Comparison of Free, Esterified, and Insoluble-Bound Phenolics and Their Bioactivities in Three Organs of Lonicera japonica and L. macranthoides

Chemical Composition of Honeysuckle (Lonicerae japonicae) Extracts and Their Potential in Inhibiting the SARS-CoV-2 Spike Protein and ACE2 Binding, Suppressing ACE2, and Scavenging Radicals

Honeysuckle (Lonicerae japonicae) has been used in functional tea products. The chemical compositions of the water and ethanol extracts of honeysuckle were examined in the present study, along with their potential in inhibiting SARS-CoV-2 spike protein binding to ACE2, suppressing ACE2 activity, and scavenging reactive free radicals. Thirty-six compounds were tentatively identified from the honeysuckle extracts using HPLC-MS/MS, with ten reported for the first time in honeysuckle. Both honeysuckle extracts inhibited the binding of SARS-CoV-2 spike protein to ACE2, as well as ACE2 activity. The ethanol extract exhibited a 100% inhibition on binding of the SARS-CoV-2 spike protein to ACE2 at 100 mg botanical equivalent/mL, whereas the water extract had a 65% binding inhibition at the same concentration. Furthermore, the water extract exhibited 90% ACE2 activity inhibition, which was stronger than that of the ethanol extract (62% inhibition) at the same botanical weight concentration. In addition, higher total phenolic contents and greater scavenging activities against hydroxyl (HO•), DPPH•, and ABTS•+ radicals were observed in the water extract than the ethanol extract counterpart on a dry botanical weight concentration basis. These findings suggest honeysuckle has the potential to reduce the risk of SARS-CoV-2 infection and the development of severe COVID-19 symptoms.

Importance of Insoluble-Bound Phenolics to the Antioxidant Potential Is Dictated by Source Material

Insoluble-bound phenolics (IBPs) are extensively found in the cell wall and distributed in various tissues/organs of plants, mainly cereals, legumes, and pulses. In particular, IBPs are mainly distributed in the protective tissues, such as seed coat, pericarp, and hull, and are also available in nutritional tissues, including germ, epicotyl, hypocotyl radicle, and endosperm, among others. IBPs account for 20-60% of the total phenolics in food matrices and can exceed 70% in leaves, flowers, peels, pulps, seeds, and other counterparts of fruits and vegetables, and up to 99% in cereal brans. These phenolics are mostly covalently bound to various macromolecules such as hemicellulose, cellulose, structural protein, arabinoxylan, and pectin, which can be extracted by acid, alkali, or enzymatic hydrolysis along with various thermal and non-thermal treatments. IBPs obtained from various sources exhibited a wide range of biological activities, including antioxidant, anti-inflammatory, antihypertensive, anticancer, anti-obesity, and anti-diabetic properties. In this contribution, the chemistry, distribution, biological activities, metabolism, and extraction methods of IBPs, and how they are affected by various treatments, are summarized. In particular, the effect of thermal and non-thermal processing on the release of IBPs and their antioxidant potential is discussed.

UPLC-Q-TOF-MS/MS Analysis of Phenolic Compounds from the Fruit of Cephalostachyum fuchsianum Gamble and Their Antioxidant and Cytoprotective Activities

Bamboo is a widely distributed graminaceous plant in China and is a potential source of bioactive substances. Incidentally, bamboo’s fruit is rich in phytochemicals such as polyphenols and flavonoids, which are significant to human health. In this study, we identified the phenolic compounds of the fruit and investigated the antioxidant activities of Cephalostachyum fuchsianum Gamble (CFG) fruit polyphenols with in vitro and in vivo tests for the first time. UPLC–Q–TOF–MS/MS analysis results showed that the fruit contained 43 phenolic compounds, including 7 hydroxybenzoic acids, 12 flavonoids, 7 coumarins, 10 hydroxycinnamic acids, 1 terpenoid, and 5 lignans. The TPC of SP extracts was higher than that of IBPs extracts in FP and FF. The SP extracts in FP showed better antioxidant activities in vitro compared to those in FF. In addition, polyphenols from CFG fruits protected against H₂O₂-induced oxidative damage in HepG2 cells, and the protective effect of polyphenols in FP was superior to that in FF. The analysis results showed that CFG fruit has great potential in exploiting natural chemical substances, which can provide valuable pieces of information for the further development and utilization of CFG.

Chemical basis of hawthorn processed with honey protecting against myocardial ischaemia

Hawthorn including many plants from the genus Crataegus (C.) is used for traditional medicines, herbal drugs, and dietary supplements all over the world. In China, C. pinnatifida Bge. var. major N, E. Br, and C. pinnatifida Bge. are two major species that are used as hawthorn. The purpose of this study is to assay the myocardial protection of hawthorn fruit processed with honey (MSZ) and screen the chemical basis of MSZ on this effect. Firstly, ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC/Q-TOF-MS) was used to analyze the chemical constituents of the sliced dry fruit of hawthorn (SZ) and MSZ. Principal component analysis (PCA) was used to differentiate them. Orthogonal partial least squares-discriminate analysis (OPLS-DA) was applied to screen different compounds between SZ and MSZ, and 32 different compounds were selected. Then a pharmacodynamic test to investigate their protective effect against myocardial ischaemia was carried out. The results demonstrated that the protective effect of MSZ was better than that of SZ on the same dose. Finally, the chemical basis for the protective effect provided by MSZ against myocardial ischaemia was speculated based on correlation analysis. Taken together, all these results suggest that phenylpropanoids, organic acids, tannins, and flavonoids might be the chemical basis of MSZ protecting against myocardial ischaemia.

Review of Distribution, Extraction Methods, and Health Benefits of Bound Phenolics in Food Plants

Phenolic compounds are important functional bioactive substances distributed in various food plants. They have gained wide interest from researchers due to their multiple health benefits. There are two forms of phenolic compounds: free form and bound form. The latter is also called bound phenolics (BPs), which are found mainly in the cell wall and distributed in various tissues/organs of the plant body. They can either chemically bind to macromolecules and food matrixes or be physically entrapped in food matrixes and intact cells. Various isolation methods, including chemical, biological, and physical methods, have been employed to extract BPs from plants. BPs have been shown to have strong biological activities, including antioxidant, probiotic, anticancer, anti-inflammation, antiobesity, and antidiabetic effects as well as beneficial effects on central nervous system diseases. This review summarizes research findings on these topics to help in better understanding of BPs and provide comprehensive information on their health effects.

Antioxidant evaluation-guided chemical profiling and structure-activity analysis of leaf extracts from five trees in Broussonetia and Morus (Moraceae)

Morus and Broussonetia trees are widely used as food and/or feed. Among 23 phenolics identified from leaves of five Moraceae species using UPLC–QTOF–MS/MS, 15 were screened using DPPH/ABTS-guided HPLCs, including seven weak (flavonoids with one hydroxyl on B-ring) and eight strong (four caffeoylquinic acids and four flavonoids, each with a double hydroxyl on B-ring) antioxidants. We then determined the activity and synergistic effects of individual antioxidants and a mixture of the eight strongest antioxidants using DPPH-guided HPLC. Our findings revealed that (1) flavonoid glucuronide may have a more negative effect on antioxidant activity than glucoside, and (2) other compounds in the mixture may exert a negative synergistic effect on antioxidant activity of the four flavonoids with B-ring double hydroxyls but not the four caffeoylquinic acids. In conclusion, the eight phenolics with the strongest antioxidant ability reliably represented the bioactivity of the five extracts examined in this study. Moreover, the Morus alba hybrid had more phenolic biosynthesis machinery than its cross-parent M. alba, whereas the Broussonetia papyrifera hybrid had significantly less phenolic machinery than B. papyrifera. This difference is probably the main reason for livestock preference for the hybrid of B. papyrifera over B. papyrifera in feed.