Aqueous stability of astilbin: effects of pH, temperature, and solvent

Maximizing Curcuminoid Extraction from Curcuma aromatica Salisb. Rhizomes via Environmentally Friendly Microwave-Assisted Extraction Technique Using Full Factorial Design

Curcuma aromatica Salisb. contains a high content of curcuminoids, which can be utilized for cosmetic purposes. The objective of this study was to optimize the extraction conditions of C. aromatica rhizomes in castor oil to maximize curcuminoid content using a simple and environmentally friendly microwave-assisted extraction method. A 32 full factorial design was employed, with two factors-microwave power and time-varying between 600-800 W and 30-90 s, respectively. Five responses were monitored, including extraction yield, bisdemethoxycurcumin, demethoxycurcumin, curcumin, and total curcuminoid contents. The results demonstrated that increasing microwave power and time led to an increase in all five responses. The optimal condition, which simultaneously maximized extraction yield and total curcuminoid content, was achieved at a microwave power of 800 W for 90 s. This condition resulted in an extraction yield of 71.020%, bisdemethoxycurcumin content of 0.036%, demethoxycurcumin content of 0.210%, curcumin content of 0.080%, and total curcuminoid content of 0.326%. The computer program accurately predicted the results with a percentage error of less than 2%. Stability data revealed that the total curcuminoid content remained stable with a percentage remaining above 90% when stored at 4°C, 30°C ± 75%RH, and 40°C ± 75%RH for three months. In summary, this study successfully applied a full factorial design to maximize curcuminoid extraction from C. aromatica rhizomes using an environmentally friendly microwave-assisted extraction method for cosmetic purposes.

Fabrication of Luteolin Loaded Zein-Caseinate Nanoparticles and its Bioavailability Enhancement in Rats

Luteolin loaded zein nanoparticles (Lut-ZNP) were prepared by using sodium caseinate as an electrostatic stabilizer. The formulation of the nanoparticles was optimized. Lut-ZNP were spray-dried, and the physicochemical properties were characterized by SEM, XRD, FT-IR and DSC. Then, the bioavailability of luteolin in rats was determined. Under the formulation of luteolin, zein and sodium caseinate with mass ratio of 1:5:15, the particle size, ζ-potential, encapsulation efficiency and loading efficiency of Lut-ZNP were 171.8 nm, -49.05 mV, 85.85% and 3.15%, respectively. Luteolin existed in the nanoparticles with amorphous form. Lut-ZNP exhibited good redispersibility in water after drying. Compared with free luteolin, the solubility, stability and release of luteolin in Lut-ZNP were greatly improved. Besides, the fecal excretion of luteolin in rats was significantly reduced after oral administration of Lut-ZNP. In addition to native luteolin, its metabolites including sulfate, glucuronidate and methylated glucuronidate were found in rat plasma. Lut-ZNP significantly increased the plasma concentrations of luteolin and its metabolites, and the bioavailability of luteolin was enhanced by 2.92 times.

Natural deep eutectic ready to use extract of astilbin: Super high in vitro bioaccessibility, α-amylase and α-glucosidase enzyme inhibition kinetics

Astilbin, a natural flavonoid, possesses multiple functionalities, while the poor bioavailability seriously restricts its application in functional food and medicine. Therefore, in this study, a natural deep eutectic solvent (NaDES) with choline chloride: lactic acid (CHCL-LAC) is selected to deliver astilbin by evaluating the bioaccessibility and antioxidant capacity during in vitro gastrointestinal digestion, and the inhibitory effect with underlying mechanism of astilbin-CHCL-LAC against α-amylase/α-glucosidase were investigated. The CHCL-LAC showed significant high astilbin bioaccessibility (84.1% bioaccessible) and DPPH and ORAC antioxidant capacity with 75.7% and 57.7% respectively after 3 h in vitro digestion, which may be attributed by hydrogen bond based supramolecule formed between astilbin and CHCL-LAC. Moreover, significant inhibitions of astilbin-CHCL-LAC on α-amylase (IC50 of 0.67 g/L) and α-glucosidase (IC50 of 0.64 g/L) were observed in mixed competitive and non-competitive manners. The dominant binding force between enzymes and astilbin were the hydrogen and hydrophobic interaction. This is the first time that the underlying mechanisms for astilbin delivered by NaDESs were revealed, suggesting that CHCL-LAC-based NaDESs are promising ready-to-use vehicles of natural inhibitors for carbohydrate-hydrolyzing enzymes.

Preparation and characterization of zein-lecithin-total flavonoids from Smilax glabra complex nanoparticles and the study of their antioxidant activity on HepG2 cells

Total flavonoids from Smilax glabra (TFSG) exhibit several biological activities; however, their poor stability limits their application. In this work, zein-lecithin-TFSG complex nanoparticles (Z-L-TFSG NPs) were prepared using the anti-solvent coprecipitation technique. The prepared Z-L-TFSG NPs were spherical with an encapsulation efficiency of 98.0%. Differential scanning calorimetry, Fourier transform infrared spectroscopy, and morphology tests revealed that the TFSG were successfully encapsulated by Z-L NPs. Z-L-TFSG NPs showed superior stability and better controlled release characteristics in simulated gastrointestinal digestion. The encapsulation of TFSG by Z-L NPs could improve their antioxidant capacity in vitro. Moreover, Z-L-TFSG NPs could enhance the protective effects of TFSG against H₂O₂-induced oxidative damage to HepG2 cells. The results indicated that the Z-L self-assembled NPs could serve as a promising drug delivery system through the integrated encapsulation of multiple flavonoids.

Influence of different pretreatments and drying methods on the chemical compositions and bioactivities of Smilacis Glabrae Rhizoma

Background

The processing of medicinal plant materials is one of the important factors influencing the components and biological activities of TCMs. Smilax glabra Roxb. is an herbal vine widely distributed in China, and its dried rhizome (Smilacis Glabrae Rhizoma, SGR) is often used in traditional medicines and functional foods. The processing methods of fresh cutting for SGR slices have been included in ancient Chinese herbal works, some local standards of TCMs, and the current Chinese Pharmacopoeia. Nevertheless, to date, the scientific basis for the processing of fresh medicinal materials for SGR slices has not been revealed.

Methods

To optimize the processing method for preparing SGR slices from the fresh rhizomes, the chemical compositions of the un-pretreated and pretreated (boiling, steaming) samples before and after drying (sun-drying, shade-drying, oven-drying), and the contents of astilbin isomers in dried SGR were analyzed by UHPLC-Q-TOF-MS/MS and UHPLC-DAD methods, respectively. Then, the antioxidant, anti-inflammatory, xanthine oxidase and α-glucosidase inhibitory activities of the prepared SGR slices were investigated by biological assays.

Results

A total of fifty-two compounds were identified from the un-pretreated and pretreated samples and a total of forty-nine compounds were identified from the subsequently dried samples. After pretreated by boiling and steaming, the contents of neoastilbin, neoisoastilbin, and isoastilbin in the prepared samples all increased. As a quality marker of SGR, the content of astilbin was unchanged or decreased slightly compared with that in the un-pretreated samples. During the drying process, the contents of the four astilbin stereoisomers in the un-pretreated samples increased significantly, while those in the pretreated samples had a slight increase or decrease. The effects of different processing methods were sorted according to the bioactivities of the prepared SGR. As a result, SGR slices prepared with no pretreatment followed by a sun-drying process have a higher astilbin content, better bioactivities and more energy savings, representing the optimum processing method for SGR slices.

Conclusions

This study reveals the scientific basis for the processing of fresh medicinal materials for SGR slices. The results provide scientific information for the quality control of SGR and its rational applications in herbal medicines and functional foods.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00614-7.

The natural source, physicochemical properties, biological activities and metabolism of astilbin

Astilbin is a dihydroflavanol found in many plants and processed foods. Astilbin possesses multiple health-beneficial bioactivities and has received great attention. Hence, the natural source, physicochemical properties, biological activities and metabolism of astilbin are summarized in the present article. Engelhardia roxburghiana Wall. and Smilax glabra Roxb. are the main resource for astilbin purification because of high content. Because of chemical instability, astilbin amount in foods is dependent on the processing and storage conditions. The degradation of astilbin includes isomerization and decomposition. The interconversion of astilbin and its isomers occurs through a chalcone intermediates, which significantly affects the taste of wine during storage. Many factors such as temperature, pH, metal ions and food additives could affect the chemical stability of astilbin. Astilbin exhibits very novel selective immunosuppressive activity, which is not found in other compounds. The rhamnose moiety of astilbin is essential for this bioactivity. After digestion, astilbin was mainly absorbed and transported in circulatory blood in its intact form, and only one metabolite, 3'-O-methylastilbin, was found. Although having many bioactivities, astilbin faces the challenge of poor bioavailability. Some promising strategies were developed for improving its bioavailability, particularly through fabrication the zein nanoparticles.

Thermal Stability of Anisoyl Kaempferol Glycosides in Jack Bean (Canavalia ensiformis (L.) DC) and Their Effect on α-Glucosidase Inhibition

Kaempferol glycosides are functional components of jack bean. The chemical stability of kaempferol glycosides under simulated food processing conditions was evaluated in this study by subjecting the methanol extract and each compound to heat treatment. During the heat treatment, rearrangement of the anisoyl group on the rhamnose moiety of the kaempferol glycoside was observed, followed by hydrolysis upon long-term heat treatment. One of the two regioisomers produced under heating conditions showed higher α-glucosidase inhibitory activity than the dominant anisoyl kaempferol glycoside. This rearrangement reaction was also observed upon the heat treatment of methyl-3-O-anisoyl-rhamnose, with the rearrangement from the 3-position to the 2-position occurring preferentially. The approach adopted in this study can be used to design appropriate food processing conditions, which, in turn, will increase the functional value of foods.

In vivo and in vitro comparison of three astilbin encapsulated zein nanoparticles with different outer shells

Three shell materials, lecithin (ZNP-L), chitosan (ZNP-CH) and sodium caseinate (ZNP-SC), were used to prepare core-shell zein nanoparticles. Astilbin was encapsulated as a model flavonoid to compare the influence of the shell materials on zein nanoparticles both in vitro and in vivo. The particle size was moderately increased by lecithin and sodium caseinate, but notably increased by chitosan. All the shell materials provided good redispersibility for the nanoparticles and significantly improved the colloidal stability. Chitosan and sodium caseinate significantly delayed and decreased the feces excretion of astilbin in rats, while lecithin exhibited a very weak effect. The results may be attributed to the difference in mucoadhesive properties between the shell materials. As a consequence, the bioavailability values of astilbin in rats were 18.2, 9.3 and 1.89 times increased through ZNP-CH, ZNP-SC and ZNP-L compared with that of free astilbin, respectively.

The interaction between gut microbiota and flavonoid extract from Smilax glabra Roxb. and its potent alleviation of fatty liver

Fatty liver is associated with intestinal microbiota dysbiosis and low-grade chronic inflammation. Herein we report the interaction of the flavonoid extract from Smilax glabra Roxb. (FSGR) with gut microbiota. Then, FSGR's function of modulating microbiota in a rat model of high-fat diet (HFD) induced fatty liver has been explored. These investigations indicated that the main compound in FSGR, such as astilbin and its isomers, could be metabolized to aglycone, while further splitting resulted in some phenolic acid compounds through a redox reaction. The data obtained clearly showed that FSGR not only alleviated the steatosis degree of liver cells and modulated the contents of short chain fatty acids (SCFAs) in the intestinal tract, but also reversed gut dysbiosis induced by HFD as prognosticated by the decreased ratio of Firmicutes/Bacteroidetes (F/B) and altered gene expression. The results demonstrated that FSGR probably could be used as a prebiotic agent to impede gut dysbiosis and fatty liver-related metabolic disorders.

Physicochemical properties of dihydromyricetin and the effects of ascorbic acid on its stability and bioavailability

BACKGROUND

Dihydromyricetin (DMY) is a natural dihydroflavonol with many bioactive effects. However, the physicochemical properties of DMY related to its bioavailability, especially its stability, are unclear.

RESULTS

The effects of pH, temperature, metal ions and ascorbic acid (AA) on the stability of DMY were studied using high-performance liquid chromatography (HPLC). The bioavailability of DMY in the presence and absence of AA was compared. Dihydromyricetin was unstable in weak alkaline solutions, and the degradation was significantly accelerated in the presence of Cu²⁺ and Fe³⁺ . The degradation process followed the first-order kinetic model. The degradation rate constant (k) increased with increasing pH and temperature. The remaining DMY was only 49% of its initial concnentration after 4 h in simulated intestinal fluid (SIF) at 37 °C. However, by supplementing with AA, the degradation of DMY was rarely occured within 6 h. The solubility of DMY at pH 3-5 was about 750 μg mL^-1 , slightly increasing to 853 μg mL^-1 at pH 6. Pharmacokinetic studies showed that the bioavailability of DMY increased from 0.122% to 0.341% by supplementing with AA (10% of DMY).

CONCLUSION

The degradation of DMY is one reason for its poor bioavailability. The presence of AA could significantly improve the stability of DMY, and further improve its bioavailability in rats. © 2020 Society of Chemical Industry.

Understanding sweetness of dry wines: First evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages

Astilbin (2R, 3R) was recently reported to contribute to wine sweetness. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). This work aimed at assaying their presence for the first time in wines as well as their taste properties. The isomers were synthesized from astilbin and purified by semi-preparative HPLC. With the four stereoisomers, a sweet taste was perceived whose intensity varied with the configuration. Their content was assayed by developing a UHPLC-Q-Exactive method. The method was applied to screen astilbin and isomers in various wines, especially in different vintages from the same estate. While young wines contained higher concentrations of astilbin than the old ones, the concentrations of the other isomers, mainly neoastilbin, were higher in the old wines, suggesting their formation over time.

Astilbin lowers the effective caffeine dose for decreasing lipid accumulation via activating AMPK in high-fat diet-induced obese mice

BACKGROUND

Caffeine has an anti-obesity effect, although chronic excessive caffeine consumption also causes caffeinism, which is marked by increased anxiety or depression, amongst other symptoms. The present study aimed to investigate whether the addition of flavonoids such as astilbin can reduce the caffeine dose needed to inhibit obesity.

RESULTS

ICR mice (n = 80) were fed with normal diet, high-fat diet (HFD), HFD supplemented with astilbin, caffeine, or astilbin + caffeine for 12 weeks. When diets supplemented with astilbin, 0.3 g kg^-1 diet caffeine had the same effect as 0.6 g kg^-1 diet caffeine alone, and 0.6 g kg^-1 diet caffeine combined with astilbin most effectively inhibited HFD-induced obesity. Astilbin improved the anti-obesity effects of caffeine on lipid accumulation via the activation of AMP-activated protein kinase α (AMPKα). (i) Activated AMPKα decreased lipid biosynthesis by suppressing the activity or mRNA expression of 3-hydroxy-3-methylglutaryl-CoA reductase, sterol regulatory element binding protein 1c and its target gene fatty acid synthase. (ii) Activated AMPKα also up-regulated lipolysis by enhancing the expression of adipose triglyceride lipase and increasing the phosphorylation of hormone-sensitive lipase. (iii) Finally, activated AMPKα increased carnitine acyltransferase and acyl-CoA oxidase activities, which further promoted fatty acid β-oxidation.

CONCLUSION

The results obtained in the present study indicate that astilbin may decrease the effective dose of caffeine needed for an anti-obesity effect and also suggest that it suppresses fat accumulation via the activation of AMPK. © 2020 Society of Chemical Industry.

Fabrication and characterization of dihydromyricetin encapsulated zein-caseinate nanoparticles and its bioavailability in rat

Dihydromyricetin (DMY) encapsulated zein-caseinate nanoparticles (DZP) were fabricated by antisolvent method. The encapsulation and loading efficiency of DMY in DZP were 90.2% and 22.6% as determined by HPLC. DZP is spherical with particle size and ζ potential of 206.4 nm and -29.6 mV, respectively. Physicochemical characterization showed that DMY existed in amorphous form in DZP and its interaction with proteins was found. The fabrication of DZP significantly improved the stability of DMY. Besides, the diffusion rate of DMY in DZP was faster than its suspensions in both simulated gastric and intestinal fluid. The adhesion of DMY in mice gastrointestinal tract was also improved. Besides DMY itself, its methylated metabolites with further sulfation and glucuronide were identified in rat plasma by UPLC-QTOF-MS. UPLC-QqQ-MS/MS quantitative analysis showed that the oral bioavailability of DMY was 1.95 times enhanced. Besides, the concentration of DMY metabolites in plasma were all increased.

New Lead Discovery of Herbicide Safener for Metolachlor Based on a Scaffold-Hopping Strategy

The use of herbicide safeners can significantly alleviate herbicide injury to protect crop plants and expand the application scope of the existing herbicides in the field. Sanshools, which are well known as spices, are N-alkyl substituted compounds extracted from the Zanthoxylum species and have several essential physiological and pharmacological functions. Sanshools display excellent safener activity for the herbicide metolachlor in rice seedlings. However, the high cost of sanshools extraction and difficulties in the synthesis of their complicated chemical structures limit their utilization in agricultural fields. Thus, the present study designed and synthesized various N-alkyl amide derivatives via the scaffold-hopping strategy to solve the challenge of complicated structures and find novel potential safeners for the herbicide metolachlor. In total, 33 N-alkyl amide derivatives (2a–k, 3a–k, and 4a–k) were synthesized using amines and saturated and unsaturated fatty acids as starting materials through acylation and condensation. The identity of all the target compounds was well confirmed by ¹H-NMR, ¹³C-NMR, and high-resolution mass spectrometry (HRMS). The primary evaluation of safener activities for the compounds by the agar method indicated that most of the target compounds could protect rice seedlings from injury caused by metolachlor. Notably, compounds 2k and 4k displayed excellent herbicide safener activities on plant height and demonstrated relatively similar activities to the commercialized compound dichlormid. Moreover, we showed that compounds 2k and 4k had higher glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO) activities in rice seedlings, compared to the metolachlor treatment. In particular, 2k and 4k are safer for aquatic organisms than dichlormid. Results from the current work exhibit that compounds 2k and 4k have excellent crop safener activities toward rice and can, thus, be promising candidates for further structural optimization in rice protection.

A Comparison of Solubility, Stability, and Bioavailability between Astilbin and Neoastilbin Isolated from Smilax glabra Rhizoma

Astilbin and neoastilbin are two flavonoid stereoisomers. In the present study, their solubility, stability, and bioavailability were compared in a rat. The results revealed that the water solubility of astilbin and neoastilbin was 132.72 μg/mL and 217.16 μg/mL, respectively. The oil–water distribution coefficient (log P) of astilbin and neoastilbin in simulated gastric fluid (SGF) was 1.57 and 1.39, and in simulated intestinal fluid (SIF) was 1.09 and 0.98, respectively. In SIF, about 78.6% astilbin remained after 4 h of incubation at 37 °C, while this value was 88.3% for neoastilbin. Most of the degraded astilbin and neoastilbin were isomerized into their cis-trans-isomer, namely neoisoastilbin and isoastilbin, respectively, and the decomposed parts were rare. For bioavailability comparison in a rat, an HPLC method for trace amounts of astilbin and neoastilbin determination in plasma was developed, and the pretreatment of plasma was optimized. A pharmacokinetic study showed that the absolute bioavailability of astilbin and neoastilbin in a rat showed no significant difference with values of 0.30% and 0.28%, respectively.

Astilbin prevents bone loss in ovariectomized mice through the inhibition of RANKL-induced osteoclastogenesis

Osteoporosis is the most common osteolytic disease characterized by excessive osteoclast formation and resultant bone loss, which afflicts millions of patients around the world. Astilbin, a traditional herb, is known to have anti-inflammatory, antioxidant and antihepatic properties, but its role in osteoporosis treatment has not yet been confirmed. In our study, astilbin was found to have an inhibitory effect on the RANKL-induced formation and function of OCs in a dose-dependent manner without cytotoxicity. These effects were attributed to its ability to suppress the activity of two transcription factors (NFATc1 and c-Fos) indispensable for osteoclast formation, followed by inhibition of the expression of bone resorption-related genes and proteins (Acp5/TRAcP, CTSK, V-ATPase-d2 and integrin β3). Furthermore, we examined the underlying mechanisms and found that astilbin repressed osteoclastogenesis by blocking Ca2+ oscillations and the NF-κB and MAPK pathways. In addition, the therapeutic effect of MA on preventing bone loss in vivo was further confirmed in an ovariectomized mouse model. Therefore, considering its ability to inhibit RANKL-mediated osteoclastogenesis and the underlying mechanisms, astilbin might be a potential candidate for treating osteolytic bone diseases.

Astilbin reduces ROS accumulation and VEGF expression through Nrf2 in psoriasis-like skin disease

Background

Psoriasis is a common and intractable skin disease affecting the physical and mental health of patients. The accumulation of ROS is involved in the pathogenesis of psoriasis and antioxidants are believed to be therapeutic. This study aimed to investigate the therapeutic efficacy of astilbin on ROS accumulation in psoriasis.

Results

The study showed that 50 μg/ml astilbin could inhibit the growth and reduce the accumulation of ROS in HaCaT cells stimulated by IL-17 and TNF-α. Astilbin could elevate the Nrf2 accumulation in the nuclei, eventually leading to the transcriptional activation of various antioxidant proteins and reducing the expression of VEGF.

Conclusions

Our results collectively suggest that astilbin could induce Nrf2 nucleus translocation, which is contribute to reduce the ROS accumulation and VEGF expression, and inhibit the proliferation of HaCaT cells.

Metabolism, Excretion, and Tissue Distribution of Astilbin-Zein Nanoparticles in Rats

The excretion, tissue distribution, and metabolic profile of astilbin in rat were studied by HPLC and UPLC-QTOF-MS. Astilbin underwent isomerization in the small intestine, and its four isomers were found in feces. Besides, taxifolin, the aglycone of astilbin, and its further metabolites by gut microbes through hydrogenation, dehydration, and ring-fission were found. The total feces excretion of astilbin was about 14.4% of administration. The forming of zein-caseinate nanoparticles can significantly delay and reduce the feces excretion of astilbin. Astilbin and its isomers were absorbed in their intact form. The main metabolites found in plasma and tissues were the methylated products. Astilbin was rapidly distributed in various tissues including brain and maintained relatively high concentration in heart. Compared with other tissues, significantly higher concentration and longer duration of astilbin were found in the gastrointestinal tract. Astilbin and its isomers were excreted in their intact and methylated form in urine.

Bioavailability Enhancement of Astilbin in Rats through Zein-Caseinate Nanoparticles

Astilbin-encapsulated zein-caseinate nanoparticles were fabricated through the antisolvent method. The encapsulation and loading efficiency of astilbin in the nanoparticles were determined by high-performance liquid chromatography. The nanoparticles were characterized by particle size, ζ potential, redispersibility, scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC). Under the optimal formulation of astilbin, zein, and sodium caseinate with a mass ratio of 1:1:2, the size and ζ potential of the nanoparticles were 152.9 nm and -40.43 mV, respectively, while the encapsulation and loading efficiency of astilbin were 80.1 and 21.8%, respectively. The nanoparticles had good redispersibility in water without a particle size change after freeze drying. The nanoparticles showed a spherical shape with a smooth surface. XRD and DSC analyses showed that astilbin existed in amorphous form in the nanoparticles. The interactions between astilbin and the protein were found, and astilbin was encapsulated in nanoparticles rather than adsorbed. The diffusion of astilbin from nanoparticles was significantly faster than that of astilbin suspensions in both simulated gastric and intestinal fluids. Astilbin was relatively stable in simulated intestinal fluids, and the encapsulation in the nanoparticles showed a slight stability improvement effect. A pharmacokinetic study showed that the absolute bioavailability of astilbin was improved from 0.32 to 4.40% in rats through nanoparticle fabrication.

Stability Study and Identification of Degradation Products of Caffeoylgluconic Acid Derivatives from Fructus Euodiae

Caffeoylgluconic acid derivatives are characteristic constituents isolated from the aqueous extract of Fructus Euodiae. In this research focusing on caffeoylgluconic acid derivatives, trans-caffeoyl-6-O-d-gluconic acid (CGA), trans-caffeoyl-6-O-d-gluconic acid methyl ester (CGA-ME), and trans-caffeoyl-6-O-d-glucono-γ-lactone (CGA-LT), a systematic study of stability was performed under different temperatures and pH levels by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-diode array detector/electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC-DAD/ESI-Q-TOF MS). From the concentration–time curves and sensitivity index (SeI), it was found that compared to CGA, which is inert to the variation of temperature and pH in the tested range, CGA-ME and CGA-LT were more sensitive, with stabilities more likely to be influenced by temperature. Considering the stability index (StI), the integrated stability of CGA was the best, and that of CGA-ME was the worst. In terms of the quasi-molecular and fragment ions of the tested compounds, the degradation products were identified or tentatively characterized, which could shed light on the degradation pathways. CGA-ME and CGA-LT were easily converted to CGA by hydrolytic reaction, all of which were susceptible to the formation of isomers. This study elucidated the degradation mechanism of caffeoylgluconic acid derivatives, contributing to better guidance on manufacturing and controlling the quality of drugs.

Determination of solubility, stability and degradation kinetics of morin hydrate in physiological solutions

Natural drugs have emerged as potential alternatives to synthetic drugs to avoid their toxic effects. Morin hydrate (MH) is a natural therapeutic agent, obtained from Maclura pomifera, Maclura tinctoria and Psidium guajava. Solubility and degradation kinetics of morin hydrate in different physiological media, namely, 0.1 N HCl (pH 1.2), sodium acetate buffer (pH 5.0), water (pH 7.0), phosphate buffer saline (pH 7.4) and tris base (pH 9.0), were investigated via classical spectroscopic methods. Stability studies of MH were performed to determine the effect of different pH media, temperature (room and freeze) and light on the degradation kinetics. Solubility and stability of MH varied significantly in different biological media and storage conditions. Solubility of MH was pH-dependent and increased with the increase in pH. Degradation kinetics and regression values (r²) values were calculated from the linear fitted models of zero, first and second order kinetics.

The stability of morin hydrate depends on pH, temperature, and light.

Astilbin decreases proliferation and improves differentiation in HaCaT keratinocytes

Psoriasis is a common chronic dermatosis characterized by keratinocyte hyperproliferation accompanied by inflammatory reactions. Pathological changes upset the balance between keratinocyte proliferation, differentiation, and death in psoriatic lesions, suggesting that molecules with topical anti-inflammatory, anti-proliferation and anti-angiogenesis abilities may be useful for its treatment. The flavonoid astilbin is the major active component extracted from the rhizome of Smilax glabra, which has been widely used in China to treat inflammatory and autoimmune diseases. Here, we investigate the potential of astilbin as a treatment for psoriasis. We reveal that astilbin inhibits the growth of HaCaT keratinocytes. Detailed study shows that astilbin leads to S phase arrest of the cell cycle by induction of p53 and p21 and activated-AMPK. Additionally, astilbin induced keratinocyte differentiation correlated with suppression of keratin 5 (KRT5) and KRT14 proteins (the markers of epidermal basal layer) and induction KRT1 and KRT10 proteins (occurring in the upper layers). Moreover, astilbin regulates the expression of VEGF in human HaCaT keratinocytes. These results suggest that astilbin may be a promising agent for psoriasis treatment.

Astilbin ameliorates experimental autoimmune myasthenia gravis by decreased Th17 cytokines and up-regulated T regulatory cells

Astilbin, a major bioactive compound extracted from Rhizoma smilacis glabrae (RSG), has been reported to possess immunosuppressive properties. Our study first evaluated the effect of astilbin on experimental autoimmune myasthenia gravis (EAMG) in Lewis rats. The results showed that astilbin could attenuate the severity of EAMG by decreasing antigen-specific autoantibodies with up-regulation of regulatory T cells and down-regulation of Th17 cells. In addition to, astilbin also reduced the efficiency of the antigen presenting cells on which the expression of MHC class II decreased. These results suggest that astilbin might be a candidate drug for immunoregulation of EAMG, and provide us new treatment ideas for human myasthenia gravis (MG).

Systematic Analysis of Absorbed Anti-Inflammatory Constituents and Metabolites of Sarcandra glabra in Rat Plasma Using Ultra-High-Pressure Liquid Chromatography Coupled with Linear Trap Quadrupole Orbitrap Mass Spectrometry

Ultra-high-pressure liquid chromatography (UHPLC) was coupled with linear ion trap quadrupole Orbitrap mass spectrometry (LTQ-Orbitrap) and was used for the first time to systematically analyze the absorbed components and metabolites in rat plasma after oral administration of the water extract of Sarcandra glabra. This extract is a well-known Chinese herbal medicine for the treatment of inflammation and immunity related diseases. The anti-inflammatory activities of the absorbed components were evaluated by measuring nitric oxide (NO) production and proinflammatory genes expression in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages. As a result, 54 components in Sarcandra glabra were detected in dosed rat plasma, and 36 of them were positively identified. Moreover, 23 metabolites were characterized and their originations were traced. Furthermore, 20 of the 24 studied components showed anti-inflammatory activities. These results provide evidence that this method efficiency detected constituents in plasma based on the anti-inflammatory mechanism of multiple components and would be a useful technique for screening multiple targets for natural medicine research.