Melaleuca quinquenervia essential oil inhibits α-melanocyte-stimulating hormone-induced melanin production and oxidative stress in B16 melanoma cells

Design, Synthesis, and Antioxidant and Anti-Tyrosinase Activities of (Z)-5-Benzylidene-2-(naphthalen-1-ylamino)thiazol-4(5H)-one Analogs: In Vitro and In Vivo Insights

Fifteen compounds (1-15) constructed on a hybrid structure combining a β-phenyl-α,β-unsaturated carbonyl template and a 2-aminothiazol-4(5H)-one scaffold were designed and synthesized as potential novel anti-tyrosinase substances. Two compounds (10 and 15) showed more potent inhibition against mushroom tyrosinase than kojic acid, and the inhibitory activity of 10 (IC50 value: 1.60 μM) was 11 times stronger than that of kojic acid. Lineweaver-Burk plots indicated that these two compounds were competitive inhibitors that bound to the mushroom tyrosinase active site, which was supported by in silico experiments. Compound 10 was an anti-tyrosinase and anti-melanogenic substance in B16F10 cells and was more potent than kojic acid, without cytotoxicity. Compound 15 exhibited the most potent effect on zebrafish larval depigmentation and showed a depigmentation effect comparable to kojic acid, even at a concentration 200 times lower. Compounds 8 and 10 exhibited strong antioxidant capacities, scavenging 2,2-diphenyl-1-picrylhydrazyl, (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid)+ radicals, and reactive oxygen species. Hybrid compounds 10 and 15 are potential therapeutic agents for skin hyperpigmentation disorders.

Application of Microwave-Assisted Water Extraction (MAWE) to Fully Realize Various Physiological Activities of Melaleuca quinquenervia Leaf Extract

Melaleuca quinquenervia is widely grown in tropical areas worldwide. Studies have demonstrated that extracts of its buds, leaves, and branches obtained through hydrodistillation, steam distillation, or solvent extraction exhibit physiological activities, including anti-melanogenic, antibacterial, and antioxidant properties; nevertheless, such extracts are mostly not effectively collected or adequately utilized. Accordingly, this study applied a rapid, effective, and easy-to-operate microwave-assisted water extraction (MAWE) technique for the first time to prepare M. quinquenervia leaf extract (MLE) with improved physiological activities. The results indicated that the optimal irradiation time and liquid/solid ratio for the production of the MLE were 180 s and 20 mL/g, respectively. Under optimal conditions, the freeze-dried MLE achieved a high yield (6.28% ± 0.08%) and highly effective broad-spectrum physiological activities. The MLE exhibited strong antioxidant, antiaging, and anti-inflammatory activities and excellent antityrosinase and antimicrobial activities. Additionally, the MLE was noncytotoxic at concentrations of ≤300 mg/L, at which it exhibited pharmacological activity. The results also indicated that the MLE comprised a total of 24 chemical compounds and 17 phenolic compounds. Among these compounds, luteolin contributed to antityrosinase activity. The extract's antiaging activity was attributed to ellagic acid and quercetin, its anti-inflammatory activity resulted from ellagic acid and kaempferol, and its antimicrobial activity resulted from quercetin and 3-O-methylellagic acid. In conclusion, the MAWE-derived MLE may be useful as a functional ingredient in cosmetic products, health foods, and botanical drugs.

Comparative Analysis of Chemical Profiles and Biological Activities of Essential Oils Derived from Torreya grandis Arils and Leaves: In Vitro and In Silico Studies

Torreya grandis (T. grandis, Taxaceae) is a well-known nut tree species. Its fruit aril and leaves possess a unique aroma, making it an ideal natural raw material for extracting essential oils (EOs). This study aims to comprehensively compare the composition, biological activities, and pharmacological mechanism of EOs extracted from the arils (AEO) and leaves (LEO) of T. grandis. The results revealed that the chemical composition of the two EOs was highly consistent, with α-pinene and D-limonene as the main components. Both EOs significantly reduced cellular melanin production and inhibited tyrosinase activity in α-MSH-stimulated B16 cells (p < 0.05). AEO and LEO suppressed inflammatory responses in LPS-stimulated RAW 264.7 macrophages, significantly inhibiting cellular NO production and proinflammatory cytokines such as TNF-α and IL-6 (p < 0.05). A network pharmacology analysis reveals that AEO and LEO share similar molecular mechanisms and pharmacological pathways for treating skin pigmentation and inflammation. Regulating inflammatory cytokines may be a critical pathway for AEO and LEO in treating skin pigmentation. These findings suggest that AEO and LEO have potential for cosmetic applications. The leaves of T. grandis could be a valuable source of supplementary materials for producing T. grandis aril EO.

Multiplicative Effects of Essential Oils and Other Active Components on Skin Tissue and Skin Cancers

Naturally derived essential oils and their active components are known to possess various properties, ranging from anti-oxidant, anti-inflammatory, anti-bacterial, anti-fungal, and anti-cancer activities. Numerous types of essential oils and active components have been discovered, and their permissive roles have been addressed in various fields. In this comprehensive review, we focused on the roles of essential oils and active components in skin diseases and cancers as discovered over the past three decades. In particular, we opted to highlight the effectiveness of essential oils and their active components in developing strategies against various skin diseases and skin cancers and to describe the effects of the identified essential-oil-derived major components from physiological and pathological perspectives. Overall, this review provides a basis for the development of novel therapies for skin diseases and cancers, especially melanoma.

Insights on Juniperus phoenicea Essential Oil as Potential Anti-Proliferative, Anti-Tyrosinase, and Antioxidant Candidate

In this study, the anti-cancer, anti-tyrosinase, and antioxidant activities of essential oils (EOs) of berries and leaves of Juniperus phoenicea grown wild in North of Tunisia were investigated. The EO yields from leaves and berries were 1.69% and 0.45%, respectively. GC-MS analysis revealed that α-pinene is the predominant component in both EOs (44.17 and 83.56%, respectively). Leaves essential oil presented high levels of β-phellandrene (18%) and camphene (15%). The EOs displayed cytotoxic effects against MCF-7 breast cancer cell, HT-29 colon cancer, and the normal cells H9C2 cardiomyoblasts. Leaves oil strongly inhibited colon cell line proliferation (IC50 of 38 µg/mL), while berries essential oil was more potent against breast cancerous cells MCF-7 (IC50 of 60 µg/mL). Interestingly, berries essential oil exhibited high ability to inhibit melanin synthesis by inhibiting enzyme mono and diphenolase activities. Overall, the results suggested that the two oils are significant sources of healthy natural chemicals.

Biological Activities of Citrus aurantium Leaf Extract by Optimized Ultrasound-Assisted Extraction

Several studies have explored the biological activities of Citrus aurantium flowers, fruits, and seeds, but the bioactivity of C. aurantium leaves, which are treated as waste, remains unclear. Thus, this study developed a pilot-scale ultrasonic-assisted extraction process using the Box-Behnken design (BBD) for the optimized extraction of active compounds from C. aurantium leaves, and their antityrosinase, antioxidant, antiaging, and antimicrobial activities were evaluated. Under optimal conditions in a 150× scaleup configuration (a 30 L ultrasonic machine) of a pilot plant, the total phenolic content was 69.09 mg gallic acid equivalent/g dry weight, which was slightly lower (3.17%) than the theoretical value. The half maximal inhibitory concentration of C. aurantium leaf extract (CALE) for 2,2-diphenyl-1-picrylhydrazyl-scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-scavenging, antityrosinase, anticollagenase, antielastase and anti-matrix metalloprotein-1 activities were 123.5, 58.5, 181.3, 196.4, 216.3, and 326.4 mg/L, respectively. Moreover, the minimal inhibitory concentrations for bacteria and fungi were 150-350 and 500 mg/L, respectively. In total, 17 active compounds were detected in CALE-with linalool, linalyl acetate, limonene, and α-terpineol having the highest concentrations. Finally, the overall transdermal absorption and permeation efficiency of CALE was 95.9%. In conclusion, our CALE demonstrated potential whitening, antioxidant, antiaging, and antimicrobial activities; it was also nontoxic and easily absorbed into the skin as well as inexpensive to produce. Therefore, it has potential applications in various industries.

Searching for Natural Plants with Antimelanogenesis and Antityrosinase Properties for Cosmeceutical or Nutricosmetics Applications: A Systematic Review

Excessive UV radiation (UVR) exposure has been shown in studies to be a major risk factor for most melanomas, causing premature skin aging as well as immune system suppression due to the increased production of hydrogen peroxide (H2O2) and other reactive oxygen species (ROS) during the melanogenesis process. Although several compounds with antioxidant and antityrosinase activities are widely used in the cosmetic industry, like kojic acid, hydroquinone, ascorbic acid, and arbutin, their use has been limited due to their adverse effects on the skin and cytotoxic issues. Recently, attempts have been made to develop new natural skin-lightening products by using plant extracts that are less toxic and exhibit numerous biological properties with great market demand. In this study, information on the depigmentation effects of various natural plant species was gathered from the SCOPUS database according to the PRISMA guidelines. A total of 414 records were retrieved, and finally, 76 articles were included in the qualitative synthesis by fulfilling all the inclusion criteria. In this review, we discuss the extraction methods and biological assays of 75 highly potential plant species, including the olive, yuzu, longan, and lotus. We concluded that the use of natural plants as skin-whitening agents is highly effective as there is a significant correlation between the content of polyphenolic compounds, antimelanogenesis, antityrosinase, and antioxidant activities. However, it is worth noting that the use of extraction methods or types of solvents is very important in determining the biological activities of plants.

Variation in Yield, Chemical Composition and Biological Activities of Essential Oil of Three Curcuma Species: A Comparative Evaluation of Hydrodistillation and Solvent-Free Microwave Extraction Methods

The essential oils of three medicinally important Curcuma species (Curcuma alismatifolia, Curcuma aromatica and Curcuma xanthorrhiza) were extracted using conventional hydro-distillation (HD) and solvent free microwave extraction (SFME) methods. The volatile compounds from the rhizome essential oils were subsequently analysed by GC-MS. The isolation of essential oils of each species was carried out following the six principles of green extraction and comparison was made between their chemical composition, antioxidant, anti-tyrosinase and anticancer activities. SFME was found to be more efficient than HD in terms of energy savings, extraction time, oil yield, water consumption and waste production. Though the major compounds of essential oils of both the species were qualitatively similar, there was a significant difference in terms of quantity. The essential oils extracted through HD and SFME methods were dominated by hydrocarbon and oxygenated compounds, respectively. The essential oils of all Curcuma species exhibited strong antioxidant activity, where SFME was significantly better than HD with lower IC₅₀ values. The anti-tyrosinase and anticancer properties of SFME-extracted oils were relatively better than that of HD. Further, among the three Curcuma species, C. alismatifolia essential oil showed the highest rates of inhibition in DPPH and ABTS assay, significantly reduced the tyrosinase activity and exhibited significant selective cytotoxicity against MCF7 and PC3 cells. The current results suggested that the SFME method, being advanced, green and fast, could be a better alternative for production of essential oils with better antioxidant, anti-tyrosinase and anticancer activities for application in food, health and cosmetic industries.

Marine Algal Polyphenols as Skin Protective Agents: Current Status and Future Prospectives

The skin is the outermost anatomical barrier, which plays a vital role in the maintenance of internal homeostasis and protection against physical, chemical, and biological detractors. Direct contact with various stimuli leads to several physiological changes that are ultimately important for the growth of the cosmetic industry. Due to the consequences of using synthetic compounds in skincare and cosmeceutical-related industries, the pharmaceutical and scientific communities have recently shifted their focus to natural ingredients. The nutrient-rich value of algae, which are some of the most interesting organisms in marine ecosystems, has attracted attention. Secondary metabolites isolated from seaweeds are potential candidates for a wide range of economic applications, including food, pharmaceuticals, and cosmetics. An increasing number of studies have focused on polyphenol compounds owing to their promising biological activities against oxidation, inflammation, allergies, cancers, melanogenesis, aging, and wrinkles. This review summarizes the potential evidence of the beneficial properties and future perspectives of using marine macroalgae-derived polyphenolic compounds for advancing the cosmetic industry.

Development of Native Essential Oils from Forestry Resources in South Korea

South Korea’s forests occupy approximately 70% of the mainland, therefore, there is considerable potential for waste coming from the forest. Extracting essential oils from underutilised biomass is an economic and sustainable method for the production of high-added-value products. These days, countries’ ownership of domestic natural resources is becoming vital, so there is an urgent need for developing the essential oils from native plants. To increase the value of native essential oils in South Korea, the National Institute of Forest Science (NiFoS) established the to develop the native essential oils as well as develop more research infrastructure by sharing information on native essential oils and enhancing their value. We review the selected essential oils which are listed in the from the literature on major chemical constituents, biological activity, and potential uses of essential oils. Those utilising forest resources for commercial essential oil production need to consider the stable supply of plant material in terms of forest management and conservation. Therefore, Pinaceae (Larix kaempferi, Pinus densiflora, Pinus koraiensis) and Cupressaceae (Chamaecyparis obtusa and Chamaecyparis pisifera) could be potential candidates for commercial essential oil as their waste materials are easily obtained from the plantation after forest management. With their unique fragrance and the bioactive compounds in their oils, potential candidates can be utilised in various industry sectors.

Bioassay-guided Fractionation of Clove Buds Extract Identifies Eugenol as Potent Melanogenic Inducer in Melanoma Cells

Clove, a dried flower buds of Syzygium aromaticum, is used in traditional medicine, for culinary purposes, and in essential oil production. In our preliminary screening of crude drugs used in Japanese Kampo formulas, a methanol (MeOH) extract of clove buds was found to exhibit a melanin induction. To date, the effects of clove buds or their constituents on the activation of melanogenesis remain unclear. Thus, this study aimed to isolate active compounds from the MeOH extract of clove buds associated with melanin synthesis in melanoma cells and to investigate the molecular mechanism involved. The MeOH extract of clove buds increased melanin content in murine B16-F1 melanoma cells. To identify the active compounds responsible for melanin induction, the MeOH extract was suspended in water and successively partitioned using hexane, ethyl acetate (EtOAc), and n-butanol (n-BuOH). Comparative analysis revealed that the EtOAc fraction induced melanin synthesis. Bioassay-guided separation of the EtOAc fraction isolated three compounds including eugenol. The analysis of structure-activity relationships of eugenol and structurally related compounds indicated that eugenol was the most potent melanin inducer among the 11 compounds, and that a hydroxyl group at C-1 and a methoxy group at C-2 may contribute to melanin induction. Eugenol induced melanin synthesis in human HMV-II melanoma cells as well as in B16-F1 cells. Further analysis indicated that eugenol may invoke intracellular tyrosinase activity and expression of tyrosinase, tyrosinaserelated protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF). These results suggest that eugenol enhances melanin synthesis by upregulating the expression of MITF and subsequent expression of melanogenic enzymes, and that it may be a potent therapeutic agent for hypopigmentation.

Current Knowledge in Skin Metabolomics: Updates from Literature Review

Metabolomic profiling is an emerging field consisting of the measurement of metabolites in a biological system. Since metabolites can vary in relation to different stimuli, specific metabolic patterns can be closely related to a pathological process. In the dermatological setting, skin metabolomics can provide useful biomarkers for the diagnosis, prognosis, and therapy of cutaneous disorders. The main goal of the present review is to present a comprehensive overview of the published studies in skin metabolomics. A search for journal articles focused on skin metabolomics was conducted on the MEDLINE, EMBASE, Cochrane, and Scopus electronic databases. Only research articles with electronically available English full text were taken into consideration. Studies specifically focused on cutaneous microbiomes were also excluded from the present search. A total of 97 papers matched all the research criteria and were therefore considered for the present work. Most of the publications were focused on inflammatory dermatoses and immune-mediated cutaneous disorders. Skin oncology also turned out to be a relevant field in metabolomic research. Only a few papers were focused on infectious diseases and rarer genetic disorders. All the major metabolomic alterations published so far in the dermatological setting are described extensively in this review.

Chemical Constituents, Antioxidant, Anti-Tyrosinase, Cytotoxicity, and Anti-Melanogenesis Activities of Etlingera elatior (Jack) Leaf Essential Oils

Essential oils of plants have been used widely in cosmetic preparations. Being both perfuming and active ingredients, the functions of essential oils mean they are high-value ingredients. In this study, the leaf of Etlingera elatior (Jack) or Torch ginger was used. The essential oils (EO) were prepared by conventional hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). The volatile compounds of EOs were analyzed by gas chromatography spectroscopy (GC-MS). The antioxidant activities by means of DPPH radical scavenging and ferric-reducing antioxidant power (FRAP) were determined. The inhibition of tyrosinase activity was investigated. The cytotoxicity was performed against human fibroblast cell lines (NIH/3T3) and melanoma cell lines (A375 and B16F10). The decreasing melanin content was measured in melanoma cell lines. The resulting essential oils were detected for 41 compounds from HD extraction dominants by terpenes, namely sesquiterpenes (48.499%) and monoterpenes (19.419%), while 26 compounds were detected from MAHD with the fatty alcohols as the major group. The higher antioxidant activities were found in HD EO (IC50 of 16.25 ± 0.09 mg/mL from DPPH assay and 0.91 ± 0.01 mg TEAC/g extract from FRAP assay). The survival of normal fibroblast cell lines remained at 90% at 500 µg/mL HD EO, where the EO possessed the half-maximal toxicity dose (TD50) of 214.85 ± 4.647 and 241.128 ± 2.134 μg/mL on B16F10 and A375 cell lines, respectively. This could suggest that the EO is highly selective against the melanoma cell lines. The melanin content was decreased at the half-maximum efficacy (IC50) at 252.12 ± 3.02 and 253.56 ± 3.65 in the A375 and B1610 cell lines, respectively, which were approximately 2.8-fold lower than kojic acid, the standard compound. The results of this study evidence the use of Etlingera elatior (Jack) leaf as a source of essential oil as an active agent in cosmetics.

Phytochemistry, Bioactivities and Traditional Uses of Michelia × alba

Michelia × alba (M. alba) is a flowering tree best known for its essential oil, which has long been used as a fragrance ingredient for perfume and cosmetics. In addition, the plant has been used in traditional medicine in Asia and dates back hundreds of years. To date, there is a limited number of publications on the bioactivities of M. alba, which focused on its tyrosinase inhibition, antimicrobial, antidiabetic, anti-inflammatory, and antioxidant activities. Nevertheless, M. alba may have additional unexplored bioactivities associated with its bioactive compounds such as linalool (72.8% in flower oil and 80.1% in leaf oil), α-terpineol (6.04% flower oil), phenylethyl alcohol (2.58% flower oil), β-pinene (2.39% flower oil), and geraniol (1.23% flower oil). Notably, these compounds have previously been reported to exhibit therapeutic activities such as anti-cancer, anti-inflammation, anti-depression, anti-ulcer, anti-hypertriglyceridemia, and anti-hypertensive activities. In this review paper, we examine and discuss the scientific evidence on the phytochemistry, bioactivities, and traditional uses of M. alba. Here, we report a total of 168 M. alba biological compounds and highlight the therapeutic potential of its key bioactive compounds. This review may provide insights into the therapeutic potential of M. alba and its biologically active components for the prevention and treatment of diseases and management of human health and wellness.

Metal-organic framework on porous TiO2 thin film-coated alumina beads for fractional distillation of plant essential oils

Fractionation of essential oils is technically challenging due to enormous scaffold diversities and structural complexities as well as difficulties in the implementation of the fractionation in the gas phase. Packing beads with multi-dimensional hierarchical nanostructures have been developed herein to pack fractional columns for atmospheric distillations. Activated alumina beads were coated with a porous TiO₂ thin film. Growth of Cu-BTC (benzene-1,3,5-tricarboxylate) crystals in resultant porous surfaces leads to the generation of new nanopores and increased metal centers for differential coordination with diverse components of essential oils. The TiO₂ thin film is not only an integral part of the composites but also induces the oriented growth of Cu-BTC metal organic framework (MOF) crystals through coordinative interactions. These Al₂O₃@TiO₂@Cu-BTC MOF beads show very strong absorptive capability for major components of essential oils, except for a single cyclic ether eucalyptol with steric hindrances. The eucalyptol was fractionated by using the column packed with those modified alumina beads from raw materials of Artemisia argyi, and Rosmarinus officinalis with high purities up to 96% and 93%, respectively.

Inhibition of Escherichia Virus MS2, Surrogate of SARS-CoV-2, via Essential Oils-Loaded Electrospun Fibrous Mats: Increasing the Multifunctionality of Antivirus Protection Masks

One of the most important measures implemented to reduce SARS-CoV-2 transmission has been the use of face masks. Yet, most mask options available in the market display a passive action against the virus, not actively compromising its viability. Here, we propose to overcome this limitation by incorporating antiviral essential oils (EOs) within polycaprolactone (PCL) electrospun fibrous mats to be used as intermediate layers in individual protection masks. Twenty EOs selected based on their antimicrobial nature were examined for the first time against the Escherichia coli MS2 virus (potential surrogate of SARS-CoV-2). The most effective were the lemongrass (LGO), Niaouli (NO) and eucalyptus (ELO) with a virucidal concentration (VC) of 356.0, 365.2 and 586.0 mg/mL, respectively. PCL was processed via electrospinning, generating uniform, beadless fibrous mats. EOs loading was accomplished via two ways: (1) physisorption on pre-existing mats (PCLaEOs), and (2) EOs blending with the polymer solution prior to fiber electrospinning (PCLbEOs). In both cases, 10% v/v VC was used as loading concentration, so the mats' stickiness and overwhelming smell could be prevented. The EOs presence and release from the mats were confirmed by UV-visible spectroscopy (≈5257-631 µg) and gas chromatography-mass spectrometry evaluations (average of ≈14.3% EOs release over 4 h), respectively. PCLbEOs mats were considered the more mechanically and thermally resilient, with LGO promoting the strongest bonds with PCL (PCLbLGO). On the other hand, PCLaNO and PCLaELO were deemed the least cohesive combinations. Mats modified with the EOs were all identified as superhydrophobic, capable of preventing droplet penetration. Air and water-vapor permeabilities were affected by the mats' porosity (PCL < PCLaEOs < PCLbEOs), exhibiting a similar tendency of increasing with the increase of porosity. Antimicrobial testing revealed the mats' ability to retain the virus (preventing infiltration) and to inhibit its action (log reduction averaging 1). The most effective combination against the MS2 viral particles was the PCLbLGO. These mats' scent was also regarded as the most pleasant during sensory evaluation. Overall, data demonstrated the potential of these EOs-loaded PCL fibrous mats to work as COVID-19 active barriers for individual protection masks.

Anti-Melanogenic Activity of Calocedrus formosana Wood Essential Oil and Its Chemical Composition Analysis

Calocedrus formosana (Cupressaceae) is one of the five precious woods of Taiwan. In this study, we investigated the anti-melanogenic activity of C. formosana wood essential oil (CFEO) and its bioactive components in vitro. Initially, CFEO exhibited strong mushroom tyrosinase activity in the cell-free mushroom tyrosinase assay system with an IC₅₀ value of 2.72 µg/mL. Next, treatment with CFEO significantly as well as dose-dependently reduced a combination of α-melanocyte-stimulating hormone and forskolin (α-MSH-FSK)-induced melanin synthesis in B16-F10 cells. Indeed, 80 μg/mL CFEO completely inhibited melanin production, which is similar to that of control cells. Further studies revealed that treatment with CFEO significantly inhibited melanogenesis regulatory proteins, including TRP-1, TRP-2, and MITF, whereas tyrosinase was unaffected by either α-MSH-FSK or CFEO. In addition, the composition of the CFEO was characterized. The major components of CFEO were α-terpineol (23.47%), shonanic acid (10.45%), terpinen-4-ol (12.23%), thymol (5.3%), piperitone (3.44%), berbenone (2.81%), thujic acid (1.65%), and chaminic acid (0.13%). Among them, shonanic acid (1), thujic acid (2), and chaminic acid (3) were uncommon constitutes in essential oils, which could be the index compounds of CFEO, and the structure of these compounds were confirmed by spectral analysis. Furthermore, we found that thymol is an active ingredient responsible for CFEO's anti-melanogenic activity. Based on these results, we suggest that CFEO or thymol could be a potential candidate for the development of skin whitening products for cosmetic purposes.

Phenolic acids and flavonoids-rich Glechoma hederacea L. (Lamiaceae) water extract against H2 O2 -induced apoptosis in PC12 cells

Reactive oxygen species (ROS)-induced oxidative stress is reportedly associated with progressive neuronal cell damage. Glechoma hederacea L. (Lamiaceae), belonging to the Labiatae family, has demonstrated several biologic activities including depigmentation, antimelanogenic, antitumor, antioxidative, hepatoprotective, and anti-inflammatory activities. Previously, we reported that rosmarinic acid, chlorogenic acid, caffeic acid, rutin, genistin, and ferulic acids were the most abundant phytochemicals detected in hot water extracts of G. hederacea L. (HWG). This study aimed to study the neuroprotective effects of phenolic acids and flavonoid-rich HWG against hydrogen peroxide (H₂ O₂ )-induced oxidative damage in PC12 cells and its inhibitory effect on acetylcholinesterase (AChE). The experiment analyzed cytotoxicity, ROS production, mitochondrial transmembrane potential (MMP) level, and caspase-3 activity and used comet assay and antioxidant enzyme activity to determine the redox status of PC12 cells. Results showed that the inhibitory effect of HWG on AChE was in a competitive pattern (IC₅₀ , 23.23 mg/ml). HWG antagonized H₂ O₂ -mediated cytotoxicity and DNA damage, reduced ROS production, stabilized MMP, and inhibited caspase-3 activity and apoptosis. Furthermore, HWG inhibited the release of cytochrome C and apoptosis-inducing factors (AIF) and decreased the malondialdehyde levels in PC12 cells. Collectively, HWG rich in antioxidant phenolic acids and flavonoids may have neuroprotective effects. PRACTICAL APPLICATIONS: Polyphenolic compounds are one of the most important natural products, known to possess a range of health-promoting effects. In this study, it was found that HWG, which is rich in antioxidant phenolic acids and flavonoids, can protect PC12 cells from oxidative stress induced by H₂ O₂ and may have neuroprotective effects.

Using a Cellular System to Directly Assess the Effects of Cosmetic Microemulsion Encapsulated DeoxyArbutin

DeoxyArbutin (dA) is a tyrosinase inhibitor that has effective skin-lightening activity and has no obvious cytotoxicity toward melanocytes. With the aim of directly evaluating the effects of microemulsions containing dA on cells, we developed oil-in-water (O/W) microemulsions with relatively lower cytotoxicities by using polysorbate-series surfactants. Measurement of the transparent properties and particle size analysis at different storage time periods revealed that the developed microemulsions were stable. Moreover, the developed microemulsions had direct effects on B16-F10 mouse melanoma cells. The anti-melanogenesis activities of dA-containing microemulsions were evidently better than that of the free dA group. The results demonstrated that the developed microemulsion encapsulating dA may allow the use of deoxyArbutin instead of hydroquinone to treat dermal hyperpigmentation disorders in the future.

In vitro anti-melanogenic effect of Perilla frutescens leaf extracts

Introduction: Perilla frutescens (L.) Britt leaves contain various phenolic compounds, especially flavonoids, which potentially inhibit tyrosinase, the key enzyme catalyzing the melanin synthesis pathway. This work aimed to investigate the anti-melanogenic effect of Perilla frutescens extracts through the inhibition of non-cellular as well as cellular tyrosinase activities. Methods: The total extract from Perilla frutescens leaves was obtained by percolation method with 50% ethanol followed by liquid–liquid partition with ethyl acetate (EA) and chloroform (CF) to obtain the EA, CF and EA/CF extracts. The mushroom tyrosinase inhibitory effect of the obtained extracts was screened by dopachrome formation reactions from its substrate 3,4-dihydroxy-L-phenylalanine. The extracts with potential activity were further evaluated for the anti-melanogenic effects in the B16F10 melanoma cell line. Results: EA and EA/CF extracts significantly inhibited mushroom tyrosinase activity with the IC50s of 0.14 and 0.07 mg/mL, respectively, in the same range of that from kojic acid (0.12 mg/mL). Consistently, in B16F10 cells, these extracts inhibited tyrosinase enzyme; their IC50 values were 2 times lower than that of kojic acid. Moreover, both EA and EA/CF extracts remarkably reduced melanin levels in a concentration-dependent manner. Conclusion: The EA and EA/CF extracts from Perilla frutescens leaves were able to inhibit melanogenesis by reducing tyrosinase activity.

1,8-Cineole: a review of source, biological activities, and application

1,8-Cineole (also known as eucalyptol) is mostly extracted from the essential oils of plants, which showed extensively pharmacological properties including anti-inflammatory and antioxidant mainly via the regulation on NF-κB and Nrf2, and was used for the treatment of respiratory diseases and cardiovascular, etc. Although various administration routes have been used in the application of 1.8-cineole, few formulations have been developed to improve its stability and bioavailability. This review retrospects the researches on the source, biological activities, mechanisms, and application of 1,8-cineole since 2000, which provides a view for the further studies on the application and formulations of 1,8-cineole.

GC/MS Profiling, In Vitro and In Silico Pharmacological Screening and Principal Component Analysis of Essential Oils from Three Exotic and Two Endemic Plants from Mauritius

The chemical and pharmacological profiles of essential oils (EOs) hydrodistilled in yields of 0.03-0.77 % (w/w) from three exotic (Cinnamomum camphora, Petroselinum crispum, and Syzygium samarangense) and two endemic (Pittosporum senacia subsp. senacia and Syzygium coriaceum) medicinal plants were studied. GC-MS/GC-FID analysis of the EOs identified the most dominant components to be myristicin (40.3 %), myrcene (62.2 %), 1,8-cineole (54.0 %), β-pinene (21.3 %) and (E)-β-ocimene (24.4 %) in P. crispum, P. senacia and C. camphora, S. samarangense and S. coriaceum EOs, respectively. All EOs were found to possess anti-amylase (0.70-1.50 mM ACAE/g EO) and anti-tyrosinase (109.35-158.23 mg KAE/g) properties, whereas no glucosidase inhibition was displayed. Only Syzygium EOs acted as dual inhibitors of both acetyl- and butyryl-cholinesterases, while P. senacia and C. camphora EOs inhibited acetylcholinesterase selectively and P. crispum EO was inactive (AChE: 4.64-4.96 mg GALAE/g; BChE: 5.96 and 7.10 mg GALAE/g). Molecular docking revealed 1,8-cineole to present the best binding affinities with butyrylcholinesterase, amylase and tyrosinase, while both myristicin and β-pinene with acetylcholinesterase and finally β-pinene with glucosidase. In vitro antioxidant potency was also demonstrated in different assays (DPPH: 13.52-53.91 mg TE/g, ABTS: 5.49-75.62 mg TE/g; CUPRAC: 45.38-243.21 mg TE/g, FRAP: 42.49-110.64 mg TE/g; and phosphomolybdenum assay: 82.61-160.93 mM TE/g). Principal component analysis revealed the EOs to differ greatly in their bioactivities due to their chemodiversity. This study has unveiled some interesting preliminary pharmacological profiles of the EOs that could be explored for their potential applications as phytotherapeutics.

Essential Oils of Alpinia nantoensis Retard Forskolin-Induced Melanogenesis via ERK1/2-Mediated Proteasomal Degradation of MITF

The anti-melanogenic activity of essential oils of Alpinia nantoensis and their bioactive ingredients were investigated in vitro. Treatment with leaf (LEO) and rhizome (REO) essential oils of A. nantoensis, significantly reduced forskolin-induced melanin production followed by down-regulation of tyrosinase (TYR) and tyrosinase related protein-1 (TRP-1) expression at both transcriptional and translational levels. Further studies revealed that down-regulation TYR and TRP-1 were caused by LEO/REO-mediated suppression of Microphthalmia-associated transcription factor (MITF), as evidenced by reduced nuclear translocation of MITF. Also, we found that LEO/REO induce the sustained activation of ERK1/2, which facilitate subsequent proteasomal degradation of MITF, as confirmed by that LEO/REO failed to inhibits MITF activity in ERK1/2 inhibitor treated cells. In addition, a significant increase of ubiquitinated MITF was observed after treatment with LEO and REO. Furthermore, the chemical composition of LEO and REO were characterized by gas chromatography-mass spectrometry (GC-MS) resulted that camphor, camphene, α-pinene, β-pinene, isoborneol and _D-limonene were the major compounds in both LEO and REO. Further studies revealed that α-pinene and _D-limonene were the active components responsible for the anti-melanogenic properties of LEO and REO. Based on the results, this study provided a strong evidence that LEO and REO could be promising natural sources for the development of novel skin-whitening agents for the cosmetic purposes.

Phytochemical Analysis, Antioxidant, Antibacterial, Cytotoxic, and Enzyme Inhibitory Activities of Hedychium flavum Rhizome

Hedychium flavum Roxb., a medicinal, edible, and ornamental plant, is widely cultivated throughout China, India, and Southeast Asia. The rhizome from this plant has been used for food flavoring and in traditional Chinese medicine to treat diverse diseases, but the detailed constituents and bioactivities are still limited known. Therefore, phytochemical analysis by GC-MS and UHPLC-Q-Orbitrap-MS, and antioxidant, antibacterial, cytotoxic, and enzyme inhibitory activities tests have been conducted in the current study. Based on the GC-MS results, the essential oil (EO) of rhizome was mainly composed of coronarin E (20.3%), β-pinene (16.8%), E-nerolidol (11.8%), and linalool (8.5%). Among them, coronarin E was reported in H. flavum EO firstly. Furthermore, the spectrophotometric indicated rhizome had high total phenolic content (TPC, 50.08-57.42 mg GAEs/g extract) and total flavonoid content (TFC, 12.45-21.83 mg REs/g extract), no matter in water extract (WE) or in 70% ethanol extract (EE). UHPLC-Q-Orbitrap-MS was applied to further characterize composition, and 86 compounds were putatively identified from WE and EE, including 13 phenolic components. For the bioactivities, both WE and EE showed remarkable antioxidant activity by DPPH and ABTS tests, being superior to the positive control (butylated hydroxytoluene, BTH). EO revealed significant antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Proteus vulgaris with DIZ (10.34-24.43 mm), MIC (78.13-312.50 μg/mL), and MBC (156.25-625.00 μg/mL). Moreover, EO exhibited a considerable selectivity to human tumor cell K562 (IC₅₀ = 27.16 μg/mL), and its toxicity was more than 3.5-fold different from that of non-cancerous MRC-5 cell (IC₅₀ = 95.96 μg/mL) and L929 cell (IC₅₀ = 129.91 μg/mL). A series of apoptosis analysis demonstrated that EO induced apoptosis against K562 cells in a dose-dependent manner. In enzyme inhibitory effect assays, WE and EE showed strong α-glucosidase inhibition activity, being superior to the positive control (acarbose). Besides, the EO, WE, and EE didn't show a promising inhibition on tyrosinase (19.30-32.51 mg KAEs/g sample) and exhibited a weak inhibitory effect on cholinesterase. Based on the current results, H. flavum could be considered as a source of bioactive compounds and has high exploitation potential in the cosmetics, food, and pharmaceutical industries.

Essential Oils and Their Main Chemical Components: The Past 20 Years of Preclinical Studies in Melanoma

Simple Summary

In the last years, targeted therapy and immunotherapy modified the landscape for metastatic melanoma treatment. These therapeutic approaches led to an impressive improvement in patients overall survival. Unfortunately, the emergence of drug resistance and side effects occurring during therapy strongly limit the long-term efficacy of such treatments. Several preclinical studies demonstrate the efficacy of essential oils as antitumoral agents, and clinical trials support their use to reduce side effects emerging during therapy. In this review we have summarized studies describing the molecular mechanism through which essential oils induce in vitro and in vivo cell death in melanoma models. We also pointed to clinical trials investigating the use of essential oils in reducing the side effects experienced by cancer patients or those undergoing anticancer therapy. From this review emerged that further studies are necessary to validate the effectiveness of essential oils for the management of melanoma.

Abstract

The last two decades have seen the development of effective therapies, which have saved the lives of a large number of melanoma patients. However, therapeutic options are still limited for patients without BRAF mutations or in relapse from current treatments, and severe side effects often occur during therapy. Thus, additional insights to improve treatment efficacy with the aim to decrease the likelihood of chemoresistance, as well as reducing side effects of current therapies, are required. Natural products offer great opportunities for the discovery of antineoplastic drugs, and still represent a useful source of novel molecules. Among them, essential oils, representing the volatile fraction of aromatic plants, are always being actively investigated by several research groups and show promising biological activities for their use as complementary or alternative medicine for several diseases, including cancer. In this review, we focused on studies reporting the mechanism through which essential oils exert antitumor action in preclinical wild type or mutant BRAF melanoma models. We also discussed the latest use of essential oils in improving cancer patients’ quality of life. As evidenced by the many studies listed in this review, through their effect on apoptosis and tumor progression-associated properties, essential oils can therefore be considered as potential natural pharmaceutical resources for cancer management.

Metabolomics Reveals the Alteration of Metabolic Pathway by Alpha-Melanocyte-Stimulating Hormone in B16F10 Melanoma Cells

The purpose of this study was to understand the changes of metabolic pathway induced by alpha-melanocyte-stimulating hormone (α-MSH) in B16F10 melanoma cells in an untargeted metabolomics approach. Cells were treated with 100 nM of α-MSH and then incubated for 48 h. α-MSH increased tyrosinase activity and melanin content by 56.5 and 61.7%, respectively, compared to untreated cells after 48 h of cultivation. The clear separation between groups was observed in the principal component analysis score plot, indicating that the levels of metabolites of melanoma cells were altered by treatment with α-MSH. Metabolic pathways affected by α-MSH were involved in some amino acid metabolisms. The increased levels of fumaric acid, malic acid, oxaloacetic acid and citric acid related to the citric acid cycle pathway after α-MSH treatment suggested enhanced energy metabolism. Metabolic pathways altered by α-MSH treatment can provide useful information to develop new skin pigmentation inhibitors or anti-obesity drugs.

Chemical composition and evaluation of antioxidant activities, antimicrobial, and anti-melanogenesis effect of the essential oils extracted from Dalbergia pinnata (Lour.) Prain

ETHNOPHARMACOLOGICAL RELEVANCE

Dalbergia pinnata (Lour.) Prain (D. pinnata) is a plant widely distributed in tropical and subtropical regions of Asia, Africa, and the Americas. In humans, it is used in the prevention and treatment of diseases such as respiratory system, digestive system, cardiovascular and cerebrovascular diseases.

AIM OF THE STUDY

This study was aim to evaluate chemical composition, antioxidant activities, antimicrobial, and anti-melanogenesis properties of Essential oils (EO) from D. pinnata.

MATERIALS AND METHODS

In this paper, the EO of D. pinnata were extracted using the supercritical CO₂ extraction method and purified by molecular distillation. The volatile compounds of EO were characterized using Gas Chromatography-Mass Spectrometer (GC-MS). The antioxidant activities were evaluated by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. And two Gram-positive bacteria, three Gram-negative bacteria and a fungus were employed to evaluate the antimicrobial activity. The zebrafish was used as experimental model to evaluate the anti-melanogenesis effect of the EO from D. pinnata.

RESULTS

The EO of D. pinnata were obtained in a yield of 4.75% (v/w) calculated on dry weight basis. 14 volatile compounds could be detected and the predominant components include elemicin (91.06%), methyl eugenol (3.69%), 4-allyl-2,6-dimethoxyphenol (1.16%), and whiskey lactone (0.55%). The antioxidant assay showed that the EO could scavenge DPPH (IC50 values of 0.038 mg/mL) and ABTS (IC50 value of 0.032 mg/mL) free radical, indicating that the EO had strong antioxidant activity. The results of antimicrobial test showed that Staphylococcus aureus was most sensitive to EO with minimal inhibitory concentration (MIC) of 0.78 μL/mL, followed by Streptococcus pyogenes (6.25 μL/mL) and Candida albicans (12.5 μL/mL). Gram-negative strains, including Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium, were slightly affected by the EO. Additionally, EO from D. pinnata could reduce tyrosinase activity and melanin synthesis of zebrafish embryos in dose-dependent manner. And EO exhibited the more obvious anti-melanogenic effect compared with the positive control arbutin at the same dose (30 mg/L).

CONCLUSIONS

Our results validated the main activities attributed to D. pinnata for its antimicrobial and antioxidant. In addition, the potent inhibitory impacts of EO on the pigmentation provides a theoretical basis for the in-depth study of the EO from D. pinnata and their application in pharmaceutical and cosmetic industries.

Comparative study on skin protection activity of polyphenol-rich extract and polysaccharide-rich extract from Sargassum vachellianum

Seaweed polyphenols and polysaccharide plays a broad range of biological activity. The objective of the present study was to study and compare the skin protection activity of fucoidan rich polysaccharide extract (SPS) and polyphenol-rich extract (SPP) from the seaweed Sargassum vachellianum. The skin protection activity was analyzed based on their ability to scavenge free radicals such as hydrogen peroxide and hydroxyl radicals, UV absorption potential, tyrosinase inhibition, moisture preservation, and antibacterial activity. From the results, both SPP and SPS protects the skin from UV damage. SPP showed good free radical scavenging ability, antimicrobial activity against E.coli and S. aureus and effectively absorbed the UVB and UVA rays whereas SPS hardly absorbs the UVA and UVB rays and showed weak free radical scavenging ability and no antimicrobial activity. SPS showed considerable inhibition on tyrosinase (51.21%) and had better moisture absorption (52.1%) and retention (63.24%) abilities than SPP. The results specified that both SPS and SPP have balancing potential on skin protection and suitable combinations of both could act as an active ingredient in cosmetics.

Beneficial Role of Phytochemicals on Oxidative Stress and Age-Related Diseases

Aging is related to a number of functional and morphological changes leading to progressive decline of the biological functions of an organism. Reactive Oxygen Species (ROS), released by several endogenous and exogenous processes, may cause important oxidative damage to DNA, proteins, and lipids, leading to important cellular dysfunctions. The imbalance between ROS production and antioxidant defenses brings to oxidative stress conditions and, related to accumulation of ROS, aging-associated diseases. The purpose of this review is to provide an overview of the most relevant data reported in literature on the natural compounds, mainly phytochemicals, with antioxidant activity and their potential protective effects on age-related diseases such as metabolic syndrome, diabetes, cardiovascular disease, cancer, neurodegenerative disease, and chronic inflammation, and possibly lower side effects, when compared to other drugs.

Cosmeceutical activities of ethanol extract and its ethyl acetate fraction from coffee silverskin

Background

Coffee silverskin is a thin film that covers the raw coffee bean. In general, coffee silverskin, which detaches during the coffee roasting process, is disposed as firelighters or dispatched to landfills and can cause serious environmental pollution. The aim of this study was to investigate the feasibility of using coffee silverskin as a functional material in cosmetics by evaluating its bioactive ingredients, antioxidative activity, cytoprotective effect, matrix metalloproteinase-1 (MMP-1)-inhibiting effect, and anti-melanogenesis effect.

Results

To this end, a 50% ethanol (EtOH) extract and its ethyl acetate (EtOAc) fraction were prepared from coffee silverskin; caffeine was found to be the major compound in the extract. Both the 50% EtOH extract and its EtOAc fraction exhibited antioxidant activities. However, the EtOAc fraction showed a greater radical-scavenging activity and reducing power than that shown by the 50% EtOH extract. Furthermore, the EtOAc fraction increased cell viability in a UVB-irradiated human keratinocyte injury model and significantly suppressed UVB-induced MMP-1 expression and α-melanocyte-stimulating hormone (α-MSH)-stimulated melanin production in HaCaT keratinocytes and B16F1 melanocytes, respectively. Interestingly, caffeine, the major component of the EtOAc fraction, did not show an inhibitory effect. Thus, the antioxidant capacity of the coffee silverskin extract may be attributable to some compounds that exhibit a high antioxidant capacity even at low concentrations or the total antioxidant capacity of various constituent phenolic compounds.

Conclusion

Our findings indicate that coffee silverskin has the potential for application as a natural functional material in multifunctional cosmetics.

A Potent Tyrosinase Inhibitor, (E)-3-(2,4-Dihydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one, with Anti-Melanogenesis Properties in α-MSH and IBMX-Induced B16F10 Melanoma Cells

In this study, we designed and synthesized eight thiophene chalcone derivatives (1a–h) as tyrosinase inhibitors and evaluated their mushroom tyrosinase inhibitory activities. Of these eight compounds, (E)-3-(2,4-dihydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one (1c) showed strong competitive inhibition activity against mushroom tyrosinase with IC₅₀ values of 0.013 μM for tyrosine hydroxylase and 0.93 μM for dopa oxidase. In addition, we used enzyme kinetics study and docking program to further evaluate the inhibitory mechanism of 1c toward tyrosinase. As an underlying mechanism of 1c mediated anti-melanogenic effect, we investigated the inhibitory activity against melanin contents and cellular tyrosinase in B16F10 melanoma cells. As the results, the enzyme kinetics and docking results supports that 1c highly interacts with tyrosinase residues in the tyrosinase active site and it can directly inhibit tyrosinase as competitive inhibitor. In addition, 1c exhibited dose-dependent inhibitory effects in melanin contents and intracellular tyrosinase on α-MSH and IBMX-induced B16F10 cells. Overall, our results suggested that 1c might be considered potent tyrosinase inhibitor for use in the development of therapeutic agents for diseases associated with hyperpigment disorders.

Zerumbone, a Tropical Ginger Sesquiterpene of Zingiber officinale Roscoe, Attenuates α-MSH-Induced Melanogenesis in B16F10 Cells

Zerumbone (ZER), an active constituent of the Zingiberaceae family, has been shown to exhibit several biological activities, such as anti-inflammatory, anti-allergic, anti-microbial, and anti-cancer; however, it has not been studied for anti-melanogenic properties. In the present study, we demonstrate that ZER and Zingiber officinale (ZO) extract significantly attenuate melanin accumulation in α-melanocyte-stimulating hormone (α-MSH)-stimulated mouse melanogenic B16F10 cells. Further, to elucidate the molecular mechanism by which ZER suppresses melanin accumulation, we analyzed the expression of melanogenesis-associated transcription factor, microphthalmia-associated transcription factor (MITF), and its target genes, such as tyrosinase, tyrosinase-related protein 1 (TYRP1), and tyrosinase-related protein 2 (TYRP2), in B16F10 cells that are stimulated by α-MSH. Here, we found that ZER inhibits the MITF-mediated expression of melanogenic genes upon α-MSH stimulation. Additionally, cells treated with different concentrations of zerumbone and ZO showed increased extracellular signal-regulated kinases 1 and 2 (ERK1/2) phosphorylation, which are involved in the degradation mechanism of MITF. Pharmacological inhibition of ERK1/2 using U0126 sufficiently reversed the anti-melanogenic effect of ZER, suggesting that increased phosphorylation of ERK1/2 is required for its anti-melanogenic activity. Taken together, these results suggest that ZER and ZO extract can be used as active ingredients in skin-whitening cosmetics because of their anti-melanogenic effect.

The Effect of Volatile Oil from Vernonia anthelmintica Seeds on Melanin Synthesis in B16 Cells and Its Chemical Analysis by GC-QTOF-MS

Vernonia anthelmintica Willd. seeds have been used in folk medicine for the treatment of leukoderma in Xinjiang, China, for more than 300 years. The promoting activities of its volatile oil (AVO) in melanogenesis and its chemical composition were investigated in this paper. The bioactivities of AVO were examined by melanin synthesis and tyrosinase activity assay in B16 cells. Using GC-QTOF-MS technology, each compound of AVO contains a single separated peak in GC and the retention indices of every GC peak were calculated by the retention times of C7~C30 n-alkanes that were injected at the same chromatographic conditions. Then each individual peak was identified by comparing its mass spectrum with the MS library (NIST 14). As a result, AVO increased the melanin content and tyrosinase activity in a dose-dependent manner at concentrations of 10-30μg·mL⁻¹. The 64 compounds were identified in AVO which occupied 95.15% of total peak area in GC. They mainly contained caryophyllene (23.73%), sabinene (18.15%), α-thujene (6.57%), thymol (5.29%), 4-epi-α-acoradiene (4.98%), limonene (4.92%), anethole (3.44%), etc. According to the results the AVO can promote melanogenesis and upregulate tyrosinase activity in B16 cells.

Structure⁻Activity Relationship of the Tyrosinase Inhibitors Kuwanon G, Mulberrofuran G, and Albanol B from Morus Species: A Kinetics and Molecular Docking Study

Kuwanon G (KG) and benzofuran flavonoids such as mulberrofuran G (MG) and albanol B (AB) isolated from Morus sp. are reported to exhibit anti-Alzheimer’s disease, anti-inflammatory, fungicidal, anti-cancer, anti-bacterial, and anti-tyrosinase properties. We investigated the inhibition of mono- and diphenolase activity of mushroom tyrosinase by KG, MG, and AB. KG and MG displayed acceptable inhibition activity compared to kojic acid. AB did not show any activity up to 350 µM. MG displayed six-fold higher inhibition of l-tyrosine oxidation (IC₅₀ = 6.35 ± 0.45 µM) compared to kojic acid (IC₅₀ = 36.0 µM). Kinetic studies revealed that KG and MG inhibited monophenolase activity of tyrosinase in a competitive manner. Docking simulations of KG and MG demonstrated favorable binding energies with amino acid residues of the active sites of tyrosinase. Our investigation of the structure-activity relationship of the fused benzofuran flavonoids (MG vs. AB) implicated the methyl cyclohexene ring moiety in tyrosinase inhibition. The enzyme substrate and relative structural analyses demonstrated that KG and MG from Morus sp. could be useful natural tyrosinase inhibitors in foods or cosmetics.

In Vitro Antioxidant and Cytotoxic Activities of 18 Plants from the Erkowit Region, Eastern Sudan

We investigated the antioxidant potential and cytotoxicity towards human CCRF-CEM leukemia cells of 57 extracts obtained from 18 plants collected in the Erkowit region, eastern Sudan. The antioxidant activity was determined by measuring the radical scavenging effects against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and N,N-dimethyl-p-phenylendiamine (DMPD), metal-chelation capacity, ferric-reducing (FRAP) and phosphomolibdenum-reducing antioxidant power (PRAP) methods using ELISA microtiter assays. Total phenol and flavonoid amounts of the extracts were determined spectrophotometrically. Cytotoxicity towards CCRF-CEM cells was evaluated by the resazurin reduction assay. Geranium favosum followed by Kalanchoe glaucescens, Malva parviflora, Aizoon canariense, and Coleus barbatus, respectively, possessed the highest antioxidant activity among the studied plants. Chrozophora oblongifolia and K. glaucescens exerted considerable cytotoxicity against CCRF-CEM leukemia cells. These plants may serve as source for the further development of natural antioxidant and antitumor agents.