Scopoletin: a review of its source, biosynthesis, methods of extraction, and pharmacological activities.

Scopoletin, also known as 6-methoxy-7 hydroxycoumarin, is one of the naturally occurring coumarin commonly found in many edible plants and plays an important role in human health. Despite the various potential pharmacological properties, the biosynthesis process, method of extraction, and mechanism of action on this compound have not been documented well. In this current review, the biosynthesis pathway, distribution of scopoletin in the plant kingdom, and extraction techniques are elaborated. The in vitro, in vivo, and in silico pharmacological studies are also discussed on antioxidant, antimicrobial, anticancer, anti-inflammation, and neuroprotective aspects of scopoletin. This study may help to understand the benefit of scopoletin containing plants and would be beneficial for the prevention and treatment of diseases.

A synergy interaction of artocarpin and tetracycline against Pseudomonas aeruginosa and its mechanism of action on membrane permeability.

The emergence of antibacterial resistance has significantly increased. Pseudomonas aeruginosa is associated with nosocomial infection and difficult to control. Artocarpin, a flavonoid from Artocarpus heterophyllus Lam. exhibits several pharmacological properties including antibacterial. The study was performed to evaluate interaction between artocarpin and antibiotics including tetracycline against P. aeruginosa. Its mechanism of action on membrane permeability was also investigated. Broth microdilution was conducted for the susceptibility assay. The interaction of artocarpin and antibiotics was evaluated using checkerboard method, the effect on alteration of membrane cell was investigated using bacteriolysis and the released of 260 nm materials. Artocarpin showed moderate to weak activity against the Gram-negative bacteria including P. aeruginosa with MIC values in the range of 31.25-250 µg/mL. A synergistic effect against P. aeruginosa was produced by the combination of artocarpin (31.25 µg/mL) and tetracycline (1.95 µg/mL) with FICI of 0.37. The time-killing assay showed that artocarpin enhance the antibacterial activity of tetracycline against P. aeruginosa by completely inhibiting the bacterial growth. Additionally, the mixture of artocarpin (31.25 µg/mL) and tetracycline (1.95 µg/mL) disrupted membrane permeability and lead to cell death. These results proposed that the combination of artocarpin and tetracycline may be used to overcome P. aeruginosa infection.

Antidiabetic Properties of Dietary Chrysin: A Cellular Mechanism Review.

Diabetes mellitus is the most common chronic metabolic disorder and is considered one of the leading causes of morbidity and mortality. The improperly-treated chronic hyperglycemia of diabetes has been related to several long-term complications and multiple organ failures, including nephropathy, which can lead to kidney failure, retinopathy with the potential loss of vision, and cardiovascular symptoms. Current commercially available synthetic glucose-lowering agents have been reported to have several adverse effects. Therefore, the search for alternative remedies such as medicinal plants and their active compounds have attracted attention. Chrysin is an active flavonoid that exists widely in various plants and diets and has been reported to possess pharmacological properties, including antidiabetic activity. Many studies have been conducted to characterize the antidiabetic of chrysin, as well as its potential pathways, in in vitro and in vivo experiments. Chrysin has shown promise as an antidiabetic agent in animal studies, thus, demonstrating its potential to be developed as an antidiabetic drug. This review discussed the antidiabetic action of chrysin and its mechanisms, including targeting different mechanisms such as stimulation of insulin signaling, blockage of endoplasmic reticulum stress and oxidative damage, promotion of skeletal glucose uptake, as well as modulation of apoptosis and autophagy signaling. Additionally, this review would be useful for further studies regarding the mechanism of work of plant derived-compound as a potential antidiabetic agent.

An experimental design approach for the optimization of scopoletin extraction from Morinda citrifolia L. using accelerated solvent extraction.

Scopoletin is regarded as a major constituent of noni (Morinda citrifolia L), which contributes to the antioxidative, anti-inflammatory, immunomodulatory, and hepatoprotective properties in noni. It is also suggested as a marker for identification and quality control of noni and its derivative products. With the increasing interest in noni due to its health benefits and therapeutic effects, it is important to establish a reliable extraction and analysis method to determine scopoletin content in noni samples. The present study proposes the use of accelerated solvent extraction (ASE) to extract scopoletin from noni, followed by detection using HPLC-DAD for rapid identification and quantification of scopoletin. The optimum operating conditions of ASE were investigated using response surface methodology (RSM), using a three factors central composite design. It was found that the optimum scopoletin yield was achieved by performing the extraction at an elevated temperature of 60 °C for 12 min, using ethanol as extraction solvent with solid to solvent ratio of 1:30 (w/v). The analytical method validation was carried out under optimum conditions. The results indicate that the proposed ASE-HPLC-DAD method was adequately sensitive for the quantification of scopoletin in extracts with limit of detection of 0.17 µg/g. The presented method also exhibits excellent linearity from 0.54 to 120.10 µg/g with R2 0.9995, high precision with RSD lower than 2% for intra-day and inter-day replication, and good recovery (99.88%). The established method was also successfully applied for scopoletin determination in noni product samples. The developed method provides a rapid and reliable method for the identification and quantification of scopoletin in noni samples that is suitable for routine procedures.

Dietary phlorizin enhances osteoblastogenic bone formation through enhancing ß-catenin activity via GSK-3ß inhibition in a model of senile osteoporosis.

Osteoporosis is one of the most prevalent forms of age-related bone diseases. Increased bone loss with advancing age has become a grave public health concern. This study examined whether phlorizin and phloretin, dihydrochalcones in apple peels, inhibited senile osteoporosis through enhancing osteoblastogenic bone formation in cell-based and aged mouse models. Submicromolar phloretin and phlorizin markedly stimulated osteoblast differentiation of MC3T3-E1 cells with increased transcription of Runx2 and osteocalcin. Senescence-accelerated resistant mouse strain prone-6 (SAMP6) mice were orally supplemented with 10 mg/kg phlorizin and phloretin daily for 12 weeks. Male senescence-accelerated resistant mouse strain R1 mice were employed as a nonosteoporotic age-matched control. Oral administration of ploretin and phorizin boosted bone mineralization in all the bones of femur, tibia and vertebra of SAMP6. In particular, phlorizin reduced serum RANKL/OPG ratio and diminished TRAP-positive osteoclasts in trabecular bones of SAMP6. Additionally, treating phlorizin to SAMP6 inhibited the osteoporotic resorption in distal femoral bones through up-regulating expression of BMP-2 and collagen-1 and decreasing production of matrix-degrading cathepsin K and MMP-9. Finally, phlorizin and phloretin antagonized GSK-3ß induction and ß-catenin phosphorylation in osteoblasts and aged mouse bones. Therefore, phlorizin and phloretin were potential therapeutic agents encumbering senile osteoporosis through promoting bone-forming osteoblastogenesis via modulation of GSK-3ß/ß-catenin-dependent signaling.

Chrysin ameliorates podocyte injury and slit diaphragm protein loss via inhibition of the PERK-eIF2α-ATF-CHOP pathway in diabetic mice.

Glomerular epithelial podocytes are highly specialized cells that play a crucial role in maintaining normal function of the glomerular filtration barrier via their foot processes. Chrysin (5,7-dihydroxyflavone) is a natural flavonoid found in propolis and mushrooms that has anti-inflammatory, antioxidant and anticancer properties. This study aimed to evaluate the renoprotective effects of chrysin on podocyte apoptotic loss and slit diaphragm protein deficiency in high glucose-exposed podocytes and in db/db mouse kidneys. Exposure to high glucose (33 mmol/L) caused glomerular podocyte apoptosis in vitro, which was dose-dependently attenuated by nontoxic chrysin (1-20 µmol/L) through reduction of DNA fragmentation. Chrysin treatment dose-dependently restored the increased Bax/Bcl-2 ratio, and suppressed Apaf-1 induction and the elevated cytochrome c release in high glucose-exposed renal podocytes. In diabetic db/db mice, oral administration of chrysin (10 mg·kg-1·d-1, for 10 weeks) significantly attenuated proteinuria, and alleviated the abnormal alterations in glomerular ultrastructure, characterized by apoptotic podocytes and foot process effacement. In addition, this compound improved the induction of slit diaphragm proteins podocin/nephrin in the diabetic glomeruli. Exposure to high glucose elevated the unfolded protein response (UPR) to ER stress in renal podocytes, evidenced by up-regulation of PERK-eIF2α-ATF4-CHOP. Chrysin treatment blocked such ER stress responses pertinent to podocyte apoptosis and reduced synthesis of slit diaphragm proteins in vitro and in vivo. These observations demonstrate that targeting ER stress is an underlying mechanism of chrysin-mediated amelioration of diabetes-associated podocyte injury and dysfunction.

α-Asarone blocks 7ß-hydroxycholesterol-exposed macrophage injury through blocking elF2α phosphorylation and prompting beclin-1-dependent autophagy.

Macrophage apoptosis is salient in advanced atherosclerotic lesions and is induced by several stimuli including endoplasmic reticulum (ER) stress. This study examined that α-asarone present in purple perilla abrogated macrophage injury caused by oxysterols via ER stress- and autophagy-mediated mechanisms. Nontoxic α-asarone at 1-20 µM attenuated 7ß-hydroxycholesterol-induced activation of eukaryotic initiation factor 2α in macrophages leading to C/EBP homologous protein (CHOP) expression and apoptosis due to sustained ER stress. The α-asarone treatment increased the formation of autophagolysosomes localizing in perinuclear regions of 7ß-hydroxycholesterol-exposed macrophages. Consistently, this compound promoted the induction of the key autophagic proteins of beclin-1, vacuolar protein sorting 34 and p150 responsible for vesicle nucleation, and prompted the conversion of microtubule-associated protein 1A/1B-light chain 3 and the induction of p62, neighbor of BRCA1 and autophagy-related (Atg) 12-Atg5-Atg16L conjugate involved in phagophore expansion and autophagosome formation. Additionally, α-asarone increased ER phosphorylation of bcl-2 facilitating beclin-1 entry to autophagic process. Furthermore, the deletion of Atg5 or beclin-1 gene enhanced apoptotic CHOP induction. Collectively, α-asarone-stimulated autophagy may be potential multi-targeted therapeutic avenues in treating ER stress-associated macrophage apoptosis.

Astragalin Inhibits Allergic Inflammation and Airway Thickening in Ovalbumin-Challenged Mice.

Lung inflammation and oxidative stress are the major contributors to the development of obstructive pulmonary diseases. Macrophages are involved in pulmonary inflammation and alveolar damage in emphysema. Astragalin is an anti-inflammatory flavonoid present in persimmon leaves and green tea seeds. This study elucidated that astragalin inhibited inflammatory cell infiltration induced by 20 µM H2O2 and blocked airway thickening and alveolar emphysema induced by 20 µg of ovalbumin (OVA) in mice. OVA induced mouse pulmonary MCP-1, and H2O2 enhanced the expression of MCP-1/ICAM-1/αv integrin in bronchial airway epithelial BEAS-2B cells. Such induction was inhibited by supplying 10-20 mg/kg of astragalin to OVA-challenged mice and 1-20 µM astragalin to oxidant-stimulated cells. Oral administration of 20 mg/kg of astragalin reduced the induction of F4/80/CD68/CD11b in airways of mice challenged with OVA. Additionally, emphysema tissue damage was observed in OVA-exposed alveoli. Mast cell recruitment in the airway subepithelium was blocked by supplementing astragalin to OVA-challenged mice. Orally treating 20 mg/kg of astragalin reduced α-SMA induction in inflammation-occurring airways and appeared to reverse airway thickening and constriction induced by an OVA episode. These results revealed that astragalin may improve airway thickening and alveolar destruction with blockade of allergic inflammation in airways. Therefore, astragalin may be a therapeutic agent antagonizing asthma and obstructive pulmonary diseases.

Dietary Compound Chrysin Inhibits Retinal Neovascularization with Abnormal Capillaries in db/db Mice.

Diabetic retinopathy (DR) develops in a significant proportion of patients with chronic diabetes, characterized by retinal macular edema and abnormal retinal vessel outgrowth leading to vision loss. Chrysin, a naturally-occurring flavonoid found in herb and honeycomb, has anti-inflammatory, antioxidant, and anti-cancer properties. This study sought to determine the protective effects of chrysin on retinal neovascularization with abnormal vessels and blood-retinal barrier (BRB) breakdown in 33 mM glucose-exposed human retinal endothelial cells and in db/db mouse eyes. High glucose caused retinal endothelial apoptotic injury, which was inhibited by submicromolar chrysin. This compound diminished the enhanced induction of HIF-1α, vascular endothelial growth factor (VEGF), and VEGF receptor-2 (VEGFR2) in high glucose-exposed retinal endothelial cells. Consistently, oral administration of 10 mg/kg chrysin reduced the induction of these proteins in db/db mouse eye tissues. In addition, chrysin restored the decrement of VE-cadherin and ZO-1 junction proteins and PECAM-1 in hyperglycemia-stimulated retinal endothelial cells and diabetic mouse retina, possibly maintaining tight cell-cell interactions of endothelial cells and pericytes. Anti-apoptotic chrysin reduced the up-regulation of Ang-1, Ang-2, and Tie-2 crucial to retinal capillary occlusion and BRB permeability. Furthermore, orally treating chrysin inhibited acellular capillary formation, neovascularization, and vascular leakage observed in diabetic retinas. These observations demonstrate, for the first time, that chrysin had a capability to encumber diabetes-associated retinal neovascularization with microvascular abnormalities and BRB breakdown.

Dietary compound α-asarone alleviates ER stress-mediated apoptosis in 7ß-hydroxycholesterol-challenged macrophages.

SCOPE: Prolonged endoplasmic reticulum (ER) stress has lost the function of protein folding capacity and the ER accumulation of unfolded proteins that eventually triggers apoptosis. Oxysterols are emerging as contributing factors in atherogenesis known to involve macrophage apoptosis. This study determined the inhibitory effect of α-asarone present in purple perilla, on 7ß-hydroxycholesterol-induced macrophage apoptosis, targeting against ER stress signaling pathway. METHODS AND RESULTS: J774A1 murine macrophages were exposed to 28 µM 7ß-hydroxycholesterol and treated with 1-10 µM α-asarone. Macrophage apoptosis and ER stress were examined by and α-Asarone blocked 7ß-hydroxycholesterol-induced DNA fragmentation and apoptosome formation. Immunoblotting showed that the oxysterol activated the ER transmembrane resident kinases of IRE1α, PERK and ATF4 and triggered caspase-12 signaling cascades, which was reversed by α-asarone. Additionally, 7ß-hydroxycholesterol activated TRAF2-ASK1-JNK1/2 complex following the IRE1α activation, and α-asarone blunted such IRE1α-mediated pathway. Real-time PCR and dual-luciferase reporter analyses revealed that α-asarone reduced transcriptional activation of ER stress-responsive genes including XBP1 and CHOP by 7ß-hydroxycholesterol. Finally, α-asarone disturbed oxysterol-elicited signaling of PERK and ATF4 responsible for CHOP induction. CONCLUSION: α-Asarone blocked 7ß-hydroxycholesterol-induced macrophage apoptosis through allaying ER stress-specific signaling involving caspase activation and CHOP induction. α-Asarone was an anti-atherosclerotic agent antagonizing ER stress-mediated macrophage apoptosis by 7ß-hydroxycholesterol.

Dietary Compound Kaempferol Inhibits Airway Thickening Induced by Allergic Reaction in a Bovine Serum Albumin-Induced Model of Asthma.

Asthma is characterized by aberrant airways including epithelial thickening, goblet cell hyperplasia, and smooth muscle hypertrophy within the airway wall. The current study examined whether kaempferol inhibited mast cell degranulation and prostaglandin (PG) release leading to the development of aberrant airways, using an in vitro model of dinitrophenylated bovine serum albumin (DNP-BSA)-sensitized rat basophilic leukemia (RBL-2H3) mast cells and an in vivo model of BSA-challenged asthmatic mice. Nontoxic kaempferol at 10-20 µM suppressed ß-hexosaminidase release and cyclooxygenase 2 (COX2)-mediated production of prostaglandin D2 (PGD2) and prostaglandin F2α (PGF2α) in sensitized mast cells. Oral administration of ≤20 mg/kg kaempferol blocked bovine serum albumin (BSA) inhalation-induced epithelial cell excrescence and smooth muscle hypertrophy by attenuating the induction of COX2 and the formation of PGD2 and PGF2α, together with reducing the anti-α-smooth muscle actin (α-SMA) expression in mouse airways. Kaempferol deterred the antigen-induced mast cell activation of cytosolic phospholipase A2 (cPLA2) responsive to protein kinase Cµ (PKCµ) and extracellular signal-regulated kinase (ERK). Furthermore, the antigen-challenged activation of Syk-phospholipase Cγ (PLCγ) pathway was dampened in kaempferol-supplemented mast cells. These results demonstrated that kaempferol inhibited airway wall thickening through disturbing Syk-PLCγ signaling and PKCµ-ERK-cPLA2-COX2 signaling in antigen-exposed mast cells. Thus, kaempferol may be a potent anti-allergic compound targeting allergic asthma typical of airway hyperplasia and hypertrophy.