Our laboratory has established a comprehensive research program focused on advancing the extraction technologies of bioactive compounds from diverse natural sources. This body of work systematically investigates both established and innovative green extraction methods to optimize the yield, purity, and functional properties of valuable natural products. The research spans the extraction of polyphenols, polysaccharides, and other phytochemicals from fruits, medicinal plants, agricultural by-products, and fungi, with a strong emphasis on sustainability and application in the food and nutraceutical industries.

1. Advancements in Green and Efficient Extraction Methods

A central theme of our research is the development and application of green extraction technologies that offer superior efficiency and environmental safety compared to conventional methods.

1.1. Deep Eutectic Solvent (DES)-Based Extraction

Our lab has pioneered the use of Deep Eutectic Solvents (DES) as a green and highly effective medium for extracting bioactive compounds. We have successfully applied DES-assisted extraction (DAE), often enhanced with microwave (MDE) or ultrasound (UADE), to various materials. For instance, MDE was shown to be a highly efficient method for extracting pectic polysaccharides from thinned unripe kiwifruits, yielding products with stronger antioxidant and immunomodulatory effects than those from hot water extraction (Wu et al., 2024). Similarly, UADE significantly increased the yield of phenolic compounds from the same kiwifruit by-product, with the resulting extract showing superior antioxidant and anti-inflammatory activities (Wu et al., 2023). Our work has also demonstrated that DES can selectively extract acidic polysaccharides from lotus leaves and enhance the extraction of polysaccharides from sweet tea and date seeds, consistently producing extracts with enhanced bioactivities (Wu et al., 2021; Wu et al., 2022; Subhash et al., 2024).

1.2. Ultrasound- and Microwave-Assisted Extraction

We have extensively optimized Ultrasound-Assisted Extraction (UAE) and Microwave-Assisted Extraction (MAE) to enhance the recovery of antioxidants and other valuable compounds. UAE was shown to significantly improve the extraction rate of antioxidants from common beans by disrupting cellular structures (Yang et al., 2019) and was optimized using Response Surface Methodology (RSM) to maximize the yield of polyphenols from red sword bean coats, mung bean coats, and 'Jinfeng' kiwifruit (Zhou et al., 2019; Zhou et al., 2017; Mai et al., 2022). Notably, UAE was instrumental in achieving a high yield of punicalagin from pomegranate peel, a potent α-glucosidase inhibitor (Liu et al., 2022). Likewise, MAE has been optimized for extracting antioxidants from sweet tea, *Akebia trifoliata* peels, and Five-Golden-Flowers tea, proving to be a rapid and efficient technique (Shang et al., 2020; Luo et al., 2021; Zhao et al., 2018).

2. Comparative Analysis of Extraction Technologies and Structure-Function Relationships

A key aspect of our research involves systematically comparing different extraction methods to understand their impact on the physicochemical properties and biological functions of the extracted compounds. Studies on polysaccharides from loquat leaves, sweet tea, dandelion leaves, and *Dictyophora indusiata* have revealed that the choice of extraction technology—be it hot water, pressurized water (PWE), UAE, MAE, or DES—significantly affects the yield, molecular weight, uronic acid content, and ultimately, the bioactivity of the polysaccharides (Fu et al., 2020; Guo et al., 2021; Wu et al., 2022; Wu et al., 2021). For example, PWE was found to be a superior method for extracting polysaccharides with high molecular weight and potent hypolipidemic activities from Qingke barley and desirable bioactivities from dandelion leaves, while UAE often yielded polysaccharides with lower molecular weight but strong prebiotic effects (He et al., 2020; Wu et al., 2022; Fu et al., 2020). These comparative studies provide a scientific basis for selecting the optimal extraction method to obtain natural products with specific desired functionalities.

3. Extraction of Specific Classes of Bioactive Compounds

Our work also includes targeted research on the extraction, purification, and characterization of specific high-value compound classes.

3.1. Polyphenols and Flavonoids

We have developed and refined methods for extracting polyphenols from various sources. A novel combination of UAE and DES was established for the green extraction of antioxidant polyphenols from green tea, which effectively disrupted leaf cells to improve yield and antioxidant activity (Luo et al., 2020). We have also contributed comprehensive reviews that summarize current techniques for the extraction, purification, and identification of tea polyphenols and polymethoxyflavones (PMFs), providing a valuable resource for the field (Li et al., 2023; Gan et al., 2024). Further, we have optimized extraction of anthocyanins from mulberry (Zou et al., 2011) and explored the complex chemistry of theabrownins from dark tea using green extraction methods (Liu et al., 2022).

3.2. Polysaccharides and Other Bioactives

Our research has covered a wide range of polysaccharides from sources like sweet tea, where PWE was optimized for high yield and beneficial gut microbiota modulation (Lei et al., 2022). We have also provided updated reviews on the extraction and bioactivities of polysaccharides from the medicinal fungus Poria cocos and bioactive compounds from Cannabis sativa, highlighting the use of modern technologies like supercritical fluid and DES-based methods (Ng et al., 2024; Liu et al., 2022). In addition, our work extends to other valuable compounds, including the extraction of soybean lipophilic protein and essential oils from Cinnamomum camphora, where we demonstrated simultaneous recovery of polyphenols from the extraction fluid (Zhong et al., 2024; Shang et al., 2020).

4. Significance and Novelty of Our Work

The collective research from our lab holds significant value for both academic and industrial sectors. The novelty of our work lies in the pioneering application and systematic optimization of green extraction technologies, particularly DES-based methods, often in combination with ultrasound or microwaves. We have successfully demonstrated that these methods are not only more sustainable but can also yield extracts with superior bioactivity.

A key significant contribution is the valorization of agricultural and food processing by-products, such as thinned kiwifruits, fruit peels, and seed coats, transforming them from waste into sources of high-value functional ingredients. Our rigorous comparative studies provide crucial insights into structure-function relationships, guiding the tailored production of natural products for specific applications in functional foods, nutraceuticals, and pharmaceuticals. By publishing comprehensive, updated reviews on key topics like tea polyphenols and Cannabis bioactives, our lab also serves as an authoritative voice, consolidating knowledge and directing future research in the field. Overall, our work bridges the gap between fundamental extraction science and practical, sustainable applications for promoting human health.

Acknowledgement

We would like to thank the hard work and collaboration of all my team members and collaborators involved in this work.

Our Publication List

Fu, Y., Li, F., Ding, Y., Li, H. Y., Xiang, X. R., Ye, Q., Zhang, J., Zhao, L., Qin, W., Gan, R. Y., & Wu, D. T. (2020). Polysaccharides from loquat (Eriobotrya japonica) leaves: Impacts of extraction methods on their physicochemical characteristics and biological activities. International Journal of Biological Macromolecules, 146, 508–517. http://dx.doi.org/10.1016/j.ijbiomac.2019.12.273

Gan, R. Y., Liu, Y., Li, H., Xia, Y., Guo, H., Geng, F., Zhuang, Q. G., Li, H. B., & Wu, D. T. (2024). Natural sources, refined extraction, biosynthesis, metabolism, and bioactivities of dietary polymethoxyflavones (PMFs). Food Science and Human Wellness, 13(1), 27–49. http://dx.doi.org/10.26599/FSHW.2022.9250003

Guo, H., Fu, M. X., Zhao, Y. X., Li, H., Li, H. B., Wu, D. T., & Gan, R. Y. (2021). The Chemical, Structural, and Biological Properties of Crude Polysaccharides from Sweet Tea (Lithocarpus litseifolius (Hance) Chun) Based on Different Extraction Technologies. Foods, 10(8), Article 1779. http://dx.doi.org/10.3390/foods10081779

He, J. L., Guo, H., Wei, S. Y., Zhou, J., Xiang, P. Y., Liu, L., Zhao, L., Qin, W., Gan, R. Y., & Wu, D. T. (2020). Effects of different extraction methods on the structural properties and bioactivities of polysaccharides extracted from Qingke (Tibetan hulless barley). Journal of Cereal Science, 92, Article 102906. http://dx.doi.org/10.1016/j.jcs.2020.102906

Lei, J., Li, W., Fu, M. X., Wang, A. Q., Wu, D. T., Guo, H., Hu, Y. C., Gan, R. Y., Zou, L., & Liu, Y. (2022). Pressurized hot water extraction, structural properties, biological effects, and in vitro microbial fermentation characteristics of sweet tea polysaccharide. International Journal of Biological Macromolecules, 222, 3215–3228. http://dx.doi.org/10.1016/j.ijbiomac.2022.10.094

Li, H., Guo, H., Luo, Q., Wu, D. T., Zou, L., Liu, Y., Li, H. B., & Gan, R. Y. (2023). Current extraction, purification, and identification techniques of tea polyphenols: An updated review. Critical Reviews in Food Science and Nutrition, 63(19), 3912–3930. http://dx.doi.org/10.1080/10408398.2021.1995843

Liu, Y., Kong, K. W., Wu, D. T., Liu, H. Y., Li, H. B., Zhang, J. R., & Gan, R. Y. (2022). Pomegranate peel-derived punicalagin: Ultrasonic-assisted extraction, purification, and its α-glucosidase inhibitory mechanism. Food Chemistry, 374, Article 131635. http://dx.doi.org/10.1016/j.foodchem.2021.131635

Liu, Y., Liu, H. Y., Li, S. H., Ma, W., Wu, D. T., Li, H. B., Xiao, A. P., Liu, L. L., Zhu, F., & Gan, R. Y. (2022). Cannabis sativa bioactive compounds and their extraction, separation, purification, and identification technologies: An updated review. TRAC-Trends in Analytical Chemistry, 149, Article 116554. http://dx.doi.org/10.1016/j.trac.2022.116554

Liu, Y., Liu, H. Y., Xia, Y., Guo, H., He, X. Q., Li, H., Wu, D. T., Geng, F., Lin, F. J., Li, H. B., Zhuang, Q. G., & Gan, R. Y. (2021). Screening and process optimization of ultrasound-assisted extraction of main antioxidants from sweet tea (Lithocarpus litseifolius [Hance] Chun). Food Bioscience, 43, Article 101277. http://dx.doi.org/10.1016/j.fbio.2021.101277

Liu, Y., Liu, H. Y., Yang, X., Zhu, F., Wu, D. T., Li, H. B., & Gan, R. Y. (2022). Green extraction, chemical composition, and in vitro antioxidant activity of theabrownins from Kangzhuan dark tea. Current Research in Food Science, 5, 1944–1954. http://dx.doi.org/10.1016/j.crfs.2022.10.019

Luo, M., Zhou, D. D., Shang, A., Gan, R. Y., & Li, H. B. (2021). Influences of Microwave-Assisted Extraction Parameters on Antioxidant Activity of the Extract from Akebia trifoliata Peels. Foods, 10(6), Article 1432. http://dx.doi.org/10.3390/foods10061432

Luo, Q., Zhang, J. R., Li, H. B., Wu, D. T., Geng, F., Corke, H., Wei, X. L., & Gan, R. Y. (2020). Green Extraction of Antioxidant Polyphenols from Green Tea (Camellia sinensis). Antioxidants, 9(9), Article 785. http://dx.doi.org/10.3390/antiox9090785

Mai, Y. H., Zhuang, Q. G., Li, Q. H., Du, K., Wu, D. T., Li, H. B., Xia, Y., Zhu, F., & Gan, R. Y. (2022). Ultrasound-Assisted Extraction, Identification, and Quantification of Antioxidants from 'Jinfeng' Kiwifruit. Foods, 11(6), Article 827. http://dx.doi.org/10.3390/foods11060827

Ng, C. Y. J., Lai, N. P. Y., Ng, W. M., Siah, K. T. H., Zhong, L. L. D., & Gan, R. Y. (2024). Chemical structures, extraction and analysis technologies, and bioactivities of edible fungal polysaccharides from Poria cocos: An updated review. International Journal of Biological Macromolecules, 261, Article 129555. http://dx.doi.org/10.1016/j.ijbiomac.2024.129555

Shang, A., Gan, R. Y., Zhang, J. R., Xu, X. Y., Luo, M., Liu, H. Y., & Li, H. B. (2020). Optimization and Characterization of Microwave-Assisted Hydro-Distillation Extraction of Essential Oils from Cinnamomum camphora Leaf and Recovery of Polyphenols from Extract Fluid. Molecules, 25(14), Article 3213. http://dx.doi.org/10.3390/molecules25143213

Shang, A., Luo, M., Gan, R. Y., Xu, X. Y., Xia, Y., Guo, H., Liu, Y., & Li, H. B. (2020). Effects of Microwave-Assisted Extraction Conditions on Antioxidant Capacity of Sweet Tea (Lithocarpus polystachyus Rehd.). Antioxidants, 9(8), Article 678. http://dx.doi.org/10.3390/antiox9080678

Subhash, A. J., Bamigbade, G. B., al-Ramadi, B., Kamal-Eldin, A., Gan, R. Y., Ranadheera, C. S., & Ayyash, M. (2024). Characterizing date seed polysaccharides: A comprehensive study on extraction, biological activities, prebiotic potential, gut microbiota modulation, and rheology using microwave-assisted deep eutectic solvent. Food Chemistry, 444, Article 138618. http://dx.doi.org/10.1016/j.foodchem.2024.138618

Wu, D. T., Deng, W., Li, J., Geng, J. L., Hu, Y. C., Zou, L., Liu, Y., Liu, H. Y., & Gan, R. Y. (2023). Ultrasound-Assisted Deep Eutectic Solvent Extraction of Phenolic Compounds from Thinned Young Kiwifruits and Their Beneficial Effects. Antioxidants, 12(7), Article 1475. http://dx.doi.org/10.3390/antiox12071475

Wu, D. T., Feng, K. L., Huang, L., Gan, R. Y., Hu, Y. C., & Zou, L. (2021). Deep Eutectic Solvent-Assisted Extraction, Partially Structural Characterization, and Bioactivities of Acidic Polysaccharides from Lotus Leaves. Foods, 10(10), Article 2330. http://dx.doi.org/10.3390/foods10102330

Wu, D. T., Fu, M. X., Guo, H., Hu, Y. C., Zheng, X. Q., Gan, R. Y., & Zou, L. (2022). Microwave-Assisted Deep Eutectic Solvent Extraction, Structural Characteristics, and Biological Functions of Polysaccharides from Sweet Tea (Lithocarpus litseifolius) Leaves. Antioxidants, 11(8), Article 1578. http://dx.doi.org/10.3390/antiox11081578

Wu, D. T., Geng, J. L., Li, J., Deng, W., Zhang, Y., Hu, Y. C., Zou, L., Xia, Y., Zhuang, Q. G., Liu, H. Y., & Gan, R. Y. (2024). Efficient extraction of pectic polysaccharides from thinned unripe kiwifruits by deep eutectic solvent-based methods: Chemical structures and bioactivities. Food Chemistry-X, 21, Article 101083. http://dx.doi.org/10.1016/j.fochx.2023.101083

Wu, D. T., Li, F., Feng, K. L., Hu, Y. C., Gan, R. Y., & Zou, L. (2022). A comparison on the physicochemical characteristics and biological functions of polysaccharides extracted from Taraxacum mongolicum by different extraction technologies. Journal of Food Measurement and Characterization, 16(4), 3182–3195. http://dx.doi.org/10.1007/s11694-022-01439-6

Wu, D. T., Zhao, Y. X., Guo, H., Gan, R. Y., Peng, L. X., Zhao, G., & Zou, L. (2021). Physicochemical and Biological Properties of Polysaccharides from Dictyophora indusiata Prepared by Different Extraction Techniques. Polymers, 13(14), Article 2357. http://dx.doi.org/10.3390/polym13142357

Yang, Q. Q., Gan, R. Y., Ge, Y. Y., Zhang, D., & Corke, H. (2019). Ultrasonic Treatment Increases Extraction Rate of Common Bean (Phaseolus vulgaris L.) Antioxidants. Antioxidants, 8(4), Article 83. http://dx.doi.org/10.3390/antiox8040083

Zhao, C. N., Tang, G. Y., Liu, Q., Xu, X. Y., Cao, S. Y., Gan, R. Y., Zhang, K. Y., Meng, S. L., & Li, H. B. (2018). Five-Golden-Flowers Tea: Green Extraction and Hepatoprotective Effect against Oxidative Damage. Molecules, 23(9), Article 2216. http://dx.doi.org/10.3390/molecules23092216

Zhong, M. M., Sun, Y. F., Qayum, A., Liang, Q. F., Rehman, A., Gan, R. Y., Ma, H. L., & Ren, X. F. (2024). Research progress in soybean lipophilic protein (LP): Extraction, structural, techno-functional properties, and high-performance food applications. Trends in Food Science & Technology, 147, Article 104440. http://dx.doi.org/10.1016/j.tifs.2024.104440

Zhou, Y., Xu, X. Y., Gan, R. Y., Zheng, J., Li, Y., Zhang, J. J., Xu, D. P., & Li, H. B. (2019). Optimization of Ultrasound-Assisted Extraction of Antioxidant Polyphenols from the Seed Coats of Red Sword Bean (Canavalia gladiate (Jacq.) DC.). Antioxidants, 8(7), Article 200. http://dx.doi.org/10.3390/antiox8070200

Zhou, Y., Zheng, J., Gan, R. Y., Zhou, T., Xu, D. P., & Li, H. B. (2017). Optimization of Ultrasound-Assisted Extraction of Antioxidants from the Mung Bean Coat. Molecules, 22(4), Article 638. http://dx.doi.org/10.3390/molecules22040638

Zou, T. B., Wang, M., Gan, R. Y., & Ling, W. H. (2011). Optimization of Ultrasound-Assisted Extraction of Anthocyanins from Mulberry, Using Response Surface Methodology. International Journal of Molecular Sciences, 12(5), 3006–3017. http://dx.doi.org/10.3390/ijms12053006