Tyrosinase inhibitory flavonoid from Juniperus communis fruits

Volatiles of All Native Juniperus Species Growing in Greece-Antimicrobial Properties

Juniper (Juniperus L., Cupressaceae Bartlett) trees are of high commercial value, as their essential oils are widely applied in the food and cosmetic industries due to their bioactivities. The genus Juniperus comprises eight species in Greece, and in the current work, we report the chemical analyses of their volatiles (GC-MS) obtained from the leaves and cones of all indigenous species found in the country, as well as their antimicrobial properties. The studied species were J. oxycedrus L., J. excelsa M. Bieb., J. foetidissima Willd., J. communis L., J. macrocarpa Sibth. & Sm., J. turbinata Guss., J. sabina L. and J. drupacea Labill., and a total of 164 constituents were identified. Monoterpenes, followed by sesquiterpenes, appeared as the dominant compounds in all investigated species. Most of the studied essential oils belonged to the α-pinene chemotype, with amounts of α-cedrol, sabinene, limonene and myrcene among the abundant metabolites, except for J. sabina, which belonged to the sabinene chemotype. Through antimicrobial tests, it was observed that the essential oils of most of the cones showed better activity compared with the respective leaves. The essential oils of the cones of J. foetidissima, J. communis and J. turbinata showed the strongest activity against the tested microorganisms. Additionally, in these three species, the content of thujone, which is a toxic metabolite found in essential oils of many Juniperus species, was considerably low. Taking into consideration the chemical profile, safety and antimicrobial activity, these three Greek Juniperus species seemed to provide the most promising essential oils for further exploitation in the food and cosmetics industries.

Zimbro (Juniperus communis L.) as a Promising Source of Bioactive Compounds and Biomedical Activities: A Review on Recent Trends

Plant-derived products and their extracted compounds have been used in folk medicine since early times. Zimbro or common juniper (Juniperus communis) is traditionally used to treat renal suppression, acute and chronic cystitis, bladder catarrh, albuminuria, leucorrhea, and amenorrhea. These uses are mainly attributed to its bioactive composition, which is very rich in phenolics, terpenoids, organic acids, alkaloids, and volatile compounds. In the last few years, several studies have analyzed the huge potential of this evergreen shrub, describing a wide range of activities with relevance in different biomedical discipline areas, namely antimicrobial potential against human pathogens and foodborne microorganisms, notorious antioxidant and anti-inflammatory activities, antidiabetic, antihypercholesterolemic and antihyperlipidemic effects, and neuroprotective action, as well as antiproliferative ability against cancer cells and the ability to activate inductive hepato-, renal- and gastroprotective mechanisms. Owing to these promising activities, extracts and bioactive compounds of juniper could be useful for the development of new pharmacological applications in the treatment of several acute and chronic human diseases.

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.

Juniperus chinensis Fruits Attenuate Oxazolone- and 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis Symptoms in Mice

Juniperus chinensis, commonly Chinese juniper, has been used for treating inflammatory diseases. This study aimed to investigate anti-atopic dermatitis (AD) effects of standardized J. chinensis fruits extract on murine oxazolone- and 2,4-dinitrochlorobenzene (DNCB)-induced models of AD. Ear swelling, epidermis thickening, and eosinophils infiltration in the oxazolone-mediated dermatitis of BALB/c mice were significantly reduced upon topical application of J. chinensis fruits 95% EtOH extract (JCE). Besides, transdermal administration of JCE to SKH-1 hairless mice inhibited the development of DNCB-induced AD-like skin lesions by suppressing transepidermal water loss and improving skin hydration. Decreased total serum immunoglobulin E (IgE) and interleukin (IL)-4 levels could be observed in atopic dorsal skin samples of JCE-treated group. According to the phytochemical analysis, JCE was found to contain isoscutellarein-7-O-β-D-xyloside, cupressuflavone, and amentoflavone as main compounds. Therapeutic attempts with the J. chinensis fruits might be useful in the treatment of AD and related skin inflammatory diseases.

Isolation of tyrosinase and melanogenesis inhibitory flavonoids from Juniperus chinensis fruits

A new biflavonoid, amentoflavone-7-O-β-D-glucoside, and thirteen known flavonoids were isolated from the fruits of Juniperus chinensis using a bioactivity-guided method and their tyrosinase inhibitory effects were tested using a mushroom tyrosinase bioassay. Two isolates, hypolaetin-7-O-β-D-glucoside and quercetin-7-O-α-L-rhamnoside, were found to reduce tyrosinase activity at a concentration of 50 μM. Quercetin-7-O-α-L-rhamnoside attenuated cellular tyrosinase activity and melanogenesis in α-MSH plus IBMX-stimulated B16F10 melanoma cells. Molecular docking simulation revealed that quercetin-7-O-α-L-rhamnoside inhibits tyrosinase activity by hydrogen bonding with residues His85, His244, Thr261, and Gly281 of tyrosinase. Abbreviations: EtOH, ethanol; CH2Cl2, dichloromethane; EtOAc, ethylacetate; n-BuOH, n-butanol; MeOH, metanol; CHCl3,chloroform; DMSO, dimethylsulfoxide; DMEM, Dulbecco's modified Eagle's medium; FBS, fetal bovine serum; α-MSH, α-melanocyte stimulating hormone; L-DOPA, L-3, 4-dihydroxyphenylalanine.

Hypolaetin-7-O-β-D-xyloside from Juniperus communis Fruits Inhibits Melanogenesis on Zebrafish Pigmentation

Hypolaetin-7- O-β-D-xyloside (1) is a naturally occurring flavonoid from Juniperus communis fruits. This study aimed to investigate anti-melanogenic effect of hypolaetin-7- O-β-D-xyloside on zebrafish pigmentation. The phenotype-based image analysis suggested that 1 suppressed the zebrafish pigmentation in a concentration-dependent manner (1-400 μM) as a reversible competitive inhibitor against the enzyme tyrosinase. According to the molecular docking simulation, the compound 1 interacted with residues His-263 of tyrosinase via hydrogen bonding. The present study provided direct experimental evidence for skin-lightening effect of 1 in an in vivo zebrafish model. Therapeutic attempts with the 1 might be useful in the management of skin pigmentation-related diseases.

The Standardized Extract of Juniperus communis Alleviates Hyperpigmentation in Vivo HRM-2 Hairless Mice and in Vitro Murine B16 Melanoma Cells

In European folk medicine, the fruits of Juniperus communis are used in the treatment of skin-related disorders such as skin infection, itching, and psoriasis. Previously, we reported that the EtOAc fraction of J. communis (EAJC) contained tyrosinase inhibition properties in vitro non-cellular experiment. The aim of this study was to evaluate anti-melanogenic effect of standardized EAJC on a hyperpigmentation animal model. Therapeutic effects of EAJC toward skin hyperpigmentation were confirmed by both in vivo experiment and in vitro cell-based assay. Skin depigmenting effect was detected by topical treatment of EAJC for 11 d to HRM-2 melanin-possessing hairless mice. Histologic findings including significantly decreased melanin depositions could be observed in dorsal skin samples of EAJC-treated group. In addition, the EAJC (50 µg/mL) attenuated melanin production through down-regulation of tyrosinase activity and protein expression in B16 murine melanoma cells. According to the phytochemical analysis, EAJC was found to contain hypolaetin-7-O-β-D-xylopyranoside and isoscutellarein-7-O-β-D-xylopyranoside as main components. Hypolaetin-7-O-β-D-xylopyranoside was responsible for the skin-lightening effect of EAJC by reducing the number of melanocytes in dorsal skins of HRM-2 mice. The present study provided direct experimental evidence for skin-lightening effect of EAJC in UV-irradiated hairless mouse model. Therapeutic attempts with the J. communis might be useful in the management of skin pigmentation-related diseases.