Ethnopharmacology—A Bibliometric Analysis of a Field of Research Meandering Between Medicine and Food Science?

Abstract

Background: The research into bioactive natural products of medicinal plants has a long tradition, but ethnopharmacology as a well-defined field of research has a relatively short history, only dating back 50 years.
Aims: With the fast development of this field and its global importance especially in the fast developing economies of Asia it is timely to assess the most influential articles (as measured by citations) and to identify important drivers and research trends in this field.
Methods: Scopus was searched to identify relevant articles which were assessed by all three authors. The 100 most cited articles were identified and analyzed. Bibliometric software (VOSviewer) was utilized to supplement the analysis and to generate a term map that visualized the citation patterns of the 100 articles containing different terms.
Results: Forty-four of the 100 articles are reviews. On average, each of the 100 articles had 632 citations and since publication was cited 43 times annually. The four core journals were Journal of Ethnopharmacology (n = 17), Food Chemistry (n = 7), Life Sciences (n = 5), and Journal of Agricultural and Food Chemistry (n = 4). Anti-oxidant effects appeared to be a recurring and highly cited topic, whereas the links into drug discovery and neuropharmacology seemed to be less strong. Numerous medicinal plants and functional foods were the foci of research, and the foci shifted when comparing pre-2000 and post-2000 publications (with the later involving a broader spectrum of plants and foods and a wider range of biological effects). Contributions largely came from Asia, and also from the Americas, Africa, and Oceania, besides Europe.
Conclusion: We have identified and analyzed the 100 most-cited articles in ethnopharmacology. Within 50 years the field has gained a profile and while conventionally often linked to “traditional knowledge,” drug discovery and some areas of pharmacology, this analysis highlights its emerging importance in the context of disease prevention (food science), but also the development of research driven by the needs and interests of the fast developing economies most notably of Asia.

Full text

ORIGINAL RESEARCH
published: 15 March 2018
doi: 10.3389/fphar.2018.00215
Frontiers in Pharmacology | www.frontiersin.org 1March 2018 | Volume 9 | Article 215
Edited by:
Luc Pieters,
University of Antwerp, Belgium
Reviewed by:
Jose-Luis Rios,
Universitat de València, Spain
Cassandra L. Quave,
Emory University School of Medicine,
United States
*Correspondence:
Andy Wai Kan Yeung
ndyeung@hku.hk
Michael Heinrich
m.heinrich@ucl.ac.uk
Atanas G. Atanasov
a.atanasov.mailbox@gmail.com
Specialty section:
This article was submitted to
Ethnopharmacology,
a section of the journal
Frontiers in Pharmacology
Received: 05 January 2018
Accepted: 27 February 2018
Published: 15 March 2018
Citation:
Yeung AWK, Heinrich M and
Atanasov AG (2018)
Ethnopharmacology—A Bibliometric
Analysis of a Field of Research
Meandering Between Medicine and
Food Science?
Front. Pharmacol. 9:215.
doi: 10.3389/fphar.2018.00215
Ethnopharmacology—A Bibliometric
Analysis of a Field of Research
Meandering Between Medicine and
Food Science?
Andy Wai Kan Yeung 1
*, Michael Heinrich 2
*and Atanas G. Atanasov 3,4
*
1Oral and Maxillofacial Radiology, Applied Oral Sciences, Faculty of Dentistry, The University of Hong Kong, Hong Kong,
Hong Kong, 2Research Group “Pharmacognosy and Phytotherapy”, UCL School of Pharmacy, London, United Kingdom,
3Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Magdalenka, Poland, 4Department of
Pharmacognosy, University of Vienna, Vienna, Austria
Background: The research into bioactive natural products of medicinal plants has a long
tradition, but ethnopharmacology as a well-defined field of research has a relatively short
history, only dating back 50 years.
Aims: With the fast development of this field and its global importance especially in the
fast developing economies of Asia it is timely to assess the most influential articles (as
measured by citations) and to identify important drivers and research trends in this field.
Methods: Scopus was searched to identify relevant articles which were assessed by
all three authors. The 100 most cited articles were identified and analyzed. Bibliometric
software (VOSviewer) was utilized to supplement the analysis and to generate a term
map that visualized the citation patterns of the 100 articles containing different terms.
Results: Forty-four of the 100 articles are reviews. On average, each of the 100 articles
had 632 citations and since publication was cited 43 times annually. The four core
journals were Journal of Ethnopharmacology (n=17), Food Chemistry (n=7), Life
Sciences (n=5), and Journal of Agricultural and Food Chemistry (n=4). Anti-oxidant
effects appeared to be a recurring and highly cited topic, whereas the links into drug
discovery and neuropharmacology seemed to be less strong. Numerous medicinal plants
and functional foods were the foci of research, and the foci shifted when comparing
pre-2000 and post-2000 publications (with the later involving a broader spectrum of
plants and foods and a wider range of biological effects). Contributions largely came
from Asia, and also from the Americas, Africa, and Oceania, besides Europe.
Conclusion: We have identified and analyzed the 100 most-cited articles in
ethnopharmacology. Within 50 years the field has gained a profile and while
conventionally often linked to “traditional knowledge,” drug discovery and some areas of
pharmacology, this analysis highlights its emerging importance in the context of disease
prevention (food science), but also the development of research driven by the needs and
interests of the fast developing economies most notably of Asia.
Keywords: bibliometrics, ethnopharmacology, ethnobotany, ethnomedicine, medicinal plant, folk medicine,
traditional medicine

Yeung et al. Ethnopharmacology—A Bibliometric Analysis
GRAPHICAL ABSTRACT:The top papers in ethnopharmacology display a crossover of medical and food science.
INTRODUCTION
Historically, there are abundant and diversified studies reporting
on the biological, pharmacological, and medical uses of plants,
fungi, and other organisms within a local or traditional
context (Heinrich and Jäger, 2015). Many pharmaceutical agents
commonly used today originate from medicinal plants, such
as aspirin, morphine, pilocarpine, and quinine (Gilani, 2005),
and more recently galanthamine, peplin, and Crofelmer (from
Croton lechleri Müll.Arg.; Heinrich, 2013). Moreover, plants
continue to be an important source for modern drug discovery
aiming the development of new therapeutics (Atanasov et al.,
2015). Instead of being dominated by driving forces from
the “Western World,” investigations in ethnopharmacology
have next to European (Vogl et al., 2013) also strong global
contributions from the Asian, African, and native American
traditional medicine (Sheng-Ji, 2001; Steenkamp et al., 2004),
such as those originating from China (Rozema et al., 2012), India
(Booker et al., 2012), Southeast Asia, for example, Vietnam (Tran
et al., 2015), and Mexico (Heinrich, 2000) and several South and
Central American countries.
However, ethnopharmacology as a well-defined field of
research has a relatively short history, dating back about 50
years only (Heinrich and Jäger, 2015). This offers an opportunity
to make an overall assessment and identify important research
trends in this field. With such a rich and diversified literature,
it is worthwhile to conduct a bibliometric study that examines
the top 100 most-cited articles within the research field of
ethnopharmacology. Similar studies that reported the 100 most-
cited articles have been published for numerous research fields
in life science including emergency medicine (Tsai et al., 2006),
neuroimaging (Kim et al., 2016), and neuroscience (Yeung et al.,
2017a). This allows an understanding of the research trends in
the last decades and the ongoing “hot topics.” To the best of
the authors’ knowledge, no such bibliometric report has been
published for ethnopharmacology.
The current study, therefore, aims to identify and analyze
the 100 most-cited ethnopharmacology articles. The specific
objectives of this analysis were:
(1) To understand what key research themes were relevant (as
indicated by citations) in ethnopharmacology?
(2) To appreciate what we can learn from the highly cited papers
in this field in the context of ethnopharmacology’s wider and
changing relevance within the natural sciences?
(3) To identify who and what has driven this research?
(4) To assess what we can learn from this for the future
development of the field?
MATERIALS AND METHODS
Data Sources
Scopus was chosen as the source of data since it has a
broader coverage on pharmacology journals compared to
Web of Science (Gorraiz and Schloegl, 2008). It is a web-
based, multidisciplinary database hosted by Elsevier, and it
provides bibliometric data of peer-reviewed articles published
in the life, social, physical, and health sciences. In November
2017, we searched Scopus to identify articles with the
following string: TITLE-ABS-KEY (ethnopharmacology OR
ethnopharmacological OR ethnobotany OR ethnobotanical OR
ethnomedicine OR ethnomedical OR “medicinal plant” OR “folk
medicine” OR “traditional medicine”). This string searched for
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
articles that contain any of these terms or phrases in their title,
abstract, or keywords.
The articles were sorted by citation count in descending
order. All authors (AWKY, MH, and AGA) screened the
titles and abstracts of the articles to exclude those irrelevant
to ethnopharmacology in order to finally include the 100
most cited articles. In the current study, we considered as
ethnopharmacology papers those focused on traditional medical
use or biological and pharmacological activities of plants, fungi,
and other organisms used locally or traditionally as a medicine or
to improve health. The definition also includes studies aimed to
either improving local healthcare through developing products
based on such knowledge or studies in the context of drug
discovery/development from natural sources which were based
on biological resources with a clear and well-defined local or
traditional use. We excluded papers which simply contained
some of the string keywords but the major focus of the article
was not related to ethnopharmacology. These considerations are
in line with the definition of ethnopharmacology adopted by
the Journal of Ethnopharmacology1, Frontiers in Pharmacology
(section Ethnopharmacology)2and the ConSEFS advisory group
(Heinrich et al., 2018).
No additional restrictions were placed on the type of research
model (in vivo/in vitro), article type (e.g., research article, review,
editorial, letter, etc.), or publication language.
Data Extraction
The 100 most-cited articles were evaluated and the following
information extracted: (1) publication year; (2) journal title; (3)
journal impact factor at the time of publication; (4) SCImago
Journal Rank at the time of publication (SJR indicator, which
weighs citations by the importance or prestige of the citing
journals); (5) total citation count; (6) adjusted citation count
(i.e., citation count per year since publication); (7) field-weighted
citation impact (FWCI)3; (8) authorship; and (9) article type.
In addition, the scopes of the involved journals were classified
into nine categories: clinical, ethnopharmacology, and medicinal
plant research, food research (chemistry etc.), multidisciplinary
journals, microbiology and biotechnology, pharmacology and
pharmacy, phytochemistry with a link to traditional uses, plant
science, and social sciences.
Bradford’s law of scattering was applied to the 100 most-
cited articles to investigate if a few core journals accounted for
publishing one-third of these articles (Vickery, 1948; Yeung et al.,
2017c). Based on Bradford’s law, three groups of journals should
contribute to the publication of the 100 articles when it is equally
divided into three portions, whereas the number of journals
within the groups should be in the ratio of 1:n:n2. For instance,
if one journal publishes 33 articles and the next 33 articles are
1https://www.journals.elsevier.com/journal-of- ethnopharmacology/
2https://www.frontiersin.org/journals/pharmacology/sections/
ethnopharmacology#about
3FWCI shows how well cited an article is as compared to similar ones. It considers
the publication year, article type and disciplines associated with its source. It is the
ratio of the total citations actually received by the article to the total citations that
would be expected based on the average of the subject field. For instance, a FWCI
of 1.50 means the article was cited 50% more times than expected.
published by four journals, the remaining 33 articles should be
published by 16 journals (1:4:16).
Statistical Analysis
We tested if years since publication would influence the number
of citations of the articles. It was tested by Pearson’s correlation
test. Test result with p<0.05 was considered statistically
significant.
Term Map
Words in the titles and abstracts of these 100 articles were parsed,
analyzed and visualized by VOSviewer (Van Eck and Waltman,
2009), a bibliometric software that visualizes results as bubble
maps. Each bubble represented a term or phrase. Irrelevant terms
were manually screened and removed (Heersmink et al., 2011;
Yeung et al., 2017c). The bubble size indicated its frequency
of occurrence. The bubble color indicated the averaged citation
counts received by articles containing the term or phrase. A
line connects two bubbles if they co-occurred in any of the
100 articles. If two terms co-occurred more frequently, the two
bubbles will be in closer proximity. The term map visualizes
terms that appeared in at least five of the 100 articles.
RESULTS AND DISCUSSION
The 100 most-cited ethnopharmacology articles were mainly
original articles (n=51) and reviews (n=44), with a few
conference papers (n=3) and short surveys (n=2). Since
such a bibliometric assessment is not available for general
pharmacology, no direct comparison is possible. However, one
can compare the size of the respective fields. A search in
Scopus replacing our pre-defined search terms with different
ones has revealed that there are 181,207 papers tagged as
“pharmacology,” 4,998 papers as “neuropharmacology,” 3,450
papers as “ethnopharmacology,” and 39,848 papers as “traditional
medicine/ethnopharmacology.”
The number of citations received by these 100 articles ranged
from 353 to 5,253 (mean ±SD: 631.7 ±560.0, cumulative total
citations =63,166; Table 1). The adjusted citation count (i.e.,
citation count per year since publication) ranged from 10.8 to
276.5 (mean ±SD: 43.3 ±31.2, Table 1). Regardless of total
citation count or adjusted citation count, Eisenberg et al. (1998)
published the top-ranked article, a national survey reporting
trends in alternative medicines use in the United States.
The 100 articles were published in 59 journals with impact
factors ranging from 0 to 29.8 (mean ±SD: 2.7 ±3.8). Half of
the 100 articles were published either in a journal dedicated to
ethnopharmacology and medicinal plant research (n=28) or a
clinical journal (n=19; Table 2). Only one article was published
in a social sciences journal. Four core journals published 33
articles; 21 and 34 journals, respectively, published the next
33 and the last 33 articles (4:21:34). This indicated that the
distribution of publications did not fulfill Bradford’s law. The
four core journals were Journal of Ethnopharmacology (n=17),
Food Chemistry (n=7), Life Sciences (n=5), and Journal of
Agricultural and Food Chemistry (n=4).
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 1 | List of 100 most-cited ethnopharmacology articles ranked according to their total citation counts.
Rank Year Authors and title Journal Impact
factor
SJR Total
citation
count
Adjusted
citation
count
Field-weighted
citation impact
1 1998 Eisenberg D.M., Davis R.B., Ettner S.L., Appel S., Wilkey S., Van Rompay M., Kessler
R.C. Trends in alternative medicine use in the United States, 1990-1997: Results of a
follow-up national survey
Journal of the American Medical
Association
9.6 NA 5,253 276.5 124.2
2* 1999 Kähkönen MP, Hopia A.I., Vuorela H.J., Rauha J.-P., Pihlaja K., Kujala T.S., Heinonen
M. Antioxidant activity of plant extracts containing phenolic compounds
Journal of Agricultural and Food
Chemistry
1.5 0.9 2,054 114.1 12.2
3* 1998 Velioglu Y.S., Mazza G., Gao L., Oomah B.D. Antioxidant activity and total phenolics
in selected fruits, vegetables, and grain products
Journal of Agricultural and Food
Chemistry
1.5 NA 2,034 107.1 7.0
4* 1985 Klayman D.L. Qinghaosu (artemisinin): An antimalarial drug from China Science 10.9 NA 1,623 50.7 NA
5* 2001 Zheng W., Wang S.Y. Antioxidant activity and phenolic compounds in selected herbs Journal of Agricultural and Food
Chemistry
1.6 1.1 1,345 84.1 9.9
6 1999 Hammer K.A., Carson C.F., Riley T.V. Antimicrobial activity of essential oils and other
plant extracts
Journal of Applied Microbiology 1.6 1.1 1,232 68.4 5.1
7 2004 Cai Y., Luo Q., Sun M., Corke H. Antioxidant activity and phenolic compounds of 112
traditional Chinese medicinal plants associated with anticancer
Life Sciences 2.2 0.9 1,224 94.2 11.3
8* 2003 Wasser S. Medicinal mushrooms as a source of antitumor and immunomodulating
polysaccharides
Applied Microbiology and
Biotechnology
2.1 1.0 1,162 83.0 14.5
9 2002 Grover J.K., Yadav S., Vats V. Medicinal plants of India with anti-diabetic potential Journal of Ethnopharmacology 1.2 0.9 977 65.1 8.1
10 2004 Miliauskas G., Venskutonis P.R., Van Beek T.A. Screening of radical scavenging
activity of some medicinal and aromatic plant extracts
Food Chemistry 1.6 1.1 903 69.5 13.8
11* 2002 Koleva I.I., Van Beek T.A., Linssen J.P.H., De Groot A., Evstatieva L.N. Screening of
plant extracts for antioxidant activity: A comparative study on three testing methods
Phytochemical Analysis 1.5 0.8 879 58.6 5.2
12 2005 Cragg G.M., Newman D.J. Plants as a source of anti-cancer agents Journal of Ethnopharmacology 1.6 0.8 825 68.8 4.9
13 2004 Devasagayam T.P.A., Tilak J.C., Boloor K.K., Sane K.S., Ghaskadbi S.S., Lele R.D.
Free radicals and antioxidants in human health: Current status and future prospects
Journal of Association of Physicians
of India
0 0.2 819 63.0 5.0
14* 2003 Kalemba D., Kunicka A. Antibacterial and antifungal properties of essential oils Current Medicinal Chemistry 4.5 1.6 804 57.4 3.0
15* 1996 Haslam E. Natural polyphenols (vegetable tannins) as drugs: possible modes of action Journal of Natural Products 1.3 NA 797 38.0 6.8
16* 1992 Block E. The organosulfur chemistry of the genus Allium—implications for the organic
chemistry of sulfur
Angewandte Chemie International
Edition
6.0 NA 770 30.8 NA
17 2005 Edeoga H.O., Okwu D.E., Mbaebie B.O. Phytochemical constituents of some
Nigerian medicinal plants
African Journal of Biotechnology 0 0.2 766 63.8 3.5
18 2008 Harvey A.L. Natural products in drug discovery Drug Discovery Today 6.7 2.0 736 81.8 8.5
19 2001 Fabricant D.S., Farnsworth N.R. The value of plants used in traditional medicine for
drug discovery
Environmental Health Perspectives 3.2 1.4 720 45.0 2.8
20 1985 Farnsworth N.R., Akerele O., Bingel A.S., Soejarto D.D., Guo Z. Medicinal plants in
therapy
Bulletin of the World Health
Organization
1.8 NA 705 22.0 NA
21 2001 Rates S.M.K. Plants as source of drugs Toxicon 1.6 0.6 689 43.1 1.6
22* 2007 Aggarwal B.B., Sundaram C., Malani N., Ichikawa H. Curcumin: the Indian solid gold. Advances in Experimental Medicine
and Biology
0.7 0.3 669 66.9 9.5
23 2005 Ríos J.L., Recio M.C. Medicinal plants and antimicrobial activity Journal of Ethnopharmacology 1.6 0.8 665 55.4 3.7
(Continued)
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 1 | Continued
Rank Year Authors and title Journal Impact
factor
SJR Total
citation
count
Adjusted
citation
count
Field-weighted
citation impact
24 2006 Gurib-Fakim A. Medicinal plants: Traditions of yesterday and drugs of tomorrow Molecular Aspects of Medicine 0 2.2 651 59.2 4.1
25 2005 Balunas M.J., Kinghorn A.D. Drug discovery from medicinal plants Life Sciences 2.6 0.9 641 53.4 11.7
26 1997 Parmar V.S., Jain S.C., Bisht K.S., Jain R., Taneja P., Jha A., Tyagi O.D., Prasad A.K.,
Wengel J., Olsen C.E., Boll P.M. Phytochemistry of the genus Piper
Phytochemistry 1.2 NA 620 31.0 3.4
27 2004 Sparg S.G., Light M.E., Van Staden J. Biological activities and distribution of plant
saponins
Journal of Ethnopharmacology 1.5 0.8 615 47.3 3.4
28 2004 Amarowicz R., Pegg R.B., Rahimi-Moghaddam P., Barl B., Weil J.A. Free-radical
scavenging capacity and antioxidant activity of selected plant species from the
Canadian prairies
Food Chemistry 1.6 1.1 595 45.8 7.9
29 2006 Djeridane A., Yousfi M., Nadjemi B., Boutassouna D., Stocker P., Vidal N. Antioxidant
activity of some Algerian medicinal plants extracts containing phenolic compounds
Food Chemistry 2.5 1.4 593 53.9 11.2
30 2000 Nascimento G.G.F., Locatelli J., Freitas P.C., Silva G.L. Antibacterial activity of plant
extracts and phytochemicals on antibiotic-resistant bacteria
Brazilian Journal of Microbiology 0 0.2 591 34.8 0.6
31 2003 Petersen M., Simmonds M.S.J. Rosmarinic acid Phytochemistry 1.9 0.9 590 42.1 3.5
32 2006 Cos P., Vlietinck A.J., Berghe D.V., Maes L. Anti-infective potential of natural
products: how to develop a stronger in vitro ’proof-of-concept’
Journal of Ethnopharmacology 1.7 1.0 589 53.5 4.5
33 2010 Lobo V., Patil A., Phatak A., Chandra N. Free radicals, antioxidants and functional
foods: impact on human health
Pharmacognosy Reviews 0 0.2 586 83.7 4.5
34 2007 Lansky E.P., Newman R.A. Punica granatum (pomegranate) and its potential for
prevention and treatment of inflammation and cancer
Journal of Ethnopharmacology 2.1 0.9 581 58.1 6.6
35 2001 Ahmad I., Beg A.Z. Antimicrobial and phytochemical studies on 45 Indian medicinal
plants against multi-drug resistant human pathogens
Journal of Ethnopharmacology 0.8 0.7 568 35.5 2.6
36 1998 Hande K.R. Etoposide: Four decades of development of a topoisomerase II inhibitor European Journal of Cancer 2.8 NA 566 29.8 3.7
37 1998 Ahmad I., Mehmood Z., Mohammad F. Screening of some Indian medicinal plants for
their antimicrobial properties
Journal of Ethnopharmacology 0.6 NA 564 29.7 1.2
38* 1989 Bailey C.J., Day C. Traditional plant medicines as treatments for diabetes Diabetes Care 2.4 NA 560 20.0 NA
39 2006 Katalinic V., Milos M., Kulisic T., Jukic M. Screening of 70 medicinal plant extracts for
antioxidant capacity and total phenols
Food Chemistry 2.5 1.4 557 50.6 15.5
40* 1999 Wasser S.P., Weis A.L. Therapeutic effects of substances occurring in higher
basidiomycetes mushrooms: a modern perspective
Critical Reviews in Immunology 5.8 3.7 541 30.1 2.2
41* 2001 Yildirim A., Mavi A., Kara A.A. Determination of antioxidant and antimicrobial activities
of Rumex crispus L. extracts
Journal of Agricultural and Food
Chemistry
1.6 1.1 540 33.8 4.6
42 2010 Chen S., Yao H., Han J., Liu C., Song J., Shi L., Zhu Y., Ma X., Gao T., Pang X., Luo
K., Li Y., Li X., Jia X., Lin Y., Leon C. Validation of the ITS2 region as a novel DNA
barcode for identifying medicinal plant species
PLoS ONE 4.5 2.7 530 75.7 24.3
43* 1969 Chihara G., Maeda Y., Hamuro J., Sasaki T., Fukuoka F. inhibition of mouse sarcoma
180 by polysaccharides from Lentinus edodes (Berk.) sing.
Nature NA NA 519 10.8 NA
44 2003 Yeh G.Y., Eisenberg D.M., Kaptchuk T.J., Phillips R.S. Systematic review of herbs and
dietary supplements for glycemic control in diabetes
Diabetes Care 7.6 3.2 507 36.2 5.8
(Continued)
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 1 | Continued
Rank Year Authors and title Journal Impact
factor
SJR Total
citation
count
Adjusted
citation
count
Field-weighted
citation impact
45 1999 Surh Y.-J. Molecular mechanisms of chemopreventive effects of selected dietary and
medicinal phenolic substances
Mutation Research—Fundamental
and Molecular Mechanisms of
Mutagenesis
0 1.0 507 28.2 9.9
46* 2008 Nassiri Asl M., Hosseinzadeh H. Review of pharmacological effects of Glycyrrhiza sp.
and its bioactive compounds
Phytotherapy Research 1.8 0.7 505 56.1 6.9
47 2008 Ali B.H., Blunden G., Tanira M.O., Nemmar A. Some phytochemical, pharmacological
and toxicological properties of ginger (Zingiber officinale Roscoe): a review of recent
research
Food and Chemical Toxicology 2.4 0.8 500 55.6 5.6
48* 2001 Banskota A.H., Tezuka Y., Kadota S. Recent progress in pharmacological research of
propolis
Phytotherapy Research 0.7 0.4 499 31.2 2.3
49 2005 Lindequist U., Niedermeyer T.H.J., Jülich W.-D. The pharmacological potential of
mushrooms
Evidence-based Complementary
and Alternative Medicine
0 0.0 491 40.9 9.2
50 2004 Li W.L., Zheng H.C., Bukuru J., De Kimpe N. Natural medicines used in the traditional
Chinese medical system for therapy of diabetes mellitus
Journal of Ethnopharmacology 1.5 0.8 486 37.4 2.8
51 1988 Rios J.L., Recio M.C., Villar A. Screening methods for natural products with
antimicrobial activity: a review of the literature
Journal of Ethnopharmacology 0.5 NA 482 16.6 NA
52 1998 Eloff J.N. Which extractant should be used for the screening and isolation of
antimicrobial components from plants?
Journal of Ethnopharmacology 0.6 NA 481 25.3 2.4
53 2002 Roth B.L., Baner K., Westkaemper R., Siebert D., Rice K.C., Steinberg S.,
Ernsberger P., Rothman R.B. Salvinorin A: a potent naturally occurring
nonnitrogenous κopioid selective agonist
Proceedings of the National
Academy of Sciences of the
United States of America
10.7 7.2 478 31.9 3.6
54 2009 Wagner H., Ulrich-Merzenich G. Synergy research: approaching a new generation of
phytopharmaceuticals
Phytomedicine 2.2 0.9 478 59.8 15.9
55 2004 Chattopadhyay I., Biswas K., Bandyopadhyay U., Banerjee R.K. Turmeric and
curcumin: biological actions and medicinal applications
Current Science 0.7 0.3 469 36.1 1.3
56 2002 Biswas K., Chattopadhyay I., Banerjee R.K., Bandyopadhyay U. Biological activities
and medicinal properties of neem (Azadirachta indica)
Current Science 0.6 0.3 465 31.0 1.5
57 1998 Ernst E. Harmless herbs? A review of the recent literature American Journal of Medicine 4.5 NA 458 24.1 21.0
58 2002 Raskin I., Ribnicky D.M., Komarnytsky S., Ilic N., Poulev A., Borisjuk N., Brinker A.,
Moreno D.A., Ripoll C., Yakoby N., O’Neal J.M., Cornwell T., Pastor I., Fridlender B.
Plants and human health in the twenty-first century
Trends in Biotechnology 6.3 1.7 456 30.4 9.8
59 2003 Gülçin I., Oktay M., Kireçci E., Küfrevioglu Ö.I. Screening of antioxidant and
antimicrobial activities of anise (Pimpinella anisum L.) seed extracts
Food Chemistry 1.3 0.9 454 32.4 7.1
60 2002 Choi C.W., Kim S.C., Hwang S.S., Choi B.K., Ahn H.J., Lee M.Y., Park S.H., Kim S.K.
Antioxidant activity and free radical scavenging capacity between Korean medicinal
plants and flavonoids by assay-guided comparison
Plant Science 1.6 0.8 446 29.7 3.5
61 2000 Scartezzini P., Speroni E. Review on some plants of Indian traditional medicine with
antioxidant activity
Journal of Ethnopharmacology 0.6 0.5 444 26.1 2.7
62* 2003 Chainani-Wu N. Safety and anti-inflammatory activity of curcumin: a component of
tumeric (Curcuma longa)
Journal of Alternative and
Complementary Medicine
1.0 0.4 443 31.6 14.2
(Continued)
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 1 | Continued
Rank Year Authors and title Journal Impact
factor
SJR Total
citation
count
Adjusted
citation
count
Field-weighted
citation impact
63 1999 Gübitz G.M., Mittelbach M., Trabi M. Exploitation of the tropical oil seed plant
Jatropha curcas L.
Bioresource Technology 0.9 0.7 442 24.6 2.6
64 2003 Strobel G.A. Endophytes as sources of bioactive products Microbes and Infection 3.8 1.7 442 31.6 1.5
65 2008 Wang L., Zhou G.-B., Liu P., Song J.-H., Liang Y., Yan X.-J., Xu F., Wang B.-S., Mao
J.-H., Shen Z.-X., Chen S.-J., Chen Z. Dissection of mechanisms of Chinese
medicinal formula Realgar-indigo naturalis as an effective treatment for promyelocytic
leukemia
Proceedings of the National
Academy of Sciences of the
United States of America
9.4 6.9 430 47.8 5.0
66* 2002 Kronenberg F., Fugh-Berman A. Complementary and alternative medicine for
menopausal symptoms: a review of randomized, controlled trials
Annals of Internal Medicine 11.5 4.1 429 28.6 19.7
67 2000 Calixto J.B. Efficacy, safety, quality control, marketing and regulatory guidelines for
herbal medicines (phytotherapeutic agents)
Brazilian Journal of Medical and
Biological Research
0.7 0.4 429 25.2 1.7
68 2000 Stermitz F.R., Lorenz P., Tawara J.N., Zenewicz L.A., Lewis K. Synergy in a medicinal
plant: antimicrobial action of berberine potentiated by 5’-methoxyhydnocarpin, a
multidrug pump inhibitor
Proceedings of the National
Academy of Sciences of the
United States of America
10.8 7.8 425 25.0 3.8
69 2006 Pourmorad F., Hosseinimehr S.J., Shahabimajd N. Antioxidant activity, phenol and
flavonoid contents of some selected Iranian medicinal plants
African Journal of Biotechnology 0 0.3 423 38.5 3.9
70 2005 Kanadaswami C., Lee L.-T., Lee P.-P.H., Hwang J.-J., Ke F.-C., Huang Y.-T., Lee
M.-T. The antitumor activities of flavonoids
In Vivo 1.1 0.5 423 35.3 10.0
71 2007 Anwar F., Latif S., Ashraf M., Gilani A.H. Moringa oleifera: a food plant with multiple
medicinal uses
Phytotherapy Research 1.5 0.6 417 41.7 2.5
72 2002 Sabu M.C., Kuttan R. Anti-diabetic activity of medicinal plants and its relationship with
their antioxidant property
Journal of Ethnopharmacology 1.2 0.9 408 27.2 4.0
73* 2000 Mishra L.-C., Singh B.B., Dagenais S. Scientific basis for the therapeutic use of
Withania somnifera (ashwagandha): a review
Alternative Medicine Review 0.0 0.3 408 24.0 3.1
74 2003 Javanmardi J., Stushnoff C., Locke E., Vivanco J.M. Antioxidant activity and total
phenolic content of Iranian Ocimum accessions
Food Chemistry 1.3 0.9 405 28.9 5.0
75 2000 Moreno M.I.N., Isla M.I., Sampietro A.R., Vattuone M.A. Comparison of the free
radical-scavenging activity of propolis from several regions of Argentina
Journal of Ethnopharmacology 0.6 0.5 403 23.7 1.6
76 2002 Lu Y., Yeap Foo L. Polyphenolics of Salvia—a review Phytochemistry 1.7 1.0 402 26.8 2.0
77 2006 Cai Y.-Z., Mei Sun, Jie Xing, Luo Q., Corke H. Structure-radical scavenging activity
relationships of phenolic compounds from traditional Chinese medicinal plants
Life Sciences 2.4 1.0 399 36.3 8.3
78* 1988 Grunberger D., Banerjee R., Eisinger K., Oltz E.M., Efros L., Caldwell M., Estevez V.,
Nakanishi K. Preferential cytotoxicity on tumor cells by caffeic acid phenethyl ester
isolated from propolis
Experientia 1.2 NA 398 13.7 NA
79* 2004 O’Neill P.M., Posner G.H. A medicinal chemistry perspective on artemisinin and
related endoperoxides
Journal of Medicinal Chemistry 5.1 2.0 397 30.5 8.6
80 2006 Aggarwal S., Ichikawa H., Takada Y., Sandur S.K., Shishodia S., Aggarwal B.B.
Curcumin (diferuloylmethane) down-regulates expression of cell proliferation and
antiapoptotic and metastatic gene products through suppression of IκBαkinase and
Akt activation
Molecular Pharmacology 4.5 2.6 391 35.5 16.2
81 2006 Prabuseenivasan S., Jayakumar M., Ignacimuthu S. In vitro antibacterial activity of
some plant essential oils
BMC Complementary and
Alternative Medicine
0.0 0.5 390 35.5 10.1
(Continued)
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 1 | Continued
Rank Year Authors and title Journal Impact
factor
SJR Total
citation
count
Adjusted
citation
count
Field-weighted
citation impact
82 2003 Pervaiz S. Resveratrol: From grapevines to mammalian biology FASEB Journal 7.2 3.7 388 27.7 6.2
83* 1988 Sparnins V.L., Barany G., Wattenberg L.W. Effects of organosulfur compounds from
garlic and onions on benzo[a]pyrene-induced neoplasia and glutathione s-transferase
activity in the mouse
Carcinogenesis 2.6 NA 381 13.1 NA
84* 2004 van der Heijden R., Jacobs D.I., Snoeijer W., Hallard D., Verpoorte R. The
Catharanthus alkaloids: pharmacognosy and biotechnology
Current Medicinal Chemistry 4.4 1.7 379 29.2 4.6
85 1998 Alarcon-Aguilara F.J., Roman-Ramos R., Perez-Gutierrez S., Aguilar-Contreras A.,
Contreras-Weber C.C., Flores-Saenz J.L. Study of the anti-hyperglycemic effect of
plants used as antidiabetics
Journal of Ethnopharmacology 0.6 NA 379 19.9 1.5
86* 2005 Shishodia S., Sethi G., Aggarwal B.B. Curcumin: getting back to the roots Annals of the New York Academy of
Sciences
2.0 1.0 376 31.3 20.7
87 2004 Grover J.K., Yadav S.P. Pharmacological actions and potential uses of Momordica
charantia: a review
Journal of Ethnopharmacology 1.5 0.8 375 28.8 2.4
88 1998 Chatterjee S.S., Bhattacharya S.K., Wonnemann M., Singer A., Müller W.E.
Hyperforin as a possible antidepressant component of hypericum extracts
Life Sciences 2.0 NA 375 19.7 17.0
89 1997 Vaya J., Belinky P.A., Aviram M. Antioxidant constituents from licorice roots: isolation,
structure elucidation and antioxidative capacity toward LDL oxidation
Free Radical Biology and Medicine 3.6 NA 373 18.7 4.0
90 2000 Liu F., Ng T.B. Antioxidative and free radical scavenging activities of selected
medicinal herbs
Life Sciences 1.9 0.7 371 21.8 4.6
91 2002 Holetz F.B., Pessini G.L., Sanches N.R., Cortez D.A.G., Nakamura C.V., Dias Filho
B.P. Screening of some plants used in the Brazilian folk medicine for the treatment of
infectious diseases
Memorias do Instituto Oswaldo
Cruz
0.7 0.5 369 24.6 2.6
92 1998 Heinrich M., Ankli A., Frei B., Weimann C., Sticher O. Medicinal plants in Mexico:
healers’ consensus and cultural importance
Social Science and Medicine 0.0 NA 367 19.3 3.1
93* 2004 Smit A.J. Medicinal and pharmaceutical uses of seaweed natural products: a review Journal of Applied Phycology 0.8 0.5 367 28.2 2.2
94 2006 Li Y., Guo C., Yang J., Wei J., Xu J., Cheng S. Evaluation of antioxidant properties of
pomegranate peel extract in comparison with pomegranate pulp extract
Food Chemistry 2.5 1.4 366 33.3 7.4
95* 2003 Normile D. The new face of traditional Chinese medicine Science 29.8 11.2 361 25.8 7.5
96 2005 Salem M.L. Immunomodulatory and therapeutic properties of the Nigella sativa L.
seed
International Immunopharmacology 2.1 0.8 360 30.0 1.7
97 2001 Araújo C.A.C., Leon L.L. Biological activities of Curcuma longa L Memorias do Instituto Oswaldo
Cruz
0.7 0.4 358 22.4 3.1
98 2001 Srinivasan D., Nathan S., Suresh T., Lakshmana Perumalsamy P. Antimicrobial activity
of certain Indian medicinal plants used in folkloric medicine
Journal of Ethnopharmacology 0.8 0.7 356 22.3 1.7
99 2009 López-Lázaro M. Distribution and biological activities of the flavonoid luteolin Mini-Reviews in Medicinal
Chemistry
3.0 1.0 354 44.3 11.4
100 2009 Ravindran J., Prasad S., Aggarwal B.B. Curcumin and cancer cells: How many ways
can curry kill tumor cells selectively?
AAPS Journal 3.6 1.4 353 44.1 8.0
NA, not available. Impact factor and SJR were firstly available in 1975 and 1999, respectively. Hence, there are articles with impact factor or SJR labeled as “NA.” An asterisk “*” indicates that the article was not freely available to the
authors through various schemes at the time of the literature analysis (November 2017).
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 2 | Journals in which the 100 most-cited ethnopharmacology articles were published.
Journal Publication count Citation count Citation per article Topic
Journal of Ethnopharmacology 17 9,198 541 2
Food Chemistry 7 3,873 553 1
Life Sciences 5 3,010 602 2
Journal of Agricultural Food Chemistry 4 5,973 1,493 1
Phytochemistry 3 1,612 537 3
Phytotherapy Research 3 1,421 474 2
Proceedings of the National Academy of Sciences of the United States of America 3 1,333 444 6
Science 2 1,984 992 6
African Journal of Biotechnology 2 1,189 595 7
Current Medicinal Chemistry 2 1,183 592 3
Diabetes Care 2 1,067 534 5
Current Science 2 934 467 6
Memorias do Instituto Oswaldo Cruz 2 727 364 4
Journal of the American Medical Association 1 5,253 5
Journal of Applied Microbiology 1 1,232 7
Applied Microbiology and Biotechnology 1 1,162 7
Phytochemical Analysis 1 879 3
Journal of Association of Physicians of India 1 819 5
Journal of Natural Products 1 797 3
Angewandte Chemie International Edition 1 770 3
Drug Discovery Today 1 736 3
Environmental Health Perspectives 1 720 4
Bulletin of the World Health Organization 1 705 5
Toxicon 1 689 4
Advances in Experimental Medicine and Biology 1 669 4
Molecular Aspects of Medicine 1 651 4
Brazilian Journal of Microbiology 1 591 7
Pharmacognosy Reviews 1 586 2
European Journal of Cancer 1 566 4
Critical Reviews in Immunology 1 541 4
PLoS ONE 1 530 6
Nature 1 519 6
Mutation Research—Fundamental and Molecular Mechanisms of Mutagenesis 1 507 4
Food and Chemical Toxicology 1 500 4
Evidence-Based Complementary and Alternative Medicine 1 491 2
Phytomedicine 1 478 2
American Journal of Medicine 1 458 5
Trends in Biotechnology 1 456 7
Plant Science 1 446 8
Journal of Alternative and Complementary Medicine 1 443 2
Bioresource Technology 1 442 7
Microbes and Infection 1 442 7
Annals of Internal Medicine 1 429 5
Brazilian Journal of Medical and Biological Research 1 429 5
In Vivo 1 423 5
Alternative Medicine Review 1 408 5
Experientia 1 398 5
Journal of Medicinal Chemistry 1 397 3
Molecular Pharmacology 1 391 5
BMC Complementary and Alternative Medicine 1 390 2
(Continued)
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 2 | Continued
Journal Publication count Citation count Citation per article Topic
FASEB Journal 1 388 5
Carcinogenesis 1 381 5
Annals of the New York Academy of Sciences 1 376 6
Free Radical Biology and Medicine 1 373 5
Journal of Applied Phycology 1 367 8
Social Science and Medicine 1 367 9
International Immunopharmacology 1 360 4
Mini-Reviews in Medicinal Chemistry 1 354 3
AAPS Journal 1 353 5
The topics of the journals were coded as 1, food research (chemistry etc.)(number of articles, n =11); 2, ethnopharmacology and medicinal plant research (n =28); 3, phytochemistry
with a link to traditional uses (n =11); 4, pharmacology and pharmacy (n =10); 5, clinical (n =20); 6, multidisciplinary journals (n =10); 7, microbiology and biotechnology (n =7);
8, plant science (n =2); and 9, social sciences (n =1).
What Key Research Themes Were Relevant
(as Indicated by Citations) in
Ethnopharmacology?
There were 76 terms or phrases that appeared in five or more
of the 100 articles (Figure 1). Figure 1 clearly suggested that
terms or phrases related to anti-oxidant effects received much
more citations per article than the average, as reflected by the
red-orange-yellow-green bubbles concentrated on the lower right
corner of the term map. For instance, “total phenolic content”
appeared in seven articles with an average of 1,175 citations
each. “Gallic acid equivalent” appeared in five articles with an
average of 1,126 citations each. “Antioxidant activity” appeared
in 18 articles with an average of 797 citations each. “DPPH
(2,2-diphenyl-1-picrylhydrazyl)” appeared in six articles with an
average of 600 citations each. Free radical scavenging activity
appeared in five articles with an average of 592 citations each.
Meanwhile, seven articles had the phrase “herbal medicine” with
an average of 1,148 citations each. Certain terms may reflect the
geographical content of the ethnopharmacology articles, such
as “traditional Chinese medicine” (n=6) relates to China and
“Ayurveda” (n=6) relates to India. The 20 terms that appeared
most in the titles and abstracts of the 100 articles are listed in
Table 3.
Studies with a focus on antioxidant effects, and works focusing
on fruits and other food-related species and their related concepts
were often highly cited. This may be linked to the fact that
antioxidant tests are usually affordable and easily available
(Kedare and Singh, 2011) so the majority of the labs, regardless
of their budget size, could readily use them. It also reflects the
size of research fields—the food sciences field is much larger
than research into medicinal plants (as well as the associated
industries). The food sitting close to traditional medicine makes
an interesting link to the “Let food be thy medicine and medicine
be thy food” concept advocated by Hippocrates. Functional foods
have an enormous global market that has recently grown from
US$33 billion (Menrad, 2003) to US$168 billion (Vicentini et al.,
2016). A substantive body of research on functional food research
advocates the intake of antioxidant nutrients for better well-being
and health (Diplock et al., 1998). Food plants are also easily
and often commercially available through the world. In other
words, resource availability may be the key concept to interpret
the focus for antioxidants and food plants in general. Spices are
an important topic in these studies, particularly the curcumin
from turmeric (Curcuma longa L.), which was mentioned in
eight of the 100 articles, including in the titles of six of the
100 articles. This is not unexpected, since many spices are
heavily used in the traditional medicine (Vimala et al., 1999;
Aggarwal et al., 2007; Singh, 2007). While this demonstrates the
importance of the topic in bibliometric terms, readers should be
aware that antioxidant tests are often based on simple chemical
reactions that may not translate well to demonstrate effects in real
biological systems. Currently, they are not accepted as a relevant
aspect of pharmacological research (see e.g., the “Rules of Five” of
the Journal of Ethnopharmacology)4.
The 100 articles involved clinical or pre-clinical research on
numerous diseases. Diseases often mentioned in the 100 articles
included diabetes (n=7; 565 citations each) and cancer (n=12;
473 citations each). The citations of these papers are mainly from
the year 2004 onwards. For instance, there is a comprehensive
report that reviewed the effects of various medicinal plants
originating from Asia, Europe, the Middle East, and the Americas
on diabetes (Bailey and Day, 1989). Similarly, there was a report
on plant-derived compounds as anti-cancer agents (Cragg and
Newman, 2005).
Other diseases that were mentioned in at least three of the 100
articles included Alzheimer’s disease (n=3; 564 citations each),
arthritis (n=4; 478 citations each), and rheumatism (n=3; 449
citations each). In addition, six papers mentioned gastrointestinal
disease (three of them were in the abstracts while the other three
were in keywords). One paper mentioned respiratory disease.
Since these terms appeared in fewer than five of the 100 articles’
titles or abstracts, they were not visualized in Figure 1. No paper
mentioned gynecology or dermatology. Some studies show some
links into traditional medicine/ethnopharmacology, but are in
essence a clinical study, for example (Kronenberg and Fugh-
Berman, 2002).
4https://www.sciencedirect.com/science/article/pii/S0378874105008251
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
FIGURE 1 | Term map using words from titles and abstracts of the 100 most-cited ethnopharmacology articles. Words from titles and abstracts were parsed,
analyzed and visualized by VOSviewer. There were 76 terms that appeared in five or more articles and hence included in the term map. Each bubble represents a term
or phrase. The bubble size indicates its frequency of occurrence. The bubble color indicates the averaged citation counts received by articles containing the term or
phrase. A line connects two bubbles if they co-occurred in any of the 100 articles. If two terms co-occurred more frequently, the two bubbles would be in closer
proximity. Irrelevant terms were removed manually upon visual inspection of the initial map generated. Lower right corner contains numerous terms and phrases
related to anti-oxidant activity and articles containing them had more citations than the average, as indicated by the red, orange, yellow, and green bubbles.
Some important metabolites and related concepts have been
mentioned at least thrice in the 100 articles, including alkaloids
(n=5; on average 534 citations), essential oil (n=4;
774), flavonoids (n=11; 621), and tannin (n=5; 752).
These topics have constituted a large portion of the existing
ethnopharmacology literature.
The link of the 100 ethnopharmacological papers into the
context of drug discovery seemed to be marginal. Seven of the
100 papers discussed the concept of drug discovery in their titles,
abstracts, or keywords. Six of the seven papers reviewed the drug
discovery from Allium (garlic and onion), seaweed, medicinal
plants, and natural products in general (Block, 1992; Fabricant
and Farnsworth, 2001; Smit, 2004; Balunas and Kinghorn, 2005;
Gurib-Fakim, 2006; Harvey, 2008). Klayman (1985) analyzed the
development of artemisinin from the Chinese medicinal plant
Artemisia annua L. The remaining paper demonstrated a possible
major active metabolite responsible for the antidepressant effect
of the extract from St. John’s wort (Chatterjee et al., 1998), which
happens to be the only paper dealing with St. John’s wort, one of
the best studied medicinal plants. Together with a paper dealing
with opioid K inhibition and salvinorin (Roth et al., 2002), these
two are the only ones dealing with neuropharmacology among
the 100. Another interesting gap is research on Cannabis and
its active metabolites tetrahydrocannabinol (THC) and cannabis
(CBD). Here a large number of papers have been published,
but clearly not deemed to be linked to ethnopharmacology, for
example (Bisogno et al., 2001). Sustainability, access, and benefit
sharing are also clearly are not major topics (as evident from
Figure 1, the only term with relevance in this context seems to
be “availability”).
The latest papers in our top 100 list were published in 2010.
Our Scopus search has identified that only two post-2010 papers
had at least 300 citations, and both of them have exceeded the
citation count of the last paper on our top 100 list. However, they
were excluded as one focused on genomics and drug synthesis
(Cragg and Newman, 2013) (582 citations) whereas the other
one strictly dealt with chemistry (Kumar and Pandey, 2013; 399
citations).
The citation counts of the articles have no significant
correlation with the number of years since publication (r=0.134,
p=0.184). Since the articles were generally published well before
2010, an analysis of open vs. closed access is problematic and
was not conducted. Eight articles became available under an
open access (OA) model at the time of publication, but today
66 more articles are available freely through different schemes.
There seems to be no major difference in the number of OA
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 3 | The 20 terms that appeared most in the titles and abstracts of the 100
articles.
Terms Appearance Citations per article
Compound 35 604
Medicinal plant 32 640
Biological activity 31 547
Use 31 679
Extract 29 658
Source 26 663
Property 22 567
System 22 588
Number 21 573
Medicine 20 522
Species 20 640
Traditional medicine 19 520
Antioxidant activity 17 797
Constituent 18 558
Disease 18 482
Drug 18 622
Treatment 17 596
Component 16 588
Mechanism 15 566
Antimicrobial activity 13 596
articles among the highly cited and the less cited (Top 100: 8
OA articles, Rank 1000–1100: 9 OA articles, Rank 1900–2000: 5
OA articles). This is in line with the findings from life science
research that open access might be associated with more full text
downloads without an actual citation advantage (Davis et al.,
2008).
What Can We Learn From the Highly Cited
Papers in This Field in the Context of
Ethnopharmacology’s Wider and Changing
Relevance Within the Natural Sciences?
The 100 articles were binarized into pre-2000 (the year 2000
inclusive) and post-2000 publications and assessed. There were
32 pre-2000 and 68 post-2000 publications. The topics of pre-
2000 publications appeared to be more focused, with only
several specific plants or food appearing in multiple (i.e., two
or more) articles, namely garlic, onion, propolis, rosemary,
sage and Withania somnifera (L.) Dunal. Each appeared in two
articles published pre-2000. The foci of post-2000 publications,
on the other hand, seemed to be more diversified and involved
more plants or food, namely aloe vera, cinnamon, clove,
Coccinia grandis (L.) Voigt, C. longa L., Eucalyptus, ginger,
Gymnema sylvestre (Retz.) R.Br. ex Sm., Momordica charantia L.,
mushroom, origanum, pomegranate, sage (Salvia officinalis L.),
thyme and yeast. Except for C. longa,M. charantia and yeast that
have had three appearances each, the other species and foods
have appeared twice in the post-2000 publications. The post-
2000 publications have shifted foci compared to their pre-2000
counterparts, with the evidence that sage is the only plant that
has appeared multiple times both in pre-2000 and post-2000
publications.
Another noticeable point is that post-2000 publications had
evaluated wider aspects of effects of the medicinal plants and
functional food. For instance, post-2000 publications focus
more on antibacterial, anticancer, anticandidal, antifungal,
antimicrobial, antioxidant, and antitumor activities, while pre-
2000 publications only referred to antibacterial, antimicrobial,
and antioxidant activities.
Who and What Has Driven the Research?
The 100 most-cited articles were contributed by a total of
159 authors. Only one author, Bharat Bhushan Aggarwal, has
contributed to four publications making him the only one to
contribute three or more of the 100 most-cited articles. He
authored four of them. All of them were published post-2000.
No author has multiple contributions to the pre-2000 articles.
The 100 articles were contributed by 160 affiliations. Those with
three or more articles were University of Texas M. D. Anderson
Cancer Center (n=5), The University of Hong Kong (n=3),
and University of Illinois at Chicago (n=3). All but one of these
11 articles were published post-2000. No affiliation has multiple
contributions to the pre-2000 articles.
The 100 articles originated from 40 countries/territories, with
the top contributions being by The United States (n=29) and
India (n=13) (Table 4). Also noticeable countries/territories
were China (n=8), the United Kingdom (n=8), Brazil (n=5),
and Germany (n=5). In summary, the 100 articles had major
contributions, not mutually exclusive, from countries/territories
from Europe (n=41), Asia (n=39), and North America
(n=32), and some contributions from South America (n=6),
Africa (n=6), and Oceania (n=2). Comparing the articles
published pre- and post-2000, The United States, India, and
United Kingdom were listed among the top 5 contributors in
both periods. However, China and Iran have a much larger
contribution in the post-2000 publications (China: n=7, Iran:
n=4) compared to the pre-2000 publications (China: n=1, Iran:
n=0), and they have consequently replaced Brazil and Germany
as members of the top five contributors.
Geography and culture have been an integral part of
ethnopharmacology. Interestingly, only one of the 100 articles
related to the social sciences aspects, which examined the use
of medicinal plants in four indigenous groups of Mexican
Indians (Heinrich et al., 1998). Perhaps in the future, more
attention should be directed toward the cultural aspects of
ethnopharmacology.
Limitations
The list of top 100 most cited articles, by its nature, has inherent
limitations. The first and foremost limitation is the search
strategy. An article would not be identified if its title, abstract,
and keywords did not contain the pre-defined search terms.
The second limitation is the definition of ethnopharmacology.
For instance, one paper (Chatterjee et al., 1998) reported on
the efficacy of the extract from a licensed European medicinal
plant (St. John’s wort) as antidepressant, and it surely deals
with neuropharmacology, but it may or may not constitute
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Yeung et al. Ethnopharmacology—A Bibliometric Analysis
TABLE 4 | Countries/territories contributed to the 100 most cited
ethnopharmacology articles.
Country/territory Number of articles
United States 29
India 13
China 8
United Kingdom 8
Brazil 5
Germany 5
Hong Kong SAR (China) 4
Iran 4
Israel 4
Netherlands 3
South Africa 3
Spain 3
Turkey 3
Belgium 2
Canada 2
Japan 2
Poland 2
Singapore 2
South Korea 2
Ukraine 2
Countries/territories that each contributed to one article included Algeria, Argentina,
Australia, Austria, Bulgaria, Croatia, Denmark, Finland, France, Italy, Lithuania, Mauritius,
Mexico, New Zealand, Nigeria, Oman, Pakistan, Switzerland, Taiwan, and United Arab
Emirates.
ethnopharmacology sensu stricto. Meanwhile, papers would be
excluded from the current study if they were classed strictly
as drug discovery or the title, abstracts or keywords assigned
by EMTREE or MeSH did not contain the pre-defined key
words related to ethnopharmacology. For example, some very
widely used reviews on drug discovery from natural sources
are not coded in such a way that they are included in this
list: (Newman et al., 2003; Newman and Cragg, 2007) (These
papers have 1,860 and 2,594 citations recorded by Scopus,
respectively). This suggests a need for a top-level keyword (such
as ethnopharmacology or traditional medicine) to be used widely.
Ethnopharmacology or, more generally, the information which
forms the basis of research and development activities, is still
not well-recognized as an important element of the industrial
development pipeline. This contradicts the common perception
that ethnopharmacology is seen as an important source for new
medicines. In essence, this also reflects the classical separation of
the natural sciences into defined disciplines like chemistry and
pharmacology, with ethnopharmacology being more strongly
linked to pharmacology (and food science). Lastly, this work
is based on a retrospective analysis and highlights research
interests of the last decade or the last two decades and will be
changing citation preferences in the future. It can be argued
that the field may be shifting away from antioxidants and food
science as some journals are now rejecting manuscripts based
solely on in silico or simple antioxidant assays of food (Harnly,
2017). This also includes Frontiers in Pharmacology (section
Ethnopharmacology) and the Journal of Ethnopharmacology.
However, this latest shift has yet to be reflected in terms of
citations.
What Can We Learn From This for the
Future Development of the Field?
The research into bioactive natural products from medicinal
plants has a long tradition, with many groups in the nineteenth
century starting to search for the active principles in medicinal
products and with an interest in the species pharmacology
(Heinrich and Jäger, 2015). With the booming literature
in neuroscience and nutritional neuroscience (Yeung et al.,
2017b), it would not be surprising to see stronger links
of ethnopharmacology to neuroscience, neuropharmacology
and food science in the near future. This would also
bring ethnopharmacology back to its “roots,” since the early
developments were driven by scientific interests in psychoactive
plants (Heinrich, 2013). For instance, future research may shed
light on how ingredients from medicinal plants would modulate,
or even treat, eating or neuropsychiatric disorders. Such effects
may be manifested as brain perfusion changes recorded by
functional magnetic resonance imaging (Yeung et al., 2016,
2018). Metabolic syndrome and diabetes will continue to be a
key area of interest and will strengthen the links into preventive
medicine and food sciences. In future, this field should move
away further from papers focused solely on in silico or on
simple antioxidant screening reports to papers introducing new
methods applicable to ethnopharmacology, which is largely
missing from the current top 100 list.
CONCLUSIONS
We have identified the 100 most-cited articles in
ethnopharmacology. This analysis identifies what has been
seen to be of such importance in scientific terms that it is
commonly used in citations. Some surprising outcomes include
the important link to food sciences, and the relevance of some
biological assays, which, in reality, are not considered to be
of pharmacological relevance. Some other areas are notably
absent including stronger links into neuropharmacology and
a lack appreciation of social and cultural sciences approaches.
The analysis demonstrated that ethnopharmacology is at the
crossroads of several disciplines (most notably pharmacology
and food science) and it is the ethnopharmacologists’ challenge
and opportunity to define this area in new ways, including
the development of new links and foci (cf. Nina Etkin’s work,
e.g., Etkin and Ross, 1991). In a book published in 2015 a large
number of contributors provided a short definition of what they
consider ethnopharmacology to be Heinrich and Jäger (2015).
The diversity of their responses with foci on pharmacology,
clinical research, cultural sciences and studies, biological sciences
and environmental research are reflected in the diversity seen in
this bibliometric analysis. This diversity clearly is one of the key
strengths, but also a challenge of ethnopharmacology, which sees
itself to be inter- or trans-disciplinary.
Frontiers in Pharmacology | www.frontiersin.org 13 March 2018 | Volume 9 | Article 215

Yeung et al. Ethnopharmacology—A Bibliometric Analysis
AUTHOR CONTRIBUTIONS
AY, MH, and AA: conceived the work; AY: acquired data and
drafted the work; AY, MH, and AA: analyzed data; MH and AA:
critically revised the work. All authors have approved the final
content of the manuscript.
FUNDING
AA acknowledges the support by the Polish KNOW (Leading
National Research Centre) Scientific Consortium Healthy
Animal—Safe Food, decision of Ministry of Science and Higher
Education No. 05-1/KNOW2/2015.
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Conflict of Interest Statement: The authors declare that the research was
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