This is an outdated version published on 14-01-2024. Read the most recent version.

Potential role of herbal plants and beta sitosterol as a bioactive constituent in circumventing Alzheimer’s Disease

Authors

  • Apoorva Mishra 1Noida Institute of Engineering and Technology (Pharmacy Institute), 19 Knowledge Park-2, Greater Noida,201306, G.B Nagar, Uttar Pradesh, India https://orcid.org/0000-0001-6076-6022
  • Saumya Das 1Noida Institute of Engineering and Technology (Pharmacy Institute), 19 Knowledge Park-2, Greater Noida,201306, G.B Nagar, Uttar Pradesh, India https://orcid.org/0000-0002-8531-9963
  • Soni Kumari 1Noida Institute of Engineering and Technology (Pharmacy Institute), 19 Knowledge Park-2, Greater Noida,201306, G.B Nagar, Uttar Pradesh, India https://orcid.org/0000-0001-5923-6569

DOI:

https://doi.org/10.14719/pst.2420

Keywords:

neurodegeneration, herbal drugs, beta amyloid, antioxidants, sitosterol, neuroprotection

Abstract

Alzheimer's Disease (AD), a neurological ailment, mostly affects the older population all around the world. The rational therapies show limited efficacy, adverse effects, and poor patient compliance; therefore, herbal drugs are considered a suitable supplement to the drug therapy for the treatment of AD. According to research, herbal drugs reduce symptoms of AD and also improve brain functioning through the inhibition of beta amyloid, gamma-secretase, and acetylcholine, along with the regulation of antioxidants and the activation of alpha-secretase. Various herbal plants like Salvia officinalis L., Bertholletia excelsa L., Withania somnifera L., and Urtica dioica L. help slow down the progression of AD by scavenging free radicals, inhibiting lipid peroxidation, beta amyloid and tau phosphorylation. Beta sitosterol, a phytosterol found abundantly in plants, has the ability to cross the Blood Brain Barrier and thus acts as a bioactive constituent in circumventing various neurological disorders. Numerous in vitro and in vivo investigations indicate that beta sitosterol shows immunomodulatory, lipid-lowering, as well as antioxidant properties. The plant sterol, beta sitosterol, has the capacity to decrease beta-amyloid platelet synthesis, indicating that it might be helpful in the treatment and prevention of AD. Treatment with beta-sitosterol can lessen plaque burden and also enhance spatial learning and recognition abilities in patients suffering from AD.

Downloads

Download data is not yet available.

References

Jacquemont T, De Vico Fallani F, Bertrand A, Epelbaum S, Routier A, Dubois B et al. Amyloidosis and neurodegeneration result in distinct structural connectivity patterns in mild cognitive impairment. Neurobiol Aging. 2017 Jul 1;55:177-89. doi: 10.1016/j.neurobiolaging.2017.03.023, PMID 28457579.

Huang Y, Mucke L. Alzheimer mechanisms and therapeutic strategies. Cell. 2012 Mar 16;148(6):1204-22. doi: 10.1016/j.cell.2012.02.040, PMID 22424230.

Wi?ckowska A, Ko?aczkowski M, Bucki A, Gody? J, Marcinkowska M, Wi?ckowski K et al. Novel multi-target-directed ligands for Alzheimer’s disease: Combining cholinesterase inhibitors and 5-HT6 receptor antagonists. Design, synthesis and biological evaluation. Eur J Med Chem. 2016;124:63-81. doi: 10.1016/j.ejmech.2016.08.016, PMID 27560283.

Aprahamian I, Stella F, Forlenza OV. New treatment strategies for Alzheimer’s disease: Is there a hope?. Indian J Med Res. 2013;138(4):449-60. PMID 24434253.

Ma SL, Pastorino L, Zhou XZ, Lu KP. Prolyl isomerase Pin1 promotes amyloid precursor protein (APP) turnover by inhibiting glycogen synthase kinase-3? (GSK3?) activity: Novel mechanism for Pin1 to protect against Alzheimer disease. J Biol Chem. 2012;287(10):6969-73. doi: 10.1074/jbc.C111.298596, PMID 22184106.

Barnes DE, Yaffe K. The projected effect of risk factor reduction on Alzheimer’s disease prevalence. Lancet Neurol. 2011 Sep 1;10(9):819-28. doi: 10.1016/S1474-4422(11)70072-2, PMID 21775213.

Bateman RJ. Amyloid-beta production and clearance rates in Alzheimer’s disease. J Alzheimers Assoc. 2010;6(4):S101. https://doi.org/10.1016/j.jalz.2010.05.318

Guerreiro R, Bras J. The age factor in Alzheimer’s disease. Genome Med. 2015;7(1):106. doi: 10.1186/s13073-015-0232-5, PMID 26482651.

Ravi KS, Narasingappa Ramesh B, Kj S, Poyya J, Karanth J, Raju NG, G Joshi C. Neuroprotective role of herbal alternatives in circumventing Alzheimer’s disease through multi-targeting approach-A review. Egyptian Journal of Basic and Applied Sciences. 2022 Dec 31;9(1):91-124. https://doi.org/10.1080/2314808X.2021.2021749

Zhang LH, Wang X, Stoltenberg M, Danscher G, Huang L, Wang ZY. Abundant expression of zinc transporters in the amyloid plaques of Alzheimer’s disease brain. Brain Res Bull. 2008;77(1):55-60. doi: 10.1016/j.brainresbull.2008.03.014, PMID 18639746.

Ayaz M, Junaid M, Ullah F, Subhan F, Sadiq A, Ali G et al. Anti-Alzheimer’s studies on ?-sitosterol isolated from Polygonum hydropiper L. Front Pharmacol. 2017 Oct 6;8:697. doi: 10.3389/fphar.2017.00697, PMID 29056913.

Palop JJ, Chin J, Mucke L. A network dysfunction perspective on neurodegenerative diseases. Nature. 2006 Oct 19;443(7113):768-73. doi: 10.1038/nature05289, PMID 17051202.

Bertram L, Lill CM, Tanzi RE. The genetics of Alzheimer disease: Back to the future. Neuron. 2010 Oct 21;68(2):270-81. doi: 10.1016/j.neuron.2010.10.013, PMID 20955934.

Reitz C, Brayne C, Mayeux R. Epidemiology of Alzheimer disease. Nat Rev Neurol. 2011 Mar;7(3):137-52. doi: 10.1038/nrneurol.2011.2, PMID 21304480.

Singhal A, Bangar O, Naithani V. Medicinal plants with a potential to treat Alzheimer and associated symptoms. Int J NutrPharmacolNeurol Dis. 2012 May 1;2(2):84. doi: 10.4103/2231-0738.95927.

Sharma R, Kuca K, Nepovimova E, Kabra A, Rao MM, Prajapati PK. Traditional Ayurvedic and herbal remedies for Alzheimer’s disease: From bench to bedside. Expert Rev Neurotherapeutics. 2019 May 4;19(5):359-74. doi: 10.1080/14737175.2019.1596803, PMID 30884983.

Ye JY, Li L, Hao QM, Qin Y, Ma CS. ?-sitosterol treatment attenuates cognitive deficits and prevents amyloid plaque deposition in amyloid protein precursor/presenilin 1 mice. Korean J PhysiolPharmacol. 2020 Jan;24(1):39-46. doi: 10.4196/kjpp.2020.24.1.39, PMID 31908573.

Akhondzadeh S, Abbasi SH. Herbal medicine in the treatment of Alzheimer’s disease. Am J Alzheimers Dis Other Demen. 2006 Mar;21(2):113-18. doi: 10.1177/153331750602100211, PMID 16634467.

Newman DJ, Cragg GM. Natural products as sources of new drugs over the last 25 years. J Nat Prod. 2007;70(3):461-77. doi: 10.1021/np068054v, PMID 17309302.

Abascal K, Yarnell E. Alzheimer’s disease: Part 2—A botanical treatment plan. Altern Complement Ther. 2004 Apr 1;10(2):67-72. doi: 10.1089/107628004773933299.

Rasoanaivo P, Wright CW, Willcox ML, Gilbert B. Whole plant extracts versus single compounds for the treatment of malaria: Synergy and positive interactions. Malar J. 2011 Dec;10(Suppl 1);Suppl 1:S4. doi: 10.1186/1475-2875-10-S1-S4, PMID 21411015.

Howes MJ, Houghton PJ. Plants used in Chinese and Indian traditional medicine for improvement of memory and cognitive function. PharmacolBiochemBehav. 2003 Jun 1;75(3):513-27. doi: 10.1016/s0091-3057(03)00128-x, PMID 12895669.

Smith JV, Luo Y. Studies on molecular mechanisms of Ginkgo biloba extract. Appl MicrobiolBiotechnol. 2004 May;64(4):465-72. doi: 10.1007/s00253-003-1527-9, PMID 14740187.

Ramassamy C, Longpré F, Christen Y. Ginkgo biloba extract (EGb 761) in Alzheimer’s disease: Is there any evidence?.Curr Alzheimer Res. 2007 Jul 1;4(3):253-62. doi: 10.2174/156720507781077304, PMID 17627482.

Mahadevan S, Park Y. Multifaceted therapeutic benefits of Ginkgo biloba L.: chemistry, efficacy, safety and uses. J Food Sci. 2008 Jan;73(1):R14-19. doi: 10.1111/j.1750-3841.2007.00597.x, PMID 18211362.

Singhal A, Bangar O, Naithani V. Medicinal plants with a potential to treat Alzheimer and associated symptoms. Int J NutrPharmacolNeurol Dis. 2012 May 1;2(2):84. doi: 10.4103/2231-0738.95927.

Howes MR, Fang R, Houghton PJ. Effect of Chinese herbal medicine on Alzheimer’s disease. Int Rev Neurobiol. 2017 Jan 1;135:29-56. doi: 10.1016/bs.irn.2017.02.003, PMID 28807163.

Bihaqi SW, Singh AP, Tiwari M. Supplementation of Convolvulus pluricaulis attenuates scopolamine-induced increased tau and amyloid precursor protein (A?PP) expression in rat brain. Indian J Pharmacol. 2012;44(5):593-98. doi: 10.4103/0253-7613.100383, PMID 23112420.

Dubey A, Ghosh NS, Agnihotri N, Kumar A, Pandey M, Nishad S. Herbs derived bioactive compounds and their potential for the treatment of neurological disorders. Clin SchizophrRelat Psychoses. 2022 Mar 1;16(2).

Aggarwal BB, Sundaram C, Malani N, Ichikawa H. Curcumin: The Indian solid gold. In: The molecular targets and therapeutic uses of curcumin in health and disease. 2007;p. 1-75. doi: 10.1007/978-0-387-46401-5_1, PMID 17569205.

Begum AN, Jones MR, Lim GP, Morihara T, Kim P, Heath DD et al. Curcumin structure-function, bioavailability and efficacy in models of neuroinflammation and Alzheimer’s disease. J Pharmacol Exp Ther. 2008 Jul 1;326(1):196-208. doi: 10.1124/jpet.108.137455, PMID 18417733.

Lim GP, Chu T, Yang F, Beech W, Frautschy SA, Cole GM. The curry spice curcumin reduces oxidative damage and amyloid pathology in an Alzheimer transgenic mouse. J Neurosci. 2001 Nov 1;21(21):8370-77. doi: 10.1523/JNEUROSCI.21-21-08370.2001, PMID 11606625.

Yang F, Lim GP, Begum AN, Ubeda OJ, Simmons MR, Ambegaokar SS et al. Curcumin inhibits formation of amyloid ? oligomers and fibrils, binds plaques and reduces amyloid in vivo. J Biol Chem. 2005 Feb 18;280(7):5892-901. doi: 10.1074/jbc.M404751200, PMID 15590663.

Zatta P, Drago D, Bolognin S, Sensi SL. Alzheimer’s disease, metal ions and metal homeostatic therapy. Trends Pharmacol Sci. 2009 Jul 1;30(7):346-55. doi: 10.1016/j.tips.2009.05.002, PMID 19540003.

Cristóvão JS, Santos R, Gomes CM. Metals and neuronal metal binding proteins implicated in Alzheimer’s disease. Oxid Med Cell Longev. 2016 Oct;2016:9812178. doi: 10.1155/2016/9812178, PMID 26881049.

Baum L, Ng A. Curcumin interaction with copper and iron suggests one possible mechanism of action in Alzheimer’s disease animal models. J Alzheimers Dis. 2004 Jan 1;6(4):367-77. discussion 443. doi: 10.3233/jad-2004-6403, PMID 15345806.

Yan FS, Sun JL, Xie WH, Shen L, Ji HF. Neuroprotective effects and mechanisms of curcumin–Cu(II) and–Zn(II) complexes systems and their pharmacological implications. Nutrients. 2017 Dec 28;10(1):28. doi: 10.3390/nu10010028, PMID 29283372.

Ranpariya VL, Parmar SK, Sheth NR, Chandrashekhar VM. Neuroprotective activity of Matricariarecutita against fluoride-induced stress in rats. Pharm Biol. 2011 Jul 1;49(7):696-701. doi: 10.3109/13880209.2010.540249, PMID 21599496.

Reddy N, Rajasekhar R. Tinosphora cordifolia chemical constituents and medicinal properties: A review. Sch Acad J Pharmacol. 2015;4:364-69.

Tao R, Wang CZ, Kong ZW. Antibacterial/antifungal activity and synergistic interactions between polyprenols and other lipids isolated from Ginkgo biloba L. leaves. Molecules. 2013 Feb 7;18(2):2166-82. doi: 10.3390/molecules18022166, PMID 23434869.

Awasthi M, Singh S, Pandey VP, Dwivedi UN. Alzheimer’s disease: An overview of amyloid beta dependent pathogenesis and its therapeutic implications along with in-silico approaches emphasizing the role of natural products. J Neurol Sci. 2016;361:256-71. doi: 10.1016/j.jns.2016.01.008, PMID 26810552.

Daneshmand P. Neuroprotective effects of herbal extract on rat model of Alzheimer’s disease, Avicemma. J Med Biotechnol. 2016;8(3):120-25.

Gupta GL, Rana AC. Withania somnifera (Ashwagandha): A review. Pharmacogn Rev. 2007;1(1):129-36.

Rita Cardoso B, Silva Bandeira V, Jacob-Filho W, Franciscato Cozzolino SM. Selenium status in elderly: Relation to cognitive decline. J Trace Elem Med Biol. 2014 Oct 1;28(4):422-26. doi: 10.1016/j.jtemb.2014.08.009, PMID 25220532.

Mahomoodally MF, Dursun PD, Venugopala KN. Collinsonia canadensis L. In naturally occurring chemicals against Alzheimer’s disease. Academic Press. 2021 Jan 1; p. 373-77. https://doi.org/10.1016/B978-0-12-819212-2.00031-1

Lee YJ, Choi DY, Han SB, Kim YH, Kim KH, Hwang BY et al. Inhibitory effect of ethanol extract of Magnolia officinalis on memory impairment and amyloidogenesis in a transgenic mouse model of Alzheimer’s disease via regulating ?-secretase activity. Phytother Res. 2012 Dec;26(12):1884-92. doi: 10.1002/ptr.4643, PMID 22431473.

Sigurdsson S, Gudbjarnason S. Inhibition of acetylcholinesterase by extracts and constituents from Angelica archangelica and Geranium sylvaticum. Z Naturforsch C J Biosci. 2007 Oct 1;62(9-10):689-93. doi: 10.1515/znc-2007-9-1011, PMID 18069242.

Hassan MA, Balasubramanian R, Masoud AD, Burkan ZE, Sughir A, Kumar RS. Role of medicinal plants in neurodegenerative diseases with special emphasis to Alzheimer’s. Phytomedicine. 2014;5(6):454-62.

Akram M, Nawaz A. Effects of medicinal plants on Alzheimer’s disease and memory deficits. Neural Regen Res. 2017 Apr;12(4):660-70. doi: 10.4103/1673-5374.205108, PMID 28553349.

Baskar AA, Al Numair KS, Gabriel Paulraj M, Alsaif MA, Muamar MA, Ignacimuthu S. ?-sitosterol prevents lipid peroxidation and improves antioxidant status and histoarchitecture in rats with 1,2-dimethylhydrazine-induced colon cancer. J Med Food. 2012;15(4):335-43. doi: 10.1089/jmf.2011.1780, PMID 22353013.

Lee MR. The snowdrop (Galanthus nivalis): From Odysseus to Alzheimer. J R Coll Phys Edinb. 1999 Dec;29(4):349-52. https://doi.org/10.1177/147827159902900417

Benesch MG, McElhaney RN. A comparative calorimetric study of the effects of cholesterol and the plant sterols campesterol and brassicasterol on the thermotropic phase behavior of dipalmitoylphosphatidylcholine bilayer membranes. BiochimBiophys Acta. 2014;1838(7):1941-49. doi: 10.1016/j.bbamem.2014.03.019, PMID 24704414.

Baskar AA, Al Numair KS, Gabriel Paulraj M, Alsaif MA, Muamar MA, Ignacimuthu S. ?-sitosterol prevents lipid peroxidation and improves antioxidant status and histoarchitecture in rats with 1,2-dimethylhydrazine-induced colon cancer. J Med Food. 2012;15(4):335-43. doi: 10.1089/jmf.2011.1780, PMID 22353013.

Burg VK, Grimm HS, Rothhaar TL, Grösgen S, Hundsdörfer B, Haupenthal VJ et al. Plant sterols the better cholesterol in Alzheimer’s disease? A mechanistical study. J Neurosci. 2013;33(41):16072-87. doi: 10.1523/JNEUROSCI.1506-13.2013, PMID 24107941.

Shi C, Wu F, Zhu XC, Xu J. Incorporation of ?-sitosterol into the membrane increases resistance to oxidative stress and lipid peroxidation via estrogen receptor-mediated PI3K/GSK3? signaling. BiochimBiophys Acta. 2013 Mar 1;1830(3):2538-44. doi: 10.1016/j.bbagen.2012.12.012, PMID 23266618.

Shi C, Wu F, Xu J. Incorporation of ?-sitosterol into mitochondrial membrane enhances mitochondrial function by promoting inner mitochondrial membrane fluidity. J BioenergBiomembr. 2013 Jun;45(3):301-05. doi: 10.1007/s10863-012-9495-3, PMID 23225137.

Wang J, Wu F, Shi C. Substitution of membrane cholesterol with ?-sitosterol promotes nonamyloidogenic cleavage of endogenous amyloid precursor protein. Neuroscience. 2013;247:227-33. doi: 10.1016/j.neuroscience.2013.05.022, PMID 23707801.

Babu S, Jayaraman S. An update on ?-sitosterol: A potential herbal nutraceutical for diabetic management. Biomed Pharmacother. 2020 Nov 1;131:110702. doi: 10.1016/j.biopha.2020.110702, PMID 32882583.

Shi C, Liu J, Wu F, Zhu X, Yew DT, Xu J. ?-sitosterol inhibits high cholesterol-induced platelet ?-amyloid release. J BioenergBiomembr. 2011 Dec;43(6):691-97. doi: 10.1007/s10863-011-9383-2, PMID 21969169.

Saeidnia S, Manayi A, Gohari AR, Abdollahi M. The story of beta-sitosterol-A review. Eur J Med Plants. 2014 May 1;4(5):590-609. doi: 10.9734/EJMP/2014/7764.

Chandra D, Prasad K. Phytochemicals of Acorus calamus (sweet flag). J Med Plants Stud. 2017;5(5):277-81.

Lee DG, Lee J, Kim KT, Lee SW, Kim YO, Cho IH et al. High-performance liquid chromatography analysis of phytosterols in Panax ginseng root grown under different conditions. J Ginseng Res. 2018 Jan 1;42(1):16-20. doi: 10.1016/j.jgr.2016.10.004.

Irshad S, Khatoon S. Development of a validated high-performance thin-layer chromatography method for the simultaneous estimation of caffeic acid, ferulic acid, ?-sitosterol and lupeol in Convolvulus pluricaulis choisy and its adulterants/substitutes. JPC J Planar Chromatogr Mod TLC. 2018 Dec;31(6):429-36. doi: 10.1556/1006.2018.31.6.2.

Suman A, Ali M, Alam P. New prenylated isoflavanones from the roots of Glycyrrhiza glabra. Chem Nat Compd. 2009 Jul;45(4):487-91. doi: 10.1007/s10600-009-9403-1.

Valentová K, Buckiová D, K?en V, P?knicová J, Ulrichová J, Šimánek V. The in vitro biological activity of Lepidium meyenii extracts. Cell BiolToxicol. 2006 Mar;22(2):91-99. doi: 10.1007/s10565-006-0033-0, PMID 16528448.

Upendra S, Manju B, Praveen K, Geetanjali R, Neeraj K, Bikram S et al. Antimutagenic extract from Tinospora cordifolia and its chemical composition. J Med Plants Res. 2010 Dec 4;4(23):2488-94. doi: 10.5897/JMPR10.346.

Chunhieng T, Hafidi A, Pioch D, Brochier J, Didier M. Detailed study of Brazil nut (Bertholletia excelsa) oil micro-compounds: Phospholipids, tocopherols and sterols. J Braz Chem Soc. 2008;19(7):1374-80. doi: 10.1590/S0103-50532008000700021.

Nencu I, Vlase L, Istudor V, Mircea T?. Preliminary research regarding Urtica urens L. and Urtica dioica L. Amino Acids. 2015;63:710-15.

Misra L, Mishra P, Pandey A, Sangwan RS, Sangwan NS, Tuli R. Withanolides from Withania somnifera roots. Phytochemistry. 2008 Feb 1;69(4):1000-04. doi: 10.1016/j.phytochem.2007.10.024, PMID 18061221.

Malik J, Karan M, Vasisht K. Nootropic, anxiolytic and CNS-depressant studies on different plant sources of shankhpushpi. Pharm Biol. 2011 Dec 1;49(12):1234-42. doi: 10.3109/13880209.2011.584539, PMID 21846173.

Balkrishna A, Thakur P, Varshney A. Phytochemical profile, pharmacological attributes and medicinal properties of Convolvulus prostratus–A cognitive enhancer herb for the management of neurodegenerative etiologies. Front Pharmacol. 2020 Mar 3;11:171. doi: 10.3389/fphar.2020.00171, PMID 32194410.

Takayasu BS, Martins IR, Garnique AMB, Miyamoto S, Machado-Santelli GM, Uemi M et al. Biological effects of an oxyphytosterol generated by ?-sitosterol ozonization. Arch Biochem Biophys. 2020 Dec 15;696:108654. doi: 10.1016/j.abb.2020.108654, PMID 33130087.

Saeed AA, Genové G, Li T, Hülshorst F, Betsholtz C, Björkhem I et al. Increased flux of the plant sterols campesterol and sitosterol across a disrupted blood brain barrier. Steroids. 2015;99(B):183-88. doi: 10.1016/j.steroids.2015.02.005, PMID 25683892.

Shi C, Liu J, Wu F, Zhu X, Yew DT, Xu J. ?-sitosterol inhibits high cholesterol-induced platelet ?-amyloid release. J BioenergBiomembr. 2011;43(6):691-97. doi: 10.1007/s10863-011-9383-2, PMID 21969169.

Butterfield DA, Reed T, Newman SF, Sultana R. Roles of amyloid ?-peptide-associated oxidative stress and brain protein modifications in the pathogenesis of Alzheimer’s disease and mild cognitive impairment. Free Radic Biol Med. 2007 Sep 1;43(5):658-77. doi: 10.1016/j.freeradbiomed.2007.05.037, PMID 17664130.

Babu S, Krishnan M, Rajagopal P, Periyasamy V, Veeraraghavan V, Govindan R et al. Beta-sitosterol attenuates insulin resistance in adipose tissue via IRS-1/Akt mediated insulin signaling in high fat diet and sucrose induced type-2 diabetic rats. Eur J Pharmacol. 2020;873:173004. doi: 10.1016/j.ejphar.2020.173004, PMID 32045603.

Ayaz M, Junaid M, Ullah F, Subhan F, Sadiq A, Ali G et al. Anti-Alzheimer’s studies on ?-sitosterol isolated from Polygonum hydropiper L. Front Pharmacol. 2017 Oct 6;8:697. doi: 10.3389/fphar.2017.00697, PMID 29056913.

Vivancos M, Moreno JJ. ?-sitosterol modulates antioxidant enzyme response in RAW 264.7 macrophages. Free Radic Biol Med. 2005;39(1):91-97. doi: 10.1016/j.freeradbiomed.2005.02.025, PMID

Published

28-12-2023 — Updated on 14-01-2024

Versions

How to Cite

1.
Mishra A, Das S, Kumari S. Potential role of herbal plants and beta sitosterol as a bioactive constituent in circumventing Alzheimer’s Disease. Plant Sci. Today [Internet]. 2024 Jan. 14 [cited 2024 Dec. 22];11(1):454-65. Available from: https://horizonepublishing.com/journals/index.php/PST/article/view/2420

Issue

Section

Review Articles

Most read articles by the same author(s)