Secondary metabolites from the flower buds of Lonicera japonica and their in vitro anti-diabetic activities

Regulatory mechanisms and biosynthesis of chlorogenic acid in Lonicera japonica: insights from tissue culture and inducer treatments

Plant tissue culture is a fundamental and widely applied technique in plant biology and agriculture. In medicinal plant research, tissue culture plays an indispensable role in the conservation of endangered species, the rapid propagation of valuable resources, the preservation of germplasm, and the production of secondary metabolites. As a representative medicinal plant of the Lonicera genus, L. japonica is widely utilized worldwide due to its significant economic, ecological, medicinal, and ornamental value. By using tissue culture technology, it is possible to significantly enhance the production of secondary metabolites in L. japonica and effectively alleviate resource shortages, providing a new approach for its sustainable utilization. This review summarizes the recent research progress on L. japonica in the field of tissue culture, covering aspects such as direct organogenesis, indirect organogenesis through callus tissues, protoplast culture, hairy root culture, and polyploid culture. Additionally, the biosynthetic pathway of chlorogenic acid was explored in detail, and the mechanism of action of inducers in plant cells was analyzed. The study focused on the potential regulatory mechanisms of inducers on chlorogenic acid. Eventually, the future development trends of medicinal plant biotechnology are envisioned, aiming to provide a broader perspective for the in-depth study of medicinal plants and to promote continuous development and innovation in this field.

Biochemical and In Silico Aspects of Active Compounds From Nyctanthes arbor-tristis Flower As Antidiabetic Agent

Targeting alpha-glucosidase (maltase-glucoamylase [MGAM] and sucrase-isomaltase [SI]) under diabetes conditions is important to overcome hyperglycemia. Moreover, it is necessary to mitigate hyperglycemia-mediated oxidative stress to evade the progression of diabetes-associated secondary complications. Hence, in the present study, under-explored Nyctanthes arbor-tristis flowers (NAFs) were studied for inhibition of alpha-glucosidase activities. The NAF methanolic extract (NAFME) was prepared. Through liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) analysis, various phytocompounds belonging to different classes-flavonoids, iridoid glycosides, proanthocyanidin, anthocyanin, polyphenol, phenolic acid, fatty acid ester, and carotenoid-were identified. NAFME showed in vitro antioxidant activity. NAFME inhibited maltase, sucrase, glucoamylase, and isomaltase in mixed mode with Ki values of 179.93, 176.38, 126.03, and 201.56 µg/mL, respectively. In silico screening of phytocompounds identified in NAFME indicated that hinokiflavone (HKF), pelargonidin-3-O-glucoside (PG), isorhamnetin-3-glucoside-7-rhamnoside (IGR), and petunidin-3-rutinoside (PR) showed better interactions with different subunits of human alpha-glucosidase, namely, N-terminal (Nt-MGAM and Nt-SI) and C-terminal (Ct-MGAM and Ct-SI). Molecular dynamics (MD) simulation, binding free energy study (molecular mechanics-generalized Born surface area [MM/GBSA]), and post-MD simulation studies (principal component analysis [PCA] and dynamic cross-correlation matrix [DCCM]) provided an in-depth understanding of these ligands' interactions with proteins. The overall efficacy of NAFME against oxidative stress and alpha-glucosidase in vitro is understood. Moreover, in silico analysis has shown the possible potential of HKF, PG, IGR, and PR to act as alpha-glucosidase inhibitors. Further studies on the antidiabetic potential of NAFME, HKF, PG, IGR, and PR in in vivo conditions are required to fully unveil the applicability of NAFME in the management of T2DM as a complementary medicine.

Global lysine succinylation analysis unveils post-translational regulation effect on phenylpropanoid metabolism remodeling during Lonicera japonica flower development

Lonicera japonica plays a significant role in traditional Chinese medicine and as a food source, making it a focus of studies on protein succinylation and its potential role in regulating secondary metabolism during flower development. This study aimed to clarify the regulatory mechanism of protein succinylation on phenylpropanoid-related phenotypic changes by conducting a global lysine succinylation proteomic analysis across different flowering stages. A total of 586 lysine succinylated peptides in 303 proteins were identified during early and late floral stages. Functional enrichment analysis revealed that succinylated proteins primarily participated in the tricarboxylic acid (TCA) cycle, amino acid metabolism, and secondary metabolism. The abundance of succinylated aspartate transaminase (AT), 4-coumarate-CoA ligase (4CL), and phenylalanine N-hydroxylase (CYP79A2) in phenylpropanoid metabolism varied during flower development. In vitro experiments demonstrated that succinylation increased AT activity while inhibited 4CL activity. Decreased levels of total flavonoids and phenolic acids indicated significant alterations in phenylpropanoid metabolism during later floral stages. These results suggest that succinylation of TCA cycle proteins not only influences flower development but also, together with AT-4CL-CYP79A2 co-succinylation, redirects phenylpropanoid metabolism during flower development in L. japonica.

NMR-Guided Isolation of Anti-inflammatory Carabranolides from the Fruits of Carpesium abrotanoides L

Carabranolides present characteristic NMR resonances for the cyclopropane moiety, which distinctly differ from those of other compounds and were used for an NMR-guided isolation in this study. As a result, 11 undescribed carabranolides (1-11), along with five known ones (12-16), were isolated from the fruits of Carpesium abrotanoides L. Compounds 1-11 are new esters of carabrol at C-4 with different carboxylic acids. Their structures were elucidated by HRESIMS and NMR spectroscopic data analysis. The biological evaluation showed that compounds 2-4, 15, and 16 exhibited significant inhibitory activity against LPS-induced NO release with an IC50 value of 5.6-9.1 μM and dose-dependently decreased iNOS protein expression in RAW264.7 cells.

Bioactive compounds, nanoparticles synthesis, health benefits and potential utilization of edible flowers for the development of functional dairy products: a review

The food sector faces difficulty meeting the expectations for high-quality food items with safe and clean perceptions in light of customers' increased concern and economic sanctions of synthetic and hazardous chemicals. Besides their widespread use as decoration, flowers are known to be consumed as a traditional food or a component of complementary therapy in many different civilizations worldwide. Because of their nutritional importance as a source of nutrients, proteins, essential amino acids, bioactive compounds, etc., many edible flowers can be viewed as a food source rather than just a delicacy or decoration. Polyphenols, flavonoids, and carotenoids are the phytochemicals that make up the bioactive components of edible flowers. These substances have anti-inflammatory, antibacterial, and antioxidant properties that can improve the nutritional profile of dairy products. Nanoparticles have become a cutting-edge strategy to make use of these advantages. In addition to encapsulating and protecting medicinal substances, nanoparticles made from edible flowers also enable regulated release, increasing bioavailability and durability. Numerous opportunities exist for the addition of edible flower- nanoparticles to dairy products. Their inclusion can add distinctive flavours, colours, and sensations, boosting the consumer's sensory perception. This review quotes the recent studies and discusses different aspects such as nanoparticle synthesis, quantification and characterization, health benefits, novel ingredient for the development of functional food, and the bioactive compounds for different varieties of edible flowers.Kindly check and confirm the edit made in the title.  The final title  is : "Bioactive compounds,nanoparticles synthesis, health benefits andpotential utilization of edible flowers for thedevelopment of functional dairy products: areview".

Graphical abstract

The comparative analysis of Lonicerae Japonicae Flos and Lonicerae Flos: A systematical review

ETHNOPHARMACOLOGICAL RELEVANCE

Lonicerae Japonicae Flos (LJF) and Lonicerae Flos (LF) were once used as the same herb in China, but they were distinguished by Chinese Pharmacopoeia in 2005 in terms of their medicinal history, plant morphology, medicinal properties and chemical constituents. However, their functions, flavor, and meridian tropism are the same according to the Chinese pharmacopoeia 2020 edition, making researchers and customers confused.

AIM OF THE REVIEW

This review aimed to provide a comparative analysis of LJF and LF in order to provide a rational application in future research.

MATERIALS AND METHODS

The information was gathered from China National Knowledge Infrastructure (CNKI), SciFinder, Google Scholar, PubMed, Web of Science, and Chinese Masters and Doctoral Dissertations (all chosen articles were reviewed attentively from 1980.1 to 2023.8).

RESULTS

Till now, 507 chemical compounds have been isolated and identified in LJF, while 223 ones (79 overlapped compounds) are found in LF, including organic acids and derivatives, flavonoids, triterpenoids, iridoids, and essential oil components, etc. In addition, the pharmacological activities of LJF and LF, especially for their anti-influenza efficacy and mechanism, and their difference in terms of pharmacokinetic parameters, toxicology, and clinical applications were also summarized.

CONCLUSION

The current work offers comparative information between LJF and LF in terms of botany, traditional uses, phytochemistry, ethnopharmacology, pharmacokinetics, toxicology, and pharmacology, especially their anti-influenza activities. Despite the same clinical applications and similar chemical components in LJF and LF, differentiated components were still existed, resulting in differentiated pharmacological activities and pharmacokinetics parameters. Moreover, the research about anti-influenza mechanism and functional substances of LJF and LF is dramatically limited, restricting their clinical applications. In addition, few studies have investigated the metabolism feature of LF in vivo, which is one of the important bases for revealing the pharmacological mechanism of LF. At the same time, the toxicity of LJF and LF is not fully studied, and the toxic compounds of LJF and LF need to be screened out in order to standardize the drug use and improve their rational applications.

TiO2 nanotube immobilised 5-lipoxygenase-mediated screening and isolation of anti-inflammatory active compounds from the leaves of lonicera japonica thunb

In this work, a highly effective separation approach mediated by 5-Lipoxygenase (5-LOX) was established for screening and isolation of anti-inflammatory ingredients from leaves of Lonicera japonica Thunb. (LLJT). Using 5-LOX immobilised on TiO₂ nanotubes as a microreactor, the targeted screening was exploited by combining with HPLC-MS system. Four compounds confirmed as luteolin, luteoside, lonicerin, and isochlorogenic acid C and a fraction (M1) were screened out to be potent inhibitors of 5-LOX. Their anti-inflammatory activities were further investigated and confirmed by RAW 264.7 cells inflammation model and rat foot swelling model. Furthermore, M1 was prepared by MCI GEL CHP20P column chromatography, and further separated by Pre-HPLC. One new compound confirmed to be 5,7,3′,4′-tetrahydroxyflavone-7-O-sambubioside was first isolated from LLJT. The results provide a new method for the effective separation of active components derived from natural products.

Highlights

A 5-LOX mediated separation method was established for isolation of anti-inflammatory compounds.

An anti-inflammatory ingredient was separated by MCI GEL CHP20P column chromatography.

One new compound was first isolated from leaves of Lonicera japonica Thunb.

5-LOX was immobilised on TiO₂ nanotubes and exploited by combining with HPLC-MS system.

The anti-inflammatory activity of screened components was evaluated.

Lonicerae Japonicae Flos extract and chlorogenic acid attenuates high-fat-diet- induced prediabetes via CTRPs-AdipoRs-AMPK/PPARα axes

Prediabetes is considered an important reversible checkpoint in T2DM development, which can be delayed and prevented by early interventions. Lonicerae Japonicae Flos (LJF), an edible-medicinal herb, is rich in chlorogenic acid (CGA, 5-O-caffeoylquinic acid) and exerts anti-diabetes effects, but its role in prediabetes remains unclear. The purpose of this study was to explore the effects of LJF extract and CGA on rat with prediabetes. Sprague-Dawley rats were given high-fat diet (HFD) to induce prediabetes, and glycolipid metabolism parameters and molecular mechanisms were evaluated. LJF (the LJF extract treatment group) and CGA (the pure CGA treatment group) significantly attenuated HFD-induced prediabetes with impaired glucose tolerance and dyslipidemia, but their mechanisms of action are not exactly the same. Specifically, LJF prioritizes increasing protective lipid species [such as increasing blood polyunsaturated fatty acids (PUFA)-containing diacylglycerol (DAG) species, high-density lipoprotein-cholesterol (HDL-C)], whereas CGA prioritizes reducing detrimental lipid species [such as saturated fatty acid-containing DAG species, low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC)]. In addition, CGA significantly increased the content of blood very-long-chain fatty-acid (VLCFA)-containing ceramides species. This could be explained mechanically by a distinction between LJF and CGA's effects on C1q/TNF-related proteins (CTRPs) which activate adiponectin receptors, triggering several downstream reactions. Because both LJF and CGA upregulated liver expression of adiponectin receptors (AdipoR1 and AdipoR2) and enhanced the activity of downstream AMPK. LJF also increased serum levels of CTRP3 and CTRP9, especially CTRP9, whereas CGA had higher serum CTRP3 and upregulated liver PPARa expression. Additionally, ELOVL6 expression in the liver was greater in CGA than LJF. This study demonstrates that LJF and CGA exert hypoglycemic and lipid modulation capacity to prevent prediabetes may through the CTRPs-AdipoRs-AMPK/PPARα axes and promoting ELOVL6 protein expression.

Update of Indoles: Promising molecules for ameliorating metabolic diseases

Obesity and metabolic disorders have gradually become public health-threatening problems. The metabolic disorder is a cluster of complex metabolic abnormalities which are featured by dysfunction in glucose and lipid metabolism, and results from the increasing prevalence of visceral obesity. With the core driving factor of insulin resistance, metabolic disorder mainly includes type 2 diabetes mellitus (T2DM), micro and macro-vascular diseases, non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and the dysfunction of gut microbiota. Strategies and therapeutic attention are demanded to decrease the high risk of metabolic diseases, from lifestyle changes to drug treatment, especially herbal medicines. Indole is a parent substance of numerous bioactive compounds, and itself can be produced by tryptophan catabolism to stimulate glucagon-like peptide-1 (GLP-1) secretion and inhibit the development of obesity. In addition, in heterocycles drug discovery, the indole scaffold is primarily found in natural compounds with versatile biological activity and plays a prominent role in drug molecules synthesis. In recent decades, plenty of natural or synthesized indole deriviatives have been investigated and elucidated to exert effects on regulating glucose hemeostasis and lipd metabolism. The aim of this review is to trace and emphasize the compounds containing indole scaffold that possess immense potency on preventing metabolic disorders, particularly T2DM, obesity and NAFLD, along with the underlying molecular mechanisms, therefore facilitate a better comprehension of their druggability and application in metabolic diseases.

Genus Lonicera: New drug discovery from traditional usage to modern chemical and pharmacological research

BACKGROUND

Lonicera Linn. belonging to the family Caprifoliaceae, the largest genus in the plant family, includes about more than 200 species, which are mainly distributed in northern Africa, North America, Europe and Asia. Some species of this genus have been usually used in traditional Chinese medicine as well as functional foods, cosmetics and other applications, such as L. japonica Thunb. Bioactive components and pharmacological activities of the genus Lonicera plants have received an increasing interest from the scientific community. Thus, a comprehensive and systematic review on their traditional usage in China, chemical components, and their pharmacological properties of their whole plants, bioactive extracts, and bioactive isolates including partial structure-activity relationships from the genus is indispensable.

METHODS

Information on genus Lonicera of this systematic electronic literature search was gathered via the published articles, patents, clinical trials website (https://clinicaltrials.gov/) and several online bibliographic databases (PubMed, Sci Finder, Research Gate, Science Direct, CNKI, Web of Science and Google Scholar). The following keywords were used for the online search: Lonicera, phytochemical composition, Lonicerae japonica, Lonicera review articles, bioactivities of Lonicera, anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, anti-diabetic, and clinical trials. This review paper consists of a total of 225 papers covering the Lonicera genus from 1800 to 2021, including research articles, reviews, patents, and book chapters.

RESULTS

In this review (1800s-2021), about 420 components from the genus of Lonicera Linn. including 87 flavonoids, 222 terpenoids, 51 organic acids, and other compounds, together with their pharmacological activities including anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, antidiabetic, anti-allergic, immunomodulatory effects, and toxicity were summarized.

CONCLUSION

The relationship is discussed among their traditional usage, their pharmacological properties, and their chemical components, which indicate the genus Lonicera have a large prospect in terms of new drug exploitation, especially in COVID-19 treatment.

Approaches to Decrease Hyperglycemia by Targeting Impaired Hepatic Glucose Homeostasis Using Medicinal Plants

Liver plays a pivotal role in maintaining blood glucose levels through complex processes which involve the disposal, storage, and endogenous production of this carbohydrate. Insulin is the hormone responsible for regulating hepatic glucose production and glucose storage as glycogen, thus abnormalities in its function lead to hyperglycemia in obese or diabetic patients because of higher production rates and lower capacity to store glucose. In this context, two different but complementary therapeutic approaches can be highlighted to avoid the hyperglycemia generated by the hepatic insulin resistance: 1) enhancing insulin function by inhibiting the protein tyrosine phosphatase 1B, one of the main enzymes that disrupt the insulin signal, and 2) direct regulation of key enzymes involved in hepatic glucose production and glycogen synthesis/breakdown. It is recognized that medicinal plants are a valuable source of molecules with special properties and a wide range of scaffolds that can improve hepatic glucose metabolism. Some molecules, especially phenolic compounds and terpenoids, exhibit a powerful inhibitory capacity on protein tyrosine phosphatase 1B and decrease the expression or activity of the key enzymes involved in the gluconeogenic pathway, such as phosphoenolpyruvate carboxykinase or glucose 6-phosphatase. This review shed light on the progress made in the past 7 years in medicinal plants capable of improving hepatic glucose homeostasis through the two proposed approaches. We suggest that Coreopsis tinctoria, Lithocarpus polystachyus, and Panax ginseng can be good candidates for developing herbal medicines or phytomedicines that target inhibition of hepatic glucose output as they can modulate the activity of PTP-1B, the expression of gluconeogenic enzymes, and the glycogen content.

Use Chou's 5-steps rule to identify protein post-translational modification and its linkage to secondary metabolism during the floral development of Lonicera japonica Thunb

Lonicera japonica Thunb. is widely used in traditional medicine systems of East Asian and attracts a large amount of studies on the biosynthesis of its active components. Currently, there is little understanding regarding the regulatory mechanisms behind the accumulation of secondary metabolites during its developmental stages. In this study, published transcriptomic and proteomic data were mined to evaluate potential linkage between protein modification and secondary metabolism during the floral development. Stronger correlations were observed between differentially expressed genes (DEGs) and their corresponding differentially abundant proteins (DAPs) in the comparison of juvenile bud stage (JBS)/third green stage (TGS) vs. silver flowering stage (SFS). Seventy-five and 76 cor-rDEGs and cor-rDAPs (CDDs) showed opposite trends at both transcriptional and translational levels when comparing their levels at JBS and TGS relative to those at SFS. CDDs were mainly involved in elements belonging to the protein metabolism and the TCA cycle. Protein-protein interaction analysis indicated that the interacting proteins in the major cluster were primarily involved in TCA cycle and protein metabolism. In the simple phenylpropanoids biosynthetic pathway of SFS, both phospho-2-dehydro-3-deoxyheptonate aldolase (PDA) and glutamate/aspartate-prephenate aminotransferase (AAT) were decreased at the protein level, but increased at the gene level. A confirmatory experiment indicated that protein ubiquitination and succinylation were more prominent during the early floral developmental stages, in correlation with simple phenylpropanoids accumulation. Taken together, those data indicates that phenylpropanoids metabolism and floral development are putatively regulated through the ubiquitination and succinylation modifications of PDA, AAT, and TCA cycle proteins in L. japonica.

Potential Application of Lonicera japonica Extracts in Animal Production: From the Perspective of Intestinal Health

Lonicera japonica (L. japonica) extract is rich in active substances, such as phenolic acids, essential oils, flavones, saponins, and iridoids, which have a broad spectrum of antioxidant, anti-inflammatory, and anti-microbial effect. Previous studies have demonstrated that L. japonica has a good regulatory effect on animal intestinal health, which can be used as a potential antibiotic substitute product. However, previous studies about intestinal health regulation mainly focus on experimental animals or cells, like mice, rats, HMC-1 Cells, and RAW 264.7 cells. In this review, the intestinal health benefits including antioxidant, anti-inflammatory, and antimicrobial activity, and its potential application in animal production were summarized. Through this review, we can see that the effects and mechanism of L. japonica extract on intestinal health regulation of farm and aquatic animals are still rare and unclear. Further studies could focus on the regulatory mechanism of L. japonica extract on intestinal health especially the protective effects of L. japonica extract on oxidative injury, inflammation, and regulation of intestinal flora in farm animals and aquatic animals, thereby providing references for the rational utilization and application of L. japonica and its extracts in animal production.

Antioxidant and anticancer potentials of edible flowers: where do we stand?

Edible flowers are attracting special therapeutic attention and their administration is on the rise. Edible flowers play pivotal modulatory roles on oxidative stress and related interconnected apoptotic/inflammatory pathways toward the treatment of cancer. In this review, we highlighted the phytochemical content and therapeutic applications of edible flowers, as well as their modulatory potential on the oxidative stress pathways and apoptotic/inflammatory mediators, resulting in anticancer effects. Edible flowers are promising sources of phytochemicals (e.g., phenolic compounds, carotenoids, terpenoids) with several therapeutic effects. They possess anti-inflammatory, anti-diabetic, anti-microbial, anti-depressant, anxiolytic, anti-obesity, cardioprotective, and neuroprotective effects. Edible flowers potentially modulate oxidative stress by targeting erythroid nuclear transcription factor-2/extracellular signal-regulated kinase/mitogen-activated protein kinase (Nrf2/ERK/MAPK), reactive oxygen species (ROS), nitric oxide (NO), malondialdehyde (MDA) and antioxidant response elements (AREs). As the interconnected pathways to oxidative stress, inflammatory mediators, including tumor necrosis factor (TNF)-α, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukins (ILs) as well as apoptotic pathways such as Bcl-2-associated X protein (Bax), Bcl-2, caspase and cytochrome C are critical targets of edible flowers in combating cancer. In this regard, edible flowers could play promising anticancer effects by targeting oxidative stress and downstream dysregulated pathways.

Bioactive flavonoids from Rubus corchorifolius inhibit α-glucosidase and α-amylase to improve postprandial hyperglycemia

This research established an optimized method for the extraction and enrichment of flavonoids from R. corchorifolius fruit. Under the optimized extraction conditions, 12 flavonoids (1-12) were isolated, of which six (2-4, 9-10, 12) were obtained from R. corchorifolius for the first time. Compound 4 showed significant α-glucosidase (4.96 μM) and α-amylase (8.04 μM) inhibitory effects. Molecular modeling revealed that compound 4 exhibits strong binding with the active sites of α-glucosidase and α-amylase. Lineweaver-Burk plot analysis and surface plasmon resonance revealed the possible dynamic binding mechanism of the flavonoids with α-glucosidase and α-amylase. The enriched flavonoids and compound 4 showed significant hypoglycemic effects in mice administered a high dose of glucose. In this study, a variety of flavonoids with hypoglycemic activity were found for the first time, revealing the rich chemical composition of R. corchorifolius fruit and highlighting the potential value of R. corchorifolius fruit flavonoids as dietary supplements.

Distribution of enzymatic and alkaline oxidative activities of phenolic compounds in plants

In this study, we screened 287 plant tissue samples from 175 plant species for their phenolic profiles. The samples were oxidized enzymatically in planta or at high pH in vitro to determine how these two oxidative conditions would alter the initial polyphenol profiles of the plant. Compounds that contained a pyrogallol or dihydroxyphenethyl group were highly active at pH 10. Enzymatic oxidation favored compounds that contained a catechol group, whereas compounds containing a pyrogallol group or monohydroxysubstituted phenolic moieties at most were oxidized less frequently. This study gives a broad overview of the distribution and alkaline oxidative activities of water-soluble phenolic compounds in plants as well as the enzymatic oxidative activities of various plant tissues.

An update on the health benefits promoted by edible flowers and involved mechanisms

The aim of this review is to provide new findings on health effects of edible flowers since 2015. The antioxidant, anti-inflammatory, anti-cancer, hepatoprotective, neuroprotective, anti-diabetic, anti-osteoporosis, anti-obesity, and anti-hypertensive have been reviewed, and the effective concentrations of flower extracts have been summarized. Among all the health benefits mentioned, anti-osteoporosis, anti-obesity, and anti-hypertensive have rarely been mentioned before 2015. Some health benefits mechanisms of edible flowers were discussed frequently after 2015. Some newly found phytochemicals such as polysaccharides were shown to be beneficial to human health. Species of Rosa, Chrysanthemum, and Osmanthus have been reported to exert different health effects on human. For the toxicity studies, the safe level of flower extracts in cell and animal models were at hundreds of parts per million (ppm) level. In consideration of health promoting effects and toxicities of edible flowers, they could serve as potential natural health products for different health benefits.

A new nitrogen-containing iridoid glycoside from lonicera macranthoides

A new nitrogen-containing iridoid glycoside, named (7 R,3'R)-lonijapospiroside A (1), together with thirteen known iridoid glycosides, were isolated from the flower buds of Lonicera macranthoides. The structures of these compounds were established on the basis of spectroscopic analyses. Among them, compounds 1-4 are four diastereoisomers, and their absolute configurations were accurately established by the NOE spectra as well as comparison of their experimental and calculated ECD spectra. The anti-inflammatory activities of all isolates were evaluated by measuring their inhibitory effects on NO, IL-6, and TNF-α production in LPS stimulated RAW 264.7 macrophages. Compound 14 exhibited anti-inflammatory activities by inhibiting IL-6 with an IC₅₀ value of 54.70 μM, comparable to that of the positive control (hydrocortisone, IC₅₀: 62.6 ± 1.7 μM).

De novo transcriptomic analysis of light-induced flavonoid pathway, transcription factors in the flower buds of Lonicera japonica

KEY MESSAGE

Transcriptomic analysis of the relationship between gene expression patterns and flavonoid contents in the flower buds of Lonicera japonica under light-induced conditions, especially the flavonoid pathway genes and transcription factors.

ABSTRACT

Flos Lonicerae Japonicae (FLJ), the flower buds of Lonicera japonica Thunb., has been used to treat some human diseases including severe respiratory syndromes and hand-foot-and-mouth diseases owing to its putative antibacterial, and antiviral effects. Luteoloside is a flavonoid that is used by the Chinese Pharmacopoeia to evaluate the quality of FLJ. Light is an important environmental factor that affects flavonoid biosynthesis in the flower buds of L. japonica. However, how light triggers increases in flavonoid production remains unclear. To enhance our understanding of the mechanism involved in light-regulated flavonoid biosynthesis, we sequenced the transcriptomes of L. japonica exposed to three different light conditions: 100% light intensity (CK), 50% light intensity (LI50), and 25% light intensity (LI25) using an Illumina HiSeq 4000 System. A total of 77,297 unigenes with an average length of 809 bp were obtained. Among them, 43,334 unigenes (56.06%) could be matched to at least one biomolecular database. Additionally, 4188, 1545 and 1023 differentially expressed genes (DEGs) were identified by comparative transcriptomics LI25-vs-CK, LI50-vs-CK, and LI25-vs-LI50, respectively. Of note, genes known to be involved in flavonoid biosynthesis, such as 4-coumarate coenzyme A ligase (4CL), and chalcone synthase (CHS) were up-regulated. In addition, a total of 1649 transcription factors (TFs) were identified and divided into 58 TF families; 98 TFs exhibited highly dynamic changes in response to light intensity. Quantitative real-time PCR (qRT-PCR) was used to test the expression profiles of the RNA sequencing (RNA-Seq) data. This study offers insight into how transcriptional expression pattern is influenced by light in the flower buds of L. japonica, and will enhance the understanding of molecular mechanisms of flavonoid biosynthesis in response to light in L. japonica.

A proposed protocol based on integrative metabonomics analysis for the rapid detection and mechanistic understanding of sulfur fumigation of Chinese herbal medicines

In the current work, Lonicera japonica Flos (FLJ) was selected as a model Chinese herbal medicine (CHM) and a protocol was proposed for the rapid detection of sulfur-fumigated (SF) CHMs. A multiple metabonomics analysis was conducted using HPLC, NIR spectroscopy and a UHPLC-LTQ-Orbitrap mass spectrometer. First, the group discriminatory potential of each technique was respectively investigated based on PCA. Then, the effect of mid-level metabonomics data fusion on sample spatial distribution was evaluated based on data obtained using the above three technologies. Furthermore, based on the acquired HRMS data, 76 markers discriminating SF from non-sulfur-fumigated (NSF) CHMs were observed and 49 of them were eventually characterized. Moreover, NIR absorptions of 18 sulfur-containing markers were identified to be in close correlation with the discriminatory NIR wavebands. In conclusion, the proposed protocol based on integrative metabonomics analysis that we established for the rapid detection and mechanistic explanation of the sulfur fumigation of CHMs was able to achieve variable selection, enhance group separation and reveal the intrinsic mechanism of the sulfur fumigation of CHMs.

Racemic indole alkaloids from the seeds of Peganum harmala

Five pairs of new 2-oxoindole alkaloids, (±)-peganumalines A-E (1-5), and a new indole alkaloid, peganumaline F (6), along with two known analogues, were isolated from the seeds of Peganum harmala. Their structures and absolute configurations were elucidated through spectroscopic analyses and quantum chemistry calculations. Notably, (±)-peganumalines A (1) represent a pair of rare 2-oxoindole dimeric alkaloid enantiomer with the hitherto unknown carbon skeleton. All isolates were tested for antiproliferative and antibacterial activities.

Protein tyrosine phosphatase 1B inhibitors from natural sources

Since PTP1B enzyme was discovered in 1988, it has captured the research community's attention. This landmark discovery has stimulated numerous research studies on a variety of human diseases, including cancer, inflammation, and diabetes. Tremendous progress has been made in finding PTP1B inhibitors and exploring PTP1B regulatory mechanisms. This review investigates for the natural PTP1B inhibitors, and focuses on the common characteristics of the discovered structures and structure-activity relationships. To facilitate understanding, all the natural compounds are here divided into five different classes (fatty acids, phenolics, terpenoids, steroids, and alkaloids), according to their skeletons. These PTP1B inhibitors of scaffold structures could serve as a theoretical basis for new concept drug discovery and design.

Optimization of Extraction Process for Antidiabetic and Antioxidant Activities of Kursi Wufarikun Ziyabit Using Response Surface Methodology and Quantitative Analysis of Main Components

By using extraction yield, total polyphenolic content, antidiabetic activities (PTP-1B and α-glycosidase), and antioxidant activity (ABTS and DPPH) as indicated markers, the extraction conditions of the prescription Kursi Wufarikun Ziyabit (KWZ) were optimized by response surface methodology (RSM). Independent variables were ethanol concentration, extraction temperature, solid-to-solvent ratio, and extraction time. The result of RSM analysis showed that the four variables investigated have a significant effect (p < 0.05) for Y₁, Y₂, Y₃, Y₄, and Y₅ with R² value of 0.9120, 0.9793, 0.9076, 0.9125, and 0.9709, respectively. Optimal conditions for the highest extraction yield of 39.28%, PTP-1B inhibition rate of 86.21%, α-glycosidase enzymes inhibition rate of 96.56%, and ABTS inhibition rate of 77.38% were derived at ethanol concentration 50.11%, extraction temperature 72.06°C, solid-to-solvent ratio 1 : 22.73 g/mL, and extraction time 2.93 h. On the basis of total polyphenol content of 48.44% in this optimal condition, the quantitative analysis of effective part of KWZ was characterized via UPLC method, 12 main components were identified by standard compounds, and all of them have shown good regression within the test ranges and the total content of them was 11.18%.

Structure-related protein tyrosine phosphatase 1B inhibition by naringenin derivatives

Naturally occurring flavonoids co-exist as glycoside conjugates, which dominate aglycones in their content. To unveil the structure-activity relationship of a naturally occurring flavonoid, we investigated the effects of the glycosylation of naringenin on the inhibition of enzyme systems related to diabetes (protein tyrosine phosphatase 1B (PTP1B) and α-glycosidase) and on glucose uptake in the insulin-resistant state. Among the tested naringenin derivatives, prunin, a single-glucose-containing flavanone glycoside, potently inhibited PTP1B with an IC₅₀ value of 17.5±2.6µM. Naringenin, which lacks a sugar molecule, was the weakest inhibitor compared to the reference compound, ursolic acid (IC₅₀: 5.4±0.30µM). In addition, prunin significantly enhanced glucose uptake in a dose-dependent manner in insulin-resistant HepG2 cells. Regarding the inhibition of α-glucosidase, naringenin exhibited more potent inhibitory activity (IC₅₀: 10.6±0.49µM) than its glycosylated forms and the reference inhibitor, acarbose (IC₅₀: 178.0±0.27µM). Among the glycosides, only prunin (IC₅₀: 106.5±4.1µM) was more potent than the positive control. A molecular docking study revealed that prunin had lower binding energy and higher binding affinity than glycosides with higher numbers of H-bonds, suggesting that prunin is the best fit to the PTP1B active site cavity. Therefore, in addition to the number of H-bonds present, possible factors affecting the protein binding and PTP1B inhibition of flavanones include their fit to the active site, hydrogen-bonding affinity, Van der Waals interactions, H-bond distance, and H-bond stability. Furthermore, this study clearly depicted the association of the intensity of bioactivity with the arrangement and characterization of the sugar moiety on the flavonoid skeleton.

Validation of Suitable Reference Genes for Assessing Gene Expression of MicroRNAs in Lonicera japonica

MicroRNAs (miRNAs), which play crucial regulatory roles in plant secondary metabolism and responses to the environment, could be developed as promising biomarkers for different varieties and production areas of herbal medicines. However, limited information is available for miRNAs from Lonicera japonica, which is widely used in East Asian countries owing to various pharmaceutically active secondary metabolites. Selection of suitable reference genes for quantification of target miRNA expression through quantitative real-time (qRT)-PCR is important for elucidating the molecular mechanisms of secondary metabolic regulation in different tissues and varieties of L. japonica. For precise normalization of gene expression data in L. japonica, 16 candidate miRNAs were examined in three tissues, as well as 21 cultivated varieties collected from 16 production areas, using GeNorm, NormFinder, and RefFinder algorithms. Our results revealed combination of u534122 and u3868172 as the best reference genes across all samples. Their specificity was confirmed by detecting the cycling threshold (C t) value ranges in different varieties of L. japonica collected from diverse production areas, suggesting the use of these two reference miRNAs is sufficient for accurate transcript normalization with different tissues, varieties, and production areas. To our knowledge, this is the first report on validation of reference miRNAs in honeysuckle (Lonicera spp.). Restuls from this study can further facilitate discovery of functional regulatory miRNAs in different varieties of L. japonica.