Jimmy Yuk

Jimmy Yuk
Thermo Fisher Scientific | TFS · Chromatography and Mass Spectrometry Division

Ph.D.

About

61
Publications
3,879
Reads
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445
Citations
Additional affiliations
May 2019 - present
Thermo Fisher Scientific
Position
  • Managing Director
January 2018 - April 2019
Waters Corporation
Position
  • Manager
December 2014 - December 2018
Waters Corporation
Position
  • Business Development Manager
Description
  • Natural Products Research (Pharmaceuticals) Metabolomics

Publications

Publications (61)
Article
Vangueria agrestis is a shrub indigenous to tropical Africa, belonging to family Rubiaceae and traditionally is used as a decoction for treatment of fever, pain and malaria. The current study was undertaken to investigate the chemical constituents based on precursor exact mass and fragment ion information. The chemical profiling and structural char...
Article
Full-text available
Within non-communicable diseases, chronic inflammatory conditions represent one of the biggest challenges for modern medicine. Traditional Chinese Medicine (TCM) has been practiced over centuries and has accumulated tremendous empirical knowledge on the treatment of such diseases. Huangqi Jianzhong Tang (HQJZT) is a famous TCM herbal formula compos...
Article
Full-text available
Within non-communicable diseases, chronic inflammatory conditions represent one of the biggest challenges for modern medicine. Traditional Chinese Medicine (TCM) has been practiced over centuries and has accumulated tremendous empirical knowledge on the treatment of such diseases. Huangqi Jianzhong Tang (HQJZT) is a famous TCM herbal formula compos...
Article
Acer truncatum is an important ornamental, edible, and medicinal plant resource in China. Previous phytochemical research has focused on the leaf (AL) due to its long history as a tea for health. Other parts such as the branch (ABr), bark (ABa), fruit (AF), and root (AR) have drawn little attention regarding their metabolites and bioactivities. The...
Article
Full-text available
Eleutherococcus senticosus Maxim. belongs to the Araliaceae family. Phytochemical studies reveal that E. senticosus leaves contain triterpene glycosides along with organic acid derivatives and flavonoid compounds. It is believed that E. senticosus is similar to ginseng because they come from same family and both contain triterpene saponins. E. sent...
Technical Report
Here we describe the use of UNIFI Scientific Information Software with the Waters scientific microbial database and online ChemSpider libraries such as Marinlit, for confident compound identification from complex natural product microbial samples. Waters Application Note 720006412EN
Article
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 (...
Technical Report
Full-text available
Waters Application Note - 720005898EN - This application note describes how to quantify aflatoxin B1, B2, G1, and G2 confidently and rapidly using the Xevo TQ-XS and VICAM affinity sample prep
Article
Full-text available
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/QTO...
Research
Full-text available
Journal of Brazilian Chemical Society. Vol. 0. 1-8. June 2016
Article
The wide spread use and increasing demand for herbal products as economical and perceived safe alternatives to prescription drugs has led to the increase of such products being adulterated with undeclared synthetic compounds by unscrupulous manufacturers. LC-MS based methods are widely-used for the characterization of the herbal product ingredients...
Article
Full-text available
Flow injection mass spectrometry and proton nuclear magnetic resonance spectrometry, two metabolic fingerprinting methods, and DNA sequencing were used to identify and authenticate Actaea species. Initially, samples of Actaea racemosa from a single source were distinguished from other Actaea species based on principal component analysis and soft in...
Conference Paper
NMR spectroscopy is a powerful technique for identifying and quantifying components in complex mixtures such as plant extracts. Multiple compounds can be identified in the same spectrum recorded on a crude extract. Typical 1D 1H spectra require less than 10 minutes for data acquisition and analysis. Here we apply this technology to goldenseal. Gold...
Conference Paper
Natural products chemical ingredient profiling is a challenging task because of the sample complexity and the analyses required. For any natural products related study, regardless the research focus and the final end goal, ingredient profiling (to elucidate the active compounds from a particular plant), sample comparison (to understand point of ori...
Conference Paper
The critical foundation for Traditional Chinese Medicine (TCM) effectiveness originates from the chemical ingredients of the raw herbal materials. Researchers often need to identify chemical ingredients and deduce possible herbal composition for complete unknown products. This is extremely difficult. Because the extreme complexity of the sample, pl...
Article
NMR spectroscopy is a powerful technique for identifying and quantifying components in complex mixtures such as plant extracts. Multiple compounds can be identified in the same spectrum recorded on a crude extract. Typical 1D 1H spectra require less than 10 minutes for data acquisition and analysis. Here we apply this technology to goldenseal. Gold...
Technical Report
Full-text available
Valued for the perceived benefit derived from their natural compounds, botanical extracts are key ingredients in nutra-ceuticals and personal care products. Driven by consumers' desire to adopt healthier lifestyles, these billion dollar industries continue to grow, with nutraceuticals alone expected to reach $204.9 billion by 2017. 1 Often the bene...
Article
In recent years, there has been a tremendous increase in the use of natural products in the form of herbal supplements for health benefits and therapeutic effects. Unfortunately, this rise in usage has also led to the increased chance of products being adulterated with synthetic compounds by unscrupulous manufacturers. There have been reports of se...
Article
There has been a significant increase worldwide in the usage of natural products such as plant extracts for herbal remedies or nutraceuticals. This has raised many concerns as increases in the adulteration of natural products with other materials have been detected in the market. In some cases, this is due to accidental species misidentification bu...
Article
A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magnetic resonance spectroscopy. Reference spectra were measured on leaf extracts from several species, including lowbush blueberry (Vaccinium angustifolium), oval leaf huckleberry (Vaccinium ovalifolium), and cranberry (Vaccinium macrocarpon). Using princi...
Article
Ginseng cultivation in Ontario began over 100 years ago when seed was cultivated from wild ginseng plants. Today Ontario ginseng (Panax quinquefolius) comprises several unimproved landraces, which are farmer selected populations that have likely diverged significantly from wild populations, developing separately for several decades. NMR spectroscop...
Article
Cultivated American ginseng (Panax quinquefolius) is considered to be one of the most valuable medicinal crops in North America and top selling dietary supplements in the United States [1]. Canada is considered one of the largest growers of American ginseng and large quantities are exported to the Asian market [1]. Major interest has been focused o...
Article
One-dimensional (1-D) and two-dimensional (2-D) nuclear magnetic resonance (NMR)-based metabolomics was used to investigate the toxic mode of action (MOA) of endosulfan, an organochlorine pesticide, and its degradation product, endosulfan sulfate, to Eisenia fetida earthworms in soil. Three soil concentrations (0.1, 1.0 and 10.0 mg/kg) were used fo...
Article
The use of 1H-NMR-based metabolomics to distinguish and identify unique markers of five Ontario ginseng (Panax quinquefolius L.) landraces and two ginseng species (P. quinquefolius and P. ginseng) was evaluated. Three landraces (2, 3, and 5) were distinguished from one another in the principal component analysis (PCA) scores plot. Further analysis...
Article
Endosulfan is an environmentally persistent pesticide and has been shown to be genotoxic, neurotoxic and carcinogenic to surrounding organisms. Earthworms are widely used in environmental metabolomic studies to assess soil ecotoxicity. Previous nuclear magnetic resonance (NMR)-based metabolomic studies have analyzed earthworm tissue extracts after...
Article
1-D and 2-D nuclear magnetic resonance (NMR) spectroscopy is used to examine the metabolic response of the earthworm (Eisenia fetida) after contact test exposure to an organofluorine pesticide, trifluralin, and an organochlorine pesticide, endosulfan. Three sub-lethal concentrations were used for each pesticide (0.1, 0.5 and 1.0 mg cm–2 for triflur...
Article
Nuclear Magnetic Resonance (NMR) based metabolomics is a powerful approach to monitoring an organism’s metabolic response to environmental exposure. However, the discrimination between exposed and control groups, depends largely on the NMR technique chosen. Here, three 1-D NMR and three 2-D NMR techniques were investigated for their ability to disc...
Article
Full-text available
The metabolic response of the earthworm Eisenia fetida to two pesticides, dichlorodiphenyltrichloroethane (DDT) and endosulfan, was characterized in contact tests using proton nuclear magnetic resonance (1H NMR) and principal component analysis (PCA). PCA loading plots suggested that maltose, leucine and alanine were important metabolites contribut...
Article
A variety of N-(2-amino-phenyl)-4-(heteroarylmethyl)-benzamides were designed and synthesized. These compounds were shown to inhibit recombinant human HDAC1 with IC(50) values in the sub-micromolar range. In human cancer cells growing in culture these compounds induced hyperacetylation of histones, induced the expression of the tumor suppressor pro...
Article
The long-term objective of our research is to show that internal factors may be key to triggering metamorphosis and directing the life history types in lampreys (parasitism versus nonparasitism). Since neuropeptide Y family peptides are key players in the endocrine-mediated feeding and reproductive events in mammals, a role for these peptides in th...