Micropreparative isolation and NMR structure elucidation of metabolites of the drug candidate 1-isopropyl-4-(4-isopropylphenyl)-6-(prop-2-yn-1-yloxy) quinazolin-2(1H)-one from rat bile and urine

Comprehensive Metabolic Profiling of Euphorbiasteroid in Rats by Integrating UPLC-Q/TOF-MS and NMR as Well as Microbial Biotransformation

Euphorbiasteroid, a lathyrane-type diterpene from Euphorbiae semen (the seeds of Euphorbia lathyris L.), has been shown to have a variety of pharmacological effects such as anti-tumor and anti-obesity. This study aims to investigate the metabolic profiles of euphorbiasteroid in rats and rat liver microsomes (RLMs) and Cunninghamella elegans bio-110930 by integrating ultra-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-Q/TOF-MS), UNIFI software, and NMR techniques. A total of 31 metabolites were identified in rats. Twelve metabolites (M1–M5, M8, M12–M13, M16, M24–M25, and M29) were matched to the metabolites obtained by RLMs incubation and the microbial transformation of C. elegans bio-110930 and their structures were exactly determined through analysis of NMR spectroscopic data. In addition, the metabolic pathways of euphorbiasteroid were then clarified, mainly including hydroxylation, hydrolysis, oxygenation, sulfonation, and glycosylation. Finally, three metabolites, M3 (20-hydroxyl euphorbiasteroid), M24 (epoxylathyrol) and M25 (15-deacetyl euphorbiasteroid), showed significant cytotoxicity against four human cell lines with IC₅₀ values from 3.60 μM to 40.74 μM. This is the first systematic investigation into the in vivo metabolic pathways of euphorbiasteroid and the cytotoxicity of its metabolites, which will be beneficial for better predicting the metabolism profile of euphorbiasteroid in humans and understanding its possible toxic material basis.

Comprehensive characterization of in vitro and in vivo metabolites of 2',3',5'‑tri‑O‑acetyl‑N6‑(3‑hydroxyphenyl) adenosine and study of the metabolites distribution in rats by combined methods of HPLC-DAD, off-line cryoNMR, and HPLC-QTOFMS

The compound 2',3',5'‑tri‑O‑acetyl‑N₆‑(3‑hydroxyphenyl) adenosine (also known as IMM-H007) is a new adenosine analogue that displays anti-hyperlipidaemic activity in many preliminary studies. To clarify its biotransformation process, in vitro and in vivo metabolic patterns of IMM-H007 in rat liver microsomes (RLMs), urine, feces, serum, and various tissues were investigated using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD), off-line cryogenically cooled probe nuclear magnetic resonance (cryoNMR), and high-performance liquid chromatography quadrupole TOF MS (HPLC-QTOFMS) measurements. A total of 21 metabolites were detected and identified based on accurate mass measurements, diagnostic product ions, and 1D and 2D NMR data. All of the 21 metabolites were detected in vivo besides the 7 ones (LM1-3, LM4a-b, LM5, LM6 (M8)) in vitro. Among them, eight metabolites were phase I metabolites composed of the hydrolysis products LM1-3, LM4a, LM4b, LM5 and M7-8, and hydrolysis and hydroxylation products M6. Others were phase II metabolites including glucuronidation products M2, M4, M9, M11a-c, and M12a-c; and sulfation products M3, M5, and M10. Notably, 14 metabolites (LM1-3, LM4a-b, LM5, M9-10, M11a-c, M12a-c) were unreported before and the distribution of IMM-H007 and its all metabolites was reported for the first time. The results revealed IMM-H007 was metabolized mainly in the small intestine and serum, kidney, stomach, small and large intestines were important samples for metabolites presence. This work improves understanding of the metabolism, distribution, and excretion of IMM-H007, and demonstrates the HPLC/HPLC-MS/off-line cryoNMR approach can be applied for detection and identification of metabolites in complex biological matrices.

Targeted isolation and identification of bioactive compounds lowering cholesterol in the crude extracts of crabapples using UPLC-DAD-MS-SPE/NMR based on pharmacology-guided PLS-DA

The anti-hyperlipidemic effects of crude crabapple extracts derived from Malus 'Red jade', Malus hupehensis (Pamp.) Rehd. and Malus prunifolia (Willd.) Borkh. were evaluated on high-fat diet induced obese (HF DIO) mice. The results revealed that some of these extracts could lower serum cholesterol levels in HF DIO mice. The same extracts were also parallelly analyzed by LC-MS in both positive and negative ionization modes. Based on the pharmacological results, 22 LC-MS variables were identified to be correlated with the anti-hyperlipidemic effects using partial least square discriminant analysis (PLS-DA) and independent samples t-test. Further, under the guidance of the bioactivity-correlated LC-MS signals, 10 compounds were targetedly isolated and enriched using UPLC-DAD-MS-SPE and identified/elucidated by NMR together with MS/MS as citric acid(1), p-coumaric acid(2), hyperoside(3), myricetin(4), naringenin(5), quercetin(6), kaempferol(7), gentiopicroside(8), ursolic acid(9) and 8-epiloganic acid(10). Among these 10 compounds, 6 compounds, hyperoside(3), myricetin(4), naringenin(5), quercetin(6), kaempferol(7) and ursolic acid(9), were individually studied and reported to indeed have effects on lowering the serum lipid levels. These results demonstrated the efficiency of this strategy for drug discovery. In contrast to traditional routes to discover bioactive compounds in the plant extracts, targeted isolation and identification of bioactive compounds in the crude plant extracts using UPLC-DAD-MS-SPE/NMR based on pharmacology-guided PLS-DA of LC-MS data brings forward a new efficient dereplicated approach to natural products research for drug discovery.

Evaluation of relative MS response factors of drug metabolites for semi-quantitative assessment of chemical liabilities in drug discovery

Drug metabolism studies are performed in drug discovery to identify metabolic soft spots, detect potentially toxic or reactive metabolites and provide an early insight into potential species differences. The relative peak area approach is often used to semi-quantitatively estimate the abundance of metabolites. Differences in the liquid chromatography-mass spectrometry responses result in an underestimation or overestimation of the metabolite and misinterpretation of results. The relative MS response factors (RF) of 132 structurally diverse drug candidates and their 233 corresponding metabolites were evaluated using a capillary-liquid chromatography/high-resolution mass spectrometry system. All of the synthesized metabolites discussed here were previously identified as key biotransformation products in discovery investigations or predicted to be formed. The most commonly occurring biotransformation mechanisms such as oxygenation, dealkylation and amide cleavage are represented within this dataset. However, relatively few phase II metabolites were evaluated because of the limited availability of authentic standards. Approximately 85% of these metabolites had a relative RF in the range between 0.2 (fivefold under-prediction) and 2.0 (twofold over-prediction), and the median MS RF was 0.6. Exceptions to this included very small metabolites that were hardly detectable. Additional experiments performed to understand the impact of the MS platform, flow rate and concentration suggested that these parameters do not have a significant impact on the RF of the compounds tested. This indicates that the use of relative peak areas to semi-quantitatively estimate the abundance of metabolites is justified in the drug discovery setting in order to guide medicinal chemistry efforts. Copyright © 2017 John Wiley & Sons, Ltd.