Inventory, folk classification and pharmacological properties of plant species used as chewing stick in Benin Republic

Abstract

Chewing sticks are secondary forest products used by people of all ages, genders and professions in Benin but less investigated according to species concerned, their importance according to local communities and their pharmacological properties. For that purpose, an ethnobotanical survey was conducted among 105 local informants of 8 districts in southern and central Benin. The informants were requested to list the species used as chewing sticks and to rank them by priority. To assess pharmacological importance, phytochemical screening was done on four species listed as priority according to local perceptions. The most important plant families of chewing sticks harvested are Euphorbiaceae, Combretaceae, Anacardiaceae, Rubiaceae and Rutaceae. We recorded 35 species of chewing sticks which were grouped into three categories. Six major groups of chemical compounds were tested in four species listed as priority: alkaloids, tannins, flavonoids, saponins, steroids, terpenoids and heteroside cardiotonics. Chemical groups found in selected plants have in general positive actions on dental care, but some such as heterosides cardiotonics found in Pseudospondias microcarpa (in traces) are not recommended because of the risks of cardiotoxicity known for these chemical compounds.

Full text

Journal of Medicinal Plants Research Vol. 3(5), pp. 382-389, May, 2009
Available online at http://www.academicjournals.org/JMPR
ISSN 1996-0875© 2009 Academic Journals
Full Length Research Paper
Inventory, folk classification and pharmacological
properties of plant species used as chewing stick in
Benin Republic
Hugues Adeloui Akpona1,4*, Jean Didier Tewogbadé Akpona1, Simon Kodjoli Awokou2,
Achille Yemoa3 and Léonce Ogougbé Sourou Nounagnon Dossa4
1Laboratoire d’Ecologie Appliquée, Faculté des Sciences Agronomiques, Université d’Abomey-Calavi, Benin.
2Centre d’Etudes, de Recherches et de Formations Forestières (CERF), Direction Générale des Forêts et des
Ressources Naturelles. 01 BP : 1563, Cotonou, Bénin.
3Laboratoire de Pharmacognosie et des huiles essentielles FSS- FAST/ UAC, Bénin
4Direction Générale des Forêts et des Ressources Naturelles (DGFRN), Ministère de l’Environnement et de la
Protection de la Nature (MEPN), Benin.
Accepted 25 April, 2009
Chewing sticks are secondary forest products used by people of all ages, genders and professions in
Benin but less investigated according to species concerned, their importance according to local
communities and their pharmacological properties. For that purpose, an ethnobotanical survey was
conducted among 105 local informants of 8 districts in southern and central Benin. The informants
were requested to list the species used as chewing sticks and to rank them by priority. To assess
pharmacological importance, phytochemical screening was done on four species listed as priority
according to local perceptions. The most important plant families of chewing sticks harvested are
Euphorbiaceae, Combretaceae, Anacardiaceae, Rubiaceae and Rutaceae. We recorded 35 species of
chewing sticks which were grouped into three categories. Six major groups of chemical compounds
were tested in four species listed as priority: alkaloids, tannins, flavonoids, saponins, steroids,
terpenoids and heteroside cardiotonics. Chemical groups found in selected plants have in general
positive actions on dental care, but some such as heterosides cardiotonics found in Pseudospondias
microcarpa (in traces) are not recommended because of the risks of cardiotoxicity known for these
chemical compounds.
Key words: Chewing sticks, chemical compounds, Pseudospondias microcarpa, cardiotoxicity.
INTRODUCTION
Non-timber forest products (NTFPs) play an important
role in the livelihood of rural and urban people around the
globe (Griffiths et al., 2003; Emanuel et al., 2005; Gaoue
and Ticktin, 2007). For example, many NTFP’s with
medicinal value are harvested for local healthcare needs
as well as for sale in national and international industries
(Stewart, 2003; Hamilton, 2004). However, the growing
demand for NTFPs used for both subsistence and comm-
ercial trade (Hamilton, 2004; Botha et al., 2004) has, in
*Corresponding author. E-mail: akpona@gmail.com. Tél.:
00229 97 57 14 58. Fax:00229 21 30 30 84.
has, in many cases, led to unsustainable management of
forest resources (Peres et al., 2003; Botha et al., 2004).
The Convention on Biological Diversity (CBD) mandates
that contracting parties, preserve and maintain know-
ledge, innovations and practices of indigenous peoples
and local communities for the conservation and sus-
tainable use of biological diversity. This requires a better
understanding of natural resources available and already
integrated into the cultural norms of rural people.
Chewing sticks are secondary forest products used by
people of all ages, genders and professions throughout
Africa. In Benin, it is a cultural practice transferred bet-
ween generations and an inexpensive option for oral
hygiene (Akpona, 2007). It is also a key resource

Akpona et al. 383
Table 1. Information on Sex, Age, Zone and Profession of the Respondents.
Criteria Category Number of respondents
Men 63
Sex Women 42
Old persons ( 40 years old) 70
Age Young persons (< 40 years old)
35
Rural 66
Zone Urban 39
Wholesalers Retailers Total
Traders 16 44 60
Traditional healers 7
Profession
Others 38
Total 105
because it provides substantial income and provides
sanitary, medicinal and pharmaceutical benefits for com-
munities. Presently many species that are used for this
purpose are highly threatened in Benin. According to
Djossou (1985), the functional justification of vegetable
toothbrush is related to its four roles: cleaning of dental
surfaces (mechanical action), gingival massage (active-
tion of blood circulation), oral asepsis (phytotherapy) and
stimulation of parodontal structures. This suggests that
plants used as chewing sticks have phytochemical pro-
perties still not justified by pharmacists. However, little is
known about biological and pharmacological properties of
chewing sticks as a consequence of the little documen-
tation available on the species used as chewing sticks in
Benin. This study aims to
(a) Identify species used as chewing sticks in Benin.
(b) Understand folk classification and prioritization of
concerned species.
(c) To identify chemical components of the most impor-
tant species and their importance in dental hygiene.
MATERIALS AND METHODS
Study area
Republic of Benin is located at the so-called Dahomey-Gap, in
which the savannah extends as far as the sea, through a hiatus in
the West African rain forest over some 200 Km from South East
Ghana to South East Benin (Whitmore, 1990; Martin, 1991; Maley,
1996). This study was conducted in the Guinean region: from about
7°N 9°10’N (South of Abomey latitude) to about 8°N (at Savè
latitude). The districts of Savè, Abomey, Savalou and Dassa
(Centre Benin) and Comè, Cotonou, Porto-Novo (southern Benin)
were surveyed. The mean temperature is constantly high (25°C)
with daily amplitude below 5°C in the South and 10°C in the North.
The weather in Benin is characterized, these past years, by a high
variation in annual rainfall from one year to another and within each
year. Southern Benin has a subequatorial climate subdivided into
four seasons of unequal length: two rainy seasons (from April to
July and September to October), and two dry seasons (from Nov-
ember to March and end of July to August). In Benin republic, the
vegetation is characterized by a great variety and a fragmentation
of habitat caused, on the one hand by climatic, topographic and
edaphic factors and, on the other hand, by human influence on the
environment. There are no evergreen tropical forests or rain forests
in Benin. At the same time, there is an increasing population
pressure on natural ecosystems to satisfy the need for fuel wood,
construction, medicine, etc. In the South, the remaining forest
patches include the Lama Reserve and Pobè relict forests (Sokpon,
1995). In Central Benin, natural forests have been cleared and
replaced by a mosaic of savannas and dry forests. Southern Benin
represents only 10% all the country and gathers at least 50% of the
Beninese population with densities lower than 150 inhabitants with
the km² (da Matha San' T Anna, 2001). In the centre, density is
approximatively 38 habitants/km² (INSAE, 2002) Figure 1.
Inventory, identification and prioritization of chewing sticks’
species
The inventory and prioritization of chewing sticks species according
to local perception were assessed through interviews. Ethno-
botanical surveys were conducted among local people of 8 districts
in Southern and central of Benin. The sampling method was non-
random, and the informants were pre-defined (Albuquerque and
Paiva, 2004) using indications and orientations from local comm-
unities. A survey based on structured questionnaire and focus
groups discussions was carried out on 105 persons of various
socio-professional groups (Table 1). Different ethnic groups were
considered (Fon, Goun, Mina, Tchabè and Idaatcha). Respondents
were composed of the people of the two sexes belonging to all the
categories of age suggested by OMS (1974). 60% of informants
were considered from rural villages and 40% from urban centres.
Indeed, according to PAFT (1987), the percentage of rural popula-
tions using the chewing sticks is higher than the percentage of
urban centres and could even exceed 80%.
Respondents were asked to make a free listing of species used
as chewing sticks and rank them by priority. Provision sites were
also recorded for each listed species. Initially, the respondents
listed all the species used as chewing sticks. Then, it was reques-
ted from each person interviewed to mention the five main species
used from the most important to the less important. We selected the
four most important and used species taking into account the
budget planned for the phytochemical screening which could cover
only four species. Sixty nine respondents were considered for the
prioritization exercise considering that many of them (essentially
urbans) do not know enough species and could not identify the
species name (local or scientific).
For each quoted species, local name was recorded and the
species was sampled during field trips with the informant. Species

384 J. Med. Plant. Res.
Table 2. Protocol of chemical groups characterisation
Chemical groups Specific reagent Reaction
Alkaloids Mayer (potassium iodomercurate) Yellowish precipitate
Tannins FeCl3 Coloration blue-bed, green or
black
Flavonoids Shinoda (reaction to the cyanidine) Orange, red colouring or violet
Quinoid derivatives Bornträger (reaction between quinoid cycles in NH4OH
environment)
Purplish red
Saponins Determination of the foam index (IM) Positive if IM>100
Steroids and Terpenes Liebermann-Burchard (Acetic anhydride H2SO4 (50:1) Coloration blue, green or violet
Heterosides cardiotonics 1%dinitrobenzoïc acid in EtOH + 1N NaOH (1:1) coloration red crimson
Cyanogenetic
Derivatives Guignard (impregnated paper of picric acid) chestnut colour
Essential oils Drive with the vapour sense of smell
sampled were identified by botanists of the Laboratory of Ecology
Applied and National Herbarium of Benin.
Phytochemical Screening of four most important chewing
sticks species identified by local communities
We collected leaves samples from the most important chewing
sticks species as indicated by the respondents for phytochemical
analysis. Samples were ground into powder material and analyses
were done following method by Houghton and Raman (1998).
Phytochemical analysis consists of qualitative determination of
the following components in collected samples: alkaloids, tannins,
flavonoids, quinonic derivatives, the saponins, steroids and terpe-
noids, cardiotonic heterosides, cyanogenetic derivatives and essen-
tial oils (Table 2). These chemical compounds are recognized for
their antibacterial (tannins, flavonoïds, essential oils), anti-inflamm-
atory (flavonoids, saponins, essential oils, steroids and terpenoids),
analgesic (saponins, steroids and terpenoids), anaesthetic (alka-
loids), antiseptic (tannins, essential oils), anti oedema (saponins),
and healing (tannins, essential oils) properties (Houghton and
Raman,1998).
RESULTS AND DISCUSSION
Diversity and classification of chewing sticks’
species in Southern and central of Benin
Chewing sticks in Benin Republic belong to a diversity of
families of which Euphorbiaceae, Combretaceae, Anacar-
diaceae, Rubiaceae and Rutaceae are the most
important (Figure 2). Rubiaceae and Euphorbiaceae are
included in the most ecologically dominant families in
Benin (Adomou et al., 2007). Our results suggest a
probable correlation between families’ abundance and
selection of families used for medicinal purposes. Accor-
ding to this assessment, the more a species is abundant
in an area the more its medicinal uses are known.
Thirty five species of chewing sticks were recorded in
the study area and categorized using local classification
based on the sources of provision, healing properties and
knowledge of each cultural area. Three categories were
defined considering local perceptions and traditional
knowledge of Benin communities. The category 1 consis-
ted of species imported by sellers from neighbouring
countries (Ivory Coast, Ghana and Togo). Category 2
consisted of species collected and marketed locally and
category 3 contains harvested chewing stick species that
were not marketed (Table 3).
The specific richness of chewing sticks species ob-
tained in the southern and the central of Benin is not so
different with the record of Arbonnier (2002) who iden-
tified for chewing sticks purposes 40 species in the dry
zones of West Africa. However all the species inventoried
during this study except for Zanthoxylum zanthoxyloides,
Dialium guineense, Pteleopsis suberosa, Phyllantus
muellerianus, Ochna subscorpioides, Citrus sp., Bridelia
ferruginea and Anogeissus leiocarpus were not invent-
toried by Arbonnier (2002). About 70 species of woody
plants are used in Ghana as chewing sticks (Blay, 2004).
The list of species of chewing stick should be rather
dynamic since the rural populations use new species in
case of drastic reduction of species currently used for this
purpose. Our study includes new species in this list of
Arbonnier (2002) and this could be improved by inves-
tigated the northern part of the country. There is certainly
a crucial lack of data to be developed and capitalize in
each country of West Africa.
Prioritization of chewing sticks species
The percentage of positive response in the listing of
chewing sticks’ species is in the following order: Garcinia
sp. (83%), Pseudocedrella kotschyii (54%), Napoleona
vogelii (51%), Pseudospondias microcarpa (51%) and
Zanthoxylum zanthoxyloides (48%). According to the
classification based on local perception, 86% of respon-
dents consider those five species in the list of priority
species. 14% of respondents included three other spe-
cies (Anogeissus leiocarpus, Rothmania urcelliformis,
Sorindea warneckei) in the list of the five priority species.
The species of the genus Garcinia regarded as priority by
the populations is the only one of category 1. It is known

Akpona et al. 385
Figure 1. Study area
under various names: Ghanalo, Lomèlo or Côte-d'ivoire
lo which indicate their source (example, Ghanalo means
the chewing stick came from Ghana). Indeed, this
Garcinia sp. is marketed in Ghana and Togo. The trade
and use of chewing sticks are very widespread in Togo.
In Southern Togo the genus Garcinia (species gnetoïdes
and polyantha) of the family of Guttiferae growing in
dense forest is more requested (FAO, 2001). Considering
the deforestation in the forest area of Togo, the two
species mentioned above are rare and consequently, all
of chewing sticks presently used are imported from the
neighbouring Ghana (FAO, 2000). In Ghana, the best
chewing sticks in terms of quality come from 'tweapea'
(Garcinia kola) and 'nsokar' (Garcinia epunctata) trees
(Blay, 2004). In Benin, traders recognized that Garcinia
sp. comes from Togo and Ghana. This emphasized the
concept of chain in marketing due to the scarcity of this
species. If the sticks of Garcinia sp. do not have an
indigenous local name like the majority of the species of
category 2, this presupposes that the populations are not
familiar with the species because of its scarcity. There
are some wild species of Garcinia but only one is
domesticated and locally called Ahowé (Fon and Goun)
and Orogbo (Yoruba) in Southern Benin.

386 J. Med. Plant. Res.
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Figure 2. Importance of Family of Species used as Chewing Sticks.
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Chemical groups
Al Ta Fl T and St Card Sap
Figure 3. Importance of Chemical Groups in Plants.
According to the flora of Benin Republic, the probable
species are Garcinia kola, Garcinia livingstonei, and
Garcinia smeathmami (Akoègninou et al., 2006). Chew-
ing sticks based on Garcinia sp. are brought in from the
neighbouring countries while the other four priority
species are collected and marketed locally. This justified
the choice of Pseudocedrella kotschyii, Napoleona voge-
lii, Pseudospondias microcarpa and Zanthoxylum zantho-
xyloides for the phytochemical analysis.
Biological and pharmacological properties of four
most important chewing sticks species
Six major groups of chemical compounds were found in
our samples: alkaloids (Al), tannins (Ta), flavonoids (Fl),
saponins (Sap), steroids and terpenoids (St and T) and
heterosids cardiotonics (Card) (Table 4). Tannins and
alkaloids are the chemical groups most frequent and they
were found in the four species (Figure 3). These are
followed by saponins and flavonoids present in 50% of
the plants. Steroids and terpenoids are present in only
one plant (Pseudospondias microcarpa). Moreover, het-
erosides cardiotonics with genuine cardenolides were
found in traces in the same species. Anthocyanins, leuco-
anthocyanidins, quinonic derivates and cyanogenic deri-
vates are absent in all plants concerned by the phyto-
chemical analysis. Pseudospondias microcarpa contains
the others groups (alkaloids, tannins, terpenoids and ste-
roids) which have positive actions on dental care.
However, the presence of traces of heterosides cardio-
tonics is dangerous. This is because of the risks of car-
diotoxicity known for these chemical compounds. There-
fore, the use of chewing sticks containing heterosides
cardiotonics must be avoided.
Anti-inflammatory, analgesics and local anaesthetic
properties found in the chemical compounds could be
profitable in the dental gingivitis, pains and some infla-
mmatory affections of the oral cavity. Disinfectants and
antibacterial properties could be profitable for infections
of the oral cavity (Table 5).
The use of the plants as chewing sticks originated from
the Greeks and the Romans but is still practiced in parts
of Africa, Southern Asia, Tropical America and among
some populations of Indians in Northern America (Chaaib
kouri, 2004). In a survey carried out by MacGregor
(1963), it was observed that tribes in Ghana prefer plant
based chewing sticks to the modern brushes. Indeed, a
large number of these plants possess antibacterial,
antifungal, anti-tumor, anti-inflammatory or analgesic
properties. Zanthoxylum zanthoxyloides is especially

Akpona et al. 387
Table 3. Ethno-botanical diversity of the species of vegetable brush.
Local nommenclature
Species Ethnic
groups Fon Nagot Goun Yoruba
Category 1 Garcinia sp. Ahowé Kpako Ahowé Orogbo
Zanthoxylum zanthoxyloides (Lam.)
Zepern.andTimber Hêtin - - Igui ata
Napoleona vogelii Hook. and Planch. Zèdou - - -
Pseudocedrella kotschyii (Schweinf.)
Harms Atindokpé Tchaguigui - Tchakisi
Pseudospondias microcarpa (A. Rich.)
Engl. - - - Ito
Dialium guineense Willd. Asswènssweèn - - Eweanyi
Sorindea warneckei Engl. Adouhouadouhoua - - -
Ochna scweinfurthiana F. Hoffm. Adjahimèlo - - -
Olax subscorpioides Oliv. Amitin ; Mitoun - - Ifan ;èla
Lecaniodiscus cupanioides Planch. Ganhotin Akika Ganhotin Akika
Allophylus africanus P. Beauv. Allo-viaton - - -
Terminalia glaucescens Planch. Ex
Benth. « Alotoun, - Anagossiti -
Combretum collinum Fresen. - Gbodomi - -
Anogeissus leiocarpus (DC.) Guill. and
Perr. Hlihlon Ayi Hlihlon Ayi
Bridelia ferruginea Benth. - - - -
Hymenocardia acida Tul. - Okpa - -
Entada africana Guill. and Perr. Akakayi - -
Maranthes polyandra (Benth.) Prance - Tchowoco - -
Category 2
Rothmania urcelliformis (Hiern) Robyns - - - Egui
oliyéré
Clausena africana Gbodouzohouin - - -
Citrus aurantifolia (Christm. and Panzer)
Swingle Clé Ossin - -
Monodora tenuifolia Benth. - - - -
Azadirachta indica A. Juss. Kininoutin
Psidium guayava L. Kinkountin Yovolènkoun
Entada gigas (L.) Fawc.and Rendle Antoyi
Lannea humilis (Oliv.) Engl. Iran adjé
Malacantha alnifolia (Baker) Pierre Akala
Vitellaria paradoxa C.F. Gaertn. Houngo Emin Emin
Phyllantus muellerianus (Kuntze) Exell Ahoudjin
Microdesmis puberula Hookk. f. Ex.
Planch. Idoun
kpata
Waltheria indica L. - Nondi nondi - -
Nauclea latifolia Sm. - Igbèssin - -
Sarcocephalus latifolius (Sm.) E. A. Bruce - Eokodjikassi - -
Parinari curatellifolia Planch. Ex Benth. - - - -
Category 3
Pteleopsis suberosa Engl. and Diels - - -
recognized by African healers (Chaaib kouri, 2004).
Indeed, Z. zanthoxyloides is used as an internal and
external parasiticide. The roots of this plant are par-
ticularly appreciated as chewing stick. This study under-
taken on Z. zanthoxyloides did not show any toxicity of
the whole plant by oral and for the other modes of
administration but according to Pousset (1989), this
toxicity is very low. The bark of the stems, as well as
the sheets appeared less toxic (Neuwinger, 1996),
which means that the use of Z. zanthoxyloides (Lam) is
not harmful to human health.
Terminalia glaucescens does not show negative
compounds on human health. In the Central and North
of Togo, it is especially the roots of Terminalia
glaucescens that are mostly used (FAO, 2000).
Other species such as Napoleona vogelii, Pseudro-
cedrella kotschyii and Anogeissus leiocarpus are
strongly used for their importance in the treatment of
oral diseases. Moreover, the species Ochna scwein-
furthiana, already listed by Arbonnier (2002) for the
treatment of fever, malaria and furuncle is also iden-
tified during investigations and is highly commerciali-
zed.
The majority of species used as chewing sticks in

388 J. Med. Plant. Res.
Table 4. Phytochemical screening.
Species
Chemical groups
Napoleona
vogelii Pseudospondias
microcarpa Pseudocedrella
kotschyii Zanthoxylum
zanthoxyloides
Alkaloids ++ ++ +/- ++
Tanins ++ ++ +++ ++
Flavonoids - - ++ +/-
Anthocyanins - - - -
Leuco -anthocyanidins - - - -
Quinonics derivatives - - - -
Terpenoids and
Steroids
- ++ - -
Heterosides cardiotonics - +/- - -
Saponins ++ - ++ -
Cyanogenic glycosides - - - -
–: negative results ++: clearly positive results
+: positive results +/–: traces
Table 5. Properties of chemical compounds present in the plants.
Chemical groups Main biological and pharmacological properties
Alkaloids Action of local anaesthesia
Tanins Healing, anti-bacterial, antiseptic, antioxidant, enzymatic inhibition: 5-lipo
oxygenase
Flavonoids Anti-inflammatory, anti-bacterial, antiviral in vitro.
Saponins Anti-bacterial, antiseptic, antiviral.
Anti-inflammatory, anti-oedematous and analgesic.
Terpenoids and Steroids Antiviral, analgesic, anti-inflammatory and antiseptic.
Heterosides cardiotonics Cardiotonic : positive inotrope, negative chronotropic, negative dromotrope,
Cardiac toxicity
Benin has a diversity of medicinal properties which are
related to dental hygiene. However, the medicinal uses
listed by rural populations for the majority were not
pharmacologically tested to validate the remedies
indicated. The phytochemical screening was carried out
on four species which represent only 11% of the non-
exhaustive species richness of chewing sticks’ species in
Benin.
Complementary surveys are thus recommended to
identify, purify, and isolate the compounds from these
chemical groups present in the plants and to study their
efficacy in the treatment of certain infections of the oral
cavity. It is also suggested that ethno-medical study of
these vegetable drugs be carried out.
ACKNOWLEDGMENTS
This study was conducted with the financial support
provided by “National Institute of Agricultural Research of
Benin (INRAB)” via a competitive grant in 2006. We are
grateful to the local communities in the study area whose
contributions had been very useful for the implementation
of this research project. We would also like to thank Orou
G. Gaoue for the comments on an earlier version of this
paper.
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