Isolation and Identification of Antioxidant Compounds fromGynura BicolorStems and Leaves

Two new 2-arylbenzo[b]furans from Itea indochinensis and their anti-hepatocellular carcinoma and anti-oxidant effects

Two new 2-arylbenzo[b]furans (1-2) and ten known compounds (3-12) were identified from the 95% EtOH extract of the branches and leaves of Itea indochinensis for the first time. Their structures were determined mainly based on extensive analyses of UV, IR, 1D/2D NMR and HRMS spectra. The results of MTT assays demonstrated the anti-tumor potential of compound 1 with good selectivity, which displayed moderate inhibitory effects on proliferation of SK-hep-1 cells with IC50 value of 22.3 μM, while weak inhibitory effect on proliferation of HepG2 cells with an inhibition rate of 25% at 20 μM, and no obviously inhibitory effect on proliferation of A549 cells at 20 μM. In addition, compound 1 exhibited its significant scavenging capacity on ABTS·+ free radical with an IC50 value of 0.11 mg/mL, while weak scavenging effects on DPPH and O2·- radicals with scavenging ratios of 32.93% and 21.49% at 1 mg/mL, respectively.

Study on 2-arylbenzo[b]furans from Itea omeiensis and their fragmentation patterns with Q-Orbitrap mass spectrometry

One new 2-arylbenzo[b]furan named iteafuranal F (1) as well as two known analogues (2-3) were isolated from the 95% EtOH extract of aerial parts of Itea omeiensis. Their chemical structures were constructed based on extensive analyses of UV, IR, 1D/2D NMR and HRMS spectra. Antioxidant assays revealed significant superoxide anion radical scavenging capacity of 1 with IC₅₀ value of 0.66 mg/mL, which was comparable to the efficiency of positive control of luteolin. In addition, the preliminary MS fragmentation patterns in negative ion mode were established to distinguish 2-arylbenzo[b]furans with C-10 in different oxidation states: the characteristic loss of CO molecule [M-H-28]^- was observed for 3-formyl-2-arylbenzo[b]furans, and the loss of CH₂O fragment [M-H-30]^- for 3-hydroxymethyl-2-arylbenzo[b]furans, and the loss of CO₂ fragment [M-H-44]^- for 2-arylbenzo[b]furan-3-carboxylic acids.

Dihydrocaffeic Acid-Is It the Less Known but Equally Valuable Phenolic Acid?

Dihydrocaffeic acid (DHCA) is a phenolic acid bearing a catechol ring and three-carbon side chain. Despite its being found in minor amounts in numerous plants and fungi of different origins, it has attracted the interest of various research groups in many fields of science, from food to biomedical applications. The review article presented herein aims to show a wider audience the health benefits and therapeutic, industrial, and nutritional potential of dihydrocaffeic acid, by sheddinglight on its occurrence, biosynthesis, bioavailability, and metabolism. The scientific literature describes at least 70 different derivatives of dihydrocaffeic acid, both those occurring naturally and those obtained via chemical and enzymatic methods. Among the most frequently used enzymes that were applied for the modification of the parent DHCA structure, there are lipases that allow for obtaining esters and phenolidips, tyrosinases used for the formation of the catechol ring, and laccases to functionalize this phenolic acid. In many studies, both in vitro and in vivo, the protective effect of DHCA and its derivatives on cells subjected to oxidative stress and inflammation were acknowledged.

Qualitative and quantitative method for quality control of Itea ilicifolia based on antioxidant Q-markers

Itea ilicifolia Oliv is a folk medicine with antioxidant potential. In this study, the fingerprints of 14 batches of I. ilicifolia were established by HPLC with 17 common peaks. The similarities evaluated by Similarity Evaluation System for Chromatographic Fingerprint of Chinese Materia (version 2012) were >0.89. Ten compounds were identified with definite structures by comparing the retention time and characteristic UV spectral pattern with those of reference substances. The antioxidant capacities of 14 batches of I. ilicifolia were evaluated based on O₂ ^·- , DPPH and ABTS^·+ radical scavenging assays in combination with ferric reducing antioxidant power assay. Via multivariate statistical analyses of gray relation analysis, bivariate correlation analysis and partial least squares regression analysis, a study on the spectrum-effect relationship was then performed to screen eight peaks as the antioxidant Q-markers of I. ilicifolia. The contents of representative antioxidant Q-markers (isoorientin, orientin, vitexin, isovitexin and iteafuranal A) in samples were accurately determined to be 0.054-0.118%, 0.034-0.080%, 0.018-0.055%, 0.031-0.091% and 0.033-0.140%, respectively. The qualitative and quantitative analytical method based on Q-markers helps to control the antioxidant quality of I. ilicifolia, which will lay the foundation to promote the rational utilization of I. ilicifolia in curing diseases related to oxidative stress.

Integration of the Metabolomic and Transcriptome Analysis Reveals the Remarkable Compounds of G. bicolor Young and Mature Leaves under Different Iron Nutrient Conditions

Gynura bicolor (Roxb. ex Willd.) DC. (G. bicolor) is a functional vegetable rich in iron (Fe) and widely grown in Asia (e.g., Japan and China). Because most Fe in the soil exists in the form of insoluble oxides or hydroxides, it is difficult for plants to obtain Fe from the soil. A comparative metabolomic and transcriptome study was carried out to investigate the effect of Fe deficiency on metabolite synthesis and gene expression in young and mature leaves of G. bicolor. Fe deficiency caused chlorosis and decreased the chlorophyll content in young leaves. The metabolomic results for young leaves showed that l-glutamate and 4-hydroxybutanoic acid lactone significantly increased and decreased, respectively. The transcriptome results showed that the expression levels of genes involved in ferric reduction oxidase 7 and 14-kDa proline-rich protein DC2.15-like were significantly upregulated and downregulated, respectively. However, Fe deficiency had little effect on mature leaves.

Traditional uses, phytochemistry, pharmacology and toxicology of the genus Gynura (Compositae): A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Gynura cass., belonging to the tribe Senecoineae of the family Compositae, contains more than 40 accepted species as annual or perennial herbs, mainly distributed in Asia, Africa and Australia. Among them, 11 species are distributed in China. Many of the Gynura species have been used as traditional herbal medicines for the treatment of diabetes mellitus, rheumatism, eruptive fever, gastric ulcer, bleeding, abscesses, bruises, burning pains, rashes and herpes zoster infection in tropical Asia countries such as China, Thailand, Indonesia, Malaysia, and Vietnam. Some of the species have been used as vegetables, tea beverage or ornamental plants by the local people.

AIM OF THE STUDY

A more comprehensive and in-depth review about the geographical distribution, traditional uses, chemical constituents and pharmacological activities as well as safe and toxicity of Gynura species has been summarized, hoping to provide a scientific basis for rational development and utilization as well as to foster further research of these important medicinal plant resources in the future.

MATERIALS AND METHODS

A review of the literature was performed based on the existing peer-reviewed researches by consulting scientific databases including Web of Science, PubMed, Elsevier, Google Scholar, SciFinder and China National Knowledge Infrastructure.

RESULTS

Many of the Gynura species have been phytochemically studied, which led to the isolation of more than 338 compounds including phenolics, flavonoids, alkaloids, terpenoids, steroids, cerebrosides, aliphatics and other compounds. Pharmacological studies in vitro and in vivo have also confirmed the various bioactive potentials of extracts or pure compounds from many Gynura plants, based on their claimed ethnomedicinal and anecdotal uses, including antioxidant, anti-inflammation, anticancer, antidiabetic, antihypertension, antibacterial and other activities. However, pyrrolizidine alkaloids (PAs) pose a threat to the medication safety and edible security of Gynura plants because of toxicity issues, requiring the need to pay great attention to this phenomenon.

CONCLUSION

The traditional uses, phytochemistry and pharmacology of Gynura species described in this review demonstrated that these plants contain a great number of active constituents and display a diversity of pharmacological activities. However, the mechanism of action, structure-activity relationship, potential synergistic effects and pharmacokinetics of these components need to be further elucidated. Moreover, further detailed research is urgently needed to explain the mechanisms of toxicity induced by PAs. In this respect, effective detoxification strategies need to be worked out, so as to support the safe and reasonable utilization of Gynura plant resources in the future.

Dihydrocaffeic Acid Prevents UVB-Induced Oxidative Stress Leading to the Inhibition of Apoptosis and MMP-1 Expression via p38 Signaling Pathway

Chronic UVB exposure promotes oxidative stress, directly causes molecular damage, and induces aging-related signal transduction, leading to skin photoaging. Dihydrocaffeic acid (DHCA) is a phenolic compound with potential antioxidant capacity and is thus a promising compound for the prevention of UVB-induced skin photodamage. The aim of this study was to evaluate the antioxidant and protective effect of DHCA against oxidative stress, apoptosis, and matrix metalloproteinase (MMP) expression via the mitogen-activated protein kinase (MAPK) signaling pathway on L929 fibroblasts irradiated with UVB. DHCA exhibited high antioxidant capacity on 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), 2,2-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS^•+), and xanthine/luminol/xanthine oxidase (XOD) assays and reduced UVB-induced cell death in the neutral red assay. DHCA also modulated oxidative stress by decreasing intracellular reactive oxygen species (ROS) and extracellular hydrogen peroxide (H₂O₂) production, enhancing catalase (CAT) and superoxide dismutase (SOD) activities and reduced glutathione (GSH) levels. Hence, cellular damage was attenuated by DHCA, including lipid peroxidation, apoptosis/necrosis and its markers (loss of mitochondria membrane potential, DNA condensation, and cleaved caspase 9 expression), and MMP-1 expression. Furthermore, DHCA reduced the phosphorylation of MAPK p38. These findings suggest that DHCA can be used in the development of skin care products to prevent UVB-induced skin damage.

Computational Analysis of Gynura bicolor Bioactive Compounds as Dipeptidyl Peptidase-IV Inhibitor

The inhibition of dipeptidyl peptidase-IV (DPPIV) is a popular route for the treatment of type-2 diabetes. Commercially available gliptin-based drugs such as sitagliptin, anagliptin, linagliptin, saxagliptin, and alogliptin were specifically developed as DPPIV inhibitors for diabetic patients. The use of Gynura bicolor in treating diabetes had been reported in various in vitro experiments. However, an understanding of the inhibitory actions of G. bicolor bioactive compounds on DPPIV is still lacking and this may provide crucial information for the development of more potent and natural sources of DPPIV inhibitors. Evaluation of G. bicolor bioactive compounds for potent DPPIV inhibitors was computationally conducted using Lead IT and iGEMDOCK software, and the best free-binding energy scores for G. bicolor bioactive compounds were evaluated in comparison with the commercial DPPIV inhibitors, sitagliptin, anagliptin, linagliptin, saxagliptin, and alogliptin. Drug-likeness and absorption, distribution, metabolism, and excretion (ADME) analysis were also performed. Based on molecular docking analysis, four of the identified bioactive compounds in G. bicolor, 3-caffeoylquinic acid, 5-O-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, and trans-5-p-coumaroylquinic acid, resulted in lower free-binding energy scores when compared with two of the commercially available gliptin inhibitors. The results revealed that bioactive compounds in G. bicolor are potential natural inhibitors of DPPIV.