Potent anti-melanogenic activity and favorable toxicity profile of selected 4-phenyl hydroxycoumarins in the zebrafish model and the computational molecular modeling studies

Discovery of potential quality markers of Fritillariae thunbergii bulbus in pneumonia by combining UPLC-QTOF-MS, network pharmacology, and molecular docking

Fritillariae thunbergii bulbus (FTB) is a popular Chinese herbal medicine with various applications in respiratory diseases. The quality evaluation of FTB has been insufficient to date, as the active ingredients and mechanisms of action of FTB remain unclear. This study proposes a novel strategy for exploring the quality markers (Q-markers) of FTB based on UPLC-QTOF-MS analysis, network pharmacology, molecular docking, and molecular dynamics (MD) simulation. A total of 26 compounds in FTB were identified by UPLC-QTOF-MS. Ten of these compounds were screened as Q-markers based on network pharmacology for their anti-pneumonia effects, including imperialine, peimisine, peiminine, ebeiedinone, zhebeirine, puqiedine, 9-hydroxy-10,12-octadecadienoic acid, (9Z,12Z,15Z)-13-hydroxy-9,12,15-octadecatrienoic acid, 9,12,15-octadecatrienoic acid, and (2E,4Z,7Z,10Z,13Z,16Z,19Z)-2,4,7,10,13,16,19-docosaheptaenoic acid methyl ester (DAME). These Q-markers were predicted to act on multiple targets and pathways associated with pneumonia. Molecular docking results revealed that most of the Q-markers showed high affinity with at least one of the main targets of pneumonia, and the top ten complexes were confirmed with MD simulation. Network pharmacology indicated that FTB may act on the TNF signaling pathway, HIF-1 signaling pathway, JAK-STAT signaling pathway, etc. The results demonstrated that imperialine (P8), peimisine (P9), peiminine (P11), ebeiedine (P15), zhebeirine (P16), and puqiedine (P18) may be potential Q-markers of FTB, and AKT1, IL-6, VEGFA, TP53, EGFR, STAT3, PPARG, MMP9, and CASP3 may be promising therapeutic targets for pneumonia treatment that are worthy of further research.

Evaluation of whitening and antimicrobial activity of two strains of Bletilla striata WT and HL20

ETHNOPHARMACOLOGICAL RELEVANCE

Bletilla striata (Thunb.) Reixchb.f. is a perennial herb of the Orchid-aceae Bletilla and have various ethnopharmacological uses. As a traditional astringent hemostatic Chinese herbal medicine, B. striata has been widely used in the treatment of 127 different kinds of hemorrhagic diseases. Moreover, B. striata has been a beauty medicine since ancient times, with the first ancient records dating back to 2000 years ago, traditionally used to removing freckle and smooth the skin. Because of the high content of polysaccharides, which is considered the primary active substance of B. striata and having anti-aging, whitening, and anti-oxidation functions, this is also widely used in the cosmetics industry.

AIM

We screened the germplasm resources of B. striata in the early stage and the superior HL20 strain was obtained. Our research aims to analyze and compare the whitening and antimicrobial activities of different extracts (aqueous extract, ethanol extract, and aqueous extract from ethanol extract filter residue) of the selected superior varieties (HL20) and the control (WT).

MATERIALS AND METHODS

L-tyrosine and L-dopa were used as substrates to establish a tyrosinase inhibition system with arbutin as the positive control and the whitening activity was measured by the inhibition rate of TYR-M and TYR-D. Besides, an in vitro antimicrobial susceptibility test was performed to assess the antimicrobial activity of the B. striata extracts. In a nutshell, the method of punching diffusion was used to thoroughly examine the effects of three extracts from two strains on the antimicrobial activity of five types of microorganism in cosmetics microbiological testing products. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of different extracts were also assessed.

RESULTS

Results showed that the whitening and antimicrobial properties of the HL20 strain were found to be more potent than those of the WT strain. Compared with the other two extraction methods, the aqueous extract from ethanol extract filter residue of B. striata exhibited better inhibition of tyrosinase activity. The antimicrobial assay manifested that only the ethanol extract of B. striata had an inhibitory effect and had a potent antimicrobial impact on E. faecalis.

CONCLUSIONS

In summary, we evaluated the pharmacological activity of the pre-selected excellent variety (HL20) in terms of whitening and antimicrobial activity. Our results reveal that the selected strain (HL20) has certain advantages over the control (WT). These characteristics make it a candidate additive for whitening cosmetics. Our study also provides a further contribution to the product application of B. striata in cosmetics and antimicrobial agents and the selected HL20 also lays a foundation for the breeding of superior B. striata varieties.

A 7-Hydroxy 4-Methylcoumarin Enhances Melanogenesis in B16-F10 Melanoma Cells

The objectives of this study were to investigate the melanogenetic potentials of the naturally occurring 7-hydroxy coumarin derivatives 7-hydroxy 5,6-dimethoxycoumarin (7H-5,6DM), 7-hydroxy 6,8-dimethoxycoumarin (7H-6,8DM), 7-hydroxy 6-methoxycoumarin (7H-6M), and 7-hydroxy 4-methylcoumarin (7H-4M) in the melanogenic cells model for murine B16F10 melanoma cells. The initial results indicated that melanin production and intracellular tyrosinase activity were significantly stimulated by 7H-4M but not by 7H-5,6DM, 7H-6,8DM, or 7H-6M. Therefore, our present study further investigated the melanogenic effects of 7H-4M in B16-F10 cells, as well as its mechanisms of action. In a concentration-dependent manner, 7H-4M increased intracellular tyrosinase activity, leading to the accumulation of melanin without affecting the viability of B16-F10 cells. Our study further investigated the effects of 7H-4M on melanogenesis, including its ability to promote tyrosinase activity, increase melanin content, and activate molecular signaling pathways. The results indicate that 7H-4M effectively stimulated tyrosinase activity and significantly increased the expression of melanin synthesis-associated proteins, such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP1), and TRP2. Based on our findings, we can conclude that 7H-4M has the ability to activate the melanogenesis process through the upregulation of cAMP-dependent protein kinase (PKA) and the cAMP response element-binding protein (CREB). Additionally, our study showed that 7H-4M induced melanogenic effects by downregulating the extracellular signal-regulated kinase (ERK) and the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/glycogen synthesis kinase-3β (GSK-3β) cascades, while upregulating the JNK and p38 signaling pathways. Finally, the potential of using 7H-4M in topical applications was tested through primary human skin irritation tests. During these tests, no adverse reactions were induced by 7H-4M. In summary, our results indicate that 7H-4M regulates melanogenesis through various signaling pathways such as GSK3β/β-catenin, AKT, PKA/CREB, and MAPK. These findings suggest that 7H-4M has the potential to prevent the development of pigmentation diseases.

Anti-Melanogenic Potential of Natural and Synthetic Substances: Application in Zebrafish Model

Melanogenesis is a biosynthetic pathway for the formation of the pigment melanin in human skin. A key enzyme in the process of pigmentation through melanin is tyrosinase, which catalyzes the first and only limiting step in melanogenesis. Since the discovery of its methanogenic properties, tyrosinase has been the focus of research related to the anti-melanogenesis. In addition to developing more effective and commercially safe inhibitors, more studies are required to better understand the mechanisms involved in the skin depigmentation process. However, in vivo assays are necessary to develop and validate new drugs or molecules for this purpose, and to accomplish this, zebrafish has been identified as a model organism for in vivo application. In addition, such model would allow tracking and studying the depigmenting activity of many bioactive compounds, important to genetics, medicinal chemistry and even the cosmetic industry. Studies have shown the similarity between human and zebrafish genomes, encouraging their use as a model to understand the mechanism of action of a tested compound. Interestingly, zebrafish skin shares many similarities with human skin, suggesting that this model organism is suitable for studying melanogenesis inhibitors. Accordingly, several bioactive compounds reported herein for this model are compared in terms of their molecular structure and possible mode of action in zebrafish embryos. In particular, this article described the main metabolites of Trichoderma fungi, in addition to substances from natural and synthetic sources.

Statistical Analysis and Machine Learning Used in the Case of Two Behavioral Tests Applied in Zebrafish Exposed to Mycotoxins

Machine learning is a branch of artificial intelligence that allows computer systems to learn directly from examples, data, and experience. Statistical modeling is more about finding connections between variables and consequently the impact of these relationships, while also catering for prediction. It should be clear that these two methodologies are different in terms of their purpose, despite the fact that they use similar means to get there. The evaluation of the machine learning algorithm uses a set of tests to validate its accuracy. Although, for a statistical model, the analysis of regression parameters by confidence intervals, significance tests and other tests can be used to assess the legitimacy of the model. To demonstrate the applications and usefulness of this theory, an experimental study was conducted on zebrafish exposed to mycotoxin. Methods: Patulin (70 µg/L) and kojic acid (100 mg/L, 204 mg/L, and 284 mg/L) were administered by immersion to zebrafish once daily for a period of 7 days before the behavior testing. The following behavioral tests were performed: a novel tank test (NTT) (to assess the explorative behavior and anxiety); and a Y-maze test (which measures the spontaneous explorative behavior). Behavioral tests were performed on separate days. For the behavior tests, the statistical analysis was performed using ANOVA variation analysis (two-way ANOVA). All results are expressed as the mean ± standard error of the mean. The values of the general index F for which p < 0.05 were considered statistically significant. Results: Y-maze—patulin exposure led to an intensification of the locomotor activity and an increased traveled distance and number of arm entries. By increasing the spontaneous alternation between the aquarium’s arms, patulin has shown a stimulating effect on spatial memory. In the case of zebrafish exposed to 100 mg/L kojic acid, the traveled distance was shorter by 27% than the distance attained by those in the control group. The higher doses of kojic acid (204 mg/L and 284 mg/L) led to an increased locomotor activity, distance traveled, number of arm entries, and the spontaneous alternation. The increase in spontaneous alternation demonstrates that 204 mg/L and 284 mg/L kojic acid doses had a stimulating effect on spatial memory. Novel tank test—compared to the control group, the traveled distance of the patulin-exposed fish is slightly reduced. Compared to the control group, the traveled distance of the kojic acid-exposed fish is reduced, due to a shorter mobile time (by 25–27% in the case of fish exposed to 204 mg/L and 284 mg/L kojic acid). Patulin and kojic acid exhibit toxic effects on zebrafish liver, kidney, and myocardium and leads to severe alteration. We continued the analysis by trying some machine learning algorithms on the classification problems in the case of the two behavioral tests MAZE and NTT, after which we concluded that the results were better in the case of the NTT test relative to the MAZE test and that the use of decision tree algorithms leads to amazing results, knowing that their hierarchical structure allows them to learn signals from both classes. Conclusions: The groups exposed to patulin and kojic acid show histological changes in the liver, kidneys, and myocardial muscle tissue. The novel tank test, which assesses exploratory behavior, has been shown to be conclusive in the behavioral analysis of fish that have been given toxins, demonstrating that the intoxicated fish had a decreased explorative behavior and increased anxiety. We were able to detect a machine learning algorithm in the category of decision trees, which can be trained to classify the behavior of fish that were given a toxin in the category of those used in the experiment, only by analyzing the characteristic features of the NTT Behavior Test.

Comprehensive evaluation of Bletilla striata and its substitutes by combining phenotypic characteristic, chemical composition, and anti-melanogenic activity

Bletilla striata is a precious traditional Chinese medical herb with a wide range of applications in pharmacological and cosmetic fields. Because of the shortage of resources, Bletilla ochracea and Bletilla formosanare are also used as the substitutes. To distinguish the differences and homologies, the typical morphologic and microscopic characteristics of them were compared, and a UPLC fingerprint analysis coupled with chemometric methods were developed for characterization and quality evaluation of Bletillae Rhizoma. Gastrodin, protocatechuic acid, gymnoside V, blestrianol A, coelonin, gymnosides Ⅸ and batatasin II were identified as the potential chemical markers for comprehensive quality evaluation by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The anti-melanogenic activities of the three species were also compared for the first time in vivo using the zebrafish model, the results suggested that B. striata and its two substitutes had obvious anti-melanogenic activities, and they were not-toxic at depigmenting doses. Molecular docking studies revealed batatasin III, blestrianol A, coelonin, and gastrodin were possible multitarget compounds associated with melanogenesis suppression, which are important for their potential future medical application.

Discovery and identification of potential anti-melanogenic active constituents of Bletilla striata by zebrafish model and molecular docking

BACKGROUND

Bletilla striata is the main medicine of many skin whitening classic formulas in traditional Chinese medicine (TCM) and is widely used in cosmetic industry recently. However, its active ingredients are still unclear and its fibrous roots are not used effectively. The aim of the present study is to discover and identify its potential anti-melanogenic active constituents by zebrafish model and molecular docking.

METHODS

The antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis-(3-ethylbenthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The anti-melanogenic activity was assessed by tyrosinase inhibitory activity in vitro and melanin inhibitory in zebrafish. The chemical profiles were performed by ultra-high-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). Meanwhile, the potential anti-melanogenic active constituents were temporary identified by molecular docking.

RESULTS

The 95% ethanol extract of B. striata fibrous roots (EFB) possessed the strongest DPPH, ABTS, FRAP and tyrosinase inhibitory activities, with IC50 5.94 mg/L, 11.69 mg/L, 6.92 mmol FeSO4/g, and 58.92 mg/L, respectively. In addition, EFB and 95% ethanol extract of B. striata tuber (ETB) significantly reduced the melanin synthesis of zebrafish embryos in a dose-dependent manner. 39 chemical compositions, including 24 stilbenoids were tentatively identified from EFB and ETB. Molecular docking indicated that there were 83 (including 60 stilbenoids) and 85 (including 70 stilbenoids) compounds exhibited stronger binding affinities toward tyrosinase and adenylate cyclase.

CONCLUSION

The present findings supported the rationale for the use of EFB and ETB as natural skin-whitening agents in pharmaceutical and cosmetic industries.

Unravelling Anti-Melanogenic Potency of Edible Mushrooms Laetiporus sulphureus and Agaricus silvaticus In Vivo Using the Zebrafish Model

Severe drawbacks associated with the topical use of depigmenting agents in treatments of skin hyperigmentations impose a great demand for novel, effective, and safe melanogenesis inhibitors. Edible and medicinal mushrooms, known for numerous health-promoting properties, represent a rich reservoir of anti-melanogenic compounds, with the potential to be applied in preventing excessive skin pigmentation. Herein, using zebrafish (Danio rerio) as a preclinical animal model, we have demonstrated that ethanol extract of Laetiporus sulphureus (LSE) and Agaricus silvaticus (ASE) are not toxic at high doses up to 400-500 µg/mL while effectively inhibit melanogenesis in a dose-dependent manner. At depigmenting doses, the explored extracts showed no adverse effects on zebrafish embryos melanocytes. Even more, they did not provoke inflammation or neutropenia when applied at the highest dose ensuring almost complete the cells depigmentation. Since LSE and ASE have demonstrated significantly higher the therapeutic potential than kojic acid and hydroquinone, two well-known depigmenting agents, overall results of this study strongly suggest that the explored mushrooms extracts could be used as efficient and safe topical agents in treatments of skin hyperpigmentation disorders.

Streptomyces sp. BV410 isolate from chamomile rhizosphere soil efficiently produces staurosporine with antifungal and antiangiogenic properties

Applying a bioactivity‐guided isolation approach, staurosporine was separated and identified as the active principle in the culture extract of the new isolate Streptomyces sp. BV410 collected from the chamomile rhizosphere. The biotechnological production of staurosporine by strain BV410 was optimized to yield 56 mg/L after 14 days of incubation in soy flour–glucose–starch–mannitol‐based fermentation medium (JS). The addition of FeSO₄ significantly improved the staurosporine yield by 30%, while the addition of ZnSO₄ significantly reduced staurosporine yield by 62% in comparison with the starting conditions. Although staurosporine was first isolated in 1977 from Lentzea albida (now Streptomyces staurosporeus) and its potent kinase inhibitory effect has been established, here, the biological activity of this natural product was assessed in depth in vivo using a selection of transgenic zebrafish (Danio rerio) models, including Tg(fli1:EGFP) with green fluorescent protein‐labeled endothelial cells allowing visualization and monitoring of blood vessels. This confirmed a remarkable antiangiogenic activity of the compound at doses of 1 ng/ml (2.14 nmol/L) which is below doses inducing toxic effects (45 ng/ml; 75 nmol/L). A new, efficient producing strain of commercially significant staurosporine has been described along with optimized fermentation conditions, which may lead to optimization of the staurosporine scaffold and its wider applicability.

Lectin from Laetiporus sulphureus effectively inhibits angiogenesis and tumor development in the zebrafish xenograft models of colorectal carcinoma and melanoma

In spite of extensive usage of Laetiporus sulphureus (sulphur polypore) in traditional European and Asian ethno-medicine for centuries, its anticancer therapeutic potential and toxicity profile remained explored in animal models. Herein, using zebrafish (Danio rerio), as a preclinical animal model, we demonstrated that L. sulphureus lectin (LSL) and ethanol extract (LSE) are non-toxic at high doses up to 400-500 μg/mL, while they effectively inhibited angiogenesis and cancer development at much lower doses. Lectin showed 74-fold higher anti-angiogenic potency than the extract, and even 378-fold higher therapeutic potential than sunitinib-malate, cardiotoxic and myelosupressive anti-angiogenic drug of clinical relevance. Using wound healing and MTT assays, we proved LSL's strong antimigratory effect and selective endothelial cytotoxicity in relation to lung fibroblasts. In addition, employing the zebrafish xenograft models, we demonstrated that LSL almost completely reduced growth, neovascularization and metastasis of human colorectal carcinoma and mouse melanoma. Even more, LSL exerted 8-fold higher potency towards colorectal carcinoma than melanoma, showing markedly higher activity than cisplatin, while LSE failed to express any anticancer activity. Accompanied with non-toxic response, including neutropenia and inflammation, the results of this study strongly imply that LSL could be used as safe adjuvant in chemotherapy against colorectal carcinoma and melanoma.

Use of Zebrafish in Drug Discovery Toxicology

Unpredicted human safety events in clinical trials for new drugs are costly in terms of human health and money. The drug discovery industry attempts to minimize those events with diligent preclinical safety testing. Current standard practices are good at preventing toxic compounds from being tested in the clinic; however, false negative preclinical toxicity results are still a reality. Continual improvement must be pursued in the preclinical realm. Higher-quality therapies can be brought forward with more information about potential toxicities and associated mechanisms. The zebrafish model is a bridge between in vitro assays and mammalian in vivo studies. This model is powerful in its breadth of application and tractability for research. In the past two decades, our understanding of disease biology and drug toxicity has grown significantly owing to thousands of studies on this tiny vertebrate. This Review summarizes challenges and strengths of the model, discusses the 3Rs value that it can deliver, highlights translatable and untranslatable biology, and brings together reports from recent studies with zebrafish focusing on new drug discovery toxicology.

Natural and Bioinspired Phenolic Compounds as Tyrosinase Inhibitors for the Treatment of Skin Hyperpigmentation: Recent Advances

One of the most common approaches for control of skin pigmentation involves the inhibition of tyrosinase, a copper-containing enzyme which catalyzes the key steps of melanogenesis. This review focuses on the tyrosinase inhibition properties of a series of natural and synthetic, bioinspired phenolic compounds that have appeared in the literature in the last five years. Both mushroom and human tyrosinase inhibitors have been considered. Among the first class, flavonoids, in particular chalcones, occupy a prominent role as natural inhibitors, followed by hydroxystilbenes (mainly resveratrol derivatives). A series of more complex phenolic compounds from a variety of sources, first of all belonging to the Moraceae family, have also been described as potent tyrosinase inhibitors. As to the synthetic compounds, hydroxycinnamic acids and chalcones again appear as the most exploited scaffolds. Several inhibition mechanisms have been reported for the described inhibitors, pointing to copper chelating and/or hydrophobic moieties as key structural requirements to achieve good inhibition properties. Emerging trends in the search for novel skin depigmenting agents, including the development of assays that could distinguish between inhibitors and potentially toxic substrates of the enzyme as well as of formulations aimed at improving the bioavailability and hence the effectiveness of well-known inhibitors, have also been addressed.

Flavonoids as positive allosteric modulators of α7 nicotinic receptors

The use of positive allosteric modulators (PAM) of α7 nicotinic receptors is a promising therapy for neurodegenerative, inflammatory and cognitive disorders. Flavonoids are polyphenolic compounds showing neuroprotective, anti-inflammatory and pro-cognitive actions. Besides their well-known antioxidant activity, flavonoids trigger intracellular pathways and interact with receptors, including α7. To reveal how the beneficial actions of flavonoids are linked to α7 function, we evaluated the effects of three representative flavonoids -genistein, quercetin and the neoflavonoid 5,7-dihydroxy-4-phenylcoumarin- on whole-cell and single-channel currents. All flavonoids increase the maximal currents elicited by acetylcholine with minimal effects on desensitization and do not reactivate desensitized receptors, a behaviour consistent with type I PAMs. At the single-channel level, they increase the duration of the open state and produce activation in long-duration episodes with a rank order of efficacy of genistein > quercetin ≥ neoflavonoid. By using mutant and chimeric α7 receptors, we demonstrated that flavonoids share transmembrane structural determinants with other PAMs. The α7-PAM activity of flavonoids results in decreased cell levels of reactive oxygen species. Thus, allosteric potentiation of α7 may be an additional mechanism underlying neuroprotective actions of flavonoids, which may be used as scaffolds for designing new therapeutic agents.

A Zebrafish Embryo as an Animal Model for the Treatment of Hyperpigmentation in Cosmetic Dermatology Medicine

For years, clinical studies involving human volunteers and several known pre-clinical in vivo models (i.e., mice, guinea pigs) have demonstrated their reliability in evaluating the effectiveness of a number of depigmenting agents. Although these models have great advantages, they also suffer from several drawbacks, especially involving ethical issues regarding experimentation. At present, a new depigmenting model using zebrafish has been proposed and demonstrated. The application of this model for screening and studying the depigmenting activity of many bioactive compounds has been given great attention in genetics, medicinal chemistry and even the cosmetic industry. Depigmenting studies using this model have been recognized as noteworthy approaches to investigating the antimelanogenic activity of bioactive compounds in vivo. This article details the current knowledge of zebrafish pigmentation and its reliability as a model for the screening and development of depigmenting agents. Several methods to quantify the antimelanogenic activity of bioactive compounds in this model, such as phenotype-based screening, melanin content, tyrosinase inhibitory activity, other related proteins and transcription genes, are reviewed. Depigmenting activity of several bioactive compounds which have been reported towards this model are compared in terms of their molecular structure and possible mode of actions. This includes patented materials with regard to the application of zebrafish as a depigmenting model, in order to give an insight of its intellectual value. At the end of this article, some limitations are highlighted and several recommendations are suggested for improvement of future studies.