Recent Development in Bioactive Compounds and Health Benefits of Kumquat Fruits

ABSTRACT

This review paper aims to compile recent literature available regarding the overall chemical compositions, nutritional properties, essential oils, bioactive compounds and health benefits of Kumquat fruits. Kumquat fruits contain a high level of polyphenols, essential oils, minerals and vitamins, especially vitamin C. The essential oil (EO) profile of Kumquat fruit varies among different sub-species and parts of fruits. Limonene was the major EO detected in the Kumquat fruit. In addition, a significant amount of total phenolic content (TPC) and flavonoids was also observed in the kumquat extract. The TPC and flavonoid content of Kumquat fruit were significantly influenced by drying temperature, drying duration, and extraction solvents. The application of hot water as an extraction solvent resulted in efficient extraction of TPC and flavonoids compared to ethanol and methanol. In addition, Kumquat fruits exhibit potent antioxidant activity, antimicrobial activity, liver protection, and anti-cancer activity. Overall, this review will be a positive addition to the existing knowledge of this field. This paper will support the researchers and industries to select raw materials with high nutritional value and potent biological activity. In addition, this report will help to select an appropriate method and raw material to generate value-added products from Kumquat by-products.

KEYWORDS:

• Kumquat
• peel
• pulp
• bioactive compounds
• essential oils

Abbreviations

Total phenolic content (TPC), Total flavonoid content (TFC), Essential oils (EO), Headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MC), Liquid chromatography coupled to diode array detection and electrospray ionization ion trap tandem mass spectrometry (LC-DAD-ESI-ITMS), 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), 2,2ʹ-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), malondialdehyde (MDA), superoxidase dismutase (SOD), glutathione (GSH), high-density lipoprotein cholesterol (HDL-C), minimum bactericidal concentration (MBC), minimal inhibitory concentration (MIC), ionizing radiation (IR), human androgen-dependent prostate cancer (LNCaP), Ethyl acetate anhydrous (EtOAc), Methanol (MeOH), dimethyl sulfoxide (DMSO), B-cell lymphoma protein 2-associated X/ B-cell lymphoma protein 2 (Bax/Bcl2).

Acknowledgments

This research was jointly supported by two research grants (R202007 and R202017) from BNU-HKBU United International College, China.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions:

X. Li conducted the literature collection, analyzed data, and drafted the manuscript. Dr. M. Meenu verified data, drafted, and revised the manuscript. Prof. B. Xu designed and supervised the project and revised the manuscript.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website

Additional information

Funding

This work was supported by the BNU-HKBU United Internaional College [R5201911].