Nutritional assessment, multi-platform phytochemical profiling, and biological activities of Centaurea calcitrapa L....

The rise of antibiotic resistance and metabolic disorders has led to increased interest in plant-derived bioactive compounds Centaurea calcitrapa L., a medicinal plant rich in phenols and flavonoids, has been traditionally used in folk medicine; however, data regarding the nutritional composition and biological activities of its aerial flowering parts remain limited. This study evaluated the phytochemical profile, nutritional composition, and biological properties of the aerial flowering parts of C. calcitrapa. Proximate analysis indicated a nutritional value of 145.45 ± 10.03 kcal/100 g, with a high content of organic matter (87.8 ± 1.13%) and moisture (63.27 ± 3.05%). The plant contained crude fiber (25.47 ± 1.94%), carbohydrates (17.61 ± 0.95 g/100 g), proteins (13.05 ± 1.94 g/100 g), fats (2.53 ± 0.2%), and free amino acids (5.29 ± 0.23 g/100 g). Ash analysis showed total ash (12.2 ± 1.13%), with notable water-soluble (10.12 ± 0.97%) and acid-soluble ash (9.85 ± 0.84%). Phytochemical screening indicated the presence of flavonoids, phenols, saponins, and moderate tannins, while quantitative analysis demonstrated high levels of total flavonoids (178.42 ± 19.81 mg QE/g) and phenolic content (112.85 ± 6.56 mg GAE/g), indicating strong phytochemical richness. Gas chromatography-mass spectrometry was used to analyze petroleum ether extract and identify 50 plant constituents, mostly fatty acids and hydrocarbons, with oleic acid (48.426%) and palmitic acid (15.834%) as the main constituents. HPLC analysis of the methanolic extract revealed 15 phenolic compounds, including rutin, apigenin, quercetin, kaempferol, epicatechin gallate, and protocatechuic acid. The methanolic extract exhibited strong antioxidant activity, with DPPH scavenging activity reaching 90.16 ± 1.13% at 1000 µg/mL and an IC₅₀ of 24.01 ± 0.73 µg/mL, compared with 12.71 ± 0.7 µg/mL for ascorbic acid. The total antioxidant capacity showed an IC₅₀ of 37.58 ± 1.21 µg/mL. The methanolic extract revealed moderate antibacterial activity against six human pathogenic bacteria, with inhibition zones ranging from 16.89 ± 0.95 to 20.98 ± 1.52 mm. MIC values ranged from 62.5 to 125 mg/mL, while MBC values ranged from 125 to 250 mg/mL. In addition, the methanolic extract exhibited in vitro inhibitory activity against α-amylase and α-glucosidase, with IC₅₀ values of 37.26 ± 0.91 µg/mL and 20.19 ± 1.54 µg/mL, respectively. These results suggest the presence of bioactive compounds in the aerial flowering parts of C. calcitrapa. Overall, the methanolic extract demonstrated antioxidant and antibacterial activities, in addition to in vitro carbohydrate-hydrolyzing enzyme inhibitory activity. These findings indicate that C. calcitrapa may represent a promising source of bioactive constituents with potential applications in medicinal and nutritional fields.