DETERMINATION OF PHYTOCHEMICALS, ANTIOXIDANT, ANTIBACTERIAL ACTIVITIES AND ANALYSIS BY FOURIER-TRANSFORM INFRARED SPECTROSCOPY (FTIR) FOR THE FRESH ETHANOLIC EXTRACT OF BRASSICA OLERACEA

Angel Sia Chew Kiing, Nabila Perveen, Naeem Hasan Khan*

Introduction: Broccoli (Brassica oleracea var. italica) is a widely consumed cruciferous vegetable due to its high nutritional value contributed by present phytochemicals such as flavonoids, phenolic compounds, glucosinolates and terpenoids. These phytochemical compounds have antioxidant and antibacterial properties, making broccoli a potential source of natural bioactive agents for pharmaceutical and nutraceutical applications. This research focuses on evaluating the phytochemical composition, antioxidant activity, antibacterial activity and functional groups of ethanolic broccoli extract using Fourier Transform Infrared (FTIR) spectroscopy. Objectives: The objectives of this study were to determine the phytochemicals composition, evaluate the antioxidant activity, examine the antibacterial activity and perform functional groups characterization of fresh broccoli extract using FTIR spectroscopy. Method: Fresh Brassica oleracea var. italica was extracted by maceration using 95% ethanol. Qualitative phytochemical screening was performed to detect the presence of primary and major secondary metabolites. Antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay with ascorbic acid as the standard reference. Antibacterial activity was evaluated against Bacillus subtilis and Escherichia coli using broth dilution to determine minimum inhibitory concentration (MIC), followed by minimum bactericidal concentration (MBC) determination through subculturing on Mueller-Hinton agar. FTIR spectroscopy analysis was performed to identify the functional groups associated with the phytochemical constituents. Result: Phytochemicals found in broccoli extract include flavonoids, phenolic compounds, tannins, glycosides and terpenoids. Besides that, the broccoli extract exhibited concentration-dependent antioxidant activity, with the percentage of DPPH radical scavenging activity increasing from 6.11% at 100μg/ml to 86.93% at 1000μg/ml. The average IC50 value of broccoli extract was 434.45 μg/ml, compared with 1.63μg/ml for ascorbic acid, showing lower antioxidant capacity than the standard. Furthermore, the broccoli extract showed negative result towards Bacillus subtilis and Escherichia coli. No complete inhibition of bacterial growth against either B. subtilis and E. coli at concentration up to 400 mg/ml and bacterial colonies remained visible in MBC test. Additionally, FTIR analysis identified key absorption peaks corresponding to hydroxyl, alkane, aromatic ring and sulphur containing functional groups, supporting the presence of flavonoids, phenolic compounds, tannins, glycosides and terpenoids. Conclusion: It is concluded that the ethanolic extract of broccoli contained several useful phytochemicals and exhibited measurable concentration-dependent antioxidant activity, which is contributed by its flavonoid and phenolic constituents. However, antibacterial activity against B. subtilis and E. coli could not be confirmed under the conditions of this study. FTIR analysis further supported the phytochemical findings by confirming the presence of corresponding functional groups. Overall, broccoli extract showed potential as a natural source of antioxidants while further optimization of extraction methods and phytochemical characterization is recommended to improve its biological applications.