Evaluation of Bioactive Compounds from Selected Tropical Spices Extracted Using Microwave-Assisted Extraction Technology
A. F. Ofoedum *
Department of Food Science and Technology, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria.
C. I. Owuamanam
Department of Food Science and Technology, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria.
J. O. Iwouno
Department of Food Science and Technology, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria.
I. A. Olawuni
Department of Food Science and Technology, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria.
E. J. Anaeke
Department of Food Science and Technology, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria and Department of Food Science and Technology, Nnamdi Azikiwe University, Awka Anambra State, Nigeria.
C. O. Emejulu
Department of Food Science and Technology, Nnamdi Azikiwe University, Awka Anambra State, Nigeria.
G. N. Mofunanya
Department of Food Science and Technology, Nnamdi Azikiwe University, Awka Anambra State, Nigeria.
E. C. Abbah
Department of Agricultural and Bioresources Engineering, School of Engineering, Federal University of Technology Owerri, Imo State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This study evaluated the bioactive constituents and antioxidant properties of crude extracts obtained from three tropical spices, namely ginger (Zingiber officinale), Tetrapleura tetraptera and Monodora myristica, using microwave-assisted extraction. The spice materials were processed into dried powders and extracted under microwave-assisted conditions using ethyl ether as the solvent. Extract yield, qualitative and quantitative phytochemical composition and in vitro antioxidant activities were determined. The extract yield was highest for M. myristica (15.07%), followed by T. tetraptera (12.80%) and ginger (10.35%). Qualitative screening showed saponins, flavonoids, terpenoids, gingerols, alkaloids, phenolics, steroids, tannins and cardiac glycosides in varying relative abundance. Quantitative analysis showed that M. myristica had the highest flavonoid, terpenoid, tannin and phenolic contents, with values of 14.33, 7.30, 5.46 and 26.06 mg/g, respectively. T. tetraptera recorded the highest alkaloid, steroid and cardiac glycoside contents, while ginger had the highest saponin content. Antioxidant assays indicated concentration-dependent activity across the extracts. In the DPPH assay, M. myristica showed the highest activity, reaching 88.02% at 400 µg/ml, whereas ginger showed the highest FRAP activity, at 89.93% at 400 µg/ml. Lipid peroxidation inhibition also increased with concentration, with the control showing the highest activity at 400 µg/ml. The findings indicate that these tropical spices contain measurable phytochemicals and antioxidant activity under the study conditions.
Keywords: Bioactive compounds, tropical spices, microwave-assisted extraction, Zingiber officinale, Monodora myristica, Tetrapleura tetraptera, phytochemicals, antioxidant activity, DPPH, FRAP