Key Points
- Researchers conducted an in-depth metabolomic comparison of black and white pepper using advanced techniques like gas chromatography-mass spectrometry (GC-MS), ultra-high pressure liquid chromatography (UHPLC-HRMS/MS), and feature-based molecular networking. They annotated more than120 metabolites, including several compounds detected in pepper for the first time.
- The study linked metabolite profiles to biological activities. Black pepper exhibited higher total phenolics and flavonoids, and both pepper types showed moderate antioxidant activities and α-glucosidase inhibitory effects, highlighting their potential as functional ingredients.
- The distinct phytochemical compositions and bioactivities of black and white pepper support their possible application in dietary supplements. The researchers recommend broader sample sourcing across regions and harvests to validate findings and enhance generalizability.
A research team made up of members of Egyptian Russian University, Cairo University (both in Cairo, Egypt), Egypt’s National Research Centre (Giza, Egypt), the University of Agricultural Sciences and Veterinary Medicine, and the University of Medicine and Pharmacy (both in Cluj-Napoca, Romania) aimed to provide a more comprehensive and comparative analysis of the metabolite heterogeneity between black and white pepper.
The team’s earlier research (1) employed solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and nuclear magnetic resonance (NMR)-based metabolomics. These methods focused on identifying sensory and nutritive determinants. In their most recent investigation, however, they expanded their analytical approach. They integrated gas chromatography-mass spectrometry (GC-MS) following silylation with ultrahigh-pressure liquid chromatography-high tandem mass spectrometry (UHPLC-HRMS/MS). Additionally, they applied feature-based molecular networking (FBMN) to achieve broader coverage of secondary metabolites. This enhanced methodology provides a more comprehensive understanding of the compounds likely responsible for the health benefits of pepper.
Multivariate statistical analyses were applied to identify key metabolic markers differentiating the two pepper types. Furthermore, the in vitro antioxidant and α-glucosidase inhibitory activities were investigated to correlate the bioactivity with the phytochemical profile, offering insights into their functional implications. A paper based on their work was published in RSC Advances (2).
Considered one of the chief sources for food additives, with potential health benefits owing to not only their characteristic aroma but their richness in bioactive secondary metabolites, spices are a rich source of biologically active compound classes, including flavonoids, carotenoids, terpenes and others (3,4). In addition to their culinary uses, spices also play a critical role in human health, exemplified by carminative, analgesic, stomachic, antiviral, anti-inflammatory, and antioxidant effects (5).
Among the most important spices, black pepper (Piper nigrum L.; Piperaceae) and its processed variant, white pepper, are widely consumed worldwide, are among the most popular and important spices worldwide (6). Enriched with a wide variety of bioactive secondary metabolites, including alkaloids, essential oil, lignans, phenolics, carotenoids, and terpenoids, with potential health value, pepper is often used in traditional medicine for treatment of gastric complaints, cough, cold, and intermittent fever, in addition to being a rubefacient, stimulant, appetite stimulant, and anti-inflammatory product (7).
The researchers annotated a total of 51 metabolites using GC-MS belonging to fatty acids/esters (9), alkaloids/nitrogenous (6), sugars (3), sugar alcohols (5), organic acids (15), alcohols (4), and aliphatic hydrocarbons (6) in addition to phenols (3). Fatty acids/esters were enriched in black and white pepper at ca. 23.4 mg g-1. Moreover, piperine was detected at higher levels in white pepper at 5.9 mg g-1 compared to 3.4 mg g-1 in black pepper. A total of 71 metabolites were annotated using UPLC-MS/MS, with piperamides as the most abundant class, of which 6 are first time to be detected in P. nigrum fruit "types A, E and O.” In addition, 7 fatty acids were recoded along 4 flavonoids exhibiting novel glycosidic linkage of kaempferol and apigenin.
Furthermore, 5 hydroxycinnamic acids were detected; some were identified for the first time from P. nigrum fruit. Clusters of fatty acids, flavonoids and phenylamides were detected by negative mode GNPS molecular networking, whereas clusters representing the majority of alkaloids present were detected in positive mode. Assay of total phenolics and flavonoids revealed higher levels in black compared to white pepper, with values of 45.6 and 37.5 mg GAE per g for total phenolics and 9.4 & 8.5 mg RE per g for flavonoids, respectively. Assessment of antioxidant capacity using DPPH, ABTS scavenging assays, and FRAP assay revealed moderate effects at 49.79, 20.6, and 104.6 (black pepper), 29.0, 11.5, and 77.5 mg TE per g (white pepper), respectively. Moreover, black and white pepper extracts inhibited α-glucosidase enzyme with an IC50 of 0.77 and 0.62 mg mL-1, compared with acarbose (2).
The researchers believe that such promising results present future uses of P. nigrum in dietary supplements or nutraceuticals. Owing to a limited sample source from a single geographic origin, future studies incorporating a broader range of samples from different regions and harvest seasons are recommended to validate and expand upon these results using the same analytical platform reported in this study for that chief spice (2).
References
- Baky, M. H.; Kamal, I. M.; Wessjohann, L. A. et al. Assessment of Metabolome Diversity in Black and White Pepper in Response to Autoclaving Using MS- and NMR-Based Metabolomics and in Relation to its Remote and Direct Antimicrobial Effects Against Food-Borne Pathogens. RSC Adv.2024, 14, 10799-10813. DOI: 10.1039/d4ra00100a
- Baky, M. H.; Maamoun, A. A.; Nicolescu, A. et al. Multi-Targeted MS-Based Metabolomics Fingerprinting of Black and White Pepper Coupled with Molecular Networking in Relation to Their in vitro Antioxidant and Antidiabetic Effects. RSC Adv. 2025, 15 (34), 27606-27622. DOI: 10.1039/d5ra03714j
- Ashokkumar, K.; Vellaikumar, S.; Murugan, M. et al. GC/MS Analysis of Essential Oil Composition from Selected Seed Spices. Natl. Acad. Sci. Lett. 2021, 44, 503-506. DOI: 10.1007/s40009-021-01066-7
- Ashokkumar, K.; Pandian, A.; Murugan, M. et al. Profiling Bioactive Flavonoids and Carotenoids in Select South Indian Spices and Nuts. Nat. Prod. Res. 2020, 34 (9), 1306-1310. DOI: 10.1080/14786419.2018.1557179
- Baky, M.H.; Elkenawy, N. M,.; El-Nashar, H. A. S. et al. Comparison of Autoclaving and γ-Radiation Impact on Four Spices Aroma Profiles and Microbial Load Using HS-SPME GC-MS and Chemometric Tools. Sci. Rep. 2024, 14 (1), 5752. DOI: 10.1038/s41598-024-56422-6
- Rivera-Pérez, A.; Romero-González, R.; Frenich, A. G. A Metabolomics Approach Based on 1H NMR Fingerprinting and Chemometrics for Quality Control and Geographical Discrimination of Black Pepper. J. Food Compos. Anal.2022, 105, 104235. DOI: /10.1016/j.jfca.2021.104235
- Ashokkumar, K.; Murugan, M.; Dhanya, M. et al. Phytochemistry and Therapeutic Potential of Black Pepper [Piper nigrum (L.)] Essential Oil and Piperine: A Review. Clin. Phytosci.2021, 7, 52. DOI: 10.1186/s40816-021-00292-2
