Inhibitors of melanogenesis in B16 melanoma 4A5 cells from flower buds of Lawsonia inermis (Henna)

Comparative study on metabolite variations of two rose teas by plant metabolomics and revealing their skin-whitening candidates by spectrum-effect relationship analysis

INTRODUCTION

Rosa rugosa var. plena Rehd (CBR) and Rosa chinensis cv. "JinBian" (JBR) are two common species used in rose tea among different original species. CBR, the officially documented original plant of the rose species for food and medicinal purposes, is more costly than JBR. With increasing demand for different rose teas, it is meaningful to compare the chemical constituents for their quality control and reveal their skin-whitening components that will provide in-depth insights for the expansion of the rose tea industry.

OBJECTIVE

This study aims to reveal the chemical variances between CBR and JBR and determine their skin-whitening components.

METHODOLOGY

A strategy obtained by combining MS-based plant-metabolomics with spectrum-effect relationship analysis has been proposed for unveiling chemical differences between CBR and JBR and further exploring their potential skin-whitening components.

RESULTS

A total of 2030 metabolites were found that revealed considerable differences between CBR and JBR. The results of bioactivity assay demonstrated that JBR exhibited stronger tyrosinase inhibition activity than CBR. Six potential skin-whitening compounds (di-O-galloyl-HHDP-glucoside, tri-O-galloyl-HHDP-glucoside, spiraeoside, quinic acid, rugosin A, and 1,2,3,6-tetra-O-galloyl-glucose) were discovered as potential tyrosinase inhibitors, via spectrum-effect relationship analysis. This is the first time that di-O-galloyl-HHDP-glucoside, tri-O-galloyl-HHDP-glucoside, rugosin A, and 1,2,3,6-tetra-O-galloyl-glucose have been reported with tyrosinase inhibitory activity. Additionally, molecular docking analysis was used to reveal the inhibition mechanism of these compounds toward tyrosinase.

CONCLUSION

The finding of this study will be of great importance for the quality control of the two types of rose teas, and the revealed active ingredients will provide in-depth insights for the expansion of the rose tea industry.

Syringetin Promotes Melanogenesis in B16F10 Cells

Syringetin, an active compound present in red grapes, jambolan fruits, Lysimachia congestiflora, and Vaccinium ashei, is a dimethyl myricetin derivative which contains free hydroxyl groups at the C-2' and C-4' positions in ring B. Recent studies have revealed that syringetin possesses multiple pharmacological properties, such as antitumor, hepatoprotective, antidiabetic, antioxidative, and cytoprotective activities. To date, there has been no attempt to test the action of syringetin on melanogenesis. In addition, the molecular mechanism for the melanogenic effects of syringetin remains largely unknown. In this study, we investigated the effect of syringetin on melanogenesis in a murine melanoma cell line from a C57BL/6J mouse, B16F10. Our results showed that syringetin markedly stimulated melanin production and tyrosinase activity in a concentration-dependent manner in B16F10 cells. We also found that syringetin increased MITF, tyrosinase, TRP-1, and TRP-2 protein expression. Moreover, syringetin inhibited ERK and PI3K/Akt phosphorylation by stimulating p38, JNK, PKA phosphorylation levels, subsequently stimulating MITF and TRP upregulation, resulting in the activation of melanin synthesis. Furthermore, we observed that syringetin activated phosphorylation of GSK3β and β-catenin and reduced the protein level of β-catenin, suggesting that syringetin stimulates melanogenesis through the GSK3β/β-catenin signal pathway. Finally, a primary skin irritation test was conducted on the upper backs of 31 healthy volunteers to determine the irritation or sensitization potential of syringetin for topical application. The results of the test indicated that syringetin did not cause any adverse effects on the skin. Taken together, our findings indicated that syringetin may be an effective pigmentation stimulator for use in cosmetics and in the medical treatment of hypopigmentation disorders.

Lawsonia inermis flower aqueous extract expressed better anti-alpha-glucosidase and anti-acetylcholinesterase activity and their molecular dynamics

Lawsonia inermis (henna) has been used in traditional medicine throughout the world and biological property of its flower has been least explored. In the present study, the phytochemical characterization and biological activity (in vitro radical scavenging activity, anti-alpha glucosidase and anti-acetylcholinesterase) of aqueous extract prepared from henna flower (HFAE) was carried out by both Qualitative and quantitative phytochemical analysis and Fourier-transform infrared spectroscopy revealed the functional group of the phytoconstituents such as phenolics, flavonoids, saponin, tannins and glycosides. The phytochemicals present in HFAE was preliminary identified by liquid chromatography/electrospray ionization tandem mass spectrometry. The HFAE showed potent in vitro antioxidant activity and the HFAE inhibited mammalian α-glucosidase (IC50 = 129.1 ± 5.3 µg/ml; Ki = 38.92 µg/ml) and acetylcholinesterase (AChE; IC50 = 137.77 ± 3.5 µg/ml; Ki = 35.71 µg/ml) activity by competitive manner. In silico molecular docking analysis revealed the interaction of active constituents identified in HFAE with human α-glucosidase and AChE. Molecular dynamics simulation for 100 ns showed the stable binding of top two ligand/enzyme complexes with lowest binding energy such as 1,2,3,6-Tetrakis-O-galloyl-beta-D-glucose (TGBG)/human α-glucosidase, Kaempferol 3-glucoside-7-rhamnoside (KGR)/α-glucosidase, agrimonolide 6-O-β-D-glucopyranoside (AMLG)/human AChE and KGR/AChE. Through MM/GBSA analysis, the binding energy for TGBG/human α-glucosidase, KGR/α-glucosidase, AMLG/human AChE and KGR/AChE was found to be -46.3216, -28.5772, -45.0077 and -47.0956 kcal/mol, respectively. Altogether, HFAE showed an excellent antioxidant, anti-alpha glucosidase and anti-AChE activity under in vitro. This study suggest HFAE with remarkable biological activities could be further explored for therapeutics against type 2 diabetes and diabetes-associated cognitive decline.Communicated by Ramaswamy H. Sarma.

Eriodictyol Suppresses Gastric Cancer Cells via Inhibition of PI3K/AKT Pathway

Gastric cancer (GC) is among the five most common malignancies worldwide. Traditional chemotherapy cannot efficiently treat the disease and faces the problems of side effects and chemoresistance. Polygoni orientalis Fructus (POF), with flavonoids as the main bioactive compounds, exerts anti-cancer potential. In this study, we compared the anti-GC effects of the main flavonoids from POF and investigated the anti-cancer effects of eriodictyol towards GC both in vitro and in vivo. CCK-8 assays were performed to examine the inhibitory effects of common flavonoids from POF on GC cell viability. Colony formation assays were used to determine cell proliferation after eriodictyol treatment. Cell cycle distribution was analyzed using flow cytometry. Induction of apoptosis was assessed with Annexin V/PI staining and measurement of related proteins. Anti-cancer effects in vivo were investigated using a xenograft mouse model. Potential targets of eriodictyol were clarified by network pharmacological analysis, evaluated by molecular docking, and validated with Western blotting. We found that eriodictyol exhibited the most effective inhibitory effect on cell viability of GC cells among the common flavonoids from POF including quercetin, taxifolin, and kaempferol. Eriodictyol suppressed colony formation of GC cells and induced cell apoptosis. The inhibitory effects of eriodictyol on tumor growth were also validated using a xenograft mouse model. Moreover, no obvious toxicity was identified with eriodictyol treatment. Network pharmacology analysis revealed that PI3K/AKT signaling ranked first among the anti-GC targets. The molecular docking model of eriodictyol and PI3K was constructed, and the binding energy was evaluated. Furthermore, efficient inhibition of phosphorylation and activation of PI3K/AKT by eriodictyol was validated in GC cells. Taken together, our results identify eriodictyol as the most effective anti-GC flavonoids from POF and the potential targets of eriodictyol in GC. These findings suggest that eriodictyol has the potential to be a natural source of anti-GC agents.

Complementary and alternative therapies in skin cancer a literature review of biologically active compounds

Complementary and alternative medicine or therapies (CAM) are frequently used by skin cancers patients. Patient's self-administration of CAM in melanoma can reach up to 40%-50%. CAMs such as botanical agents, phytochemicals, herbal formulas ("black salve") and cannabinoids, among others, have been described in skin cancer patients. The objective of this review article was to acknowledge the different CAM for skin cancers through the current evidence, focusing on biologically active CAM rather than mind-body approaches. We searched MEDLINE database for articles published through July 2022, regardless of study design. Of all CAMs, phytochemicals have the best in vitro evidence-supporting efficacy against skin cancer including melanoma; however, to date, none have proved efficacy on human patients. Of the phytochemicals, Curcumin is the most widely studied. Several findings support Curcumin efficacy in vitro through various molecular pathways, although most studies are in the preliminary phase. In addition, the use of alternative therapies is not exempt of risks physicians should be aware of their adverse effects, interactions with standard treatments, and possible complications arising from CAM usage. There is emerging evidence for CAM use in skin cancer, but no human clinical trials support the effectiveness of any CAM in the treatment of skin cancer to date. Nevertheless, patients worldwide frequently use CAM, and physicians should educate themselves on currently available CAMs.

Luteoloside Exerts Analgesic Effect in a Complete Freund's Adjuvant-Induced Inflammatory Model via Inhibiting Interleukin-1β Expression and Macrophage/Microglia Activation

Background

Flavonoid monomers are proved to have an anti-inflammatory effect and may also be promising for chronic pain treatment. In the present study, the analgesic effect and the relevant mechanisms of luteoloside, one of the flavonoid monomers, were investigated.

Methods

The analgesic effect of luteoloside was first evaluated in complete Freud’s adjuvant induced inflammatory model by von Frey test and Hargreaves test in both male and female mice. The interleukin-1β levels in plantar tissue, serum, dorsal root ganglion, and the dorsal horn of the spinal cord were determined by enzyme-linked immunosorbent assay or immunofluorescence. The activation of macrophage/microglia was tested by Iba-1 staining.

Results

Our data showed that luteoloside exhibited both acute and chronic analgesic phenotypes. Every single dose of luteoloside solution reached the peak transient analgesic effect 2 h after administration and lasted less than 6 h. About 14 consecutive days administration (one dose per day) later, luteoloside showed a sustained analgesic effect which lasted more than 24 h. Celecoxib 20 mg/kg combined with luteoloside 40 mg/kg achieved a similar analgesic effect as celecoxib 40 mg/kg alone. Luteoloside inhibited interleukin-1β expression in plantar tissue, dorsal root ganglion, the dorsal horn of spinal cord, and serum, after 14 days of continuous administration. Furthermore, our results also showed that the activation of macrophage/microglia in dorsal root ganglions were significantly inhibited 2 h after each single dose in daily luteoloside administration and recovered to a higher level 6 h later. These findings might be involved in the mechanisms of the acute analgesic effect of luteoloside.

Conclusion

Luteoloside presents an analgesic effect via anti-inflammatory and other mechanisms such as inhibiting the activation of macrophage/microglia.

The pharmacological and biological roles of eriodictyol

Eriodictyol is a flavonoid in the flavanones subclass. It is abundantly present in a wide range of medicinal plants, citrus fruits, and vegetables that are considered to have potential health importance. Having the considerable medicinal properties, eriodictyol has been predicted to clarify the mode of action in various cellular and molecular pathways. Evidence for the existing therapeutic roles of eriodictyol includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, cardioprotective, anti-diabetic, anti-obesity, hepatoprotective, and miscellaneous. Therefore, this review aims to present the recent evidence regarding the mechanisms of action of eriodictyol in different signaling pathways in a specific disease condition. In view of the immense therapeutic effects, eriodictyol may serve as a potential drug source to enhance community health standards.

Advances in the Tyrosinase Inhibitors from Plant Source

Tyrosinase is a multifunctional copper-containing oxidase which catalyses the oxidation of tyrosine to produce melanin. The alteration in melanin biosynthesis occurs in many diseases. The pigment has a protecting role against skin photo-carcinogenesis, but anomalous melanin pigmentation is an aesthetic problem in human beings. Moreover, the formation of neuromelanin in human brain could contribute to the neurodegeneration associated with Parkinson's disease. Finally, tyrosinase is also responsible for undesired browning in fruits and vegetables. These topics encouraged the search for new inhibitors of this enzyme for pharmaceutical, cosmetic and foods industries. This review is to report recent trends in the discovery of tyrosinase inhibitors from plant sources, to provide a rationale for the continued study of natural tyrosinase inhibitors, and to recognise the potential therapeutic rewards associated with the identification of these agents.

Virtual Screening, Docking, Synthesis and Bioactivity Evaluation of Thiazolidinediones as Potential PPARγ Partial Agonists for Preparation of Antidiabetic Agents

Background:

Peroxisome proliferator-activated receptor gamma (PPARγ) is one of the key targets of insulin resistance research, in addition to being ligand-activated transcription factors of the nuclear hormone receptor superfamily with a leading role in adiposeness activation and insulin sensitivity. They regulate cholesterol and carbohydrate metabolism through direct actions on gene expression. Despite their therapeutic importance, there are dose limiting side effects associated with PPARγ drug treatments, thus a new generation of safer PPARγ drugs are being actively sought after treatment.

Methods:

In this study, we used computer aided drug design to screen new series of PPARγ ligands, and synthesized a series of potential thiazolidinedione derivatives such as 5,7- dibenzyloxybenzyl-3-hydroxymethyl-4H-coumarin-4-ketone, using 4-steps to synthesize the target compounds and built streptozotocin (STZ) induced insulin resistance rat model to measure their antidiabetic activity.

Results:

We found that 10 mg/kg concentration of compound 0701C could significantly decrease blood glucose and serum PPARγ, serum insulin levels in insulin resistance model rat.

Conclusion:

We would conclude that compound 0701C might serve as a potential PPARγ partial agonist.

Inhibition of melanin production by anthracenone dimer glycosides isolated from Cassia auriculata seeds

The methanol extract of Cassia auriculata seeds was found to inhibit melanogenesis in B16 melanoma 4A5 cells under conditions of theophylline stimulation. Two new phlegmacin-type anthracenone dimer glycosides, auriculataosides A and B, were isolated from the active methanol fraction, and their inhibitory effects were observed in the concentration range of 0.03 to 0.3 μM. Inhibition of microphthalmia-associated transcription factor, tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 protein expression was observed, suggesting that the inhibition of these factors is part of the mechanism of action underlying melanogenesis inhibition.

Anti-proliferative effect of auriculataoside A on B16 melanoma 4A5 cells by suppression of Cdc42-Rac1-RhoA signaling protein levels

Auriculataoside A, an anthracenone dimer glycoside isolated from Cassia auriculata seed, shows anti-proliferative effects on cell line B16 melanoma 4A5 cells with an IC₅₀ value of 0.82 μM. However, it shows no such effect on normal human dermal fibroblast (HDF) cells. To evaluate the mode of action underlying the anti-proliferative effect of auriculataoside A on cells, we examined changes in whole protein expression after treatment with auriculataoside A and found that the expression Cdc42, RhoA, and Rac1, which are Rho family GTPases, was reduced. Auriculataoside A also arrested the cell cycle at G1 phase. These results suggest that the suppression of the above proteins induced G1 arrest. In addition, auriculataoside A also suppressed the expression of β-catenin and c-Myc proteins. This action of auriculataoside A could be one of the mechanisms underlying its selective anti-proliferative effect on B16 melanoma cells.

Protective Effects of Compounds in Bombax ceiba flower on Benzo[a]pyrene-Induced Cytotoxicity

The methanolic extract of the flower of Bombax ceiba was found to show protective effects on cytotoxicity induced by benzo[a]pyrene (BaP) in HT1080 cells. We therefore tried to examine and estimate the active constituents. We isolated 16 compounds from the extract, including four butyrolactones and two ascorbic acid derivatives, as well as mangiferin. Among the isolated compounds, a butyrolactone derivative, (-)-loliolide, and two flavonoids, kaempferol 3- O-β-D-glucopyranoside and quercetin 3- O-β-D-glucopyranoside, protected the cells against the BaP-induced cytotoxicity. Quercetin, the aglycone of one of the active constituents, showed a weaker effect than its glycoside. This is the first report of the protective effects of the methanolic extract of B. ceiba and its constituents on BaP-induced cytotoxicity.

Triterpenoid saponins from the genus Camellia: structures, biological activities, and molecular simulation for structure–activity relationship

This review summarizes the isolation, chemical identification, and biochemical activities of Camellia triterpenoid saponins, updating a previous review and encompassing all new studies through September 2017.

Structures of Aromatic Glycosides from the Seeds of Cassia auriculata

A new benzocoumarin glycoside, cassiaglycoside I (1), a new naphthol glycoside, cassiaglycoside II (2), a new chromon glycoside, cassiaglycoside III (3), a new phenylethyl glycoside, cassiaglycoside IV (4), were isolated from the seeds of Cassia auriculata, together with seven known constituents. The chemical structures of four new constituents were characterized on the basis of chemical and physicochemical evidence.

Luteoloside Acts as 3C Protease Inhibitor of Enterovirus 71 In Vitro

Luteoloside is a member of the flavonoids family that exhibits several bioactivities including anti-microbial and anti-cancer activities. However, the antiviral activity of luteoloside against enterovirus 71 (EV71) and the potential mechanism(s) responsible for this effect remain unknown. In this study, the antiviral potency of luteoloside against EV71 and its inhibitory effects on 3C protease activity were evaluated. First, we investigated the cytotoxicity of luteoloside against rhabdomyosarcoma (RD) cells, which was the cell line selected for an in vitro infection model. In a subsequent antiviral assay, the cytopathic effect of EV71 was significantly and dose-dependently relieved by the administration of luteoloside (EC50 = 0.43 mM, selection index = 5.3). Using a plaque reduction assay, we administered luteoloside at various time points and found that the compound reduced EV71 viability in RD cells rather than increasing defensive mobilization or viral absorption. Moreover, biochemical studies focused on VP1 (a key structural protein of EV71) mRNA transcript and protein levels also revealed the inhibitory effects of luteoloside on the EV71 viral yield. Finally, we performed inhibition assays using luteoloside to evaluate its effect on recombinant 3C protease activity. Our results demonstrated that luteoloside blocked 3C protease enzymatic activity in a dose-dependent manner (IC50 = 0.36 mM) that was similar to the effect of rutin, which is a well-known C3 protease inhibitor. Collectively, the results from this study indicate that luteoloside can block 3C protease activity and subsequently inhibit EV71 production in vitro.