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Introduction: Selection of marker compounds for targeted chemical analysis is complicated when considering varying instrumentation and closely related plant species. High‐resolution gas chromatography–mass spectrometry (GC–MS), via orbitrap detection, has yet to be evaluated for improved marker compound selection. Objective: This study directly compares high‐ and low‐resolution GC–MS for botanical maker compound selection using Ocimum tenuiflorum L. (OT) and Ocimum gratissimum L. (OG) for botanical ingredient authentication. Methods: The essential oils of OT and OG were collected via hydrodistillation before untargeted chemical analysis with gas chromatography coupled to single‐quadrupole (GC‐SQ) and orbitrap (GC‐Orbitrap) detectors. The Global Natural Products Social Molecular Networking (GNPS) software was used for compound annotation, and a manual search was used to find the 41 most common Ocimum essential oil metabolites. Results: The GC‐Orbitrap resulted in 1.7‐fold more metabolite detection and increased dynamic range compared to the GC‐SQ. Spectral matching and manual searching were improved with GC‐Orbitrap data. Each instrument had differing known compound concentrations; however, there was an overlap of six compounds with higher abundance in OG than OT and three compounds with a higher abundance in OT than OG, suggesting consistent detection of the most variable compounds. An unsupervised principal component analysis (PCA) could not discern the two species with either dataset. Conclusion: GC‐Orbitrap instrumentation improves compound detection, dynamic range, and feature annotation in essential oil analysis. However, considering both high‐ and low‐resolution data may improve reliable marker compound selection, as GC‐Orbitrap analysis alone did not improve unsupervised separation of two Ocimum species compared to GC‐SQ data. Gas chromatography‐mass spectrometry (GC‐MS) is a primary method for analyzing phytochemical mixtures. Most GC‐MS features single quadropole; the development of GC‐orbitrap instruments allows for high‐resolution mass analysis. To provide a direct comparison between the two, essential oils from two species of Ocimum (basil) were analyzed by both instruments. The GC‐orbitrap resulted in greater metabolite detection, increased dynamic range, and improved feature detection but did not improve unsupervised classification. Combining the two approaches yielded the most reliable marker compound selection. [ABSTRACT FROM AUTHOR]

The E4 variant of APOE strongly predisposes individuals to late-onset Alzheimer's disease. We demonstrate that in response to lipogenesis, apolipoprotein E (APOE) in astrocytes can avoid translocation into the endoplasmic reticulum (ER) lumen and traffic to lipid droplets (LDs) via membrane bridges at ER-LD contacts. APOE knockdown promotes fewer, larger LDs after a fatty acid pulse, which contain more unsaturated triglyceride after fatty acid pulse-chase. This LD size phenotype was rescued by chimeric APOE that targets only LDs. Like APOE depletion, APOE4-expressing astrocytes form a small number of large LDs enriched in unsaturated triglyceride. Additionally, the LDs in APOE4 cells exhibit impaired turnover and increased sensitivity to lipid peroxidation. Our data indicate that APOE plays a previously unrecognized role as an LD surface protein that regulates LD size and composition. APOE4 causes aberrant LD composition and morphology. Our study contributes to accumulating evidence that APOE4 astrocytes with large, unsaturated LDs are sensitized to lipid peroxidation, which could contribute to Alzheimer's disease risk. [ABSTRACT FROM AUTHOR]