can assist the industry in authenticating the various species of ginseng and providing a quick assessment of the quality of commercial ginseng products.
Planta Medica | 2017
Bharathi Avula; Yan-Hong Wang; Giorgis Isaac; J Yuk; M Wrona; K Yu; Ikhlas A. Khan
Ultrahigh-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UHPLC-QToF-MS) profiling was used for the identification of marker compounds and generation of metabolic patterns that could be interrogated using chemometric modeling software. UHPLC-QToF-MS was used to generate comprehensive fingerprints of three botanicals (Hoodia, Terminalia, and chamomile), each having different classes of compounds. Detection of a broad range of ions was carried out in full scan mode in both positive and negative modes over the range m/z 100-1700 using high-resolution mass spectrometry. Multivariate statistical analysis was used to extract relevant chemical information from the data to easily differentiate between Terminalia species, chamomile varieties, and quality control of Hoodia products. Using nontargeted analysis, identification of 37 compounds contributed to the differences between Terminalia species, 26 flavonoids were identified to show the differences between German and Roman chamomile, and 43 pregnane glycosides were identified from Hoodia gordonii samples. The UHPLC-QToF-MS-based chemical fingerprinting with principal component analysis was able to correctly distinguish botanicals and their commercial products. This work can be used as a basis to assure the quality of botanicals and commercial products.
The Open Conference Proceedings Journal | 2013
Bharathi Avula; Yan-Hong Wang; K Yu; Dominic Moore; Warren Potts; Ikhlas A. Khan
Introduction: In recent years, Hoodia plant and the preparations of Hoodia have become increasingly popular. These dietary supplements are promoted for weight loss. The limited availability of this plant material and its increasing popularity leads to the possibility of adulterations by other species or even genera. Previous results of screenings give rise to serious concerns about the safety of commercial products claimed to be Hoodia, as a considerable amount seems to lack Hoodia. There is a strong need to develop an effective analytical protocol that can be routinely used to authenticate either plant extracts or commercial products that claimed to contain Hoodia gordonii.
Planta Medica | 2016
J Yuk; D Narendrabhai Patel; L Qiao; Giorgis Isaac; K Yu
Planta Medica | 2016
Yh Wang; Bharathi Avula; Giorgis Isaac; J Yuk; M Wrona; K Yu; Ikhlas A. Khan
Planta Medica | 2016
Bharathi Avula; Yh Wang; Giorgis Isaac; J Yuk; M Wrona; K Yu; Ikhlas A. Khan
Planta Medica | 2015
L Qiao; J Huang; D Diehl; J Yuk; M Wrona; Giorgis Isaac; K Yu
Traditional Chinese Medicine | 2016
K Yu; Mark Powell; Margaret Maziarz; Dhavalkumar Narendrabhai Patel
Planta Medica | 2016
J Yuk; D Narendrabhai Patel; Giorgis Isaac; M Wrona; K Yu