Active constituents from Sophora japonica exhibiting cellular tyrosinase inhibition in human epidermal melanocytes

Effects of Roasting on Antibacterial and Antioxidant Properties of Sophora japonica Buds-The Involvements of Rutin and Quercetin Constituents

Roasting is the most common thermal processing method established for Sophora japonica (SJ) buds applied as traditional medicines, and it has also been reported to alter several of their therapeutic functions. However, there have been no studies investigating the influences of roasting on the effects of these materials against bacteria. Therefore our study was performed to examine the alterations that this process would induce in SJ buds' antibacterial properties. Fresh buds were subjected to hot air drying or different roasting methods, as described in Materia Medica, including yellow-, dark yellow-, scorched-, and charred-roasting conditions. Antibacterial effects, total polyphenol and flavonoid contents, antioxidant activities, as well as rutin and quercetin concentrations in methanol extracts obtained from those materials, were then measured and compared. The results showed that dark yellow-roasted SJ buds exerted the strongest antibacterial and antioxidant activities and were also the richest in polyphenol contents. Analysis of rutin and quercetin revealed that, following the increment in heating temperatures up to 240 °C, the reduction in rutin content occurred in a parallel manner to the increment in quercetin content. However, overheating at 300 °C reduced both concentrations. Among the five tested samples, dark yellow-roasted SJ had the highest amounts of quercetin. Furthermore, the comparison of rutin and quercetin in antibacterial effects and antioxidant activities showed that the latter was significantly stronger in both of these functions, suggesting that the increment in quercetin content as a result of heat treatment was responsible, at least in part, for the potentiation of the two therapeutic effects.

Full-Length Transcriptome Sequencing and Comparative Transcriptomic Analyses Provide Comprehensive Insight into Molecular Mechanisms of Flavonoid Metabolites Biosynthesis in Styphnolobium japonicum

Styphnolobium japonicum L. is a commonly consumed plant in China, known for its medicinal and nutritional benefits. This study focuses on the medicinal properties influenced by flavonoid metabolites, which vary during flower development. Utilizing full-length transcriptome sequencing on S. japonicum flowers, we observed changes in gene expression levels as the flowers progressed through growth stages. During stages S1 and S2, key genes related to flavonoid synthesis (PAL, 4CL, CHS, F3H, etc.) exhibited heightened expression. A weighted gene co-expression network analysis (WGCNA) identified regulatory genes (MYB, bHLH, WRKY) potentially involved in the regulatory network with flavonoid biosynthesis-related genes. Our findings propose a regulatory mechanism for flavonoid synthesis in S. japonicum flowers, elucidating the genetic underpinnings of this process. The identified candidate genes present opportunities for genetic enhancements in S. japonicum, offering insights into potential applications for improving its medicinal attributes.

Fermentation of Robinia pseudoacacia flower for improving the antioxidation: optimized conditions, active composition, mechanism, and biotransformation process

Robinia pseudoacacia flower is a natural product with many biological activities, including antioxidation. To further develop its antioxidation, the extract was fermented by Aspergillus niger FFCC 3112 in the medium with carbon to nitrogen ratio of 1.4:1 and initial pH of 4.2 for 3.5 days to form the best antioxidant activity of the fermentation product by strain screening, single factor optimization, and response surface methodology. Further analysis, isolation and activity determination showed that a main chemical component, kaempferol-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranosyl-7-O-α-L-rhamnopyranoside, in the extract was completely hydrolyzed to kaempferol-7-O-α-L-rhamnopyranoside and kaempferol with better antioxidant activity through biotransformation, which was the basis for improving the antioxidant activity of fermentation products. Moreover, the mechanism of antioxidant and the contribution of phenolic hydroxyl groups were investigated by density functional theory. The result indicated that the antioxidant capacity of kaempferol-7-O-α-L-rhamnopyranoside and kaempferol increased with the increase of solvent polarity. In high-polarity solvents, they mainly scavenge free radicals through single electron transfer followed by proton transfer.

Synergistic Effect of Sophora japonica and Glycyrrhiza glabra Flavonoid-Rich Fractions on Wound Healing: In Vivo and Molecular Docking Studies

Glycyrrhiza glabra and Sophora japonica (Fabaceae) are well-known medicinal plants with valuable secondary metabolites and pharmacological properties. The flavonoid-rich fractions of G. glabra roots and S. japonica leaves were prepared using Diaion column chromatography, and the confirmation of flavonoid richness was confirmed using UPLC-ESI-MS profiling and total phenolics and flavonoids assays. UPLC-ESI-MS profiling of the flavonoid-rich fraction of G. glabra roots and S. japonica leaves resulted in the tentative identification of 32 and 23 compounds, respectively. Additionally, the wound healing potential of topical preparations of each fraction, individually and in combination (1:1) ointment and gel preparations, were investigated in vivo, supported by histopathological examinations and biomarker evaluations, as well as molecular docking studies for the major constituents. The topical application of G. glabra ointment and gel, S. japonica ointment and gel and combination preparations significantly increase the wound healing rate and the reduction of oxidative stress in the wound area via MDA reduction and the elevation of reduced GSH and SOD levels as compared to the wound and Nolaver®-treated groups. The molecular docking study revealed that that major compounds in G. glabra and S. japonica can efficiently bind to the active sites of three proteins related to wound healing: glycogen synthase kinase 3-β (GSK3-β), matrix metalloproteinases-8 (MMP-8) and nitric oxide synthase (iNOS). Consequently, G. glabra roots and S. japonica leaves may be a rich source of bioactive metabolites with antioxidant, anti-inflammatory and wound healing properties.

Metabolomic analysis reveals dynamic changes in secondary metabolites of Sophora japonica L. during flower maturation

Sophora japonica L. is widely consumed in China because of its medicinal and nutritional value. Its quality is greatly affected by the accumulation of metabolites, which varies with the stage of flower development. However, changes in the characteristics of the secondary metabolites during flower maturity remain unclear. Ultra-high-performance liquid chromatography coupled with electrospray ionization-triple quadrupole-linear ion trap mass spectrometry (UPLC-ESI-QTRAP-MS/MS) revealed dynamic changes in the secondary metabolites of S. japonica during the five flower-maturity stages. We monitored 331 metabolites and screened 164. The differential metabolites showed seven trends during flower maturation, with flavonoids and phenolic acids having the most varied expressions. Flower buds (S2-S3) are rich in flavonoids and are thus suitable for use in high-quality medicine or industrial extraction. Our study provides an empirical basis for the informed harvesting of S. japonica based on its mode of utilization.

Chemical Characterization and Metabolic Profiling of the Compounds in the Chinese Herbal Formula Li Chang Decoction by UPLC-QTOF/MS

Background

Li Chang decoction (LCD), a Chinese medicine formula, is commonly used to treat ulcerative colitis (UC) in clinics.

Purpose

This study aimed to identify the major components in LCD and its prototype and metabolic components in rat biological samples.

Methods

The chemical constituents in LCD were identified by establishing a reliable ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF/MS) method. Afterwards, the rats were orally administered with LCD, and the biological samples (plasma, urine, and feces) were collected for further analyzing the effective compounds in the treatment of UC.

Result

A total of 104 compounds were discriminated in LCD, including 26 flavonoids, 20 organic acids, 20 saponins, 8 amino acids, 5 oligosaccharides, 5 tannins, 3 lignans, 2 alkaloids, and 15 others (nucleosides, glycosides, esters, etc.). About 50 prototype and 94 metabolic components of LCD were identified in biological samples. In total, 29 prototype components and 22 metabolic types were detected in plasma. About 27 prototypes and 96 metabolites were discriminated in urine, and 34 prototypes and 18 metabolites were identified in feces.

Conclusion

The flavonoids, organic acids, and saponins were the major compounds of LCD, and this study promotes the further pharmacokinetic and pharmacological evaluation of LCD.

Chemical Profiles of Korean Bee Pollens and Their Catechol-O-methyltransferase Inhibitory Activities

Bee pollen is an apicultural product collected by honeybees from flower stamens and is consumed to help maintain a healthy diet. In this study, the chemical profiles of 11 Korean bee pollens were investigated using molecular networking analysis. This analysis elucidated the presence of two major clusters, hydroxycinnamoyl acid amides (HCAAs, molecular network 1 (MN₁)) and flavonoid glycosides (MN₂), in the bee pollen samples. The inhibitory properties of the bee pollens and the isolated HCAAs toward human catechol-O-methyltransferase (COMT), a key neurotransmitter involved in Parkinson's disease and depression, were determined. N¹,N⁵,N¹⁰-(E)-tricaffeoylspermidine ((E,E,E)-1) exhibited the highest activity of the four compounds isolated, with an IC₅₀ value 16 μM, and inhibited COMT competitively. Quantitative analysis of HCAAs showed that the amounts of N¹,N¹⁰-dicaffeoyl-N⁵-p-coumaroylspermidine (2) and N¹⁰-caffeoyl-N¹,N⁵-di-p-coumaroylspermidine (3) contributed to the observed differences in the COMT inhibitory activities of Korean bee pollens. This study may lead to the prevention and treatment of Parkinson's disease and depression using bee pollens.

Advantages of Hyaluronic Acid and Its Combination with Other Bioactive Ingredients in Cosmeceuticals

This study proposes a review on hyaluronic acid (HA) known as hyaluronan or hyaluronate and its derivates and their application in cosmetic formulations. HA is a glycosaminoglycan constituted from two disaccharides (N-acetylglucosamine and D-glucuronic acid), isolated initially from the vitreous humour of the eye, and subsequently discovered in different tissues or fluids (especially in the articular cartilage and the synovial fluid). It is ubiquitous in vertebrates, including humans, and it is involved in diverse biological processes, such as cell differentiation, embryological development, inflammation, wound healing, etc. HA has many qualities that recommend it over other substances used in skin regeneration, with moisturizing and anti-ageing effects. HA molecular weight influences its penetration into the skin and its biological activity. Considering that, nowadays, hyaluronic acid has a wide use and a multitude of applications (in ophthalmology, arthrology, pneumology, rhinology, aesthetic medicine, oncology, nutrition, and cosmetics), the present study describes the main aspects related to its use in cosmetology. The biological effect of HA on the skin level and its potential adverse effects are discussed. Some available cosmetic products containing HA have been identified from the brand portfolio of most known manufacturers and their composition was evaluated. Further, additional biological effects due to the other active ingredients (plant extracts, vitamins, amino acids, peptides, proteins, saccharides, probiotics, etc.) are presented, as well as a description of their possible toxic effects.

Prediction of the therapeutic mechanism responsible for the effects of Sophora japonica flower buds on contact dermatitis by network-based pharmacological analysis

ETHNOPHARMACOLOGICAL RELEVANCE

The flower buds of Sophora japonica L. are a major traditional medicine in China, Japan, and Korea and are used to stop bleeding and 'cool the blood'. Accordingly, they are used to treat bleeding haemorrhoids, hypertension, and pyoderma. In addition, it was recently found that the flower buds of S. japonica (SJ) have cosmetic whitening properties.

MATERIALS AND METHODS

Compounds in SJ and their targets and related diseases were investigated using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database and analysis platform. Target gene information was obtained from the UniProt database. Network construction was carried out using Cytoscape 3.72. Contact dermatitis (CD)-related gene searching was performed using the Cytoscape string App. Docking analysis was conducted using AutoDock Vina. Six-week-old Balb/c male mice with DNFB (1-fluoro-2,4-dinitrofluorobenzene)-induced CD were treated with a methanol extract of the flower buds of S. japonica (MESJ), and its effects on skin colour, lesions, and immune cell infiltration, and on histopathological abnormalities such as epidermal hyperplasia were investigated.

RESULTS

Eleven compounds targeted 13 CD-related genes, that is, serum albumin (ALB), prostaglandin G/H synthase (COX) 2, C-X-C motif chemokine (CXCL) 2, CXCL10, ICAM1, IFN-γ, IL-10, IL-1α, IL-1β, IL-2, IL-6, E-selectin, and TNF. In the murine DNFB model, MESJ significantly suppressed scaling, erythema, and skin thickening as compared with DNFB controls and epithelial hyperplasia and immune cell infiltrations induced by repeated DNFB application.

CONCLUSIONS

Our animal study showed that the mode of action of MESJ was closely related to the prevention of epithelial hyperplasia and immune cell infiltration. The results obtained demonstrated that the flower buds of S. japonica offer a potential means of treating CD, and suggest that the therapeutic mechanism of CD is explained by relations between 11 major components of SJ, including kaempferol and quercetin, and 13 CD-related genes.

A systematic review of synthetic tyrosinase inhibitors and their structure-activity relationship

Tyrosinase is a copper-containing oxidation enzyme, which is responsible for the production of melanin. This enzyme is widely distributed in microorganisms, animals and plants, and plays an essential role in undesirable browning of fruits and vegetables, antibiotic resistance, skin pigment formation, sclerotization of cuticle, neurodegeneration, etc. Hence, it has been recognized as a therapeutic target for the development of antibrowning agents, antibacterial agents, skin-whitening agents, insecticides, and other therapeutic agents. With great potential application in food, agricultural, cosmetic and pharmaceutical industries, a large number of synthetic tyrosinase inhibitors have been widely reported in recent years. In this review, we systematically summarized the advances of synthetic tyrosinase inhibitors in the literatures, including their inhibitory activity, cytotoxicity, structure-activity relationship (SAR), inhibition kinetics, and interaction mechanisms with the enzyme. The collected information is expected to provide a rational guidance and effective strategy to develop novel, potent and safe tyrosinase inhibitors for better practical applications in the future.

Advances in the Design of Genuine Human Tyrosinase Inhibitors for Targeting Melanogenesis and Related Pigmentations

Human tyrosinase (hsTYR) is the key enzyme ensuring the conversion of l-tyrosine to dopaquinone, thereby initiating melanin synthesis, i.e., melanogenesis. Although the protein has long been familiar, knowledge about its three-dimensional structure and efficient overexpression protocols emerged only recently. Consequently, for decades medicinal chemistry studies aiming at developing skin depigmenting agents relied almost exclusively on biological assays performed using mushroom tyrosinase (abTYR), producing a plethoric literature, often of little useful purpose. Indeed, several recent reports have pointed out spectacular differences in terms of interaction patterns and inhibition values between hsTYR and abTYR, including for widely used standard tyrosinase inhibitors. In this review, we summarize the last developments regarding the potential role of hsTYR in human pathologies, the advances in recombinant expression systems and structural data retrieving, and the pioneer generation of true hsTYR inhibitors. Finally, we present suggestions for the design of future inhibitors of this highly attractive target in pharmacology and dermocosmetics.

Chemical constituents of the leaves of Anthonotha macrophylla (Leguminosae)

The present study deals with the isolation and the characterization of the chemical constituents from the leaves of Anthonotha macrophylla (Leguminosae). Using various chromatographic techniques (TLC, CC, HPLC), the methanolic extract of the leaves of Anthonotha macrophylla yielded one new alkaloid (1) as well as six known compounds amongst which an alkane (2), isolated for the first time from a natural product, an ester of fatty acid (3), two isocoumarines (4-5), a sterol (6) and a disaccharide (7). Their structures were elucidated using spectroscopic technics including extensive 1-D and 2-D NMR, HR-SM experiments.

Polyamine derivatives from the bee pollen of Quercus mongolica with tyrosinase inhibitory activity

Eighteen constituents, including nine new compounds, were isolated from the bee pollen of Quercus mongolica. The structures of the new compounds were established on the basis of combined spectroscopic analysis. Structurally, the nine new compounds are polyamine derivatives with phenolic moieties which were assigned as one putrescine derivative, mogolicine A (2), seven spermidine derivatives, mongolidines A-G (3-5, 8, 12, 14, 17) and one spermine derivative, mogoline A (18). Evaluation of the biological activity of isolated compounds revealed that the polyamine derivatives with coumaroyl and caffeoyl moieties showed tyrosinase inhibition with IC₅₀ values of 19.5-85.8 μM; however, the addition of a methoxy group to phenolic derivatives reduced the inhibitory activity.

Profiling of the Major Phenolic Compounds and Their Biosynthesis Genes in Sophora flavescens Aiton

Sophorae Radix (Sophora flavescens Aiton) has long been used in traditional medicine in East Asia due to the various biological activities of its secondary metabolites. Endogenous contents of phenolic compounds (phenolic acid, flavonol, and isoflavone) and the main bioactive compounds of Sophorae Radix were analyzed based on the qualitative HPLC analysis and evaluated in different organs and at different developmental stages. In total, 11 compounds were detected, and the composition of the roots and aerial parts (leaves, stems, and flowers) was significantly different. trans-Cinnamic acid and p-coumaric acid were observed only in the aerial parts. Large amounts of rutin and maackiain were detected in the roots. Four phenolic acid compounds (benzoic acid, caffeic acid, ferulic acid, and chlorogenic acid) and four flavonol compounds (kaempferol, catechin hydrate, epicatechin, and rutin) were higher in aerial parts than in roots. To identify putative genes involved in phenolic compounds biosynthesis, a total of 41 transcripts were investigated. Expression patterns of these selected genes, as well as the multiple isoforms for the genes, varied by organ and developmental stage, implying that they are involved in the biosynthesis of various phenolic compounds both spatially and temporally.

Inhibiting STAT3 signaling is involved in the anti-melanoma effects of a herbal formula comprising Sophorae Flos and Lonicerae Japonicae Flos

A herbal formula (SL) comprising Sophorae Flos and Lonicerae Japonicae Flos was traditionally used to treat melanoma. Constitutively active signal transducer and activator of transcription 3 (STAT3) has been proposed as a therapeutic target in melanoma. Here we investigated whether an ethanolic extract of SL (SLE) exerted anti-melanoma activities by inhibiting STAT3 signaling. B16F10 allograft model, A375 and B16F10 cells were employed to assess the in vivo and in vitro anti-melanoma activities of SLE. A375 cells stably expressing STAT3C, a constitutively active STAT3 mutant, were used to determine the role of STAT3 signaling in SLE’s anti-melanoma effects. Intragastric administration of SLE (1.2 g/kg) potently inhibited melanoma growth in mice and inhibited STAT3 phosphorylation in the tumors. In cultured cells, SLE dramatically reduced cell viability, induced apoptosis, suppressed migration and invasion, and restrained STAT3 activation and nuclear localization. STAT3C overexpression in A375 cells diminished SLE’s effects on cell viability, apoptosis and invasion. Collectively, SLE exerted potent anti-melanoma effects partially by inhibiting STAT3 signaling. This study provides pharmacological justification for the traditional use of this formula in treating melanoma, and suggests that SLE has the potential to be developed as a modern alternative and/or complimentary agent for melanoma treatment and prevention.

Ferulic Acid and Naturally Occurring Compounds Bearing a Feruloyl Moiety: A Review on Their Structures, Occurrence, and Potential Health Benefits

The ubiquitous compound 4-hydroxy-3-methoxycinnamic acid, also known as ferulic acid (FA), constitutes a bioactive ingredient of many foods that may offer beneficial effects against disorders related to oxidative stress, including cancer, diabetes, and neurodegenerative diseases. This review discusses the antioxidant properties of FA, establishing relationships to several biological activities already described for this natural product. Next, 387 naturally occurring compounds, all isolated from plants and published between 1990 and 2015, the structures of which bear 1 or more feruloyl moieties, are covered in this review along with their structural formulas, botanical sources, and bioactivities. The compounds' distribution, structural patterns, bioactivities, and perspectives on food research are also succinctly discussed.

Local and traditional uses, phytochemistry, and pharmacology of Sophora japonica L.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora japonica (Fabaceae), also known as Huai (Chinese: ), is a medium-sized deciduous tree commonly found in China, Japan, Korea, Vietnam, and other countries. The use of this plant has been recorded in classical medicinal treatises of ancient China, and it is currently recorded in both the Chinese Pharmacopoeia and European Pharmacopoeia. The flower buds and fruits of S. japonica, also known as Flos Sophorae Immaturus and Fructus Sophorae in China, are most commonly used in Asia (especially in China) to treat hemorrhoids, hematochezia, hematuria, hematemesis, hemorrhinia, uterine or intestinal hemorrhage, arteriosclerosis, headache, hypertension, dysentery, dizziness, and pyoderma. To discuss feasible trends for further research on S. japonica, this review highlights the botany, ethnopharmacology, phytochemistry, biological activities, and toxicology of S. japonica based on studies published in the last six decades.

MATERIALS AND METHODS

Information on the S. japonica was collected from major scientific databases (SciFinder, PubMed, Elsevier, SpringerLink, Web of Science, Google Scholar, Medline Plus, China Knowledge Resource Integrated (CNKI), and "Da Yi Yi Xue Sou Suo (http://www.dayi100.com/login.jsp)" for publications between 1957 and 2015 on S. japonica. Information was also obtained from local classic herbal literature, government reports, conference papers, as well as PhD and MSc dissertations.

RESULTS

Approximately 153 chemical compounds, including flavonoids, isoflavonoids, triterpenes, alkaloids, polysaccharides, amino acids, and other compounds, have been isolated from the leaves, branches, flowers, buds, pericarps, and/or fruits of S. japonica. Among these compounds, several flavonoids and isoflavonoids comprise the active constituents of S. japonica, which exhibit a wide range of biological activities in vitro and in vivo such as anti-inflammatory, antibacterial, antiviral, anti-osteoporotic, antioxidant, radical scavenging, antihyperglycemic, antiobesity, antitumor, and hemostatic effects. Furthermore, flavonoids and isoflavonoids can be used as quality control markers for quality identification and evaluation of medicinal materials and their preparations. Information on evaluating the safety of S. japonica is very limited, so further study is required. To enable safer, more effective, and controllable therapeutic preparations, more in-depth information is urgently needed on the quality control, toxicology data, and clinical value of crude extract and active compounds of S. japonica.

CONCLUSIONS

S. japonica has long been used in traditional Chinese medicine (TCM) due to its wide range of biological activities, and is administered orally. Phytochemical and pharmacological studies of S. japonica have increased in the past few years, and the extract and active components of this plant can be used to develop new drugs based on their traditional application as well as their biological activities. Therefore, this review on the ethnopharmacology, phytochemistry, biological activities, and toxicity of S. japonica offers promising data for further studies as well as the commercial exploitation of this traditional medicine.

Inhibitory and Acceleratory Effects of Inonotus obliquus on Tyrosinase Activity and Melanin Formation in B16 Melanoma Cells

The aim of the present study is to preliminarily investigate the antimelanogenesis effect of Inonotus obliquus extracts by cell-free mushroom tyrosinase assay. It was found that petroleum ether and n-butanol extracts might contain unknown potential tyrosinase inhibitors, while its ethyl acetate extract might contain some unknown accelerators. Six compounds were isolated and their structures were identified by interpretation of NMR data and nicotinic acid was first discovered in Inonotus obliquus. In cells testing, betulin and trametenolic acid decreased tyrosinase activity and melanin content, while inotodiol and lanosterol significantly increased tyrosinase activity and melanin content, showing an AC⁡₅₀ of 9.74 and 8.43 μM, respectively. Nicotinie acid, 3β,22,25-trihydroxy-lanosta-8-ene, had a little or no effect on tyrosinase. Betulin exhibited a mode of noncompetitive inhibition with a K_I = K_IS of 0.4 μM on tyrosinase activity showing an IC₅₀ of 5.13 μM and being more effective than kojic acid (6.43 μM), and trametenolic acid exhibited a mode of mixed inhibition with a K_I of 0.9 μM, K_IS of 0.5 μM, and an IC₅₀ of 7.25 μM. We proposed betulin and trametenolic acid as a new candidate of potent tyrosinase inhibitors and inotodiol and lanosterol as accelerators that could be used as therapeutic agent.

Norartocarpetin from a folk medicine Artocarpus communis plays a melanogenesis inhibitor without cytotoxicity in B16F10 cell and skin irritation in mice

Background

Many natural products used in preventive medicine have also been developed as cosmeceutical ingredients in skin care products, such as Scutellaria baicalensis and Gardenia jasminoides. Norartocarpetin is one of the antioxidant and antityrosinase activity compound in Artocarpus communis; however, the cytotoxicity, skin irritation and antimelanogenesis mechanisms of norartocarpetin have not been investigated yet.

Methods

In the present study, cell viability in vitro and skin irritation in vivo are used to determine the safety of norartocarpetin. The melanogenesis inhibition of norartocarpetin was determined by cellular melanin content and tyrosinase in B16F10 melanoma cell. Moreover, we examined the related-melanogenesis protein by western blot analysis for elucidating the antimelanogenesis mechanism of norartocarpin.

Results

The result of the present study demonstrated that norartocarpetin not only present non-cytotoxic in B16F10 and human fibroblast cells but also non-skin irritation in mice. Moreover, our result also first found that norartocarpetin downregulated phospho-cAMP response element-binding (phospho-CREB) and microphthalmia-associated transcription factor (MITF) expression, which in turn decreased both synthesis of tyrosinases (TRP-1 and TRP-2) and cellular melanin content. This process is dependent on norartocarpetin phosphorylation by mitogen-activated protein kinases such as phospho-JNK and phospho-p38, and it results in decreased melanogenesis.

Conclusion

The present study suggests that norartocarpetin could be used as a whitening agent in medicine and/or cosmetic industry and need further clinical study.

An ethnobotanical survey of medicinal plants used in Rwanda for voluntary depigmentation

ETHNOPHARMACOLOGICAL RELEVANCE

Voluntary depigmentation, a very common practice in sub-Saharan Africa, often performed with pharmaceutical products diverted from their pharmacological use, may cause severe dermatological and systemic side effects. The present work aims at investigating whether and which herbs were used in Rwanda for similar purposes before the advent of the current depigmentation craze; this may give clues at herbal treatments possibly advantageous compared to current products.

MATERIAL AND METHODS

Sixty-one traditional healers, mostly representatives of their associations, were surveyed by questionnaires for knowledge and practice of voluntary depigmentation. Recipes or plants used, plant parts, harvest area, preparation methods, dosage and route of administration were recorded. Most of the cited herbs were harvested with the help of traditional healers and identified by comparison with voucher specimens; herbal vouchers of the five most cited herbs were deposited in official herbaria.

RESULTS

All surveyed traditional healers have knowledge of voluntary depigmentation; the population currently practicing do not recourse to their services but obtain bleaching products directly from the market. Traditional healers disclosed recipes prescribed or self-used (often by women) in their youth; others cited recipes are used to treat skin diseases with properties of "clarification", "black skin stain removal", in cases of hyperpigmentation, and/or "skin softening". Curiously, from the 28 recipes cited by traditional healers, all are mono-herbal preparations; most of the plants are mixed with butter for application to the skin.

CONCLUSION

Compared to other pathophysiological conditions, there is currently a very limited use of herbal preparations for depigmentation. Five herbs had a citation percentage equal or above to 50%, Brillantaisia cicatricosa Lindau (Acanthaceae), Chenopodium ugandae (Aellen) Aellen (Chenopodiaceae), Dolichopentas longiflora Oliv. (Rubiaceae), Protea madiensis Oliv. (Proteaceae) and Sesamum angolense Welw. (Pedaliaceae); in vitro experiments indicated a modulation of melanogenesis by these plant extracts, confirming the information obtained from traditional healers.