Research in Plant Metabolites

Research in Plant Metabolites

Evaluating the Effect of Eggplant Calyx Extract on Alpha-Amylase Enzyme Activity In Vitro

Document Type : Original Article

Authors
Ghazal Labbeiki 1
Fahime Alitane 2
solmaz saremnezhad 3
1 1)Department of Food Science and Technology, TeMS.C., Islamic Azad University, Tehran, Iran 2) Nutrition and Food Sciences Research Center, TeMS.C., Islamic Azad University, Tehran, Iran.
2 Department of Biotechnology, TeMS.C.,Islamic Azad University, Tehran, Iran
3 Department of Food Science and Technology, TeMS.C., Islamic Azad University, Tehran, Iran. ) Nutrition and Food Sciences Research Center, TeMS.C., Islamic Azad University, Tehran, Iran.
10.22034/jrpsm.2025.548996.1091
Abstract
In recent years, the utilization of bioactive compounds derived from plant materials and agricultural by-products has attracted increasing attention as a sustainable approach for developing functional and therapeutic agents. Food waste, particularly fruits and vegetables, constitutes a considerable portion of agricultural resource losses. Parts such as eggplant peel and calyx are commonly discarded, although they can serve as valuable sources of bioactive constituents. In this study, extracts of fresh purple eggplant calyx were prepared using a combined extraction technique involving ultrasonic waves and two solvents (absolute ethanol and ethanol–water 50%). The α-amylase inhibitory activity, as a key indicator of blood glucose regulation, was evaluated, and the chemical composition of the extracts was identified using liquid chromatography–mass spectrometry (LC–MS) and gas chromatography–mass spectrometry (GC–MS). The results showed that the eggplant calyx extract was rich in phenolic and flavonoid compounds and exhibited notable enzyme inhibitory potential (64.8% for hydroalcoholic extract and 39.7% for ethanolic extract). The extraction yield of the hydroalcoholic extract (24.9%) was significantly higher than that of the ethanolic extract (3.67%), attributed to the balanced polarity of the water–ethanol mixture. These findings indicate that eggplant calyx, as a low-cost and readily available plant waste, can be considered a natural and economical source for developing bioactive compounds with potential antidiabetic effects applicable in food and pharmaceutical industries. It is noteworthy that, although the antidiabetic properties of eggplant calyx have been mentioned in traditional medicine texts, no experimental or laboratory
Keywords
Food waste
Solanum melongena
Ultrasonic waves
Antidiabetic effects
alfa-Amylase Inhibition
Agoreyo, B. O., Egharevba, M. E., Omage, J. I., & Okungbowa, E. S. (2016). Alkaloid,
flavonoid, fatty acid and vitamin profiles of the unripe fruit of Solanum melongena L. (Round
Variety). African Scientist, 17(2), pp. 123-134, Retrieved September 20, 2025,
from http://publications.africanscientistjournal.org/
Agregan, R., Munekata, P. E. S., Feng, X., Araujo, G., Gullon, B., & Lorenzo, J. M. (2021).
Recent advances in the extraction of polyphenols from eggplant and their application in foods. LWT -
Food Science and Technology, 146, 111381, pp.1-13, Retrieved September 20, 2025,
from https://doi.org/10.1016/j.lwt.2021.111381
Al Nachar, K., Hasian, J., Katramiz, K. (2020). Determination of Antioxidant Properties of
Eggplant Fruit Calyx in Different Types of Solvents. World Journal of Pharmaceutical Research, 9(15),
pp.22–40, Retrieved September 20, 2025, from https://doi.org/10.20959/wjpr202015-19279
Aleixandre, A., Gil, J. V., Sineiro, J., & Rosell, C. M. (2022). Understanding phenolic acids
inhibition of α-amylase and α-glucosidase and influence of reaction conditions. Food Chemistry, 372,
131231, pp.1-9. Retrieved October 20, 2025, from https://doi.org/10.1016/j.foodchem.2021.131231
Castillejo, N., & Martinez-Zamora, L. (2024). Bioactive compounds from fruit and vegetable
waste: extraction and possible utilization. Foods, 13(5), 775, pp.1-5, Retrieved September 20, 2025,
from https://doi.org/10.3390/foods13050775
Colak, N., Kurt-Celebi, A., Gruz, J., Strnad, M., Hayirlioglu-Ayaz, S., Choung, M.-G.,
Esatbeyoglu, T., Ayaz, F.A. (2022). The phenolics and antioxidant properties of black and purple versus
white eggplant cultivars. Molecules, 27(8): 2410, pp.1-20, Retrieved September 20, 2025,
from https://doi.org/10.3390/molecules27082410
EL Bazzar, H., Mohamed, S., Mahmoud, Y., Bazan, L., Ibrahim, N., Mahmoud, R., Abou El
Ezz, R., Ibrahim, H., Afifi, M. (2022). Pharmacodynamics evaluation of Eggplant wastes formulated
as lyophilized tablets in an attempt for preparation of a bioactive natural antidiabetic dosage form.
Journal of Fundamental and Clinical Research, 2(1), pp. 74-83, Retrieved September 20, 2025,
from https://doi.org/10.21608/jfcr.2022.245600
Eng Kiat Loo, A., & Huang, D. (2007). Assay-guided fractionation study of α-amylase inhibitors
from Garcinia mangostana pericarp. Journal of Agricultural and Food Chemistry, 55(24), pp. 9805–
9810, Retrieved September 20, 2025, from https://doi.org/10.1021/jf072439l
Ferarsa, S., Zhang, W., Moulai-Mostefa, N., Ding, L., Jaffrin, M.Y., Grimi, N. (2018). Recovery
of anthocyanins and other phenolic compounds from purple eggplant peels and pulps using ultrasonicassisted extraction. Food Bioproducts Processing, 109, pp. 19–28. Retrieved September 20, 2025,
from https://doi.org/10.1016/j.fbp.2018.02.006
Food and Agriculture Organization of the United Nations. (2019). The state of food and
agriculture: Moving forward on food loss and waste reduction. Retrieved September 20, 2025,
from http://www.fao.org/publications
Jarret, R. L., Levy, I., Potter, T. L., & Cermak, S. C. (2016). Oil and fatty acids in eggplant
(Solanum melongena L.) and some related and unrelated Solanum spp. American Journal of Applied
Sciences, 11(2), pp. 76–81, Retrieved September 20, 2025, from https://thescipub.com/ajas
Jiang, X., Li, Y., Ma, Y., Gao, F., & Yu, Y. (2025). Inhibition mechanism of starch digestion by
luteolin, eriodictyol, and their complex in vitro: Multispectral, kinetic, and theoretical calculations
analysis. International Journal of Biological Macromolecules, 308, 142649, Retrieved October 20,
2025, from https://doi.org/10.1016/j.ijbiomac.2025.142649
Jokovic, N., Matejic, J., Zvezdanovic, J., Stojanovic-Radic, Z., Stankovic, N., MihajilovKrstev, T., & Bernstein, N. (2024). Onion peel as a potential source of antioxidants and antimicrobial
agents. Agronomy, 14(3), 453. Retrieved September 20, 2025,
from https://doi.org/10.3390/agronomy14030453
Kainat, F., Ali, M., Akbar, A., Masih, R., Mehnaz, S., & Sadiq, M. B. (2023). Ultrasonic
extraction of phenolic compounds from eggplant peel and formulation of eggplant peel extract-enriched
ice-cream. Journal of Food Quality, 2023, Article ID 3267119, pp.1-10, Retrieved September 20, 2025,
from https://doi.org/10.1155/2023/3267119
Kaveh, S., Sadeghi Mahoonak, A., Sarabandi, K. (2020), The Effect of Solvent Type, Time and
Extraction Method on the Chemical Compositions and Antioxidant Activity of Eggplant Peel Extract,
Quarterly Scientific Journal of Technical and Vocational University, 17(2), pp. 135-150, Retrieved
September 20, 2025, from https://karafan.tvu.ac.ir/article_587337.html (In Persian)
Kazempour, M., Shahangian, S. S., & Sariri, R. (2024). Dracocephalum kotschyi: Inhibition of
critical enzyme relevant to type-2 diabetes, essential oil composition, bactericidal and anti-oxidant
activity. Caspian Journal of Environmental Sciences, 22(2), pp. 289–303, Retrieved September 20,
2025, from https://cjes.guilan.ac.ir
Kwon, Y.-I., Apostolidis, E., Shetty, K. (2008). In vitro studies of eggplant (Solanum melongena)
phenolics as inhibitors of key enzymes relevant for type 2 diabetes and hypertension. Bioresource
Technology, 99(8), pp.2981-2988, Retrieved September 20, 2025,
from https://doi.org/10.1016/j.biortech.2007.06.035
Latifi, Z., Abedian Kenari, S., Mashayekh, A. (2024). Investigation of chemical compounds using
GC-MS and antimicrobial properties of hydroethanolic extracts of pumpkin and some plants of the
Cruciferous Family (Brassicaceae). Applied Microbiology in Food Industries, 10(1), pp.15-31.
Retrieved September 20, 2025, from http://amfi.ir/article-1-69-fa.html (In Persian)
Li, X., Bai, Y., Jin, Z., & Svensson, B. (2022). Food-derived non-phenolic α-amylase and αglucosidase inhibitors for controlling starch digestion rate and guiding diabetes-friendly
recipes. Lwt, 153, 112455, pp.1-7. Retrieved October 20, 2025,
from https://doi.org/10.1016/j.lwt.2021.112455
Liao, J., Xue, H., Li, J. (2022). Extraction of phenolics and anthocyanins from purple eggplant
peels by multi-frequency ultrasound: Effects of different extraction factors and optimization using
uniform design. Ultrasonics Sonochemistry, 90: 106174, pp.1-9, Retrieved September 20, 2025,
from https://doi.org/10.1016/j.ultsonch.2022.106174
Lim, S. C., Lee, T. B., & Han, S. I. Y. (2025). Caffeic acid phenethyl ester inhibits metastatic
properties of acid-adapted gastric cancer cells. Anticancer Research, 45, pp.1525–1534, Retrieved
September 20, 2025, from https://doi.org/10.21873/anticanres.17534
Mafakheri, S., Hallaj, R., Asghari, B. (2022). Study on phytochemical and antioxidant properties
of dragonhead (Dracocephalum moldavica L.) seed oil, ethanol, and aqueous extracts. Iranian Journal
of Medicinal and Aromatic Plants Research, 38(1), pp. 176-189, Retrieved September 20, 2025,
from https://doi.org/10.22070/ijmapr.2022.126020 (In Persian)
Martinez-Gonzalez, A. I., Diaz-Sanchez, A. G., De La Rosa, L. A., Bustos-Jaimes, I., & AlvarezParrilla, E. J. S. A. P. A. M. (2019). Inhibition of α-amylase by flavonoids: Structure activity
relationship (SAR). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 206,
pp.437-447, Retrieved October 20, 2025, from https://doi.org/10.1016/j.saa.2018.08.057
M'hiri, N., Ioannou, I., Paris, C., Ghoul, M., Boudhrioua, N. (2017). Antioxidants of Maltease
orange peel: comparative investigation of the efficiency of four extraction methods. Journal of Applied
Pharmaceutical Science, 7(11), pp. 126–135, Retrieved September 20, 2025,
from https://doi.org/10.7324/JAPS.2017.71119
Miller, G. L. (1959). Use of dinitrosalicylic acid reagent for determination of reducing sugar.
Analytical Chemistry, 31(3), pp. 426-428, Retrieved September 20, 2025,
from https://doi.org/10.1021/ac60147a030
Moradi, D., Ramezan, Y., Eskandari, S., Mirsaeedghazi, H., & Javanmard Dakheli, M. (2022).
Optimization of polyphenol recovery from potato peel and its incorporation into low-density
polyethylene films activated by cold plasma. Biomass Conversion and Biorefinery, 13, pp.14209–
14223, Retrieved September 20, 2025, from https://doi.org/10.1007/s13399-022-03492-z
Nwanna, E. E., Ibukun, E. O., & Oboh, G. (2013). Inhibitory effects of methanolic extracts of two
eggplant species from South-western Nigeria on starch hydrolysing enzymes linked to type-2 diabetes.
African Journal of Pharmacy and Pharmacology, 7(23), pp.1575-1584, Retrieved October 20, 2025,
from https://doi.org/10.5897/AJPP2013.3606
Ogoko, E. C. (2020). Chemical Information from GCMS of Ethanol Extract of Solanum melongena
(Aubergine) Leaf. Communication in Physical Sciences, 6(1): 658-668. Retrieved September 20, 2025,
from https://journalcps.com/index.php/volumes
Parvazi-Qomi, N., Labbeiki, GH., (2024). Optimization of the eggplant calyx extract extraction
process using ultrasonic waves and evaluation of the antioxidant, antimicrobial, and qualitative
properties of the extract, Master's thesis, Islamic Aazd University of Tehran Medical Sciences Branch,
Iran. )In Persian)
Ramzan, K., Zehra, S. H., Balciunaitiene, A., & Viskelis, P. (2025). Valorization of Fruit and
Vegetable Waste: An Approach to Focusing on Extraction of Natural Pigments. Foods, 14 (1402),
pp.1402-1426, Retrieved September 20, 2025, from https://doi.org/10.3390/foods14081402
Rimando, A. M., & Perkins-Veazie, P. M. (2005). Determination of citrulline in watermelon
rind. Journal of Chromatography A, 1078 pp, 196–200. Retrieved September 20, 2025,
from https://doi.org/10.1016/j.chroma.2005.05.009
Sigma-Aldrich. (2014). Enzyme Assay Protocols and Reagents. Retrieved September 20, 2025,
from https://www.sigmaaldrich.com
Silva-Beltran, N. P., Chaidez-Quiroz, C., Lopez-Cuevas, O., Ruiz-Cruz, S., Lopez-Mata, M.
A., Del-Toro-Sánchez, C. L., Marquez-Rios, E., & Ornelas-Paz, J. J. (2017). Phenolic compounds
of potato peel extracts: Their antioxidant activity and protection against human enteric
viruses. Journal of Microbiology and Biotechnology, 27(2), pp.234–241, Retrieved September 20,
2025, from https://doi.org/10.4014/jmb.1606.06007
Soltani Nobakht, Y., Yaghmaei, P., Ebrahim Habibi, A. (2015). The inhibitory effect of aromatic
compounds on bovine serum alpha-amylase activity: Searching for potential compounds effective in
blood sugar control. Iran Journal of Diabetes and Metabolism, 14(3), pp.163–168, Retrieved October
20, 2025, from http://ijdld.tums.ac.ir/article-۱-۵۳۶۵-fa.html (In Persian)
Subra-Paternault, P., Garcia-Mendoza, M. D. P., Savoire, R., & Harscoat-Schiavo, C. (2022).
Impact of hydro-alcoholic solvents on the oil and phenolics extraction from walnut (Juglans regia L.)
press-cake and the self-emulsification of extracts. Foods, 11(2), 186, pp.1-14, Retrieved September 20,
2025, from https://www.mdpi.com/2304-8158/11/2/186
Yarmohammadi, F., Ghasemzadeh Rahbardar, M., & Hosseinzadeh, H. (2021). Effect of
eggplant (Solanum melongena) on the metabolic syndrome: A review. Iranian Journal of Basic Medical
Sciences, 24(4), pp.420-427, Retrieved September 20, 2025,
from https://doi.org/10.22038/ijbms.2021.50276.11452
Zhang, S., Zhao, B., Zhang, X., Wu, F., Zhao, Q. (2023). The metabolomics response of Solanum
melongena L. leaves to various forms of Pb. Nanomaterials, 13(22): 2911, pp.1-15, Retrieved
September 20, 2025, from https://doi.org/10.3390/nano1322911