A sphingolipid and tyrosinase inhibitors from the fruiting body ofphellinus linteus

Highly potent anti-melanogenic effect of 2-thiobenzothiazole derivatives through nanomolar tyrosinase activity inhibition

Compounds with sulfhydryl substituents and azole compounds exhibit potent anti-tyrosinase potency. 2-Thiobenzothiazole (2-TBT), a hybrid structure of sulfhydryl and azole, exists in two tautomeric forms, with the thione form being predominant according to several studies. 2-TBT derivatives were synthesized as potential tyrosinase inhibitors as the thione tautomeric form has the same N-CS moiety as phenylthiourea (PTU), which is suitable for chelation with the copper ions present in the tyrosinase active site. Eight of the ten 2-TBT derivatives inhibited the monophenolase and diphenolase activities of mushroom tyrosinase, with IC50 values of 0.02-0.83 μM. Kinetic studies and molecular dynamics simulations were performed to determine their mode of action and confirm that the 2-TBT derivatives bind to the tyrosinase active site with high stability. Derivatives 3, 4, 8, and 10 strongly inhibited melanogenesis in B16F10 cells in a pattern similar to the results of cellular tyrosinase inhibition, thereby suggesting that their ability to inhibit melanogenesis was due to their tyrosinase inhibitory activity. In a depigmentation experiment using zebrafish embryos, all 2-TBT derivatives showed better potency than kojic acid, even at 400 to 2000 times lower concentration, and 1 and 10 reduced zebrafish larva pigmentation more strongly than PTU even at 20 times lower concentration. Experiments investigating the changes in tyrosinase inhibitory activity of 2-TBT derivatives in the presence and absence of CuSO4 and their copper chelating ability supported that these derivatives exert their anti-melanogenic effect by chelating the copper ions of tyrosinase. These results suggest that 2-TBT derivatives are promising candidates for the treatment of hyperpigmentation-related disorders.

Investigation of the Efficacy of Benzylidene-3-methyl-2-thioxothiazolidin-4-one Analogs with Antioxidant Activities on the Inhibition of Mushroom and Mammal Tyrosinases

Based on the fact that substances with a β-phenyl-α,β-unsaturated carbonyl (PUSC) motif confer strong tyrosinase inhibitory activity, benzylidene-3-methyl-2-thioxothiazolidin-4-one (BMTTZD) analogs 1-8 were prepared as potential tyrosinase inhibitors. Four analogs (1-3 and 5) inhibited mushroom tyrosinase strongly. Especially, analog 3 showed an inhibitory effect that was 220 and 22 times more powerful than kojic acid in the presence of l-tyrosine and l-dopa, respectively. A kinetic study utilizing mushroom tyrosinase showed that analogs 1 and 3 competitively inhibited tyrosinase, whereas analogs 2 and 5 inhibited tyrosinase in a mixed manner. A docking simulation study indicated that analogs 2 and 5 could bind to both the tyrosinase active and allosteric sites with high binding affinities. In cell-based experiments using B16F10 cells, analogs 1, 3, and 5 effectively inhibited melanin production; their anti-melanogenic effects were attributed to their ability to inhibit intracellular tyrosinase activity. Moreover, analogs 1, 3, and 5 inhibited in situ B16F10 cellular tyrosinase activity. In three antioxidant experiments, analogs 2 and 3 exhibited strong antioxidant efficacy, similar to that of the positive controls. These results suggest that the BMTTZD analogs are promising tyrosinase inhibitors for the treatment of hyperpigmentation-related disorders.

Resultant compound from sublimation test for Gentianae Radix in Japanese Pharmacopoeia was 5-(hydroxymethyl)furfural

Gentianae Radix, an herbal medicine, has been used as a gastrointestinal drug in Japan. In the Japanese Pharmacopoeia 18th Revision, the sublimation test is specified as an identification test for Gentianae Radix. The compound obtained in this sublimation test was believed to be gentisin, a xanthone family compound. However, the compound we identified using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and 1H- and 13C-NMR was 5-(hydroxymethyl)furfural (5-HMF). The same compound was found to be a sublimate of Gentianae Scabrae Radix and Gentianae Macrophyllae Radix, belonging to the same genus as Gentianae Radix. These results indicate the necessity to revise the identification test for Gentianae Radix to a more unique method.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Antiproliferative p-terphenyl derivatives isolated from the fungus Sarcodon scabripes

The ethanol extract of the fungus Sarcodon scabripes collected from north-central British Columbia, Canada, showed strong antiproliferative activity. Bioassay-guided purification using liquid-liquid extraction and Sephadex LH-20 size-exclusion chromatography, followed by HPLC-MS and 1D/2D NMR analyses, led to the isolation of five known compounds; four p-terphenyl (1-4) derivatives and one phenolic aldehyde (5). Compounds 1, 4, and 5 were isolated for the first time from the Sarcodon genus. The cytotoxicity MTT assay showed that compounds 1-5 have antiproliferative activity against human cervical cancer cells (HeLa). For compounds 1-4, this is the first report of their antiproliferative activity against cancer cells. For compound 2, this is the first report on its bioactivity. To our knowledge, this is the first description of the isolation of bioactive constituents from S. scabripes.

Chemoenzymatic Synthesis of Complex Phenylpropanoid Derivatives by the Botrytis cinerea Secretome and Evaluation of Their Wnt Inhibition Activity

In this study, a series of complex phenylpropanoid derivatives were obtained by chemoenzymatic biotransformation of ferulic acid, caffeic acid, and a mixture of both acids using the enzymatic secretome of Botrytis cinerea. These substrates were incubated with fungal enzymes, and the reactions were monitored using state-of-the-art analytical methods. Under such conditions, a series of dimers, trimers, and tetramers were generated. The reactions were optimized and scaled up. The resulting mixtures were purified by high-resolution semi-preparative HPLC combined with dry load introduction. This approach generated a series of 23 phenylpropanoid derivatives, 11 of which are described here for the first time. These compounds are divided into 12 dimers, 9 trimers (including a completely new structural scaffold), and 2 tetramers. Elucidation of their structures was performed with classical spectroscopic methods such as NMR and HRESIMS analyses. The resulting compound series were analyzed for anti-Wnt activity in TNBC cells, with several derivatives demonstrating specific inhibition.

A norbisabolane and an arabitol benzoate from Talaromyces marneffei, an endophytic fungus of Epilobium angustifolium

A norbisabolane and an arabitol benzoate, Talaromarnine A (1), Talaromarnine B (2), together with eight known compounds were obtained from cultures of Talaromyces marneffei, an endophytic fungus of Epilobium angustifolium. Their structures were elucidated by IR, MS, 1D and 2D NMR spectra, and their absolute configuration was determined by single-crystal X-ray diffraction and molecular computation. These compounds were tested for monoamine oxidase, acetylcholinesterase and PI3K inhibitory activity, but no compounds exhibited significant activities.

The phytochemistry and pharmacology of medicinal fungi of the genus Phellinus: a review

Phellinus Quél is one of the largest genera of Hymenochaetaceae, which is comprised of about 220 species. Most Phellinus macro-fungi are perennial lignicolous mushrooms, which are widely distributed on Earth. Some Phellinus fungi are historically recorded as traditional medicines used to treat various diseases in eastern Asian countries, especially China, Japan and Korean. Previous phytochemical studies have revealed that Phellinus fungi produce diverse secondary metabolites, which mainly contain polysaccharides, flavones, coumarins, terpenes, steroids, and styrylpyranones. Pharmacological documents have demonstrated that Phellinus mushrooms and their compounds have a variety of bioactivities, such as anti-tumor, immunomodulation, anti-oxidative and anti-inflammation, anti-diabetes, neuro-protection, and anti-viral effects. This review surveys the literature reporting the isolation, characterization, and bioactivities of secondary metabolites from the fungi of the genus Phellinus, focusing on studies published in the literature up to April 2020. Herein, a total of more than 300 compounds from 13 Phellinus species and their isolation, characterization, chemistry, pharmacological activities, and relevant molecular mechanisms are comprehensively summarized.

Anthelmintic A-Type Procyanidins and Further Characterization of the Phenolic Composition of a Root Extract from Paullinia pinnata

Extracts from the roots of Paullinia pinnata L. are used in West Africa as traditional remedies for a variety of diseases including infestations with soil-transmitted helminths. Based on the results of an ethnopharmacological survey in Ghana, an aqueous acetone (70%) extract was investigated for its anthelmintic and phytochemical properties. Partitioning of the crude extract followed by several fractionation steps of the ethyl acetate phase using Sephadex® LH-20, fast centrifugal partition chromatography, RP-18-MPLC and HPLC led to isolation of six oligomeric A-type procyanidins (1 to 6). To determine the anthelmintic activity, the crude extract, fractions and isolated compounds were tested in vitro against the model organism Caenorhabditis elegans. A significantly better activity was observed for the trimeric A-type procyanidin (1) compared to a B-type trimer. However, this effect could not be generalized for the tetrameric procyanidins, for which the type of the interflavan-linkage (4→6 vs. 4→8) had the greatest impact on the bioactivity. Besides the procyanidins, three novel compounds, isofraxidin-7-O-α-l-rhamnopyranosyl-(1″→6')-β-d-glucopyranoside (17), 4-methoxycatechol-2-O-(5''-O-vanilloyl-β-apiofuranosyl)-(1''→2')-β-glucopyranoside (18) and a 6-(3-methoxy-4-hydroxyphenyl)-hexane-2,4-diol-2-O-hexoside (19) were isolated together with further ten known compounds (7 to 16), mainly coumarins and coumarinolignans. Except for 3-β-d-glucopyranosyloxy-4-methyl-2(5H)-furanone (15), none of the isolated compounds has previously been described for P. pinnata. The anthelmintic activity was attributed to the presence of procyanidins, but not to any of the other compound classes. In summary, the findings rationalize the traditional use of P. pinnata root extracts as anthelmintic remedies.

A comprehensive review on tyrosinase inhibitors

Tyrosinase is a multi-copper enzyme which is widely distributed in different organisms and plays an important role in the melanogenesis and enzymatic browning. Therefore, its inhibitors can be attractive in cosmetics and medicinal industries as depigmentation agents and also in food and agriculture industries as antibrowning compounds. For this purpose, many natural, semi-synthetic and synthetic inhibitors have been developed by different screening methods to date. This review has focused on the tyrosinase inhibitors discovered from all sources and biochemically characterised in the last four decades.

Insights Into the Explication of Potent Tyrosinase Inhibitors with Reference to Computational Studies

Background:

Pigment melanin has primarily a photo defensive role in human skin, its unnecessary production and irregular distribution can cause uneven skin tone ultimately results in hyper pigmentation. Melanin biosynthesis is initiated by tyrosine oxidation through tyrosinase, the key enzyme for melanogenesis. Not only in humans, tyrosinase is also widely distributed in plants and liable for browning of vegetables and fruits. Search for the inhibitors of tyrosinase have been an important target to facilitate development of therapies for the prevention of hyperpigmentary disorders and an undesired browning of vegetables and fruits.

Methods:

Different natural and synthetic chemical compounds have been tested as potential tyrosinase inhibitors, but the mechanism of inhibition is not known, and the quest for information regarding interaction between tyrosinase and its inhibitors is one of the recent areas of research. Computer based methods hence are useful to overcome such issues. Successful utilization of in silico tools like molecular docking simulations make it possible to interpret the tyrosinase and its inhibitor’s intermolecular interactions and helps in identification and development of new and potent tyrosinase inhibitors.

Results:

The present review has pointed out the prominent role of computer aided approaches for the explication of promising tyrosinase inhibitors with a focus on molecular docking approach. Highlighting certain examples of natural compounds whose antityrosinase effects has been evaluated using computational simulations.

Conclusion:

The investigation of new and potent inhibitors of tyrosinase using computational chemistry and bioinformatics will ultimately help millions of peoples to get rid of hyperpigmentary disorders as well as browning of fruits and vegetables.

Chemical Constituents From the Vietnamese Medicinal Plant Anemone chapaensis and Their Cytotoxic Activity

Our current research on phytochemical profile of the folk medicinal plant Anemone chapaensis Gagnep. led to the isolation of a new saponin, chapaenoside (1), along with 13 known compounds (2-14). Their structures were elucidated on the basis of extensive chemical and spectroscopic methods (Nuclear Magnetic Resonance [NMR] spectroscopy and mass spectrometry) as well as comparison with the literature data. The isolated compounds were tested for their cytotoxic activities against 9 cancer cell lines by MTT method. The result indicated that the major saponin prosapogenin CP6 (5) showed selectively strong activity against NCI-N87, RD, Panc-1, and MIA Paca-2 cells with the IC50 values of 5.4, 7.5, 7.5, and 2.7 μM, respectively. The results of phytochemical constituents and principal bioactive saponins from A. chapaensis contributed not only to its phytochemical profile associated with chemotaxonomy but also to biological evidence of the title plant.

A Review: The Bioactivities and Pharmacological Applications of Phellinus linteus

Phellinus linteus is a popular medicinal mushroom that is widely used in China, Korea, Japan, and other Asian countries. P. linteus comprises various bioactive components, such as polysaccharides, triterpenoids, phenylpropanoids, and furans, and has proven to be an effective therapeutic agent in traditional Chinese medicine for the treatment and the prevention of various diseases. A number of studies have reported that P. linteus possesses many biological activities useful for pharmacological applications, including anticancer, anti-inflammatory, immunomodulatory, antioxidative, and antifungal activities, as well as antidiabetic, hepatoprotective, and neuroprotective effects. This review article briefly presents the recent progress made in understanding the bioactive components, biological activities, pharmacological applications, safety, and prospects of P. linteus, and provides helpful references and promising directions for further studies of P. linteus.

Diversity and Ecology of Marine Algicolous Arthrinium Species as a Source of Bioactive Natural Products

In our previous study, all Arthrinium isolates from Sargassum sp. showed high bioactivities, but studies on marine Arthrinium spp. are insufficient. In this study, a phylogenetic analysis of 28 Arthrinium isolates from seaweeds and egg masses of Arctoscopus japonicus was conducted using internal transcribed spacers, nuclear large subunit rDNA, β-tubulin, and translation elongation factor region sequences, and their bioactivities were investigated. They were analyzed as 15 species, and 11 of them were found to be new species. Most of the extracts exhibited radical-scavenging activity, and some showed antifungal activities, tyrosinase inhibition, and quorum sensing inhibition. It was implied that marine algicolous Arthrinium spp. support the regulation of reactive oxygen species in symbiotic algae and protect against pathogens and bacterial biofilm formation. The antioxidant from Arthrinium sp. 10 KUC21332 was separated by bioassay-guided isolation and identified to be gentisyl alcohol, and the antioxidant of Arthrinium saccharicola KUC21221 was identical. These results demonstrate that many unexploited Arthrinium species still exist in marine environments and that they are a great source of bioactive compounds.

Polycyclic polyprenylated acylphloroglucinols and biphenyl derivatives from the roots of Garcinia nuntasaenii Ngerns. & Suddee

Seven previously undescribed compounds, including three polycyclic polyprenylated acylphloroglucinols (garcinuntins A-C), three biphenyl derivatives (garcinuntabiphenyls A-C) and a lanostane triterpene (garcinuntine), along with thirteen known compounds were isolated from the root of Garcinia nuntasaenii Ngerns. & Suddee. Their structures were elucidated on the basis of spectroscopic techniques. For garcinuntins A-C, the absolute configurations were confirmed by the combination of single X-ray crystallography and ECD calculations. Anti-HIV activity using anti-HIV-1 reverse transcriptase and syncytium inhibition assays, and cytotoxic activity against a panel of cultured mammalian cancer cell lines of isolated compounds were investigated.

Phenolic Derivatives from Periplaneta americana

Periplaneta americana is a medicinal insect used for the treatment of the wound healing in China. In this study, four new compounds, named periplanols A-D (1-4), together with twelve known compounds, were isolated from the whole bodies of this species. Their structures were elucidated by extensive spectroscopic methods. All the isolates except compounds 6, 9, 11, and 14 were tested for their wound healing related activities towards nitric oxide (NO) inhibitory effect, cell proliferation in HDFs, cell migration and angiogenesis in HUVEC, respectively.

Bioactivity-guided isolation of anti-inflammatory triterpenoids from the sclerotia of Poria cocos using LPS-stimulated Raw264.7 cells

Poria cocos Wolf (Polyporaceae) has been used as a medicinal fungus to treat various diseases since ancient times. This study aimed to investigate the anti-inflammatory chemical constituents of the sclerotia of P. cocos. Based on bioassay-guided fractionation using lipopolysaccharide (LPS)-stimulated Raw264.7 cells, chemical investigation of the EtOH extract of the sclerotia of P. cocos resulted in the isolation and identification of eight compounds including six triterpenoids, namely poricoic acid A (1), 3-O-acetyl-16α-hydroxydehydrotrametenolic acid (2), polyporenic acid C (3), 3β-hydroxylanosta-7,9(11),24-trien-21-oic acid (4), trametenolic acid (5), and dehydroeburicoic acid (6), as well as (-)-pinoresinol (7) and protocatechualdehyde (8). The structures of the isolated compounds were determined by spectroscopic analysis, including ¹H and ¹³C NMR spectra, and LC/MS analysis. The anti-inflammatory activities of the isolates were evaluated by estimating their effect on the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in LPS-stimulated Raw264.7 as well as on the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Compounds 1-5 inhibited NO production and iNOS expression in LPS-stimulated Raw264.7 cells. Among them, compound 1 exerted the highest anti-inhibitory activity and reduced PGE₂ levels via downregulation of COX-2 protein expression. The findings of this study provide experimental evidence that the sclerotia of P. cocos are a potential source of natural anti-inflammatory agents for use in pharmaceuticals and functional foods. Furthermore, the most active compound 1, seco-lanostane triterpenoid, could be a promising lead compound for the development of novel anti-inflammatory agents.

Preparative Separation of Phenolic Compounds from Chimonanthus praecox Flowers by High-Speed Counter-Current Chromatography Using a Stepwise Elution Mode

High-speed counter-current chromatography (HSCCC) has been successfully used for the separation of eight compounds from Chimonanthus praecox flowers. Firstly, the crude extract of Chimonanthus praecox flowers was dissolved in a two-phase solvent system composed of petroleum ether–ethyl acetate–methanol–H₂O (5:5:3:7, v/v) and divided into two parts: the upper phase (part I) and the lower phase (part II). Then, HSCCC was applied to separate the phenolic acids from part I and part II, respectively. Considering the broad polarity range of target compounds in part I, a stepwise elution mode was established. Two optimal solvent systems of petroleum ether–ethyl acetate–methanol–H₂O–formic acid (FA) (5:5:3:7:0.02, 5:5:4.3:5.7:0.02, v/v) were employed in this separation. Five phenylpropanoids and two flavonoids were successfully separated from 280 mg of part I, including 8.7 mg of 3,4-dihydroxy benzoic acid (a, 95.3% purity), 10.9 mg of protocatechualdehyde (b, 96.8% purity), 11.3 mg of p-coumaric acid (c, 98.9% purity), 12.2 mg of p-hydroxybenzaldehyde (d, 95.9% purity), 24.7 mg of quercetin (e, 97.3% purity), 33.8 mg of kaempferol (f, 96.8% purity), and 24.6 mg of 4-hydroxylcinnamic aldehyde (g, 98.0% purity). From 300 mg of part II, 65.7 mg of rutin (h, 98.2% purity), 7.5 mg of 3,4-dihydroxy benzoic acid (a, 77.4% purity), and 4.7 mg of protocatechualdehyde (b, 81.6% purity) were obtained using the solvent system EtOAc–n-butanol (n-BuOH)–FA–H₂O (4:1:0.5:5, v/v). The structures of the eight pure compounds were confirmed by electrospray ionization-mass spectrometry (ESI-MS), ¹H-NMR and ¹³C-NMR. To the best of our knowledge, compounds a–d and f were the first separated and reported from the Chimonanthus praecox flower extract.

Structure-activity relationships of the thujaplicins for inhibition of human tyrosinase

Tyrosinase inhibitors have become increasingly critical agents in cosmetic, agricultural, and medicinal products. Although a large number of tyrosinase inhibitors have been reported, almost all the inhibitors were unfortunately evaluated by using commercial available mushroom tyrosinase. Here, we examined the inhibitory effects of three isomers of thujaplicin (α, β, and γ) on human tyrosinase and analyzed their binding modes using homology model and docking studies. As the results, γ-thujaplicin was found to strongly inhibit human tyrosinase with the IC50 of 1.15 μM, extremely superior to a well-known tyrosinase inhibitor kojic acid (IC50 = 571.17 μM). MM-GB/SA binding free energy decomposition analyses suggested that the potent inhibitory activity of γ-thujaplicin may be due to the interactions with His367, Ile368, and Val377 (hot spot amino acid residues) in human tyrosinase. Furthermore, the binding mode of α-thujaplicin indicated that Val377 and Ser380 may cause van der Waals clashes with the isopropyl group of α-thujaplicin. These results provide a novel structural insight into the hot spot of human tyrosinase for the specific binding of γ-thujaplicin and a way to optimize not only thujaplicins but also other lead compounds as specific inhibitors for human tyrosinase in a rational manner.

Phytoceramides and acylated phytosterol glucosides from Pterospermum acerifolium Willd. seed coat and their osteogenic activity

Phytochemical investigation of seed coats of Pterospermum acerifolium afforded two phytoceramides (1, 2) and two acylated phytosterol glucosides (3, 4) together with five known compounds (5-9). Their structures were elucidated on the basis of extensive spectroscopic analysis using 1D, 2D NMR and Mass spectrometry. Compounds 1, 2, 3, and 4 were assessed for their osteogenic activity using primary cultures of osteoblasts harvested from neonatal rat calvaria. Among these compounds, 1 and 2 markedly stimulated osteoblast differentiation assessed by alkaline phosphatase production and osteoblast mineralization by alizarin red-S staining.

Pharmacological modulation of histone demethylase activity by a small molecule isolated from subcritical water extracts of Sasa senanensis leaves prolongs the lifespan of Drosophila melanogaster

BACKGROUND

Extracts of Sasa senanensis Rehder are used in traditional Japanese medicine; however, little is known about the underlying mechanisms of their potential health benefits.

METHODS

S. senanensis leaves were extracted with subcritical water. An active small-molecule was isolated using reversed-phase high-performance liquid chromatography (HPLC), and identified as 3,4-dihydroxybenzaldehyde (protocatechuic aldehyde or PA). The effects of PA on the activity of histone demethylase, the Drosophila melanogaster lifespan and gene expression in Drosophila S2 cells were investigated.

RESULTS

PA inhibited the activity of Jumonji domain-containing protein 2A (JMJD2A) histone demethylase in a dose-dependent manner with a half-maximal inhibitory concentration (IC50) of 11.6 μM. However, there was no effect on lysine-specific demethylase 1 (LSD1), histone deacetylase 1 (HDAC1) or HDAC8. PA significantly extended the lifespan of female, but not male, Drosophila. In Drosophila S2 cells, the eukaryotic translation initiation factor 4E binding protein (4E-BP) was up-regulated by PA exposure.

CONCLUSIONS

Our findings provide insight into the possible relationship between the pharmacological modulation of histone demethylation and lifespan extension by PA; they might also be important in the development of alternative therapies for age-related disorders.

Effects of Litchi chinensis fruit isolates on prostaglandin E(2) and nitric oxide production in J774 murine macrophage cells

BACKGROUND

Litchi chinensis is regarded as one of the 'heating' fruits in China, which causes serious inflammation symptoms to people.

METHODS

In the current study, the effects of isolates of litchi on prostaglandin E(2) (PGE(2)) and nitric oxide (NO) production in J774 murine macrophage cells were investigated.

RESULTS

The AcOEt extract (EAE) of litchi was found effective on stimulating PGE(2) production, and three compounds, benzyl alcohol, hydrobenzoin and 5-hydroxymethyl-2-furfurolaldehyde (5-HMF), were isolated and identified from the EAE. Benzyl alcohol caused markedly increase in PGE(2) and NO production, compared with lipopolysaccharide (LPS) as positive control, and in a dose-dependent manner. Hydrobenzoin and 5-HMF were found in litchi for the first time, and both of them stimulated PGE(2) and NO production moderately in a dose-dependent manner. Besides, regulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNA expression and NF-κB (p50) activation might be involved in mechanism of the stimulative process.

CONCLUSION

The study showed, some short molecular compounds in litchi play inflammatory effects on human.

The hunt for natural skin whitening agents

Skin whitening products are commercially available for cosmetic purposes in order to obtain a lighter skin appearance. They are also utilized for clinical treatment of pigmentary disorders such as melasma or postinflammatory hyperpigmentation. Whitening agents act at various levels of melanin production in the skin. Many of them are known as competitive inhibitors of tyrosinase, the key enzyme in melanogenesis. Others inhibit the maturation of this enzyme or the transport of pigment granules (melanosomes) from melanocytes to surrounding keratinocytes. In this review we present an overview of (natural) whitening products that may decrease skin pigmentation by their interference with the pigmentary processes.

An updated review of tyrosinase inhibitors

Tyrosinase is a multifunctional, glycosylated, and copper-containing oxidase, which catalyzes the first two steps in mammalian melanogenesis and is responsible for enzymatic browning reactions in damaged fruits during post-harvest handling and processing. Neither hyperpigmentation in human skin nor enzymatic browning in fruits are desirable. These phenomena have encouraged researchers to seek new potent tyrosinase inhibitors for use in foods and cosmetics. This article surveys tyrosinase inhibitors newly discovered from natural and synthetic sources. The inhibitory strength is compared with that of a standard inhibitor, kojic acid, and their inhibitory mechanisms are discussed.

Prediction of tyrosinase inhibition activity using atom-based bilinear indices

A set of novel atom-based molecular fingerprints is proposed based on a bilinear map similar to that defined in linear algebra. These molecular descriptors (MDs) are proposed as a new means of molecular parametrization easily calculated from 2D molecular information. The nonstochastic and stochastic molecular indices match molecular structure provided by molecular topology by using the kth nonstochastic and stochastic graph-theoretical electronic-density matrices, M(k) and S(k), respectively. Thus, the kth nonstochastic and stochastic bilinear indices are calculated using M(k) and S(k) as matrix operators of bilinear transformations. Chemical information is coded by using different pair combinations of atomic weightings (mass, polarizability, vdW volume, and electronegativity). The results of QSAR studies of tyrosinase inhibitors using the new MDs and linear discriminant analysis (LDA) demonstrate the ability of the bilinear indices in testing biological properties. A database of 246 structurally diverse tyrosinase inhibitors was assembled. An inactive set of 412 drugs with other clinical uses was used; both active and inactive sets were processed by hierarchical and partitional cluster analyses to design training and predicting sets. Twelve LDA-based QSAR models were obtained, the first six using the nonstochastic total and local bilinear indices and the last six with the stochastic MDs. The discriminant models were applied; globally good classifications of 99.58 and 89.96 % were observed for the best nonstochastic and stochastic bilinear indices models in the training set along with high Matthews correlation coefficients (C) of 0.99 and 0.79, respectively, in the learning set. External prediction sets used to validate the models obtained were correctly classified, with accuracies of 100 and 87.78 %, respectively, yielding C values of 1.00 and 0.73. This subset contains 180 active and inactive compounds not considered to fit the models. A simulated virtual screen demonstrated this approach in searching tyrosinase inhibitors from compounds never considered in either training or predicting series. These fitted models permitted the selection of new cycloartane compounds isolated from herbal plants as new tyrosinase inhibitors. A good correspondence between theoretical and experimental inhibitory effects on tyrosinase was observed; compound CA6 (IC(50)=1.32 microM) showed higher activity than the reference compounds kojic acid (IC(50)=16.67 microM) and L-mimosine (IC(50)=3.68 microM).

Inhibitory constituents of aldose reductase in the fruiting body of Phellinus linteus

In an effort to characterize active principles for diabetic complication from medicinal mushroom, aldose reductase inhibitors were isolated from the fruiting body of Phellinus linteus and identified as hispidin (5), phelligridimer A (6), davallialactone (7), methyldavallialactone (8), hypholomine B (9), interfungins A (10), and inoscavin A (11), together with protocatechuic acid (1), protocatechualdehyde (2), caffeic acid (3), and ellagic acid (4). Their structures were elucidated by spectroscopic analyses. Among them, davallialactone (7), hypholomine B (9), and ellagic acid (4) exhibited potent rat lens aldose reductase and human recombinant aldose reductase inhibitory activity with IC50 values of 0.33, 0.82, 0.63 microM and 0.56, 1.28, 1.37 microM, respectively.

Performance evaluation of a silk protein-based matrix for the enzymatic conversion of tyrosine to L-DOPA

L-DOPA (3,4-dihydroxyphenyl-L-alanine), one of the most important intermediates in the melanin biosynthesis pathway, is used for the treatment of Parkinson's disease. With a view of developing a cheaper and more effective method for the bioconversion of tyrosine to L-DOPA, the potential and performance of a novel fibrous matrix prepared from Bombyx mori silk protein fibroin were evaluated for the immobilization of tyrosinase. Cross-linkage between fibroin and tyrosinase using glutaraldehyde was evident from Fourier transform infra red spectroscopy. Maximum product formation occurred when 1000 U enzyme was immobilized on 20 mg fibroin. The optimum conditions for maximal L-DOPA production using immobilized tyrosinase were 40 degrees C and pH 5.5, conditions that caused a 50% loss of free enzyme activity. Immobilized tyrosinase also showed to have a higher degree of stability during storage and it retained 80% of its original activity after repeated reuses. The efficiency of this immobilized tyrosinase system to produce L-DOPA was high, as evident from a high effectiveness factor, between 0.7 and 0.8, thereby making this method feasible for the large-scale production of L-DOPA.

Antioxidant constituents and a new triterpenoid glycoside fromFlos Lonicerae

As a component of our continuing investigations into herb-derived antioxidant agents, we have evaluated the antioxidant effects of Flos Lonicerae (Lonicera japonica flowers), via 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, total reactive oxygen species (ROS), hydroxyl radical (*OH), and peroxynitrite (ONOO-) assays. Among the methanolic extract and the dichloromethane, ethyl acetate, n-butanol, and water fractions, the EtOAc fraction of Flos Lonicerae exhibited marked scavenging/inhibitory activities, as follows: IC50 values of 4.37, 27.58 +/- 0.71, 0.47 +/- 0.05, and 12.13 +/- 0.79 microg/mL in the DPPH, total ROS, ONOO-, and *OH assays, respectively. Via a bioactivity-guided fractionation approach, a new triterpenoid glycoside, oleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-xylopyranosyl(1-->6)]-beta-D-glucopyranosyl ester (12), along with eleven known compounds, including chrysoeriol (1), luteolin (2), 5-hydroxymethyl-2-furfural (3), caffeic acid (4), protocatechuic acid (5), chrysoeriol 7-O-beta-D-glucopyranoside (6), isorhamnetin 3-O-beta-D-glucopyranoside (7), kaempferol 3-O-beta-D-glucopyranoside (8), quercetin 3-O-beta-D-glucopyranoside (9), hederagenin 3-O-alpha-L-arabinopyranoside (10), and luteolin 7-O-beta-D-glucopyranoside (11), were isolated from the EtOAc fraction. The structures of isolated compounds 1-12 were elucidated via spectroscopic analyses. Compound 12 was isolated from a natural source for the first time. Compounds 2, 4, 5, 7, 9, and 11 evidenced marked scavenging activities, with IC50 values of 2.08-11.76 microM for DPPH radicals, and 1.47-6.98 microM for ONOO-.

Two novel furan derivatives from Phellinus linteus with anti-complement activity

Two novel stereoisomers of furan derivatives, phellinusfurans A (1) and B (2), were isolated from the fruiting body of Phellinus linteus. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2 exhibited significant anti-complement activity with IC50 values of 33.6 and 33.7 microM, respectively, in inhibiting the hemolytic activity of human serum against erythrocytes.