Next Article in Journal
Adsorption and Absorption Techniques for the Separation of Gaseous C2–C5 Olefins
Previous Article in Journal
Development and Validation of a Method for the Analysis of Multiple Pesticides in Fishery Products Using Gas Chromatography with Micro-Electron Capture Detection and Gas Chromatography–Tandem Mass Spectrometry
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Separations
Volume 12
Issue 6
10.3390/separations12060143
separations-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu

by
Jianan Wang
,
Chunli Chen
,
Fangjie Mou
,
Bin Wang
and
Jingzhou Dong
*
School of Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430048, China
*
Author to whom correspondence should be addressed.
Separations 2025, 12(6), 143; https://doi.org/10.3390/separations12060143
Submission received: 19 April 2025 / Revised: 21 May 2025 / Accepted: 23 May 2025 / Published: 28 May 2025
(This article belongs to the Topic Advances in Analysis of Food and Beverages, 2nd Edition)
Browse Figures
Versions Notes

Abstract

:
Premna microphylla is a medicinal plant species distributed in Southeast Asia and China. P. microphylla leaves have been widely used for processing edible gels called Chai tofu, which have many medicinal values, such as clearing heat and detoxifying. However, the main functional components of P. microphylla leaves and Chai tofu are still unknown. In this study, selenium-enriched cultivation of P. microphylla was conducted, and the main compositions of pectins, flavonoids, total phenolics, carotenoids, chlorophylls, and proteins were separated and comparatively analyzed. The results are that kaempferol was the main composition of flavonoids, with the average contents of 5.19% DW (dried weight) in leaves and 3.83% DW in Chai tofu; the composition of the Chai tofu pectin included glucose, fructose, and mannose. Contents of phenolics, kaempferol, chlorophyll, and carotenoids were significantly increased by the selenium enrichment cultivation in a concentration-dependent manner (R2 = 0.989, 0.994, 0.94, 0.948). Moreover, selenium enrichment produced selenized pectins with Se-O bonds. Selenium-enriched P. microphylla is an important plant source for functional foods. Related processing and extraction techniques deserve further research.

1. Introduction

Functional food sources, as an emerging food category, are of dramatically increased interest to human beings [1], since functional foods contain medicinal components that are good for human health [2]. These medicinal components include flavonoids [3,4], polysaccharides [5,6], phenolics [7], chlorophylls [8], carotenoids [9], saponins [10,11], and so on. Plant species highly rich in these medicinal components, typically Sophora japonica (rutin), Ampelopsis grossedentata (dihydromericytin), Lycium barbarum (polysaccharides), Punica granatum (polyphenols), Mangifera indica (carotenoids), Gynostemma pentaphyllum (saponins), Panax ginseng (saponins), and so on, are widely used as traditional medicines.
As a traditional medicinal plant species in the Chinese medicinal monograph “Bencaojing Jizhu”, P. microphylla plants have been recorded to have some important medicinal values such as clearing heat, detoxifying, and hemostasis. In southwest China, leaves of P. microphylla have been widely used for processing edible gels called Chai tofu, which is an important functional food, with the health benefits of clearing heat, detoxifying, relaxing bowels, and diuresis. In recent years, there have been some reports on chemical components such as triterpene glycosides and twelve new components from P. microphylla leaves [12,13], xanthones from roots [14], and 18 components from stems [15].
However, as a medicinal food source, there are few reports on the main functional components of flavonoids, total phenolics, proteins, carotenoids, chlorophylls, and polysaccharides of P. microphylla leaves and processed tofu.
Selenium was reported to have physiological functions such as antioxidation [16], anticancer [17], immunity stimulation [18], and HIV inhibition [19]. The bioactivity of selenium depends on its chemical form. Organic selenium-containing compounds such as selenomethionine and methylselenocysteine were better tolerated and exhibited anticarcinogenic activity [20]. Many plants showed the ability to transform inorganic selenium into organic selenium [21]. So, selenium-tolerant plants were used for processing organic selenium supplementation. Furthermore, in our previous study, selenium had been found to have promotive effects on the accumulation of some secondary metabolites [22,23,24]. In this study, selenium enrichment cultivation of P. microphylla was conducted, and the functional components, such as total phenolics, flavonoids, pectins, chlorophylls, carotenoids, and proteins, of selenium-enriched P. microphylla leaves and Chai tofu were comparatively analyzed.

2. Materials and Methods

2.1. Chemicals

Standards of galactose, glucose, Folin−Ciocalteu reagents, fructose, kaempferol, mannose, rutin, and xylose were purchased from Sangon Biotech (Shanghai, China). Silica gel GF254 (Labshark) chromatoplates from Changde Bekman Biotech (Hengyang, China) were used for TLC analysis of acid-hydrolyzed pectin. The chromatoplates were dried at 120 °C for 2 h before use. Acetonitrile, ethanol, and acetic acid were of HPLC grade; the other chemicals were of analytical grade.

2.2. Instruments

A soil water detector (FT-TS600, from Shandong Fengtu Networmk Science and Technology. Co., Ltd., Weifang, China) was used to monitor the soil moisture content. An ultrasonic cleaning bath (Shenzhen JietaiUltrasonic cleaning apparatus Co., Ltd., Shenzhen, China, PS-40, 40 kHz, 240 W) was employed for the extraction of flavonoids, phenolics, carotenoids, and chlorophylls. An Agilent1100 series with an LC–MSD trap SL (Agilent Technologies, Berlin, Germany) with a Lichrospher C18 column (4.6 × 250 mm, Jiangsu Hanbon Sci & Tech Co., Ltd., Huai’an, China) was used for analysis of flavonoids. An ultraviolet–visible spectrophotometer (Shanghai Youke instrument and meter Co., Ltd., Shanghai, China) was used for analysis of the phenolic components, carotenoids, proteins, and chlorophylls. The infrared spectrometer Tensor 27 (Bruker, Germany) was used for IR spectrum analysis on the pectin of P. microphylla leaves from selenium-enriched cultivation.

2.3. Selenium Enrichment Cultivation

Sodium selenite was reported to be a good form of selenium fertilizer for plants [23] and was used as a selenium source in this study. Sodium selenite was added into the MS solution (KNO3 1900 mg; NH4NO3 1650 mg; KH2PO4 170 mg; MgSO4·7H2O 370 mg; CaCl2·2H2O 440 mg; KI 0.83 mg; H3BO3 6.2 mg; MnSO4·4H2O 22.3 mg; ZnSO4·7H2O 8.6 mg; Na2MoO4·2H2O 0.25 mg; CuSO4·5H2O 0.025 mg; CoCl2·6H2O 0.025 mg; Na2EDTA 37.25 mg; FeSO4·7H2O 27.85 mg L−1) to final Se concentrations of 10, 20, 30, 40, and 50 mg/kg dried quartz sands (called Se-MS solution). Quartz sands were collected by a 30-mesh screen and cleaned with pure water. The dried quartz sands were well mixed with the prepared Se-MS solution in the ratio of 0.25 kg Se-MS solution/1.0 kg dried quartz sands (called selenium soils). Seedlings of P. microphylla were planted in the prepared selenium soils. The cultivation was conducted outdoors under a glass canopy and irrigated with distilled water to maintain the stable water contents (60–70%), which was monitored with a soil moisture detector (FT-TS600). The cultivation was from April to June, in Hubei Minzu University, Enshi, China, with the average temperature of 25.5 °C and an altitude of 531.8 m. Leaves were harvested after 90 days of growth, then washed and dried at 80 °C to constant weight for analysis of functional components. The fresh leaves were washed for Chai tofu processing.

2.4. Preparation of Chai Tofu

Chai tofu samples were prepared according to the traditional method: straw ashes were extracted with water in the ratio of 5/1, w/w, for 2 h, and filtrated with a filter cloth as ash water, then fresh microphylla leaves were ground into mud with the ash water, in the ratio of 1/2, g/g, and filtered with 60 mesh gauze. The filtrates were cooled at 4 °C for 4 h, and then green Chai tofu was obtained (Figure 1); some of the Chai tofu samples were vacuum-dried at 65 °C and then ground into powders for further analysis.

2.5. Quantitation and Composition Analysis on Chai Tofu Pectin

Pectin quantitation: the filtrates obtained above were purified with savage reagent to remove proteins and then centrifuged and filtered. The filtrates were then freeze-dried and ground into powders. These powders were refluxed with petroleum ether to remove lipids at 60 °C for 2 h, then refluxed with 80% ethanol (v/v) to remove sugars at 90 °C for 4 h. The residues were dried at 80 °C for 4 h and ultrasonicated with pure water for 30 min at 80 °C for three cycles, and then the extracts were filtered. The filtrates were collected as pectin samples. Pectin quantitation was conducted by the carbazole method [25]. Namely, the contents of pectin were calculated according to the calibration curves, with glucose as a standard. The regression equation is Y = 0.0063X + 0.0046, R2 = 0.9998, where the linearity range = 15–90 µg/mL, Y is the absorbance at 530 nm, X is the concentration of glucose (µg/mL), and R2 is the coefficient of correlation.
Pectin composition: composition analysis on Chai tofu pectin was conducted by thin-layer chromatography (TLC) with glucose, fructose, mannose, xylose, and galactose as standards. The pectin samples were hydrolyzed with 1.0 M H2SO4, at 95 °C, for 10 h, then neutralized with Ca(OH)2 solution to pH 7.0. The sugar composition of the hydrolyzed pectin was analyzed with thin-layer chromatography (TLC) at room temperature for 10 min. The ratios of developing agents were n-butyl alcohol/ethyl acetate/isopropanol/acetic acid/water = 1.5/3.5/3.5/1.5. The developed TLC plate was sprayed with 10% H2SO4 and heated with a hair-drier to show developed points.

2.6. Flavonoids Analysis

Dried P. microphylla leaf powders and Chai tofu powders were de-oiled with petroleum ether, and then extracted with 80% ethanol, separately. The ethanol extracts were used for flavonoid analysis. The extracts were scanned within 190–1000 nm and then separated by the HPLC method with a DAD detector. The HPLC method used acetonitrile as solvent A (0.5% acetic acid as solvent B) for 0–18 min, 18–50%, 18–20 min, and 50–18%. The column temperature was set at 25 °C, the sample volume injected was 5.0 µL, and the flow rate was 1.0 mL/min. LC-(APCI)MS was used for qualitative analysis of the flavonoids. The MS parameters were set as follows: ion source, APCI; nebulizer, 50 psi; dry gas temperature, 350 °C; dry gas flow, 10.0 L/min; APCI temperature, 400 °C; HV capillary, 4000 V; and scan range, 500 to 1000 m/z. Nitrogen was used as a drying gas (10.0 L/min).

2.7. Analysis on Phenolics, Chlorophylls, Carotenoids, and Protein of P. microphylla Leaves

The contents of total phenolics were determined according to the published Folin−Ciocalteu method [26]. Quantitation of carotenoids was conducted according to our published method [23] with some modifications. Namely, fresh leaves and Chai tofu were ground into mud with absolute methanol, respectively, and then filtered. Carotenoids of the residues were extracted with methanol three times. The filtrates were measured at 450 nm, using E 1 cm 1 % = 2500 for carotenoids quantification.
Quantitation of chlorophylls: 0.2 g of fresh leaves was cut into small pieces and ground with 10 mL of absolute methanol, placed in a 50 mL centrifuge tube, which was filled to 30 mL with absolute methanol, and then kept in a dark place until the sample color changed to white. A total of 1 mL of the filtered extract was diluted with 3 mL of absolute methanol, and the absorbance was measured at 645 nm, 652 nm, and 663 nm. Chai tofu sample analysis was conducted with the same method. The concentrations (in mg/mL) of chlorophyll a (Ca), chlorophyll b (Cb), and chlorophylls (Ca+b) were calculated according to the following formulae:
Ca = 0.0127D663 − 0.00269D645
Cb = 0.0229D645 − 0.00468D663
Ca+b = [(0.0202D645 + 0.00802D663 + D652)/34.5]/2
where D is absorbance.
Total protein was quantified according to the published method [27]. Namely, dried leaves were ground into powders, and the flour samples were put into acetone to be defatted overnight at room temperature. The defatted flour was extracted with 0.5% SDS and 0.6% β-mercaptoethanol for 30 min at room temperature, and then centrifuged at 3000× g for 15 min. The residue was removed. The total protein of the samples was determined by the commonly used method of Kjeldahl using a nitrogen conversion factor of 5.95.

3. Results

3.1. Composition of Selenized P. microphylla Pectin: Glucose, Fructose, and Mannose

In this study, the pectin composition of selenium-enriched P. microphylla leaves was separated and identified as glucose, fructose, and mannose (Figure 2). Pectin was the main composition of Chai tofu, with the average content of 25.71 ± 3.66% DW (Table 1). So, P. microphylla was not only a functional food source, but also a good source for pectin production.
The characteristic peaks in the IR spectrum of the pectin from selenium-enriched P. microphylla leaves indicated the chemical groups and bonds as –OH (3448.35), C-H (2927.07), S=O (1441.01), C-O-C (1224.36), and Se-O-C stretching vibrations (663.65) [28] (Figure 3), which was in accordance with the published selenium polysaccharides [29]. This IR spectrum indicated that P. microphylla pectins were selenized into Se-polysaccharides, which might be another type of organic selenium source.

3.2. The Other Functional Components: Phenolics, Flavonoids, Chlorophylls, Carotenoids, and Proteins

UV spectra of the ethanol extracts showed a typical UV spectrum of flavonoids (Figure 4). The main composition of microphylla flavonoids was identified to be kaempferol (Figure 5, Table 2), with an average content of 5.19 ± 0.55% DW in leaves and 3.83 ± 0.33% DW in Chai tofu samples (Table 1). The total phenolics of P. microphylla leaves were 7.33 ± 1.43% DW and 5.36 ± 1.72% DW in the Chai tofu samples (Table 1).
P. microphylla leaves contained chlorophylls of 1.25 ± 0.35 mg/kg FW (fresh weight), carotenoids of 1.66 ± 0.25 mg/kg FW, and proteins of 12.5 ± 2.27% DW. Chai tofu contained chlorophylls of 0.85 ± 0.22% FW, carotenoids of 0.82 ± 0.15% FW, and protein of 9.22 ± 2.11% DW.

3.3. Selenium Enrichment Promotes Accumulation of Phenolics, Carotenoids, and Chlorophylls

Analysis of the selenium-enriched P. microphylla leaves showed a significant positive correlation between selenium concentrations and chlorophylls, carotenoids, phenolics, and kaempferol, with the correlation coefficients R2 = 0.94, 0.948, 0.994, and 0.989, respectively (Table 3). Selenium enrichment significantly promoted the accumulation of kaempferol, chlorophylls, carotenoids, and phenolics in a very significantly selenium-dependent manner. So, selenium-enrichment cultivation should be used in P. microphylla cultivation.

4. Discussion

4.1. Pectin and Selenized Pectin: Important Functional Food Sources

Pectin, as a kind of plant polysaccharide, has been reported to have many important bioactivities for the human body [30,31]. Pectin cannot be absorbed by the human body, but can be a good carbon source for intestinal microbes [32]. The mechanism of P. microphylla pectin bioactivities in the human body might be that it promotes the propagation of the intestinal gut microbiota, which has been proved to play an important role in regulating human health [33,34] or ameliorate inflammation via the enhancement of intestinal resistance in the host [35].
Selenocarrageenan, a type of selenized carrageenan polysaccharide, has been reported to promote the intestinal beneficial microbiota of Apostichopus japonicus [36], alleviate inflammation, and promote gut microbiota of mice [37]. The selenized pectin extracted from selenium-enriched P. microphylla leaves might be a potential functional food source; the related processing technology and medicinal values deserve further research.

4.2. The Main Medicinal Components: Kaempferol and Phenolics

P. microphylla was a traditional natural medicine and recorded as clearing heat and detoxifying in the Chinese medicinal monograph “Bencaojing Jizhu”. Kaempferol was the main flavonoid composition in P. microphylla leaves and Chai tofu. It has been reported that kaempferol showed many medicinal values such as prevention and treatment of pulmonary diseases [38], treatment of obesity by promoting white fat browning [39], potential for diabetes management [40], inhibiting ferroptosis and inflammation [41], inhibiting prostate cancer [42], and so on. These pharmacological studies provided a scientific basis for the development and utilization of P. microphylla leaves. Polyphenols have been reported to show main medicinal effects such as intestinal protection [43,44], antioxidation [45,46], and antimicrobial activities [47], and play an important role in the treatment of diseases as obesity, cancer, and diabetes [48]. The addition of P. microphylla leaf extracts significantly increased the radical scavenging capacity of packed tofu [49], improved mechanical efficacy, and reduced the solubility of gelatin–kappa–carrageenan-based edible film [50]. This research provides a scientific basis for the medicinal effects of Chai tofu. Kaempferol was the main flavonoid composition of P. microphylla leaves, so P. microphylla leaves could be a good source for kaempferol extraction and production.
Selenium within 10–50 mg/kg concentrations significantly increased the accumulation of kaempferol and polyphenols, which was partially in accordance with our previous study [22]. So, the selenium-enriched cultivation of P. microphylla plants for kaempferol production deserves further research.

4.3. Other Functional Components:

In the processing of Chai tofu, other functional components such as chlorophyll and carotenoids were mostly extracted into pectin mixtures by plant ash water. Chlorophyll and carotenoids have been reported to have many bioactivities [51,52]. The chlorophyll and carotenoids mixed in the pectin increased the medicinal values of Chai tofu. Furthermore, chlorophyll and carotenoids were both increased by selenium enrichment in a very significant selenium-dependent manner. So, the selenium-enriched Chai tofu, rich in kaempferol, polyphenols, chlorophyll, carotenoids, and proteins, could be an important functional food that is much healthier than traditional plant pectins.
Kaempferol, as the main flavonoid composition, and selenized pectin were first reported in this study. Kaempferol, with a content of 5.19% in P. microphylla leaves, indicated that P. microphylla could be a good source of kaempferol production. In the future, P. microphylla could be developed as a functional food source. The selenized pectin could be developed as basic functional food materials. And the medicinal value of the selenized pectin deserves further research.

5. Conclusions

In conclusion, the main composition of the flavonoids of P. microphylla leaves and Chai tofu was kaempferol. Chai tofu also contained other functional components as phenolics, carotenoids, chlorophylls, and proteins. Selenium enrichment produced Se-pectin, which could be a new source of organic selenium. Selenium also significantly promoted the accumulation of kaempferol, phenolics, carotenoids, and chlorophylls. These findings provided the scientific basis for the medicinal values of Chai tofu and the development of P. microphylla resources. Selenium-enriched Chai tofu has the potential to be developed as an important functional food, and related techniques deserve further study.

Author Contributions

J.W.: conceptualization; methodology; formal analysis; data curation; writing—original draft; writing—review and editing; visualization. B.W.: methodology; writing—review and editing; formal analysis; data curation; writing—original draft; visualization. C.C.: conceptualization; methodology; investigation; visualization. F.M.: conceptualization; methodology; investigation. J.D.: conceptualization; methodology; resource; project administration; supervision. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partially funded by the Doctor Research Project (53210052493), Wuhan Polytechnic University, Wuhan, China.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Acknowledgments

We are grateful to anonymous reviewers and scientific editors for critical review and valuable suggestions.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Marilisa, A.; Monica, A. Re-thinking functional food development through a holistic approach. J. Funct. Foods 2021, 81, 104466. [Google Scholar] [CrossRef]
  2. Oboh, G. Phytomedicine and functional foods: Keys to sustainable healthcare delivery. J. Food Biochem. 2021, 45, 13634. [Google Scholar] [CrossRef] [PubMed]
  3. Diniz, T.C.; Silva, J.C.; Lima-Saraiva, S.R.G. The Role of Flavonoids on Oxidative Stress in Epilepsy. Oxid. Med. Cell Longevevity 2015, 2015, 171756. [Google Scholar] [CrossRef]
  4. Peluso, I.; Miglio, C.; Morabito, G.; Ioannone, F.; Serafini, M. Flavonoids and immune function in human: A systematic review. Crit. Rev. Food Sci. Nutr. 2015, 55, 383–395. [Google Scholar] [CrossRef]
  5. Zhang, L.; Reddy, N.; Koyyalamudi, S.R. Isolation, Characterization, and Biological Activities of Polysaccharides from Medicinal Plants and Mushrooms. Stud. Nat. Prod. Chem. 2014, 42, 117–151. [Google Scholar] [CrossRef]
  6. Shrestha, G.; Clair, L.L.; O’Neill, K.L. The Immunostimulating Role of Lichen Polysaccharides: A Review. Phytother. Res. 2015, 29, 317–322. [Google Scholar] [CrossRef]
  7. Acosta-Estrada, B.A.; Gutiérrez-Uribe, J.A.; Serna-Saldívar, S.O. Bound phenolics in foods, a review. Food Chem. 2014, 152, 46–55. [Google Scholar] [CrossRef]
  8. Mishra, V.K.; Bacheti, R.K.; Husen, A. Medicinal Uses of Chlorophyll: A critical overview. In Chlorophyll: Structure, Function and Medicinal Uses; Hua Le, H., Salcedo, E., Eds.; Nova Science Publishers, Inc.: Hauppauge, NY, USA, 2011; pp. 177–196. Available online: https://www.novapublishers.com/catalog/product_info.php?products_id=22468 (accessed on 21 May 2025)ISBN 978-1-62100-015-0.
  9. Feller, R.; Ângelo, P.M.; Mazzutti, S.; Moecke, E.H.S.; Junior, A.F. Polyunsaturated ω-3 and ω-6 fatty acids, total carotenoids and antioxidant activity of three marine microalgae extracts obtained by supercritical CO2 and subcritical n -butane. J. Supercritic. Fluid. 2018, 133, 437–443. [Google Scholar] [CrossRef]
  10. Sun, Y.W.; Qiu, H.C.; Ming-Chun, O.U.; Chen, R.L.; Liang, G. Saponins isolated from Schizocapsa plantaginea inhibit human hepatocellular carcinoma cell growth in vivo and in vitro via mitogen-activated protein kinase signaling. Chin. J. Nat. Med. 2018, 16, 29–40. [Google Scholar] [CrossRef]
  11. Liu, M.W.; Wei, R.; Su, M.X.; Li, H.; Fang, T.W.; Zhang, W. Effects of Panax notoginseng saponins on severe acute pancreatitis through the regulation of mTOR/Akt and caspase-3 signaling pathway by up regulating miR-181b expression in rats. BMC Complement. Altern. Med. 2018, 18, 51. [Google Scholar] [CrossRef]
  12. Zhan, Z.J.; Tang, L.; Shan, W.G. A new triterpene glycoside from Premna microphylla. Chem. Nat. Comp. 2009, 45, 197–199. [Google Scholar] [CrossRef]
  13. Hu, Z.; Xue, Y.; Yao, G.; Luo, Z.; Wang, Y.; Zhang, Y. Chemical constituents from the leaves of Premna microphylla Turcz. J. Chin. Pharm. Sci. 2013, 22, 431–434. [Google Scholar] [CrossRef]
  14. Wang, D.Y.; Xu, S.Y. Two new xanthones from Premna microphylla. Nat. Prod. Res. 2003, 17, 75–77. [Google Scholar] [CrossRef] [PubMed]
  15. Duan, H.; Wang, W.; Li, Y.X.; Khan, G.J.; Chen, Y.; Shen, T. Identification of phytochemicals and antioxidant activity of Premna microphylla Turcz. stem through UPLC-LTQ-Orbitrap-MS. Food Chem. 2022, 373, 131482. [Google Scholar] [CrossRef]
  16. Wen, S.; Hui, Y.; Chuang, W. Biosynthesis and antioxidation of nano-selenium using lemon juice as a reducing agent. Green. Process. Synth. 2021, 10, 178–188. [Google Scholar] [CrossRef]
  17. Subha, V.; Shanmugam, K.; Sahadevan, R. In Vivo Studies and Flow Cytometric Investigation on Anticancer Potential of Selenium Nanoparticles Synthesized via Aqueous Extract of Clerodendron phlomidis. Proc. Antica. Res. 2024, 8, 71–81. [Google Scholar] [CrossRef]
  18. Debata, N.R.; Sethy, K.; Swain, R.K.; Mishra, S.K.; Panda, N.; Maity, S. Supplementation of nano-selenium (SeNPs) improved growth, immunity, antioxidant enzyme activity, and selenium retention in broiler chicken during summer season. Trop. Anim. Health Prod. 2023, 55, 260. [Google Scholar] [CrossRef]
  19. Pourmoradian, S.; Rezazadeh, L.; Tutunchi, H.; Ostadrahimi, A. Selenium and zinc supplementation in HIV-infected patients. Int. J. Vitam. Nutr. Res. 2024, 94, 153–159. [Google Scholar] [CrossRef]
  20. Hadrup, N.; Ravn-Haren, G. Toxicity of repeated oral intake of organic selenium, inorganic selenium, and selenium nanoparticles: A review. J. Trace Elem. Med. Biol. 2023, 79, 127235. [Google Scholar] [CrossRef]
  21. Sors, T.G.; Ellis, D.R.; Salt, D.E. Selenium uptake, translocation, assimilationand metabolic fate in plants. Photosynth. Res. 2005, 86, 373–389. [Google Scholar] [CrossRef]
  22. Dong, J.Z.; Liu, M.R.; Lei, C.; Zheng, X.J.; Wang, Y. Effects of selenium and light wavelengths on liquid culture of Cordyceps militaris link. Appl. Biochem. Biotechnol. 2012, 166, 2030–2036. [Google Scholar] [CrossRef] [PubMed]
  23. Dong, J.Z.; Wang, Y.; Wang, S.H.; Yin, L.P.; Xu, G.J.; Zheng, C.; Lei, C.; Zhang, M.Z. Selenium Increases Chlorogenic Acid, Chlorophyll and Carotenoids of Lycium chinense Leaves. J. Sci. Food Agri. 2013, 93, 310–315. [Google Scholar] [CrossRef] [PubMed]
  24. Lei, C.; Ma, Q.; Tang, Q.; Ai, X.; Zhou, Z.; Yao, L.; Wang, Y.; Wang, Q.; Dong, J. Sodium selenite regulates phenolica and tuber development of purple potatoes. Sci. Hortic. 2014, 165, 142–147. [Google Scholar] [CrossRef]
  25. Xu, W.; Wang, G.H.; Wang, C.W.; Chen, Y.Q.; Wng, W.G.; Zhang, J.F. Determination of Premna microphylla pectin content by carbazole spectrophotometric method. Food Mach. 2006, 22, 133–135. [Google Scholar]
  26. Alnsour, L.; Issa, R.; Awwad, S.; Albals, D.; Al-Momani, I. Quantification of Total Phenols and Antioxidants in Coffee Samples of Different Origins and Evaluation of the Effect of Degree of Roasting on Their Levels. Molecules 2022, 27, 1591. [Google Scholar] [CrossRef]
  27. Ritika, B.Y.; Bhupender, S.K.; Baljeet, S.Y. Electrophoretic characterization and functional properties of rice proteins from Indian rice cultivars. Int. J. Food Props. 2013, 16, 1776–1788. [Google Scholar] [CrossRef]
  28. Yuan, B.; Yang, X.Q.; Kou, M.; Lu, C.Y.; Wang, Y.Y.; Peng, J. Selenylation of polysaccharide from the sweet potato and evaluation of antioxidant, antitumor, and antidiabetic activities. J. Agric. Food Chem. 2017, 65, 605. [Google Scholar] [CrossRef]
  29. Sun, Y.; Zhou, C.; Huang, S.C.; Jiang, C.J. Selenium polysaccharide SPMP-2a from Pleurotus geesteranus alleviates H2O2-induced oxidative damage in HaCaT cells. Biomed. Res. Int. 2017, 2017, 4940384. [Google Scholar] [CrossRef]
  30. Yue, Y.Y.; Wang, B.T.; Xi, W.X.; Liu, X.; Tang, S.; Tan, X.; Li, G.J.; Huang, L.H.; Liu, Y.; Bai, J.Y. Modification methods, biological activities and applications of pectin: A review. Int. J. Biol. Macromol. 2023, 253, 127523. [Google Scholar] [CrossRef]
  31. Emran, T.B.; Islam, F.; Mitra, S.; Paul, S.; Nath, N.; Khan, Z.; Das, R.; Chandran, D.; Sharma, R.; Lima, C.M.G.; et al. Pectin: A Bioactive Food Polysaccharide with Cancer Preventive Potential. Molecules 2022, 27, 7405. [Google Scholar] [CrossRef]
  32. Zhu, Y.; Zhang, T.; Wang, H. Physicochemical properties, structure and biological activities of a novel low-molecular-weight hawthorn pectin. Process Biochem. 2022, 122, 282–291. [Google Scholar] [CrossRef]
  33. Nan, H.E.; Jing, M.A.; Mei-Rui, Q. Advanced research of intestinal microbes and epigenetic modification, and tumor prevention and treatment. Infect. Dis. Inf. 2019, 32, 304–311. [Google Scholar]
  34. Yang, X. Dietary pectin from Premna microphylla Turcz leaves prevents obesity by regulating gut microbiota and lipid metabolism in mice fed high-fat diet. Foods 2024, 13, 2248. [Google Scholar] [CrossRef] [PubMed]
  35. Song, S.Y.S. Polysaccharides from Premna microphylla Turcz ameliorate inflammation via the enhancement of intestinal resistance in host. J. Ethnopharmacol. 2021, 276, 11428. [Google Scholar] [CrossRef] [PubMed]
  36. Wang, K.; Liu, L.; He, Y.; Miao, J. Effects of dietary supplementation with k-selenocarrageenan on the selenium accumulation and intestinal microbiota of the sea cucumbers Apostichopus japonicus. Biol. Trace Elem. Res. 2021, 199, 2753–2763. [Google Scholar] [CrossRef]
  37. Wang, K.; Qin, L.; Cao, J.; Zhang, L.; Liu, M.; Qu, C. k-Selenocarrageenan oligosaccharides prepared by deep-sea enzyme alleviate inflammatory responses and modulate gut microbiota in ulcerative colitis mice. Int. J. Mol. Sci. 2023, 24, 4672. [Google Scholar] [CrossRef]
  38. Lv, J.L.; Luo, Z.X.; Huang, D.Q. The therapeutic potential of kaempferol in the prevention and treatment of pulmonary diseases: A bibliometric analysis. Asian J. Surg. 2025, 48, 494–495. [Google Scholar] [CrossRef]
  39. Xu, C.Y.; Zhang, X.X.; Wang, Y.H.; Wang, Y.; Zhou, Y.X.; Li, F.F.; Hou, X.L.; Xia, D.Z. Dietary kaempferol exerts anti-obesity effects by inducing the browing of white adipocytes via the AMPK/SIRT1/PGC-1α signaling pathway. Cur. Res. Food Sci. 2024, 8, 100728. [Google Scholar] [CrossRef]
  40. Song, C.M.; Zheng, W.; Song, C.Y.; Zhou, H.F.; Yao, J.Y. Protective Effects of Food-Derived Kaempferol on Pancreaticβ-Cells in Type 1 Diabetes Mellitus. Foods 2024, 13, 3797. [Google Scholar] [CrossRef]
  41. Wang, A.; Yang, J.L.; Deng, J.P.; Wang, K.T.; Chen, G.D.; Lin, D.S. Kaempferol promotes flap survival by inhibiting ferroptosis and inflammation through network pharmacology and in vivo experiments. Wound Repair. Regen. 2025, 33, 13250. [Google Scholar] [CrossRef]
  42. Li, W.; Liu, H.; Zheng, J.; Wang, D.C.; Wang, Z.Y.; Hong, M.; Zhou, Y.X. Kaempferol modulates ɑ2M secretion in bone marrow-derivedmacrophages by downregulating GR/PER1-mediated lipid metabolism toattenuate the emotional stress-aggravated metastasis of prostate cancer. J. Ethnopharmacol. 2025, 339, 119162. [Google Scholar] [CrossRef] [PubMed]
  43. Li, Z.; Chu, T.J.; Sun, X.; Zhuang, S.; Hou, D.B.; Zhang, Z.H.; Sun, J.L.; Liu, Y.H.; Li, J.; Bian, Y.F. Polyphenols-rich Portulaca oleracea L. (purslane) alleviates ulcerative colitis through restiring the intestinal barrier, gut microbiota and metabolites. Food Chem. 2025, 468, 142391. [Google Scholar] [CrossRef] [PubMed]
  44. Yuan, H.X.; Huang, H.; Du, Y.L.; Zhao, J.Q.; Yu, S.Y.; Lin, Y.H.; Chen, Y.; Shan, C.H.; Zhao, Y.; Belwal, T.; et al. Sea buckthorn polyphenols on gastrointestinal health and the interactions with gut microbiota. Food Chem. 2025, 469, 142591. [Google Scholar] [CrossRef]
  45. Pandey, V.; Chur, A.; Pandey, H.K.; Nasim, M. Estimation of ascorbic acid, ß carotene, total chlorophyll, phenolics and antioxidant activity of some European vegetables grown in mid hill conditions of western Himalaya. J. New Biol. Rep. 2018, 4, 238–242. [Google Scholar]
  46. Kaur, R.; Manchanda, P.; Sidhu, G.S. Optimization of extraction of bioactive phenolics and their antioxidant potential from callus and leaf extracts of Stevia rebaudiana Bertoni. J. Food Meas. Charact. 2022, 16, 461–470. [Google Scholar] [CrossRef]
  47. Balaky, H.H.; Galali, Y.M.; Osman, A.A.; Eyyüp, K.; Hakk, M. Evaluation of antioxidant and antimicrobial activities of mandarin peel (Citrus reticulata Blanco) with microwave assisted extract using two different solvents. Asian J. Plant Sci. 2020, 19, 223–229. [Google Scholar] [CrossRef]
  48. Zhang, Y.Y.; Cai, P.; Cheng, G.H.; Zhang, Y.Q. A Brief Review of Phenolic Compounds Identified from Plants: Their Extraction, Analysis, and Biological Activity. Nat. Prod. Commun. 2022, 17, 1–14. [Google Scholar] [CrossRef]
  49. Huang, Z.; Xing, G.; Tu, C.; Rui, X.; Dong, M. Effect of Premna microphylla Turcz leaves’ extract addition on physicochemical and antioxidant properties of packed tofu by lactic fermentation. Int. J. Food Sci. Technol. 2020, 55, 2541–2550. [Google Scholar] [CrossRef]
  50. Huang, P.H.; Chen, Y.J.; Lin, Y.W.; Huang, D.W. Gelatin-kappa-carrageenan-based edible film incorporated with ethanol extracts from Premna microphylla Turcz leaves for preservation of sailfish fillets. LWT 2024, 208, 116710. [Google Scholar] [CrossRef]
  51. Murshed, H.M.; Uddin, M.N.; Ashrafuzzaman, M. Variation of phenolics, antioxidant activity and carotenoids contents in some medicinal plants. J. Bangladesh Agri. Univ. 2021, 19, 178–183. [Google Scholar] [CrossRef]
  52. Ebrahimi, P.; Shokramraji, Z.; Tavakkoli, S.; Mihaylova, D.; Lante, A. Chlorophylls as Natural Bioactive Compounds Existing in Food By-Products: A Critical Review. Plants 2023, 12, 1533. [Google Scholar] [CrossRef] [PubMed]
Separations 12 00143 g001
Figure 1. Chai tofu samples.
Figure 1. Chai tofu samples.
Separations 12 00143 g001
Separations 12 00143 g002
Figure 2. TLC separation of P. microphylla pectin (1 = sample; 2 = glucose; 3 = fructose; 4 = D-mannose; 5 = xylose; 6 = galactose).
Figure 2. TLC separation of P. microphylla pectin (1 = sample; 2 = glucose; 3 = fructose; 4 = D-mannose; 5 = xylose; 6 = galactose).
Separations 12 00143 g002
Separations 12 00143 g003
Figure 3. IR spectrum of the pectin from selenium-enriched P. microphylla.
Figure 3. IR spectrum of the pectin from selenium-enriched P. microphylla.
Separations 12 00143 g003
Separations 12 00143 g004
Figure 4. UV—visible spectrum of the extracts of P. microphylla leaves.
Figure 4. UV—visible spectrum of the extracts of P. microphylla leaves.
Separations 12 00143 g004
Separations 12 00143 g005
Figure 5. LC−MS separation of P. microphylla flavonoid (A = HPLC detection, wavelength = 325 nm; B = total ion chromatography).
Figure 5. LC−MS separation of P. microphylla flavonoid (A = HPLC detection, wavelength = 325 nm; B = total ion chromatography).
Separations 12 00143 g005
Table 1. Contents of the main components of P. micropgylla leaves and Chai Tofu samples (n = 5, SPSS 16.0).
Table 1. Contents of the main components of P. micropgylla leaves and Chai Tofu samples (n = 5, SPSS 16.0).
CompoundsKaempferol
(%, DW)		Phenolics
(%, DW)		Proteins
(%, DW)		Pectins
(%, DW)		Chlorophyll
(mg/kg, FW)		Carotenoids
(mg/kg, FW)
Leaves5.19 ± 0.557.33 ± 1.4312.5 ± 2.2725.71 ± 3.661.25 ± 0.351.66 ± 0.25
Chai Tofu3.83 ± 0.335.36 ± 1.729.25 ± 2.1122.94 ± 6.880.85 ± 0.220.82 ± 0.15
Note: DW = dried weight; FW = fresh weight.
Table 2. UV-MS data of the main flavonoid of P. micropgylla leaves.
Table 2. UV-MS data of the main flavonoid of P. micropgylla leaves.
PeaksComponentsMW[M + H]+[M − H]−UV Spectra (nm)Retention Time (min)
1Kaempferol286287.1/243.1/157.1284.8/255.1266.1, 301 (sh), 369.57.007
Table 3. Contents of the main components of Chai Tofu samples from selenium-enriched P. micropgylla leaves.
Table 3. Contents of the main components of Chai Tofu samples from selenium-enriched P. micropgylla leaves.
Selenium (mg/kg)Kaempferol (%)Phenolics (%)Chlorophylls (mg/kg)Carotenoids (mg/kg)Proteins (%)Pectins (%)
R20.9890.9940.940.9480.0930.404
105.45 ± 0.337.56 ± 1.051.73 ± 0.61.87 ± 0.3512.73 ± 1.1725.88 ± 3.96
205.75 ± 0.178.15 ± 2.252.05 ± 0.651.96 ± 0.512.34 ± 2.5826.43 ± 5.05
306.05 ± 0.288.86 ± 1.332.25 ± 0.732.36 ± 0.2512.58 ± 3.2925.95 ± 3.16
406.52 ± 0.149.36 ± 1.352.55 ± 0.52.87 ± 0.4511.52 ± 2.7526.1 ± 5.35
506.95 ± 0.239.85 ± 2.153.25 ± 0.573.44 ± 0.6112.66 ± 2.3226.85 ± 5.15
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Wang, J.; Chen, C.; Mou, F.; Wang, B.; Dong, J. Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu. Separations 2025, 12, 143. https://doi.org/10.3390/separations12060143

AMA Style

Wang J, Chen C, Mou F, Wang B, Dong J. Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu. Separations. 2025; 12(6):143. https://doi.org/10.3390/separations12060143

Chicago/Turabian Style

Wang, Jianan, Chunli Chen, Fangjie Mou, Bin Wang, and Jingzhou Dong. 2025. "Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu" Separations 12, no. 6: 143. https://doi.org/10.3390/separations12060143

APA Style

Wang, J., Chen, C., Mou, F., Wang, B., & Dong, J. (2025). Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu. Separations, 12(6), 143. https://doi.org/10.3390/separations12060143

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop