Comprehensive Two-Dimensional Gas Chromatography as a Bioanalytical Platform for Drug Discovery and Analysis.

Over the last decades, comprehensive two-dimensional gas chromatography (GC×GC) has emerged as a significant separation tool for high-resolution analysis of disease-associated metabolites and pharmaceutically relevant molecules. This review highlights recent advances of GC×GC with different detection modalities for drug discovery and analysis, which ideally improve the screening and identification of disease biomarkers, as well as monitoring of therapeutic responses to treatment in complex biological matrixes. Selected recent GC×GC applications that focus on such biomarkers and metabolite profiling of the effects of drug administration are covered. In particular, the technical overview of recent GC×GC implementation with hyphenation to the key mass spectrometry (MS) technologies that provide the benefit of enhanced separation dimension analysis with MS domain differentiation is discussed. We conclude by highlighting the challenges in GC×GC for drug discovery and development with perspectives on future trends.

Evaluation of Cryogen-Free Thermal Modulation-Based Enantioselective Comprehensive Two-Dimensional Gas Chromatography for Stereo-Differentiation of Monoterpenes in Citrus spp. Leaf Oils.

This study evaluates the applicability of enantioselective gas chromatography (eGC) and enantioselective comprehensive two-dimensional gas chromatography (eGC×GC) coupled with flame ionization detection for the stereospecific analysis of designated chiral monoterpenes within essential oils distilled from the leaves of Citrus hystrix (CH), C. limon (CL), C. pyriformis (CP), and C. microcarpa (CM). A cryogen-free solid-state modulator with a combination of enantioselective first-dimension and polar second-dimension column arrangements was used to resolve potential interferences in Citrus spp. leaf oils that can complicate the accurate determination of enantiomeric compositions. Interestingly, considerable variations were observed for the enantiomeric fractions (EFs) of the chiral terpenes. (+)-limonene was identified as the predominant enantiomer (60.3-98.9%) in all Citrus oils, (+)-linalool was the major enantiomer in CM (95.9%), (-)-terpenin-4-ol was the major isomer in CM (66.4%) and CP (61.1%), (-)-α-pinene was the dominant antipode in CL (55.5%) and CM (92.1%). CH contained (-)-citronellal (100%) as the pure enantiomer, while CL and CP have lower proportions (9.0-34.6%), and citronellal is absent in CM. The obtained enantiomeric compositions were compared and discussed with results from eGC using the same enantioselective column. To our knowledge, this work encapsulates the first report that details the EFs of these chiral monoterpenes in Citrus spp. leaf oil.

Comprehensive two-dimensional gas chromatography with mass spectrometry: an advanced bioanalytical technique for clinical metabolomics studies.

The detection of human-derived metabolites as potential diagnostic biomarkers of genetic disorders, metabolic diseases, systemic diseases, and infectious diseases has been much studied in recent years, especially as technical capabilities improve, and statistical procedures are increasingly able to tease critical chemical attributes from complex data sets. Given the complex distribution of human biological matrices, the characterization and/or identification of these chemical entities is technically challenging, and is often confounded by incomplete chromatographic resolution or insufficient discriminatory power of the mass spectrometry (MS) domain. Recently, comprehensive two-dimensional gas chromatography (GC×GC) has evolved into a mature higher separation order technique that offers unprecedented resolving power, which in turn can greatly advantage clinical metabolomics studies via the expansion of metabolite coverage. In this contribution, the current state of knowledge in the development of GC×GC coupled to MS as a high-resolution bioanalytical technique for the analysis of clinical metabolites is reviewed. Selected recent applications (years 2012 to 2021) that emphasize improved GC×GC-MS strategies for clinical human metabolites' detection, identification, and quantitative analysis are described. In addition, we share our perspectives on current challenges and potential future directions of GC×GC in clinical applications.

Phytochemical Constituents and Antiproliferative Activities of Essential Oils from Four Varieties of Malaysian Zingiber officinale Roscoe against Human Cervical Cancer Cell Line.

This study evaluates the volatile metabolic constituents and anticancer potential of essential oils distilled from the rhizomes of four Malaysian Zingiber officinale Roscoe (Zingiberaceae family) varieties (Bentong (BE), Cameron Highlands (CH), Sabah (SA), and Bara (BA)). The ginger essential oils were analyzed by gas chromatography coupled with quadrupole mass spectrometry (GC qMS). A total of 58 secondary compounds were tentatively identified, representing 82.6-87.4% of the total ion count. These metabolites comprise mainly of monoterpene hydrocarbons (19.7-25.5%), oxygenated monoterpenes (23.6-33.7%), sesquiterpene hydrocarbons (21.3-35.6%), oxygenated sesquiterpenes (1.5-3.9%), and other minor classes of compounds (0.7-2.7%). Principal component analysis (PCA) enabled differentiation of the analyzed ginger essential oils according to their varieties, with respect to their metabolites and relative quantities. The antiproliferative activity against the HeLa cervical cancer cell line was investigated via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The oils were found to exhibit strong antiproliferative activities with IC50 values of 23.8, 35.3, 41.3, and 42.5 µg/mL for BA, BE, SA, and CH, respectively. These findings suggest that the differences among the secondary metabolites and their abundance in different varieties of Z. officinale essential oils appear to be related to their antiproliferative potential. The strong antiproliferative effects of these oils signified their potential in the prevention and chemotherapy of cervical carcinoma treatment.

Phytochemical Composition, Antioxidant and Antiproliferative Activities of Citrus hystrix, Citrus limon, Citrus pyriformis, and Citrus microcarpa Leaf Essential Oils against Human Cervical Cancer Cell Line.

The essential oil derived from Citrus plants has long been used for medicinal purposes, due to its broad spectrum of therapeutic characteristics. To date, approximately 162 Citrus species have been identified, and many investigational studies have been conducted to explore the pharmacological potential of Citrus spp. oils. This study investigated the volatile constituents of essential oil distilled from the leaves of C. hystrix, C. limon, C. pyriformis, and C. microcarpa, using gas chromatography-quadrupole mass spectrometry. A total of 80 secondary compounds were tentatively identified, representing 84.88-97.99% of the total ion count and mainly comprising monoterpene (5.20-76.15%) and sesquiterpene (1.36-27.14%) hydrocarbons, oxygenated monoterpenes (3.91-89.52%) and sesquiterpenes (0.21-38.87%), and other minor chemical classes (0.10-0.52%). In particular, 27 compounds (1.19-39.06%) were detected across all Citrus species. Principal component analysis of the identified phytoconstituents and their relative quantities enabled differentiation of the Citrus leaf oils according to their species, with the loading variables contributing to these metabolic differences being identified. The Citrus leaf oils were tested for their antioxidant and antiproliferative activities using 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The results indicated that C. limon displayed the highest DPPH radical scavenging ability (IC50 value of 29.14 ± 1.97 mg/mL), while C. hystrix exhibited the lowest activity (IC50 value of 279.03 ± 10.37 mg/mL). On the other hand, all the Citrus oils exhibit potent antiproliferative activities against the HeLa cervical cancer cell line, with IC50 values of 11.66 µg/mL (C. limon), 20.41 µg/mL (C. microcarpa), 25.91 µg/mL (C. hystrix), and 87.17 µg/mL (C. pyriformis).