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  1. Wound Healing Property of Curcuminoids as a Microcapsule-Incorporated Cream
    Ang LF, Darwis Y, Koh RY, Gah Leong KV, Yew MY, Por LY, et al.
    Pharmaceutics, 2019 May 01;11(5).
    PMID: 31052413 DOI: 10.3390/pharmaceutics11050205
    Curcuminoids have been used for the management of burns and wound healing in traditional Chinese medicine practices but the wide application of curcuminoids as a healing agent for wounds has always been a known problem due to their poor solubility, bioavailability, colour staining properties, as well as due to their intense photosensitivity and the need for further formulation approaches to maximise their various properties in order for them to considerably contribute towards the wound healing process. In the present study, a complex coacervation microencapsulation was used to encapsulate curcuminoids using gelatin B and chitosan. This study also focused on studying and confirming the potential of curcuminoids in a microencapsulated form as a wound healing agent. The potential of curcuminoids for wound management was evaluated using an in vitro human keratinocyte cell (HaCaT) model and the in vivo heater-inflicted burn wound model, providing evidence that the antioxidant activities of both forms of curcuminoids, encapsulated or not, are higher than those of butylated hydroxyanisole and butylated hydroxytoluene in trolox equivalent antioxidant capacity (TEAC) and (2,2-diphenyl-1-picryl-hydrazyl-hydrate) (DPPH) studies. However, curcuminoids did not have much impact towards cell migration and proliferation in comparison with the negative control in the in vitro HaCaT study. The micoencapsulation formulation was shown to significantly influence wound healing in terms of increasing the wound contraction rate, hydroxyproline synthesis, and greater epithelialisation, which in turn provides strong justification for the incorporation of the microencapsulated formulation of curcuminoids as a topical treatment for burns and wound healing management as it has the potential to act as a crucial wound healing agent in healthcare settings.
  2. Neuroprotective effects of orientin on hydrogen peroxide‑induced apoptosis in SH‑SY5Y cells
    Law BN, Ling AP, Koh RY, Chye SM, Wong YP
    Mol Med Rep, 2014 Mar;9(3):947-54.
    PMID: 24366367 DOI: 10.3892/mmr.2013.1878
    Neurodegenerative diseases remain a global issue which affects the ageing population. Efforts towards determining their aetiologies to understand their pathogenic mechanisms are underway in order to identify a pathway through which therapeutic measures can be applied. One such pathogenic mechanism, oxidative stress (OS), is widely considered to be involved in neurodegenerative disease. Antioxidants, most notably flavonoids, have promising potential for therapeutic use as shown in in vitro and in vivo studies. In view of the importance of flavonoids for combating OS, this study investigated the neuroprotective effects of orientin, which has been reported to be capable of crossing the blood‑brain barrier. The maximum non‑toxic dose (MNTD) of orientin against SH‑SY5Y neuroblastoma cells was determined using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay. The effects of the MNTD and the half MNTD (½MNTD) of orientin on cell cycle progression and intracellular reactive oxygen species (ROS) levels, as well as the activity of caspases 3/7, 8 and 9 after exposure to 150 µM of hydrogen peroxide (H2O2) were also determined using flow cytometry, a 2',7'‑dichlorodihydrofluorescein‑diacetate (DCFH‑DA) assay and caspase assay kits, respectively. The results revealed that orientin at ≤20 µM was not cytotoxic to SH‑SY5Y cells. After treatment with orientin at the MNTD, the percentage of apoptotic cells was significantly reduced compared with that in cells treated with 150 µM H2O2 alone. The results also showed that, although orientin at the MNTD and ½MNTD did not reduce intracellular ROS levels, it significantly inhibited the activity of caspases 3/7. Caspase 9 was significantly inactivated with orientin at the MNTD. Findings from this study suggest that the neuroprotection conferred by orientin was the result of the intracellular mediation of caspase activity.
  3. Madecassoside activates anti‑neuroinflammatory mechanisms by inhibiting lipopolysaccharide‑induced microglial inflammation
    Sasmita AO, Ling APK, Voon KGL, Koh RY, Wong YP
    Int J Mol Med, 2018 May;41(5):3033-3040.
    PMID: 29436598 DOI: 10.3892/ijmm.2018.3479
    Neurodegeneration is typically preceded by neuroinflammation generated by the nervous system to protect itself from tissue damage, however, excess neuroinflammation may inadvertently cause more harm to the surrounding tissues. Attenuating neuroinflammation with non‑steroidal anti‑inflammatory drugs can inhibit neurodegeneration. However, such treatments induce chronic side effects, including stomach ulcers. Madecassoside, a triterpene derived from Centella asiatica, is considered to be an alternative treatment of inflammation. In the present study, the anti‑neuroinflammatory properties of madecassoside were assessed in BV2 microglia cells, which were pre‑treated with madecassoside at a maximum non‑toxic dose (MNTD) of 9.50 µg/ml and a ½ MNTD of 4.75 µg/ml for 3 h and stimulated with 0.1 µg/ml lipopolysaccharide (LPS). The effect of madecassoside was assessed by determining reactive oxygen species (ROS) levels in all groups. Furthermore, the expression of pro‑ and anti‑neuroinflammatory genes and proteins were analyzed using reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. The results demonstrated that ROS levels in cells treated with the MNTD of madecassoside were significantly reduced compared with cells treated with LPS alone (P<0.05). The expression of pro‑neuroinflammatory genes, including inducible nitric oxide synthase, cyclooxygenase‑2, signal transducer and activator of transcription 1 and nuclear factor‑κB, were significantly downregulated in a dose‑independent manner following treatment with madecassoside. Conversely, the anti‑neuroinflammatory component heme oxygenase 1 was significantly upregulated by 175.22% in the MNTD‑treated group, compared with cells treated with LPS alone (P<0.05). The gene expression profiles of pro‑ and anti‑inflammatory genes were also consistent with the results of western blotting. The results of the present study suggest that madecassoside may be a potent anti‑neuroinflammatory agent. The antioxidative properties of madecassoside, which serve a major role in anti‑neuroinflammation, indicate that this compound may be a functional natural anti‑neuroinflammatory agent, therefore, further in vivo or molecular studies are required.
  4. Fulltext Screening of anti-dengue activity in methanolic extracts of medicinal plants
    Tang LI, Ling AP, Koh RY, Chye SM, Voon KG
    BMC Complement Altern Med, 2012;12:3.
    PMID: 22244370 DOI: 10.1186/1472-6882-12-3
    Dengue fever regardless of its serotypes has been the most prevalent arthropod-borne viral diseases among the world population. The development of a dengue vaccine is complicated by the antibody-dependent enhancement effect. Thus, the development of a plant-based antiviral preparation promises a more potential alternative in combating dengue disease.
  5. Fulltext Pteropine Orthoreovirus (PRV7S) does not Establish Persistent Infection in NP460 Cells but with Inflammatory Response Triggered
    Loh MKA, Siew ZY, Leong PP, Koh RY, Chye SM, Wong ST, et al.
    Biomed Environ Sci, 2023 Sep 20;36(9):886-891.
    PMID: 37803902 DOI: 10.3967/bes2023.114
  6. Inhibition of transforming growth factor-β via the activin receptor-like kinase-5 inhibitor attenuates pulmonary fibrosis
    Koh RY, Lim CL, Uhal BD, Abdullah M, Vidyadaran S, Ho CC, et al.
    Mol Med Rep, 2015 May;11(5):3808-13.
    PMID: 25585520 DOI: 10.3892/mmr.2015.3193
    Idiopathic pulmonary fibrosis is a chronic pulmonary disease that is characterized by formation of scar tissue in lungs. Transforming growth factor-β (TGF-β) is considered an important cytokine in the pathogenesis of this disease. Hence, the antifibrotic effect of an inhibitor of the TGF-β type I receptor, namely, SB 431542, was investigated in our study. SB 431542 was used to treat TGF-β-treated IMR-90 cells; the expression of α-smooth muscle actin (α-SMA) was detected at the protein level by using an anti-α-SMA antibody, and at the gene level by reverse transcription-quantitative PCR. The effect of the inhibitor on cell proliferation was determined by a cell growth assay. The inhibitor was also administered into bleomycin-treated mice. Histopathological assessment and determination of total collagen levels were carried out to evaluate the severity of lung fibrosis in these mice. Our results demonstrated that treatment with SB 431542 inhibits TGF-β‑induced α-SMA expression in lung fibroblasts, at both the protein and the mRNA levels (P<0.05). However, the inhibitor did not significantly reduce lung fibroblast proliferation. In the bleomycin-induced pulmonary fibrosis mouse model, bleomycin treatment caused important morphological changes, accompanied by an increase in the collagen level of the lungs. Early treatment with SB 431542 prevented the manifestation of histopathological alterations, whereas delayed treatment significantly decreased the collagen level (P<0.05). These results suggest that inhibition of TGF-β signaling, via inhibition of the activin receptor-like kinase-5 (ALK-5) by SB 431542, may attenuate pulmonary fibrosis.
  7. Fulltext A Review on Medicinal Properties of Orientin
    Lam KY, Ling AP, Koh RY, Wong YP, Say YH
    Adv Pharmacol Sci, 2016;2016:4104595.
    PMID: 27298620 DOI: 10.1155/2016/4104595
    Medicinal plants continue to play an important role in modern medications and healthcare as consumers generally believe that most of them cause fewer or milder adverse effects than the conventional modern medicines. In order to use the plants as a source of medicinal agents, the bioactive compounds are usually extracted from plants. Therefore, the extraction of bioactive compounds from medicinal plants is a crucial step in producing plant-derived drugs. One of the bioactive compounds isolable from medicinal plants, orientin, is often used in various bioactivity studies due to its extensive beneficial properties. The extraction of orientin in different medicinal plants and its medicinal properties, which include antioxidant, antiaging, antiviral, antibacterial, anti-inflammation, vasodilatation and cardioprotective, radiation protective, neuroprotective, antidepressant-like, antiadipogenesis, and antinociceptive effects, are discussed in detail in this review.
  8. Clinacanthus Nutans Hexane Extracts Induce Apoptosis Through a Caspase-Dependent Pathway in Human Cancer Cell Lines
    Ng PY, Chye SM, Ng ChH, Koh RY, Tiong YL, Pui LP, et al.
    Asian Pac J Cancer Prev, 2017 04 01;18(4):917-926.
    PMID: 28545188
    Background: Clinacanthus nutans (C.nutans) is a plant consumed as a cancer treatment in tropical Asia. Despite
    the availability of numerous anecdotal reports, evaluation of active anticancer effects has remained elusive. Therefore
    we here examined antiproliferative, reactive oxygen species (ROS)-inducing and apoptosis mechanisms of whole plant
    extracts in different cancer cell lines. Methods: Antiproliferative actions of five solvent extracts (hexane, chloroform,
    ethyl acetate, methanol and water) of C.nutans were tested on non-small cell lung cancer (A549), nasopharygeal cancer
    (CNE1) and liver cancer (HepG2) cells using MTT assay. The most potent anticancer extract was then assessed by flow
    cytometry to study cell cycle changes . Intracellular levels of ROS were quantified by DCFH-DA assay. Involvement of
    the caspase pathway in induction of apoptosis was assessed using caspase assay kits. GC-MS analysis was performed
    to identify phytoconstituents in the extracts. Results: Hexane and chloroform extracts were antiproliferative against
    all three cell lines, while the ethyl acetate extract, at 300 μg/mL, was antiproliferative in the CNE1 but not A549 and
    HepG2 cases. Methanol and water extracts did not inhibit cancer cell proliferation. The most potent anticancer hexane
    extract was selected for further testing. It induced apoptosis in all three cell lines as shown by an increase in the
    percentage of cell in sub-G1 phase. Dose-dependent increase in ROS levels in all three cell lines indicated apoptosis to
    be possibly modulated by oxidative stress. At high concentrations (>100 μg/mL), hexane extracts upregulated caspases
    8, 9 and 3/7 across all three cell lines. GC-MS analysis of the hexane extract revealed abundance of 31 compounds.
    Conclusion : Among the five extracts of C.nutans, that with hexane extract demonstrated the highest antiproliferative
    activity against all three cancer cell lines tested. Action appeared to be via ion of intracellular ROS, and induction of
    apoptosis via intrinsic and extrinsic caspase pathways.
  9. Fulltext Edible bird's nest ameliorates oxidative stress-induced apoptosis in SH-SY5Y human neuroblastoma cells
    Yew MY, Koh RY, Chye SM, Othman I, Ng KY
    BMC Complement Altern Med, 2014;14:391.
    PMID: 25308934 DOI: 10.1186/1472-6882-14-391
    Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting the senile population with manifestation of motor disability and cognitive impairment. Reactive oxygen species (ROS) is implicated in the progression of oxidative stress-related apoptosis and cell death of the midbrain dopaminergic neurons. Its interplay with mitochondrial functionality constitutes an important aspect of neuronal survival in the perspective of PD. Edible bird's nest (EBN) is an animal-derived natural food product made of saliva secreted by swiftlets from the Aerodamus genus. It contains bioactive compounds which might confer neuroprotective effects to the neurons. Hence this study aims to investigate the neuroprotective effect of EBN extracts in the neurotoxin-induced in vitro PD model.
  10. Cytotoxic and apoptogenic effects of Strobilanthes crispa Blume extracts on nasopharyngeal cancer cells
    Koh RY, Sim YC, Toh HJ, Liam LK, Ong RS, Yew MY, et al.
    Mol Med Rep, 2015 Oct;12(4):6293-9.
    PMID: 26239257 DOI: 10.3892/mmr.2015.4152
    The chemotherapeutic agents used to treat nasopharyngeal cancer (NPC) exhibit low efficacy. Strobilanthes crispa Blume is widely used for its anticancer, diuretic and anti‑diabetic properties. The present study aimed to determine the cytotoxic and apoptogenic effects of S. crispa on CNE‑1 NPC cells. A 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5 diphenyl tetrazolium bromide assay was used to evaluate the cytotoxic effects of S. crispa against CNE‑1 cells. The rate of apoptosis was determined using propidium iodide staining and caspase assays. Ethyl acetate, hexane and chloroform extracts of S. crispa leaves all exhibited cytotoxic effects on CNE‑1 cells, at a half maximal inhibitory concentration (IC50) of 119, 123.5 and 161.7 µg/ml, respectively. In addition, hexane, chloroform and ethyl acetate extracts of S. crispa stems inhibited CNE‑1 cell proliferation, at a IC50 of 49.4, 148.3 and 163.5 µg/ml, respectively. Flow cytometric analysis revealed an increased proportion of cells in the sub G1 phase and a decreased proportion of cells in the G2/M phase, following treatment with the extracts. However, the extracts did not alter the activities of caspase ‑3/7, ‑8 and ‑9. No cytotoxic effect was observed when the cells were treated with the methanol and water extracts of S. crispa stems and leaves. In conclusion, the S. crispa extracts were cytotoxic against CNE‑1 cells and these extracts were able to induce apoptosis, independent of caspase activation.
  11. Fulltext Unravelling the genetic links between Parkinson's disease and lung cancer
    Leong YQ, Koh RY, Chye SM, Ng KY
    Biol Chem, 2023 May 25;404(6):551-567.
    PMID: 36634094 DOI: 10.1515/hsz-2022-0228
    Increase evidence from epidemiological studies have shown an inverse association between Parkinson's disease (PD) and lung cancer. PD and lung cancer are both geriatric diseases, where these two diseases are sharing some common genetic determinants. Several PD-associated genes including alpha synuclein (SNCA), PTEN-induced kinase 1 (PINK1), parkin, parkinsonism associated deglycase (DJ-1), leucine-rich repeat kinase 2 (LRRK2), F-box protein 7 (FBXO7) and ubiquitin C-terminal hydrolase L1 (UCHL1) were reported to have altered expressions in lung cancer patients. This indicates that certain PD-associated genes might be important in conferring anticancer effects. This review aims to depict the physiological functions of these genes, and discuss the putative roles of these PD-associated genes in lung cancer. The understanding of the roles of these genes in the lung cancer progression might be important in the identification of new treatment targets for lung cancer. Gene therapy that aims to alter the expressions of these genes could be developed for future anticancer therapy. As a result, studying the roles of these genes in lung cancer may also help to understand their involvements as well as their roles in the pathogenesis of PD.
  12. Fulltext Anticancer mechanisms of Strobilanthes crispa Blume hexane extract on liver and breast cancer cell lines
    Koh RY, Lim FP, Ling LSY, Ng CPL, Liew SF, Yew MY, et al.
    Oncol Lett, 2017 Oct;14(4):4957-4964.
    PMID: 29085507 DOI: 10.3892/ol.2017.6821
    Cancer is a major public health concern not only in developed countries, but also in developing countries. It is one of the leading causes of mortality worldwide. However, current treatments may cause severe side effects and harm. Therefore, recent research has been focused on identifying alternative therapeutic agents extracted from plant-based sources in order to develop novel treatment options for cancer. Strobilanthes crispa Blume is a plant native to countries including Madagascar and Indonesia. It has been used as an anti-diabetic, diuretic and laxative in traditional folk medicine. Furthermore, S. crispa has potential in treating cancer, as evidenced in previous studies. In the present study, the cytotoxic and apoptotic activities of S. crispa crude extracts were investigated in liver and breast cancer cell lines. Hexane, ethyl acetate, chloroform, methanol and water extracts prepared from the leaves, and stems of S. crispa were evaluated for their cytotoxicity on HepG-2 and MDA-MB-231 cells using an MTT assay. The anti-proliferative properties of stem hexane (SH) extract on both cell lines were analysed using cell doubling time determination and cell cycle analysis, while the apoptogenic properties was determined through the detection of caspase-8. Among the extracts tested, SH extract exhibited the lowest half maximal inhibitory concentrations in both the cell lines. The SH extract induced morphological changes in HepG-2 and MDA-MB-231 cells, and significantly delayed cell population doubling time. Furthermore, it altered cell cycle profile and significantly increased caspase-8 activity in HepG-2 cells, but not in MDA-MB-231 cells. In conclusion, the SH extract of S. crispa possesses potent anticancer properties and may be a suitable chemotherapeutic target.
  13. Antioxidant value and antiproliferative efficacy of mitragynine and a silane reduced analogue
    Goh TB, Koh RY, Mordi MN, Mansor SM
    Asian Pac J Cancer Prev, 2014;15(14):5659-65.
    PMID: 25081682
    BACKGROUND: To investigate the antioxidant value and anticancer functions of mitragynine (MTG) and its silane-reduced analogues (SRM) in vitro.

    MATERIALS AND METHODS: MTG and SRM was analyzed for their reducing power ability, ABTS radical inhibition and 1,1-diphenyl-2-picryl hydrazylfree radicals scavenging activities. Furthermore, the antiproliferation efficacy was evaluated using MTT assay on K 562 and HCT116 cancer cell lines versus NIH/3T3 and CCD18-Co normal cell lines respectively.

    RESULTS: SRM and MTG demonstrate moderate antioxidant value with ABTS assay (Trolox equivalent antioxidant capacity (TEAC): 2.25±0.02 mmol trolox / mmol and 1.96±0.04 mmol trolox / mmol respectively) and DPPH (IC50=3.75±0.04 mg/mL and IC50=2.28±0.02 mg/mL respectively). Both MTG and SRM demonstrate equal potency (IC50=25.20±1.53 and IC50= 22.19±1.06 respectively) towards K 562 cell lines, comparable to control, betulinic acid (BA) (IC5024.40±1.26). Both compounds showed concentration-dependent cytototoxicity effects and exert profound antiproliferative efficacy at concentration > 100 μM towards HCT 116 and K 562 cancer cell lines, comparable to those of BA and 5-FU (5-Fluorouracil). Furthermore, both MTG and SRM exhibit high selectivity towards HCT 116 cell lines with selective indexes of 3.14 and 2.93 respectively compared to 5-FU (SI=0.60).

    CONCLUSIONS: These findings revealed that the medicinal and nutitional values of mitragynine obtained from ketum leaves that growth in tropical forest of Southeast Asia and its analogues does not limited to analgesic properties but could be promising antioxidant and anticancer or chemopreventive compounds.

  14. 5-Methoxytryptamine reacts with natural food flavour to produce 6-methoxy tetrahydro-β-carbolines: in vitro investigation of their antioxidant and cytotoxicity properties
    Goh TB, Koh RY, Yam MF, Azhar ME, Mordi MN, Mansor SM
    Food Chem, 2015 Sep 15;183:208-16.
    PMID: 25863630 DOI: 10.1016/j.foodchem.2015.03.044
    Various 6-methoxytetrahydro-β-carboline derivatives, namely BEN (6-methoxy-1-phenyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ANI (6-methoxy-1-(4-methoxyphenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ACE (6-methoxy-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole) and VAN (2-methoxy-4-(6-methoxy-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-l)phenol), were prepared via the Maillard reaction using food flavours and 5-methoxytryptamine in aqueous medium and were investigated for their in vitro antioxidant and cytotoxicity properties. These derivatives were found to exhibit moderate antioxidant properties, based on a combination of DPPH, ABTS and FRAP assays. The results suggested that the Maillard reaction could be used to generate β-carboline antioxidants. It was beneficial that VAN showed the highest antioxidant activity but the least cytotoxic activities on non-tumourous cell lines of NIH/3T3, CCD18-Co and B98-5 using MTT assay. ACE, ANI and BEN showed mild toxicity at effective antioxidative concentrations derived from DPPH and ABTS assays. Furthermore, they are safer compared to 5-fluorouracil, cisplatin and betulinic acid on NIH/3T3, CCD18-Co and B98-5 cells. In conclusion, the antioxidant and cytotoxicity properties of 6-methoxytetrahydro-β-carbolines were demonstrated for the first time.
  15. Synthesis, characterization, and anti-cancer activity of new chalcone derivatives containing naphthalene and fluorine moieties
    Lim YH, Oo CW, Koh RY, Voon GL, Yew MY, Yam MF, et al.
    Drug Dev Res, 2020 Jul 28.
    PMID: 32720715 DOI: 10.1002/ddr.21715
    In recent years, chalcones and their derivatives have become the focus of global scientists due to increasing evidence reported towards their potency in antitumor and anti-cancer. Here, the chalcones designed and synthesized in our present study were derived from the derivatives of naphthaldehyde and acetophenone. Both these precursors have been reported in demonstrating a certain degree of anticancer property. Also, the substituents on these precursors such as hydroxyl, methoxy, prenyl, and chloro were shown able to enhance the anticancer efficiency. Hence, it is the interest of the current study to investigate the anticancer potential of the hybrid molecules (chalcones) consisting of these precursors with different alkoxy substituents and with or without the fluorine moiety. Two series of chalcone derivatives were designed, synthesized, and characterized using the elemental analysis, IR, 1 H and 13 C NMR spectroscopy, subsequently evaluated for their anti-cancer activity. Interestingly, the results showed that the fluorinated chalcones 11-15 exhibited stronger cytotoxic activity towards the breast cancer cell lines (4T1) compared to non-fluorinated chalcone derivatives. Remarkably, the selectivity index obtained for these fluorinated chalcones derivatives against the breast cancer 4T1 cell line was higher than those exhibited by cisplatin, which is one of the most frequently deployed chemotherapy agents in current medical practice. These findings could provide an insight towards the potential of fluorinated chalcones being developed as an anti-cancer agent with moderate activity towards breast cancer cell and low inhibition of fibroblast cell at a concentration of 100 μM.
  16. Receptor-Interacting Protein Kinase 1 (RIPK1) as a Potential Therapeutic Target: An Overview of Its Possible Role in the Pathogenesis of Alzheimer's Disease
    Chan HH, Koh RY, Lim CL, Leong CO
    Curr Alzheimer Res, 2019;16(10):907-918.
    PMID: 31642777 DOI: 10.2174/1567205016666191023102422
    Alzheimer's Disease (AD) is an age-dependent neurodegenerative disorder, the most common type of dementia that is clinically characterized by the presence of beta-amyloid (Aβ) extracellularly and intraneuronal tau protein tangles that eventually leads to the onset of memory and cognition impairment, development of psychiatric symptoms and behavioral disorders that affect basic daily activities. Current treatment approved by the U.S Food and Drug Administration (FDA) for AD is mainly focused on the symptoms but not on the pathogenesis of the disease. Recently, receptor-interacting protein kinase 1 (RIPK1) has been identified as a key component in the pathogenesis of AD through necroptosis. Furthermore, genetic and pharmacological suppression of RIPK1 has been shown to revert the phenotype of AD and its mediating pathway is yet to be deciphered. This review is aimed to provide an overview of the pathogenesis and current treatment of AD with the involvement of autophagy as well as providing a novel insight into RIPK1 in reverting the progression of AD, probably through an autophagy machinery.
  17. Fulltext Anti-adipogenic effects of extracts of Ficus deltoidea var. deltoidea and var. angustifolia on 3T3-L1 adipocytes
    Woon SM, Seng YW, Ling AP, Chye SM, Koh RY
    J Zhejiang Univ Sci B, 2014 Mar;15(3):295-302.
    PMID: 24599694 DOI: 10.1631/jzus.B1300123
    This study examined the anti-adipogenic effects of extracts of Ficus deltoidea var. deltoidia and var. angustifolia, a natural slimming aid, on 3T3-L1 adipocytes.
  18. Anticancer Potential of Syzygium Species: a Review
    Chua LK, Lim CL, Ling APK, Chye SM, Koh RY
    Plant Foods Hum Nutr, 2019 Mar;74(1):18-27.
    PMID: 30535971 DOI: 10.1007/s11130-018-0704-z
    Cancer is a preventable and treatable disease, however, the incidence rates are on the rise. Classical treatment modalities for cancer include surgery, radiotherapy and chemotherapy. However, these are associated with detrimental side effects such as nausea and emesis. Therefore, researchers currently vest interest in complementary and alternative medicines for cancer treatment and prevention. Plants such as Syzygium sp. are a common basis of complementary medicines due to its abundance of bioactive phytochemicals. Numerous natural compounds derived from Syzygium sp., such as phenolics, oleanolic acids, and betulinic acids, and dimethyl cardamonins, were reported to have anticancer effects. Many possess the ability to inhibit cell proliferation and induce apoptosis. In this review, we discuss the vast potential Syzygium sp. harbours as a source of anticancer natural compounds due to its abundance, easy acceptability, affordability and safety for regular consumption.
  19. Mechanisms of action of amyloid-beta and its precursor protein in neuronal cell death
    Leong YQ, Ng KY, Chye SM, Ling APK, Koh RY
    Metab Brain Dis, 2020 01;35(1):11-30.
    PMID: 31811496 DOI: 10.1007/s11011-019-00516-y
    Extracellular senile plaques and intracellular neurofibrillary tangles are the neuropathological findings of the Alzheimer's disease (AD). Based on the amyloid cascade hypothesis, the main component of senile plaques, the amyloid-beta (Aβ) peptide, and its derivative called amyloid precursor protein (APP) both have been found to place their central roles in AD development for years. However, the recent therapeutics have yet to reverse or halt this disease. Previous evidence demonstrates that the accumulation of Aβ peptides and APP can exert neurotoxicity and ultimately neuronal cell death. Hence, we discuss the mechanisms of excessive production of Aβ peptides and APP serving as pathophysiologic stimuli for the initiation of various cell signalling pathways including apoptosis, necrosis, necroptosis and autophagy which lead to neuronal cell death. Conversely, the activation of such pathways could also result in the abnormal generation of APP and Aβ peptides. An elucidation of actions of APP and its metabolite, Aβ, could be vital in suggesting novel therapeutic opportunities.
  20. Fulltext Effects of Amyloid Precursor Protein Overexpression on NF-κB, Rho-GTPase and Pro-Apoptosis Bcl-2 Pathways in Neuronal Cells
    Chan HH, Leong YQ, Voon SM, Pan ML, Leong CO, Lim CL, et al.
    Rep Biochem Mol Biol, 2021 Jan;9(4):417-425.
    PMID: 33969135 DOI: 10.52547/rbmb.9.4.417
    Background: Alzheimer's disease (AD) is a neurodegenerative disorder that causes cognitive dysfunction. Previous studies have suggested that amyloid plaques, mainly comprising of amyloid-beta peptides, play a pivotal role in AD pathophysiology. This study focuses on the evaluation of the effects of amyloid precursor protein (APP) overexpression on NF-κB, Rho-GTPase and Bcl-2 mediated pro-apoptotic pathways in neuronal cells.

    Methods: A lentiviral transduction system was used to generate SH-SY5Y cells overexpressing APP. Immunoblotting was conducted to determine expression levels of NF-κB, Rho-GTPase, and Bcl-2 family proteins in the APP overexpressed cells.

    Results: In the NF-κB signaling pathway, APP-overexpressing SH-SY5Y cells showed that there was a reduction of p-NF-κB (p< 0.05) and IKKα. Subsequently, there was upregulation of protein expression of NF-Κb, IKKβ and IκBα. On the other hand, protein expression of RhoC (p< 0.05) and Rac1/2/3 was upregulated as compared to the control group. Meanwhile, a decrease in RhoA, Cdc42 (p< 0.05) and p-Rac1/cdc42 protein levels was observed in the APP-overexpressed group. Lastly, in the pro-apoptotic pathway, the expression of Bcl-2, Bid, Bok and Puma (p< 0.05) was up regulated in the APP-overexpressed group. Downregulation of Bad and Bim expression was observed in the APP-overexpressed as compared to the control group, and Bax expression remained unchanged in the APP-overexpressed group.

    Conclusion: APP overexpression regulated signaling in the NF-κB, Rho-GTPase and Bcl-2 family pathways in neuronal cells, suggesting that these are involved in promoting neuronal survival and modulating synaptic plasticity in AD. However, further studies are essential to elucidate the APP-mediated mechanism of action.

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