Carbon deficiencies (CDs) of long-chain fatty acid methyl esters (FAMEs) and dicarboxylic acid dimethyl esters (DDMEs), which lead to decreased response in a flame ionization detection (FID) system, were determined by using full responding hydrocarbons (heptadecane, eicosane and alpha-cholestane) as references. For saturated FAMEs ranging from C12 to C22 and for DDMEs ranging from C4 to C10, CDs between 1.3+/-0.12 and 1.7+/-0.36 per ester group were recorded. All values were significantly (P < 0.05) greater than 1. Generally, response factors for gas-chromatographic analysis using FID have been calculated on the theory that the CD of FAMEs is 1 per ester group. However, this theory could not be confirmed experimentally for short-chain FAMEs of less than 8 carbons as CDs of around 1.5 were reported for C4 and C6 FAMEs. The study presented here contributes an approach to this problem by confirming the validity of response factors calculated from a CD of 1.5 per ester group as well as for long-chain FAMEs and DDMEs.
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http://dx.doi.org/10.1016/j.chroma.2004.06.038 | DOI Listing |
Sci Rep
December 2024
Department of Pharmacognosy, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea.
Despite significant advancements with combination anti-retroviral agents, eradicating human immunodeficiency virus (HIV) remains a challenge due to adverse effects, adherence issues, and emerging viral resistance to existing therapies. This underscores the urgent need for safer, more effective drugs to combat resistant strains and advance acquired immunodeficiency syndrome (AIDS) therapeutics. Eight triterpene esters (1-8) were identified from Uncaria rhynchophylla hooks.
View Article and Find Full Text PDFNat Commun
December 2024
Key Laboratory of Phytochemistry and Natural Medicines, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China.
The functionalized polycycle with densely contiguous tertiary stereocenters is a formidable challenge in synthesizing the parvistemoline family of Stemona alkaloids. We herein report their catalytic, asymmetric total syntheses in 13-14 steps from commercially available 2-(methoxycarbonyl)-pyrrole, featuring the development and deployment of an Ir/Pd-synergistically-catalyzed allylation of α-non-substituted keto esters with secondary aryl-substituted alcohols, stereodivergently accessible to four stereoisomers. Using chiral Pd-enolate and Ir π-allyl complex under neutral conditions, no epimerization occurs.
View Article and Find Full Text PDFFood Chem X
January 2025
School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China.
Douchiba (DCB) is a nutritious food rich in various functional components such as Tetramethylpyrazine (TTMP), and the strain fermentation is crucial for enhancing its quality. This work utilized S2-2 and S6-J1 with high TTMP production for fermentation of soybeans to optimize the pre-fermentation process and to evaluate the flavor quality of mature DCB. The concentration of TTMP in DCB fermented by mixed microbial (MG) was 2.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
Graduate Program in Chemistry, Federal University of Alfenas, Alfenas, MG 37130-001, Brazil; Institute of Chemistry, Federal University of Alfenas, Alfenas, MG 37130-001, Brazil. Electronic address:
The objective of this study was to produce new and renewable bio-based plasticizers from used soybean cooking oil (USCO). First, USCO was completely converted into free fatty acids (FFAs) using lipase from Candida rugosa. Next, these FFAs were enzymatically esterified with benzyl alcohol in solvent-free systems.
View Article and Find Full Text PDFJ Asian Nat Prod Res
December 2024
CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Three new terpenoid derivatives (1,6,7)-hydrobenzosydowic acid (), (1 ,6,7)-hydrobenzosydowic acid (), and (7 ,10)-11-dehydroxy-iso-10-hydroxysydowic acid (), along with the known analogues ()-2-(1-(4-nitrobenzoyl)pyrrolidine-2-carboxamido)benzoic acid () and trihydroxybutyl ester of 4-carboxydiorcinol () were isolated from the deep-sea-derived fungus DFFSCS007. Their structures were determined by spectroscopic analysis. Compound with a nitrobenzene group was isolated from nature for the first time.
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