Ultraviolet radiation (UVR) from sunlight is an environmental human carcinogen. Skin exposure to UVR would increase the oxidative stress, deoxyribonucleic acid (DNA) damage, melanogenesis and photocarcinogenesis. Therefore, development of photoprotective agent is necessary in order to reduce the cutaneous toxicity. The use natural active compounds like stilbenes and its derivatives have gained attention as photoprotection to skin due to its broad biological activities such as antioxidant, anti-inflammatory, anti melanogenesis and chemoprevention. This review article aims to analyse the existing literature on the photoprotective effect of stilbenes and its derivatives which include the resveratrol, pterostilbene, piceatannol and oxyresveratrol on in vitro and in vivo studies. This article describes the stilbenes and its derivatives protect and prevent UVR induced skin disorders via the reduction of oxidative stress, alleviation of DNA damage, inhibition of melanogenesis and anti photocarcinogenic effect.

Dietary antioxidant supplements such as L-glutathione have gained considerable attention in dermatology and cosmeceutical fields. L-glutathione possesses antiaging, antimelanogenic, antioxidant, and anticancer properties. This study aimed to investigate the inhibitory effects of L-glutathione on melanogenesis activity and oxidative stress in ultraviolet B (UVB)-irradiated BALB/c mice. Eighteen female BALB/c mice were randomly divided into 3 groups: a control group (n=6), a group without UVB irradiation and L-glutathione administration; a UVB irradiated group (n=6), a group irradiated with a UVB dose of 250 mJ/cm2 for 3 min; and a treatment group (n=6), a group irradiated with UVB and treated with 100 mg/kg of L-glutathione by oral gavage. Treatment was given for 14 days, and UVB irradiation was given on days 9, 11, and 13. Oral L-glutathione significantly (P<0.05) reduced lipid peroxidation and elevated superoxide dismutase activity the and glutathione level. L-glutathione also inhibited melanin content and tyrosinase activity significantly (P<0.05) as compared with the UVB-irradiated group. Histopathological examination also showed that L-glutathione reduced the deposition of melanin pigment in the basal layer of the epidermis as compared with that in UVB-irradiated mice. All in all, the present study demonstrated that L-glutathione has the potential to be developed as a photoprotection agent against UVB-induced oxidative stress and melanogenesis.

Sekolah tahfiz merupakan institusi yang mengkhususkan pendidikan kepada pelajar yang boleh menghafaz serta mengingati keseluruhan al-Quran. Aktiviti menghafaz al-Quran dengan teknik pengucapan berulang kali akan membantu meningkatkan keupayaan otak untuk memproses, mengingati maklumat dan membina memori. Kehadiran logam berat akan memberi kesan kepada sistem saraf serta mengganggu fungsi sistem saraf pusat dan periferi di mana akan seterusnya menyebabkan berlakunya kecelaan fungsi mental dan kognitif. Keupayaan untuk belajar, mengingati atau menghafaz, penggunaan bahasa dan untuk memahami sesuatu akan terganggu serta mengurangkan IQ dan perhatian. Kajian keratan rentas telah dilakukan bagi mengukur dan mengenal pasti hubungan di antara tahap logam berat, hafazan al-Quran dan tahap kecerdasan (IQ) dalam kalangan pelajar di sekolah tahfiz berbanding sekolah bukan tahfiz terpilih di Selangor. Kepekatan logam berat ditentukan melalui analisa sampel kuku dan rambut pelajar dengan menggunakan Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Ujian kecerdasan Wechsler Adult Intelligence Scale Edisi Kedua (WASI-II) digunakan untuk mengukur IQ pelajar. Borang soal selidik yang digunakan untuk mengumpulkan data demografik dianalisa menggunakan SPSS versi 23.0. Berdasarkan ujian korelasi Pearson yang dilakukan, terdapat korelasi negatif yang sangat lemah tetapi signifikan antara logam mangan dalam sampel rambut dengan tahap hafazan al-Quran (r =-0.178, p = 0.017). Selain itu, terdapat korelasi positif yang lemah tetapi signifikan antara IQ dengan tahap hafazan al-Quran (r = 0.375, p = < 0.001). Kesimpulannya, semakin tinggi kepekatan logam mangan akan menyebabkan penurunan tahap hafazan al-Quran serta apabila semakin tinggi tahap hafazan al-Quran akan menyebabkan tahap kecerdasan (IQ) juga semakin meningkat.

Canarium odontophyllum or locally known as Dabai in Sarawak is a fruit largely consumed by the locals. Based on previous studies, the plant possessed various biological activities, such as antimicrobial, antioxidant, antifungal and anticancer. Our aim was to investigate the mutagenicity and antimutagenicity of C. odontophyllum acetone leaves extracts by using the Ames test (Salmonella reverse mutagenicity assay).The Ames test also involved the pre-incubation method against Salmonella typhimurium TA98 and TA100 bacterial strains in the absence and presence of metabolic activator S9 system. C. odontophyllum crude acetone extracts were diluted with 10% DMSO to obtain three different concentrations of 3.125, 12.5 and 50 mg/ml. To determine the mutagenicity effects of the extracts, each concentration of the extract was evaluated based on the two-fold value of the number of revertant's colony in negative control plate as the cut-of point. No mutagenic activity was observed for the frameshift mutation (TA98) and base-pair substitution mutation (TA100) in all concentrations of C. odontophyllum in the presence and absence of metabolic activator S9 system. Antimutagenicity test was carried out to determine the potential of C. odontophyllum extracts to inhibit the mutation induced by specific mutagens. The highest antimutagenic activity was seen in the presence of metabolic activator S9 system with inhibition percentage greater than 50% in both bacteria strains TA98 (62.38%) and TA100 (58.24%). In conclusion, C. odontophyllum acetone leaves extract was not mutagenic and had significant inhibitory effects on mutagenicity in both bacterial strains with and without the metabolic activator S9 system. Our results could contribute to the safe use of C. odontophyllum. In addition, based on the significant antimutagenic activity demonstrated by the C. odontophyllum acetone leaves extracts, the extract could also be developed as a chemopreventive agent.

Extended dermal exposure of ultraviolet B (UVB) can induce erythema, hyperpigmentation, epidermal hyperplasia and cancer. Natural active compound such as pterostilbene (PS) is a potential UV-protecting agent as it has broad biological activities. This study aimed to evaluate the photoprotective effect of pterostilbene on ultraviolet-B-induced BALB/c mice. Twenty-four female mice were randomised into four groups (n=6/group): vehicle control (VC); UVB irradiated only (UVB only); UVB irradiation treated with pterostilbene 10 mg/kg (PS10+UVB); (iv) UVB irradiation treated with pterostilbene 20 mg/kg (PS20+UVB). The PS treatments were given for 14 days, and UVB was given at dose 250 mJ/cm2 on days 9, 11, and 13 of the treatment periods. The results showed that PS lessened redness and scaling on the skin of UVB-irradiated mice. The skinfold thickness and epidermal thickness in the PS-treated group were significantly reduced (p<0.05) in comparison with those in the UVB only group. The PS10 and PS20 groups (5.927 ± 0.354 and 5.660 ± 0.765 nmol/g, respectively) demonstrated significantly decreased MDA levels (P<0.05) relative to the UVB only group (13.343 ± 1.350 nmol/g). The GSH level in both PS10 (0.555 ± 0.020 µmol/mg) and PS20 (0.568 ± 0.055 µmol/mg) groups increased significantly (p<0.05) compared with that in the UVB only group (0.376 ± 0.025 µmol/mg). SOD activity in the PS20 group (1.388 ± 0.172 U/min/mg) increased significantly (p<0.05) compared with that in the UVB only group (0.561 ± 0.034 U/min/mg). Histological observation showed that PS reduced leukocyte infiltration and epidermal hyperplasia. Hence, oral PS may exert a photoprotective effect by acting as an anti-inflammatory and antioxidant agent on UVB-irradiated mice skin.

Drug Metabolizing Enzyme (DME) has been a target of natural chemopreventive agents to inhibit, retard and reverse the process of carcinogenesis. Pterostilbene, an analog to resveratrol has been reported to possess various pharmacological benefits including chemoprevention. In our study, benzo[a]pyrene-induced HT-29 colorectal cell line was used as the DME model. The activity of phase I enzyme CYP1A as determined by the 7-ethoxyresorufin O-deethylation (EROD) assay was found to be inhibited significantly by pterostilbene at 50 µM, 75 µM and 100 µM (p ≤ 0.01, p ≤ 0.05, p ≤ 0.01 respectively) compared to the benzo[a]pyrene treated group. Meanwhile, pterostilbene induced glutathione-S-transferase (GST) activity significantly (p ≤ 0.01) at 50 µM as compared to the untreated. In addition, However, the protein expression of CYP1A1 and GST in pterostilbene treated group was not significantly affected compared to untreated. On the other hand, pterostilbene at 25 and 75 µM were able to increase the protein expression of transcription factor Nrf2 significantly (p ≤ 0.01). Results indicated that pterostilbene could reduce metabolic activation of procarcinogens and increase the detoxification process which can be potentially developed as chemopreventive agent. ABSTRAK Enzim Metabolisma Dadah (EMD) telah menjadi sasaran agen kemopencegahan semulajadi untuk menghalang, merencat dan membalikkan proses karsinogenesis. Pterostilbene, analog kepada resveratrol telah dilaporkan mempunyai pelbagai manfaat farmakologi termasuk kemopencegahan. Dalam kajian kami, sel pirena telah digunakan sebagai model EMD. Aktiviti enzim CYP1A fasa I ditentukan oleh asai 7-ethoxyresorufin O-deethylation (EROD) didapati merencat secara signifikan oleh pterostilbene pada kepekatan 50 μM, 75 μM dan 100 μM (p ≤ 0.01, p ≤ 0.05, p ≤ 0.01 masing-masing) berbanding dengan kumpulan yang dirawat dengan benzo [a]pirena. Selain itu, pterostilbene juga mengaruh aktiviti glutation-S-transferase (GST) secara signifikan (p ≤ 0.01) pada kepekatan 50 μM berbanding dengan kumpulan yang tidak dirawat. Di samping itu, pengekspresan protein CYP1A1 dan GST dalam kumpulan yang dirawat pterostilbene tidak memberi kesan secara signifikan berbanding kumpulan tidak dirawat. Sebaliknya, pterostilbene pada kepekatan 25 μM dan 75 μM dapat meningkatkan pengekspresan protein faktor transkripsi Nrf2 secara signifikan (p ≤ 0.01). Hasil kajian menunjukkan bahawa pterostilbene dapat mengurangkan pengaktifan metabolik prokarsinogen dan meningkatkan proses detoksifikasi yang berpotensi dapat dijadikan sebagai agen kemopencegahan.

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Pterostilbene is a potent antioxidant and anti-inflammatory agent. However, its chemopreventive effects via anti-tyrosinase activity and inhibitory effects on melanin content have not been reported previously. Hence, this study aimed to investigate the anti-melanogenic activity of pterostilbene on UVB-irradiated B164A5 mouse melanoma cells. The effects of pterostilbene and resveratrol on cell viability were determined by MTT assay, whereas melanin content and tyrosinase assay were employed to assess melanogenesis activity. Western blot analysis was performed to determine the tyrosinase expression. Based on the MTT assay, the IC50 value of pterostilbene on UVB-irradiated B164A5 cells was 34.0 ± 3.43 μM, in comparison to resveratrol (>100 μM). Next, 5 and 10 μM pterostilbene showed a significant dose-dependent inhibition ( P < .01) of tyrosinase activity in UVB-irradiated B164A5 cells at 37.14 ± 2.71% and 58.36 ± 6.8%, respectively. The findings from the tyrosinase assay also confirmed the downregulation of tyrosinase expression in UVB-irradiated B164A5 cells as measured by Western blot analysis. Finally, 10 μM pterostilbene showed a significantly decreased melanin content ( P < .01) in UVB-irradiated B164A5 cells, at 27.34 ± .98 μg/mL. In conclusion, pterostilbene showed anti-melanogenic activity that was 10 times more potent than resveratrol in the UVB-irradiated B164A5 cell.