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Physicochemical and functional properties of ozone-oxidized starch

Chan HT, Bhat R, Karim AA

J Agric Food Chem, 2009 Jul 8;57(13):5965-70.
PMID: 19489606 DOI: 10.1021/jf9008789

The effects of oxidation by ozone gas on some physicochemical and functional properties of starch (corn, sago, and tapioca) were investigated. Starch in dry powder form was exposed to ozone for 10 min at different ozone generation times (OGTs). Carboxyl and carbonyl contents increased markedly in all starches with increasing OGTs. Oxidation significantly decreased the swelling power of oxidized sago and tapioca starches but increased that of oxidized corn starch. The solubility of tapioca starch decreased and sago starch increased after oxidation. However, there was an insignificant changed in the solubility of oxidized corn starch. Intrinsic viscosity [eta] of all oxidized starches decreased significantly, except for tapioca starch oxidized at 5 min OGT. Pasting properties of the oxidized starches followed different trends as OGTs increased. These results show that under similar conditions of ozone treatment, the extent of starch oxidation varies among different types of starch.
An overview on the chemistry, pharmacology and anticancer properties of tetrandrine and fangchinoline (alkaloids) from Stephania tetrandra roots

Chan EWC, Wong SK, Chan HT

J Integr Med, 2021 07;19(4):311-316.
PMID: 33583757 DOI: 10.1016/j.joim.2021.01.001

Tetrandrine (TET) and fangchinoline (FAN) are dominant bisbenzylisoquinoline (BBIQ) alkaloids from the roots of Stephania tetrandra of the family Menispermaceae. BBIQ alkaloids comprise two benzylisoquinoline units linked by oxygen bridges. The molecular structures of TET and FAN are exactly the same, except that TET has a methoxy (-OCH3) group, while FAN has a hydroxyl (-OH) group at C7. In this overview, the current knowledge on the chemistry, pharmacology and anticancer properties of TET and FAN have been updated. The focus is on colon and breast cancer cells, because they are most susceptible to TET and FAN, respectively. Against colon cancer cells, TET inhibits cell proliferation and tumor growth by inducing apoptosis and G1 cell cycle arrest, and suppresses adhesion, migration and invasion of cells. Against breast cancer cells, FAN inhibits cell proliferation by inducing apoptosis, G1-phase cell cycle arrest and inhibits cell migration. The processes involve various molecular mechanisms and signaling pathways. Some insights on the ability of TET and FAN to reverse multi-drug resistance in cancer cells and suggestions for future research are provided.
Apocynaceae species with antiproliferative and/or antiplasmodial properties: a review of ten genera

Chan EW, Wong SK, Chan HT

J Integr Med, 2016 Jul;14(4):269-84.
PMID: 27417173 DOI: 10.1016/S2095-4964(16)60261-3

Apocynaceae is a large family of tropical trees, shrubs and vines with most species producing white latex. Major metabolites of species are triterpenoids, iridoids, alkaloids and cardenolides, which are known for a wide range of biological and pharmacological activities such as cardioprotective, hepatoprotective, neuroprotective, anti-inflammatory, anticancer and antimalarial properties. Prompted by their anticancer and antimalarial properties, the current knowledge on ten genera (Allamanda, Alstonia, Calotropis, Catharanthus, Cerbera, Dyera, Kopsia, Nerium, Plumeria and Vallaris) is updated. Major classes of metabolites are described using some species as examples. Species with antiproliferative (APF) and/or antiplasmodial (APM) properties have been identified. With the exception of the genus Dyera, nine genera of 22 species possess APF activity. Seven genera (Alstonia, Calotropis, Catharanthus, Dyera, Kopsia, Plumeria and Vallaris) of 13 species have APM properties. Among these species, Alstonia angustiloba, Alstonia macrophylla, Calotropis gigantea, Calotropis procera, Catharanthus roseus, Plumeria alba and Vallaris glabra displayed both APF and APM properties. The chemical constituents of these seven species are compiled for assessment and further research.
Casticin from Vitex species: a short review on its anticancer and anti-inflammatory properties

Chan EWC, Wong SK, Chan HT

J Integr Med, 2018 05;16(3):147-152.
PMID: 29559215 DOI: 10.1016/j.joim.2018.03.001

This short review provides an update of the anticancer and anti-inflammatory properties of casticin from Vitex species. Casticin is a polymethylflavone with three rings, an orthocatechol moiety, a double bond, two hydroxyl groups and four methoxyl groups. Casticin has been isolated from various tissues of plants in the Vitex genus: fruits and leaves of V. trifolia, aerial parts and seeds of V. agnus-castus and leaves of V. negundo. Studies have reported the antiproliferative and apoptotic activities of casticin from Vitex species. The compound is effective against many cancer cell lines via different molecular mechanisms. Studies have also affirmed the anti-inflammatory properties of casticin, with several molecular mechanisms identified. Other pharmacological properties include anti-asthmatic, tracheospasmolytic, analgesic, antihyperprolactinemia, immunomodulatory, opioidergic, oestrogenic, anti-angiogenic, antiglioma, lung injury protection, rheumatoid arthritis amelioration and liver fibrosis attenuation activities. Clinical trials and commercial use of the casticin-rich fruit extract of V. agnus-castus among women with premenstrual syndrome were briefly discussed.
Phenolic constituents and anticancer properties of Morus alba (white mulberry) leaves

Chan EWC, Wong SK, Tangah J, Inoue T, Chan HT

J Integr Med, 2020 May;18(3):189-195.
PMID: 32115383 DOI: 10.1016/j.joim.2020.02.006

Flavonoids are by far the most dominant class of phenolic compounds isolated from Morus alba leaves (MAL). Other classes of compounds are benzofurans, phenolic acids, alkaloids, coumarins, chalcones and stilbenes. Major flavonoids are kuwanons, moracinflavans, moragrols and morkotins. Other major compounds include moracins (benzofurans), caffeoylquinic acids (phenolic acids) and morachalcones (chalcones). Research on the anticancer properties of MAL entailed in vitro and in vivo cytotoxicity of extracts or isolated compounds. Flavonoids, benzofurans, chalcones and alkaloids are classes of compounds from MAL that have been found to be cytotoxic towards human cancer cell lines. Further studies on the phytochemistry and anticancer of MAL are suggested. Sources of information were PubMed, PubMed Central, ScienceDirect, Google, Google Scholar, J-Stage, PubChem and China National Knowledge Infrastructure.
Fulltext Exploring beyond the limit: How comparative stochastic performance affects retesting outcomes in six commercial SARS CoV-2 nucleic acid amplification tests

Chan HT, Keung MHT, Nguyen I, Ip ELO, Chew SM, Siler D, et al.

J Clin Virol Plus, 2022 Aug;2(3):100079.
PMID: 35528049 DOI: 10.1016/j.jcvp.2022.100079

OBJECTIVES: To examine the comparative stochasticity profile of six commercial SARS-CoV-2 nucleic acid amplification tests (NAATs) and how this may affect retesting paradigms.
METHODS: Commercial quality control (QC) material was serially diluted in viral transport media to create a panel covering 10-10,000 copies/ml. The panel was tested across six commercial NAATs. A subset of high cycle threshold results was retested on a rapid PCR assay to simulate retesting protocols commonly used to discriminate false positives.
RESULTS: Performance beyond the LOD differed among assays, with three types of stochasticity profiles observed. The ability of the rapid PCR assay to reproduce a true weak positive specimen was restricted to its own stochastic performance at the corresponding viral concentration.
CONCLUSION: Stochastic performance of various NAATs overlap across low viral concentrations and affect retesting outcomes. Relying on retesting alone to discriminate false positives risk missing true positives even when a more sensitive assay is deployed for confirmatory testing.