Pak choi (Brassica rapa L. subsp. chinensis): Phytochemical Diversity, Biological Activities, and Emerging Applications in Nutrition, Health and Cosmetics

Brassica rapa L. subsp. chinensis (pak choi) is an important leafy vegetable with increasing global relevance as a source of biologically active phytochemicals. Despite extensive research on individual compounds, a comprehensive and integrative understanding of its phytochemical profile and functional potential remains limited. This review critically synthesizes current knowledge on the chemical composition, biological activities, and emerging applications of pak choi, with particular emphasis on its nutraceutical and biotechnological significance. Pak choi is characterized by a diverse spectrum of bioactive constituents, including glucosinolates, phenolic compounds, carotenoids, vitamins, minerals, and amino acids, which collectively contribute to its antioxidant, anti-inflammatory, chemopreventive, and metabolic regulatory effects. A major challenge highlighted in this analysis is the high variability of phytochemical composition, driven by genotype, developmental stage, environmental conditions, cultivation systems, and post-harvest processing. Importantly, this review advances current understanding by integrating phytochemical, biological and technological perspectives, emphasizing the interplay between compound composition, bioactivity, and processing-dependent transformations. Particular attention is given to glucosinolate-derived metabolites and their role in modulating key molecular pathways. Furthermore, both beneficial and adverse aspects of pak choi consumption are addressed, including antinutritional factors, contamination risks, and the impact of culinary processing on compound stability and bioavailability. Emerging applications in functional foods, nutraceuticals, cosmetics and plant biotechnology are also discussed, including the potential of in vitro culture systems and targeted metabolite production. Taken together, pak choi represents a multifunctional plant resource at the interface of food science, pharmacology, and biotechnology, with strong potential for future translational applications.