In vitro tyrosinase inhibitory and antioxidant potential of Consolida orientalis, Onosma isauricum and Spartium junceum from Turkey

(1)

In vitro tyrosinase inhibitory and antioxidant potential of Consolida

orientalis, Onosma isauricum and Spartium junceum from Turkey

G. Zengin

a,

⁎

, M.F. Mahomoodally

b

, C.M.N. Picot-Allain

b

, Y.S. Cakmak

c

, S. Uysal

a

, A. Aktumsek

a

Department of Biology, Faculty of Science, Selcuk University, Campus/Konya, Turkey

b_{Department of Health Sciences, Faculty of Science, University of Mauritius, Réduit, Mauritius} c

Department of Biotechnology and Molecular Biology, Faculty of Science and Letters, Aksaray University, Aksaray, Turkey

a b s t r a c t

a r t i c l e i n f o

Article history: Received 6 October 2017

Received in revised form 21 December 2017 Accepted 10 January 2018

Available online 20 February 2018 Edited by J Van Staden

Traditionally used botanical remedies have attracted much interest as pharmacological targets in the manage-ment and/or treatmanage-ment of several diseases. Recently, they have been probed as tyrosinase inhibitors for the man-agement of epidermal hyperpigmentation. This study aims to investigate into the antioxidant and tyrosinase inhibitory potential of methanol, ethyl acetate, and water extracts of three medicinal plants (Consolida orientalis (J. Gay) Schrödinger, Onosma isauricum Boiss. & Heldr. and Spartium junceum L.), from Turkey. Methanolic extract of O. isauricum and S. junceum showed the highest phenolic (63.08 mgGAE/g extract) andflavonoid contents (45.55 mgRE/g extract). Additionally, O. isauricum methanolic extract exhibited the most powerful antioxidant capacity followed by methanolic extract of S. junceum (86.02 and 62.81 mgAAE/g extract, respectively). S. junceum extracts yielded the higher kojic acid equivalent values (21.42–23.04 mgKAE/g extract), confirming that these extracts were the most potent inhibitors of tyrosinase. S. junceum showed promising activity that warrant further studies and could be considered as a potent candidate for the development of phytoremedies for the management of epidermal hyperpigmentation. To the best of our knowledge, this study can be considered as thefirst report of on the antioxidant and tyrosinase inhibitory action of C. orientalis, O. isauricum, and S. junceum from Turkey.

Keywords: Antioxidant Tyrosinase Phenolic Flavonoid Hyperpigmentation Enzyme inhibitors Botanical remedies 1. Introduction

Tyrosinase is a copper containing enzyme which catalyzes the o-hydroxylation of monophenols to o-diphenols and their subsequent oxidation to o-quinones (Chang, 2009). Tyrosinase is also involved in the biosynthesis of melanin, due to its key role in converting o-dopaquinone to dopachrome, which further polymerizes to form the pigment (Sugumaran and Barek, 2016). Melanin pigment is widely distributed in nature and is found in animals, plants, fungi, and bacteria (Solano, 2014). In humans, melanin plays a pivotal role, both in the ab-sorption of free radicals, and in the protection of the organism against harmful UV rays (Brenner and Hearing, 2008).

However, excessive melanin production, due to genetic and/or environmental factors, leads to pigmentary skin disorders. These dermatological events include melasma, solar melanosis, ephelides, senile lentigos, and acne scars (Trivedi et al., 2017). Thus, tyrosinase inhibitorsﬁnd application in cosmetics for the treatment of epidermal hyperpigmentation. The use of cosmetic products containing synthetic tyrosinase inhibitors, namely hydroquinone and kojic acid, is associated to undesirable side effects, such as skin irritation, post inﬂammatory

pigmentation, skin cancer, ochronosis, and dermatitis (Pillaiyar et al., 2017). Additionally, existing agents present other limitations, such as high toxicity, low stability, poor skin penetration, and reduced activity (Souza et al., 2012). Therefore, the development of novel compounds for the treatment of hyperpigmentation has attracted the attention of the scientiﬁc community. Identifying lead compound(s) from plants which possess tyrosinase inhibition effect and other bioactive proper-ties such as antioxidant functions, is highly desirable.

Medicinal plants represent a rich source of phytochemicals and have been appraised as natural inhibitors of tyrosinase. Additionally, the de-velopment of template molecules from plants offers great scope to the cosmeto-pharma industry, as well as the agro-industry. Indeed, for cen-turies, the cosmetic application of natural ingredients has been praised. Currently, natural products have received renewed interest, due to health concerns regarding synthetic molecules (Loizzo et al., 2012; Ribeiro et al., 2015). The inactivation of tyrosinase by natural agents, to prevent undesirable enzymatic browning, provides new avenues for future prospects in the agro-industrial sector (Taranto et al., 2017).

In the present study, we aimed at studying the antioxidant and ty-rosinase inhibitory effects of three medicinal plants, namely Consolida orientalis, Onosma isauricum, and Spartium junceum. Consolida orientalis, native to the south/east regions of Europe, occurs profusely in south-east Hungary (Hohmann et al., 2002). Previously,Nemati et al. (2013)

⁎ Corresponding author.

E-mail address:gokhanzengin@selcuk.edu.tr(G. Zengin).

https://doi.org/10.1016/j.sajb.2018.01.010

Contents lists available atScienceDirect

South African Journal of Botany

(2)

reported the anticancer potential of C. orientalis ethanolic extract on HeLa cell line. Delcosine, gigactonine, 14-demethyltuguaconitine, takaosamine, and 18-demethylpubescenine were isolated from C. orientalis (Hohmann et al., 2002). S. junceum belonging to the Fabaceae family, is commonly known as Spanish Broom and is a perennial, leguminous shrub, cultivated in the Mediterranean regions (Cerchiara et al., 2010). This species is used for its diuretic, purgative, and anti-ulcer properties (Menghini et al., 2006). LaterGhasemi et al. (2015)reported the presence of 30 constituents in S. junceum essential oil including linalool, tetradecanoic acid, camphor, and dodecanoic acid. Several species of Onosma are used in the Turkish folk medicine for the treatment of various disorders such as bronchitis, to alleviate pain, hemorrhoids, and tonsillitis (Tosun et al., 2008). The chloroform and ethanolic extracts of O. isauricum were found to inhibit p-benzoquinone-induced abdominal constriction and carrageenan-induced hind paw edema, thus exhibiting anti-in_{ﬂammatory and} anti-nociceptive activities (Tosun et al., 2008). However, to the best of our knowledge, no data exists on the possible inhibitory action of C. orientalis, O. isauricum, and S. junceum on tyrosinase. Therefore, the present study was designed to assess the tyrosinase inhibitory potential of the ethyl acetate, methanol, and aqueous extracts of these plants along with their antioxidant and phytochemical proﬁles.

2. Materials and methods 2.1. Plant materials

Aerial parts of C. orientalis, O. isauricum (Alaeddin Keykubat Campus, Selcuk University), and S. junceum (Konya-Beysehir road) were collected from Konya in the summer of 2013. Taxonomic identiﬁcation was carried out by Dr. Murad Aydın Sanda, senior taxonomist of the Department of Biology, Selcuk University, Turkey.

The plant materials were allowed to dry at room temperature in a shaded place for two weeks. Dried aerial parts were ground to aﬁne powder using a laboratory mill. Ten grams of powdered samples were separately extracted with ethyl acetate and methanol in a Soxhlet apparatus for 6–8 h. The extracts were then concentrated in vacuo at 40 °C using a rotary evaporator. To obtain the water extracts, the pow-dered samples were boiled with 250 mL of distilled water for 30 min. The aqueous extracts were furtherﬁltered and lyophilized (−80 °C, 48 h). All samples were stored at +4 °C in dark.

2.2. Total bioactive components

The total phenolic content was determined using the Folin-Ciocâlteu colorimetric method (Slinkard and Singleton, 1977). The results were expressed as gallic acid equivalents (GAE/g extract). The totalﬂavonoid content was determined following the AlCl3method described byBerk et al. (2011)and the results were expressed as rutin equivalents (RE/g extract).

2.3. Antioxidant activity

The antioxidant activity of the extracts was evaluated using different assays (free radical scavenging (DPPH, ABTS and superoxide), reducing power (CUPRAC and ferric reducing power [by potassium ferricyanide method]), phosphomolybdenum,β-carotene/linoleic acid and metal chelating assays) as previously described (Zengin et al., 2015). 2.4. Anti-tyrosinase activity

Tyrosinase inhibitory activity was measured using the modiﬁed dopachrome method withL-DOPA as substrate, as previously reported (Zengin, 2016). The extracts (25μL) were mixed with tyrosinase solu-tion (200 U/mL, 40μL) and phosphate buffer (100 μL, 40 mM, pH 6.8) in a 96-well microplate and incubated for 15 min at 25 °C. The reaction

was then initiated by the addition ofL-DOPA (10 mM, 40μL). A blank was prepared by adding sample solution to the reaction mixture without the enzyme. The absorbance was read at 492 nm after 10 min incubation at 25 °C. The absorbance of the blank was subtracted from that of the sample and the tyrosinase inhibitory activity was expressed as kojic acid equivalents (mgKAE/g extract).

2.5. Statistical analysis

All the assays were carried out in triplicate. The results are expressed as mean values and standard deviation (SD). The differences between the different extracts were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's honest signiﬁcant difference post hoc test withα = 0.05. This approach was carried out using SPSS v. 14.0 software.

3. Results and discussion

It has been stated that the use of depigmentation cosmetic products coupled with antioxidant properties are highly desirable, since oxida-tive stress is induced by UV rays activated melanogenesis (Muddathir et al., 2017). UV rays were found to promote the formation of reactive oxygen species (ROS), especially superoxide radicals which activate tyrosinase, thus inducing melanogenesis (Baldea et al., 2009). Further-more, altered melanin production was related to the formation of malignant melanoma, eventually resulting in skin cancer (Jdey et al., 2017). Interestingly, plant secondary metabolites exhibit potent antiox-idant efﬁcacy, due to their ability to donate electrons and/or chelate transition metals (Segura Campos et al., 2015).

The total phenolic and ﬂavonoid contents of C. orientalis,

O. isauricum, and S. junceum were measured against the standards gallic acid and rutin, respectively.Table 1depicts that the highest total phenolic content was obtained for O. isauricum methanolic extract (63.08 mgGAE/g extract). Conversely, S. junceum methanolic extract (45.55 mgRE/g extract) possessed the highest totalﬂavonoid content. Total antioxidant capacity determination indicates that O. isauricum methanolic extract showed the highest antioxidant potential, followed by S. junceum methanolic extract (86.02 and 62.81 mgAAE/g extract, re-spectively). In fact, the total phenolic content was previously associated to observed antioxidant activity of plant extracts (Piluzza and Bullitta, 2011).

The ability of the plant extracts (at 0.2, 0.5, and 1 mg/mL) to stabilize DPPH radical varied signiﬁcantly (Table 2). As the concentration of the tested plant extracts increased, the DPPH scavenging ability also in-creased. Among investigated samples O. isauricum methanol extract ex-hibited the highest DPPH scavenging activity (92.91% at 1 mg/mL compared to 91.69% for BHA at 0.4 mg/mL). The lowest recorded activity was for C. orientalis ethyl acetate extract (Table 2). This result is

Table 1

Total phenolics/ﬂavonoids contents and total antioxidant ability (phosphomolybdenum assay) of the studied extracts.

Plant species Extracts Total phenolic content (mgGAE/g extract) Totalﬂavonoid content (mgRE/g extract) Total antioxidant ability (mgAAE/g extract) C. orientalis EA 7.03 ± 0.50a 7.74 ± 0.14 1.21 ± 0.01 MeOH 23.05 ± 1.57 29.83 ± 0.63 21.46 ± 2.22 Water 23.35 ± 048 14.23 ± 0.39 4.82 ± 0.32 O. isauricum EA 15.72 ± 0.20 11.41 ± 0.25 31.17 ± 2.33 MeOH 63.08 ± 2.94 43.06 ± 0.62 86.02 ± 2.63 Water 62.63 ± 0.35 9.90 ± 1.83 55.36 ± 0.69 S. junceum EA 23.71 ± 1.78 22.53 ± 1.19 34.12 ± 4.39 MeOH 46.31 ± 2.79 45.55 ± 0.14 62.81 ± 3.43 Water 43.64 ± 0.07 15.30 ± 0.11 36.23 ± 0.12 a

Results are mean values ± SD from three experiments. EA: ethyl acetate, MeOH: methanol. GAE: gallic acid equivalent, RE: rutin equivalent, AAE: ascorbic acid equivalent.

(3)

supported also by the fact that C. orientalis ethyl acetate extract contained the lowest amount of total phenolics andflavonoids. The aim of using different extractive solvents was to provide comparative data and also, an insight into the bioactivity of phytochemicals of differ-ing polarities present in the investigated samples. The efficacy of the plant extracts to scavenge ABTS radical was also assessed. Herein, S. junceum methanol extract (190.23 mgTE/g extract) showed the highest scavenging ability against ABTS. DPPH, and ABTS radicals are currently used to assess the antioxidant potential of plant extracts, purified fractions or isolated compounds. However, the ABTS method has several advantages over the DPPH assay due to its ability to act at different pHs compared to the DPPH radical which requires acidic pH (Pekal and Pyrzynska, 2015). In addition, ABTS is soluble in aqueous and organic solvents, thereby allowing the determination of antioxidant activity of samples of different polarities (Shalaby and Shanab, 2013). Interestingly, it was found that ABTS radical readily reacts with studied samples in a similar manner as compared to DPPH.

Results for the superoxide radical scavenging assay indicated that the plant extracts quenched superoxide radical at different extent. FromTable 3, 1 g of O. isauricum water extract exhibited the highest trolox equivalent value (159.92 mg TE). It was noted that O. isauricum water extract possessed a high amount of total phenolics but a low level of totalﬂavonoids. Moreover, it is, thus, argued that the superoxide radical quenching activity might be ascribed to other phenolics, rather thanﬂavonoids, as previously reported (Tumbas et al., 2010).

Tables 4 and 5depict the reducing capacity of the studied plant ex-tracts (at 0.4, 0.8, and 2 mg/mL) against copper (II) and iron (III), respec-tively. The trend observed showed that, when the concentration of the plant extracts increased, the value of absorbance increased, resulting an increasement in reducing potential. O. isauricum methanol extract exhibited the highest reducing potential against copper (II), followed by its water extract and S. junceum methanol extract, showing values ranging from 3.072–1.948 at 2 mg/mL compared to 1.902 and 1.482

for BHA and BHT at 0.1 mg/mL (the data not shown inTable 4).

Likewise, a similar trend was observed for the FRAP assay. The values obtained for this assay ranged from 1.110–0.582 for O. isauricum methanolic extract, O. isauricum water extract, and S. junceum methano-lic extract compared to 0.933 and 0.616 for BHA and BHT, respectively (data not shown inTable 5).

The ability of the extracts to scavenge linoleate-derived free radicals and subsequently preventβ-carotene bleaching was also investigated (Končić et al., 2011). This test measures the ability of antioxidants to delayβ-carotene discoloration which is induced by conjugated diene hydroperoxides, produced from linoleic acid oxidation (Bouaziz et al., 2015). From the present study, it was observed that the inhibition of linoleic acid oxidation was higher in water extracts, and the order of ac-tivity for the plant extracts was S. junceumN O. isauricum N C. orientalis (90.86–86.20% compared to 95.07 and 93.83%, for BHA and BHT, respec-tively). Indeed, several studies have reported the ability of phytochem-icals to prevent_{β-carotene bleaching (}Khlif et al., 2015; Pisoschi et al., 2016; Ben Salem et al., 2017). The focus on the chelation of transition metals, that act as catalysts during oxidative stress processes has been extensively addressed. FromTable 6, it was noted that the water extracts (value ranging from 36.49 to 69.95 mgEDTAE/g extract) of the selected medicinal plants possessed higher chelating abilities as compared to their corresponding ethyl acetate and methanol extracts (value ranging from 4.15 to 36.05 mgEDTAE/g extract).

Considering that melanogenesis can be controlled through the inhi-bition of tyrosinase, the use of tyrosinase inhibitors in cosmetic products is an ideal approach for the treatment of dermatological events linked to melanin hyperpigmentation (Jdey et al., 2017). Furthermore, the use of tyrosinase inhibitors is highly appreciated in the food industry to pre-vent enzymatic browning. Currently, a large number of natural com-pounds have been reported to possess tyrosinase inhibitory potential. Kojic acid obtained from Aspergillus oryzae and a by-product of malted rice, arbutin, obtained from bearberry plant, and azelaic acid, isolated from wheat, rye or barley were reported to possess inhibitory action against tyrosinase (Aumeeruddy-Elalﬁ et al., 2016). Hydroquinone

Table 2

DPPH radical scavenging abilities (%) of the studied extracts. Plant species Extracts Concentration (mg/mL)

0.2 0.5 1.0 C. orientalis EA 3.75 ± 0.68a _{6.74 ± 0.15} _{15.27 ± 3.58} MeOH 8.97 ± 0.77 19.59 ± 1.79 38.11 ± 1.02 Water 5.78 ± 0.34 18.65 ± 0.28 40.18 ± 0.06 O. isauricum EA 4.69 ± 0.96 9.90 ± 0.93 18.67 ± 0.12 MeOH 34.75 ± 1.76 74.24 ± 0.28 92.91 ± 0.15 Water 31.44 ± 1.33 79.43 ± 2.01 80.52 ± 2.38 S. junceum EA 8.88 ± 1.02 18.46 ± 0.06 32.79 ± 0.34 MeOH 20.48 ± 1.82 45.57 ± 1.20 77.68 ± 0.65 Water 14.88 ± 0.37 33.20 ± 5.06 73.65 ± 0.01 a

Results are mean values ± SD from three experiments. EA: ethyl acetate, MeOH: methanol.

Table 3

ABTS and superoxide radical scavenging abilities of the studied extracts. Plant species Extracts ABTS radical scavenging

ability (mgTE/g extract)

Superoxide radical scavenging ability (mgTE/g extract) C. orientalis EA 123.68 ± 1.66a 107.83 ± 1.11 MeOH 142.77 ± 1.20 92.82 ± 2.74 Water 98.41 ± 1.17 132.15 ± 4.73 O. isauricum EA 131.94 ± 1.48 103.23 ± 8.28 MeOH 188.68 ± 1.58 97.50 ± 2.29 Water 130.91 ± 1.61 159.92 ± 4.83 S. junceum EA 148.44 ± 4.22 72.72 ± 2.06 MeOH 190.23 ± 1.22 113.32 ± 2.95 Water 137.61 ± 6.31 93.14 ± 1.48 a

Results are mean values ± SD from three experiments. EA: ethyl acetate, MeOH: methanol. TE: trolox equivalents.

Table 4

Cupric reducing powers of the studied extracts (absorbances at 450 nm). Plant species Extracts Concentration (mg/mL)

0.4 0.8 2.0 C. orientalis EA 0.002 ± 0.001a _{0.058 ± 0.003} _{0.309 ± 0.021} MeOH 0.113 ± 0.010 0.290 ± 0.001 0.776 ± 0.019 Water 0.126 ± 0.013 0.301 ± 0.001 0.693 ± 0.07 O. isauricum EA 0.078 ± 0.001 0.236 ± 0.002 0.867 ± 0.001 MeOH 0.643 ± 0.008 1.331 ± 0.038 3.072 ± 0.004 Water 0.471 ± 0.010 1.066 ± 0.019 2.253 ± 0.023 S. junceum EA 0.138 ± 0.002 0.335 ± 0.004 1.152 ± 0.042 MeOH 0.460 ± 0.014 0.773 ± 0.008 1.948 ± 0.025 Water 0.224 ± 0.017 0.515 ± 0.004 1.249 ± 0.008 a

Table 5

Ferric reducing powers of the studied extract (absorbances at 700 nm). Plant species Extracts Concentration (mg/mL)

0.4 0.8 2.0 C. orientalis EA 0.019 ± 0.001a 0.022 ± 0.002 0.066 ± 0.002 MeOH 0.076 ± 0.003 0.143 ± 0.001 0.333 ± 0.013 Water 0.065 ± 0.007 0.128 ± 0.001 0.280 ± 0.002 O. isauricum EA 0.021 ± 0.001 0.050 ± 0.001 0.146 ± 0.020 MeOH 0.211 ± 0.001 0.499 ± 0.01 1.110 ± 0.023 Water 0.237 ± 0.004 0.502 ± 0.004 0.984 ± 0.012 S. junceum EA 0.053 ± 0.001 0.100 ± 0.006 0.254 ± 0.002 MeOH 0.151 ± 0.01 0.265 ± 0.018 0.582 ± 0.012 Water 0.097 ± 0.005 0.198 ± 0.016 0.480 ± 0.013 a

(4)

was widely used as topical treatment for skin whitening, not without risk. Its use was revoked by the FDA in 2006, due to skin irritation prob-lems, mutagenicity, and cytotoxicity (Stratford et al., 2012). The devel-opment of lead molecules possessing antioxidant activity, tyrosinase inhibitory action, which are readily absorbed by the skin, along with min-imal side effects, is highly desirable.

In the current study, three medicinal plants prepared, using different solvents were assessed for their tyrosinase inhibition potential. The use of different polarity solvents, was aimed to extract phytochemicals of different polarities in an endeavor to select the most active ones. S. junceum extracts yielded the highest kojic acid equivalent values, meaning that the extracts were the most potent inhibitors of tyrosinase (Table 6). The following order of inhibition was observed for S. junceum: ethyl acetate extractN water extract N methanol extract. A previous

study reported the presence of flavonoids, flavones, isoflavones,

quinolizidinic alkaloids and saponins in the aerial parts of S. junceum (Menghini et al., 2006). A comprehensive review of the tyrosinase in-hibitory potential ofﬂavonoid derivatives, emphasized that the latter are promising compounds for the development of novel tyrosinase inhibitors (Erdogan Orhan and Tareq Hassan Khan, 2014).Zhang and Zhou (2013)reported the tyrosinase inhibitory effects of saponins. Furthermore, the function of tyrosinase in neuromelanin production and neuronal damage related to Parkinson's disease has been highlighted (Neagu et al., 2016). Tyrosinase was found to oxidize the catechol ring of dopamine, a neurotransmitter responsible for movement, eventually producing highly reactive dopamine-quinone species, thus, favoring Parkinson's disease (Custódio et al., 2016; Bizzarri et al., 2017).

Magalingam et al. (2015)reported the protective action ofﬂavonoids in Parkinson's disease.

4. Conclusion

Findings from the present study showed the potential of medicinal plants in the discovery and development of new lead compounds/ fractions/different extracts with tyrosinase inhibitory and antioxidant properties. Experimental data collected from this study revealed that C. orientalis, O. isauricum, and S. junceum exhibit important enzyme inhib-itory properties. A particular interest is the inhibinhib-itory potential of S. junceum, which can be qualiﬁed as having potent tyrosinase inhibitory activity. Therefore, the tyrosinase inhibitory properties of S. junceum, makes it a suitable candidate for further studies geared towards the management of epidermal hyperpigmentation processes.

References

Aumeeruddy-Elalﬁ, Z., Gurib-Fakim, A., Mahomoodally, M., 2016.Kinetic studies of tyrosinase inhibitory activity of 19 essential oils extracted from endemic and exotic medicinal plants. South African Journal of Botany 103, 89–94.

Baldea, I., Mocan, T., Cosgarea, R., 2009.The role of ultraviolet radiation and tyrosine stimulated melanogenesis in the induction of oxidative stress alterations in fair skin melanocytes. Experimental Oncology 31, 200–208.

Ben Salem, M., Affes, H., Athmouni, K., Ksouda, K., Dhouibi, R., Sahnoun, Z., Hammami, S., Zeghal, K.M., 2017.Chemicals compositions, antioxidant and anti-inﬂammatory activity of Cynara scolymus leaves extracts, and analysis of major bioactive polyphenols by HPLC. Evidence-Based Complementary and Alternative Medicine 1–14.

Berk, S., Tepe, B., Arslan, S., Sarikurkcu, C., 2011.Screening of the antioxidant, antimicrobial and DNA damage protection potentials of the aqueous extract of Asplenium ceterach DC. African Journal of Biotechnology 10, 8902–8908.

Bizzarri, B.M., Martini, A., Seraﬁni, F., Aversa, D., Piccinino, D., Botta, L., Berretta, N., Guatteo, E., Saladino, R., 2017.Tyrosinase mediated oxidative functionalization in the synthesis of DOPA-derived peptidomimetics with anti-Parkinson activity. RSC Advances 7, 20502–20509.

Bouaziz, A., Abdalla, S., Baghiani, A., Charef, N., 2015.Phytochemical analysis, hypotensive effect and antioxidant properties of Myrtus communis L. growing in Algeria. Asian Paciﬁc Journal of Tropical Biomedicine 5, 19–28.

Brenner, M., Hearing, V.J., 2008.The protective role of melanin against UV damage in human skin. Photochemistry and Photobiology 84, 539–549.

Cerchiara, T., Chidichimo, G., Ragusa, M., Belsito, E., Liguori, A., Arioli, A., 2010. Character-ization and utilCharacter-ization of Spanish broom (Spartium junceum L.) seed oil. Industrial Crops and Products 31, 423–426.

Chang, T.-S., 2009.An updated review of tyrosinase inhibitors. International Journal of Molecular Sciences 10, 2440–2475.

Custódio, L., Silvestre, L., Rocha, M.I., Rodrigues, M.J., Vizetto-Duarte, C., Pereira, H., Barreira, L., Varela, J., 2016.Methanol extracts from Cystoseira tamariscifolia and Cystoseira nodicaulis are able to inhibit cholinesterases and protect a human dopami-nergic cell line from hydrogen peroxide-induced cytotoxicity. Pharmaceutical Biology 54, 1687–1696.

Erdogan Orhan, I., Tareq Hassan Khan, M., 2014.Flavonoid derivatives as potent tyrosinase inhibitors–a survey of recent ﬁndings between 2008–2013. Current Topics in Medicinal Chemistry 14, 1486–1493.

Ghasemi, Y., Abedtash, H., Morowvat, M.H., Mohagheghzadeh, A., Ardeshir-Rouhani-Fard, S., 2015.Essential oil composition and bioinformatic analysis of Spanish broom (Spartium junceum L.). Trends in Pharmaceutical Sciences 1 (2), 97–104.

Hohmann, J., Forgo, P., Hajdú, Z., Varga, E., Máthé, I., 2002.Norditerpenoid alkaloids from Consolida orientalis and complete 1H and 13C NMR signal assignments of some lycoctonine-type alkaloids. Journal of Natural Products 65, 1069–1072.

Jdey, A., Falleh, H., Jannet, S.B., Hammi, K.M., Dauvergne, X., Ksouri, R., Magné, C., 2017.

Phytochemical investigation and antioxidant, antibacterial and anti-tyrosinase per-formances of six medicinal halophytes. South African Journal of Botany 112, 508–514.

Khlif, I., Jellali, K., Michel, T., Halabalaki, M., Skaltsounis, A.L., Allouche, N., 2015.Characteristics, phytochemical analysis and biological activities of extracts from Tunisian Chetoui Olea europaea variety. Journal of Chemistry 1–11.

Končić, M.Z., Barbarić, M., Perković, I., Zorc, B., 2011.Antiradical, chelating and antioxidant activities of hydroxamic acids and hydroxyureas. Molecules 16, 6232–6242.

Loizzo, M., Tundis, R., Menichini, F., 2012.Natural and synthetic tyrosinase inhibitors as antibrowning agents: an update. Comprehensive Reviews in Food Science and Food Safety 11, 378–398.

Magalingam, K.B., Radhakrishnan, A.K., Haleagrahara, N., 2015.Protective mechanisms of ﬂavonoids in Parkinson's disease. Oxidative Medicine and Cellular Longevity 2015, 1–14.

Menghini, L., Massarelli, P., Bruni, G., Pagiotti, R., 2006.Anti-inﬂammatory and analgesic effects of Spartium junceum L.ﬂower extracts: a preliminary study. Journal of Medicinal Food 9, 386–390.

Muddathir, A., Yamauchi, K., Batubara, I., Mohieldin, E., Mitsunaga, T., 2017.Anti-tyrosinase, total phenolic content and antioxidant activity of selected Sudanese medicinal plants. South African Journal of Botany 109, 9–15.

Neagu, E., Radu, G.L., Albu, C., Paun, G., 2016. Antioxidant activity, acetylcholinesterase and tyrosinase inhibitory potential of Pulmonaria ofﬁcinalis and Centarium umbellatum extracts. Saudi Journal of Biological Scienceshttps://doi.org/10.1016/j. sjbs.2016.02.016.

Nemati, F., Dehpouri, A.A., Eslami, B., Mahdavi, V., Mirzanejad, S., 2013.Cytotoxic proper-ties of some medicinal plant extracts from Mazandaran, Iran. Iranian Red Crescent Medical Journal 15 (11), e8871.

Pekal, A., Pyrzynska, K., 2015.Effect of pH and metal ions on DPPH radical scavenging activity of tea. International Journal of Food Sciences and Nutrition 66, 58–62.

Pillaiyar, T., Manickam, M., Namasivayam, V., 2017.Skin whitening agents: medicinal chemistry perspective of tyrosinase inhibitors. Journal of Enzyme Inhibition and Medicinal Chemistry 32, 403–425.

Piluzza, G., Bullitta, S., 2011.Correlations between phenolic content and antioxidant properties in twenty-four plant species of traditional ethnoveterinary use in the Mediterranean area. Pharmaceutical Biology 49, 240–247.

Pisoschi, A.M., Pop, A., Cimpeanu, C., Predoi, G., 2016.Antioxidant capacity determination in plants and plant-derived products: a review. Oxidative Medicine and Cellular Longevity 2016, 1–36.

Ribeiro, A.S., Estanqueiro, M., Oliveira, M.B., Sousa Lobo, J.M., 2015.Main beneﬁts and applicability of plant extracts in skin care products. Cosmetics 2, 48–65.

Segura Campos, M.R., Ruiz Ruiz, J., Chel-Guerrero, L., Betancur Ancona, D., 2015.Coccoloba uvifera (L.)(Polygonaceae) fruit: phytochemical screening and potential antioxidant activity. Journal of Chemistry 1–9.

Shalaby, E.A., Shanab, S.M., 2013.Comparison of DPPH and ABTS assays for determining antioxidant potential of water and methanol extracts of Spirulina platensis. Indian Journal of Geo-Marine Sciences 42, 556–564.

Slinkard, K., Singleton, V.L., 1977.Total phenol analysis: automation and comparison with manual methods. American Journal of Enology and Viticulture 28, 49–55.

Table 6

Inhibition of linoleic acid oxidation (β-carotene/linoleic acid assay), metal chelating, and tyrosinase inhibitory effects of the studied extracts.

Plant species Extracts Inhibition of linoleic acid oxidation (%, at 2 mg/concentration) Metal chelating ability (mgEDTAE/g extract) Tyrosinase inhibition (mgKAE/g extract) C. orientalis EA 27.99 ± 4.89a _{5.12 ± 0.03} _{20.55 ± 0.48} MeOH 76.78 ± 7.34 6.18 ± 0.10 14.40 ± 0.71 Water 86.20 ± 1.97 36.49 ± 0.91 10.55 ± 0.63 O. isauricum EA 38.97 ± 1.86 19.55 ± 0.80 19.96 ± 0.89 MeOH 85.41 ± 0.52 33.52 ± 0.84 15.33 ± 0.81 Water 88.98 ± 0.58 68.05 ± 3.62 14.83 ± 1.21 S. junceum EA 74.82 ± 5.65 4.15 ± 0.08 23.04 ± 0.39 MeOH 82.38 ± 1.18 36.05 ± 1.92 21.42 ± 0.63 Water 90.86 ± 2.68 69.95 ± 4.33 21.99 ± 1.26 BHA – 95.07 ± 0.75 nt nt BHT – 93.83 ± 0.27 nt nt

a_{Results are mean values ± SD from three experiments. EA: ethyl acetate, MeOH:}

(5)

Solano, F., 2014.Melanins: skin pigments and much more—types, structural models, bio-logical functions, and formation routes. New Journal of Science 1–28.

Souza, P.M., Elias, S.T., Simeoni, L.A., de Paula, J.E., Gomes, S.M., Guerra, E.N.S., Fonseca, Y.M., Silva, E.C., Silveira, D.m., Magalhaes, P.O., 2012.Plants from Brazilian Cerrado with potent tyrosinase inhibitory activity. PLoS One 7, e48589.

Stratford, M.R., Ramsden, C.A., Riley, P.A., 2012.The inﬂuence of hydroquinone on tyrosinase kinetics. Bioorganic & Medicinal Chemistry 20, 4364–4370.

Sugumaran, M., Barek, H., 2016.Critical analysis of the melanogenic pathway in insects and higher animals. International Journal of Molecular Sciences 17, 1753.

Taranto, F., Pasqualone, A., Mangini, G., Tripodi, P., Miazzi, M.M., Pavan, S., Montemurro, C., 2017.Polyphenol oxidases in crops: biochemical, physiological and genetic aspects. International Journal of Molecular Sciences 18, 377.

Tosun, A., Akkol, E.K., Bahadır, Ö., Yeşilada, E., 2008.Evaluation of anti-inﬂammatory and antinociceptive activities of some Onosma L. species growing in Turkey. Journal of Ethnopharmacology 120, 378–381.

Trivedi, M., Murase, J., Inouye, T., 2017.A review of laser and light therapy in melasma [25E]. Obstetrics & Gynecology 129, 58S.

Tumbas, V.,Čanadanović-Brunet, J., Gille, L., Đilas, S., Ćetković, G., 2010.Superoxide anion radical scavenging activity of bilberry (Vaccinium myrtillus L.). Journal of Berry Research 1, 13–23.

Zengin, G., 2016.A study on in vitro enzyme inhibitory properties of asphodeline anatolica: new sources of natural inhibitors for public health problems. Industrial Crops and Products 83, 39–43.

Zengin, G., Sarikurkcu, C., Uyar, P., Aktumsek, A., Uysal, S., Kocak, M.S., Ceylan, R., 2015.

Crepis foetida L. subsp. rhoeadifolia (Bieb.) Celak. as a source of multifunctional agents: cytotoxic and phytochemical evaluation. Journal of Functional Foods 17, 698–708.

Zhang, H., Zhou, Q., 2013.Tyrosinase inhibitory effects and antioxidative activities of saponins from Xanthoceras sorbifolia nutshell. PLoS One 8, e70090.