Annual Research & Review in Biology
37(11): 57-63, 2022; Article no.ARRB.93589
ISSN: 2347-565X, NLM ID: 101632869
Secondary Metabolites and Mineral Elements of
Manotes expansa and Aframomum alboviolaceum
Leaves Collected in the Democratic Republic of
Congo
Carlos N. Kabengele a, Giresse N. Kasiama a, Etienne M. Ngoyi a,
Jason T. Kilembe a, Juvenal Bete a, Damien S. T. Tshibangu a,
Koto-Te-Nyiwa Ngbolua b,c, Dorothée D. Tshilanda a and Pius T. Mpiana a*
a
Department of Chemistry, Faculty of Sciences, University of Kinshasa, B.P. 190, Kinshasa XI,
Democratic Republic of the Congo.
b
Department of Biology, Faculty of Sciences, University of Kinshasa, B.P. 190, Kinshasa XI,
Democratic Republic of the Congo.
c
Department of Basic Sciences, Faculty of Medicine, University of Gbado-Lite, P.O. Box 111,
Gbado-Lite, Democratic Republic of the Congo.
Authors’ contributions
This work was carried out in collaboration among all authors. All authors read and approved the final
manuscript.
Article Information
DOI: 10.9734/ARRB/2022/v37i1130549
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Original Research Article
Received 06 September 2022
Accepted 13 November 2022
Published 19 November 2022
ABSTRACT
Background and Aims: Manotes expansa Sol. ex Planch. and Aframomum alboviolaceum (Ridl.)
Schum. are two plants belonging respectively to the family Connaraceae R.Br. and Zingiberaceae
Martino widely used in traditional medicine for the treatment of eye diseases, fever, headaches,
gastritis as well as asthma. The aim of the present study is the valorization of these two plants
collected in the Democratic Republic of Congo by a quantitative and qualitative analysis of
secondary metabolites and mineral elements in their leaves.
Materials and Methods: The determination of secondary metabolites in the leaves of Manotes
expansa and Aframomum alboviolaceum was carried out by UV-Visible spectrophotometry and Xray fluorescence spectrophotometry for the identification and quantitative analysis of mineral
elements.
_____________________________________________________________________________________________________
*Corresponding author: E-mail: holyrobi@gmail.com, pt.mpiana@unikin.ac.cd;
Kabengele et al.; ARRB, 37(11): 57-63, 2022; Article no.ARRB.93589
Results: The results showed that the leaves of these two plants are rich in phenolic compounds,
i.e. 442.2 mgEqAG/g for the leaves of A. alboviolaceum, 370.64 mgEqAG/g for the red leaves and
282.64 mgEqAG/g green leaves of M. expansa. Although being part of the same plant, the red and
green leaves of M. expansa presented a totally different phytochemical profile. The contents of
condensed tannins, anthocyanins and flavonoids are respectively 0.3%, 0.68% and 3.29% for the
leaves of A. alboviolaceum; 0.58%, 0.36% and 6.89% for the red leaves, and 0.65%, 0.26% and
7.55% for the green leaves of M. expansa. The mineral content in the leaves of both plants
remains dominated by the high concentration of potassium (K), calcium (Ca), Magnesium (Mg),
Manganese (Mn) and Iron (Fe).
Conclusion: The high content of phenolic compounds and essential trace elements makes the
leaves of M. expansa and A. alboviolaceum potential candidates to alleviate several health
problems in Africa in general and particularly in the Democratic Republic of Congo.
Keywords: Manotes expansa; Aframomum alboviolaceum; mineral content; secondary metabolites;
Democratic Republic of Congo.
These two plants belonging respectively to the
family Connaraceae R.Br. and Zingiberaceae
Martinov are widely used for their therapeutic
properties in management of several diseases
such as: eye diseases, fever, headaches,
gastritis,
asthma,
amoebiasis,
painful
menstruation, tuberculosis, diarrhea, dysentery,
anemia, etc. [7-9]. Thus, a qualitative and
quantitative study of different secondary
metabolites and mineral elements present in the
leaves of these two plants collected in the
Democratic Republic of Congo was carried
out.
1. INTRODUCTION
Long time ago, plants have been used by
humans for various needs including food and
medicine. Almost 40% of currently available
drugs have been derived directly or indirectly
from natural precursors from plants. The
therapeutic power of plants is always associated
to the different chemical compounds often found
in the plant kingdom (secondary metabolites and
mineral elements) [1,2]. The study of plant
chemistry has always been a topical issue
despite its antiquity, this is mainly due to the fact
that the plant kingdom represents an important
source of huge variety of bioactive molecules
that are used in food industry, cosmetology and
pharmacy etc. Among these compounds,
Anthocyanins, alkaloids, saponins, tannins,
terpenes and flavonoids etc. [3]. In addition, the
leaves of plants are also sources of mineral
elements and vitamins that are available to
everyone. The human body for example consists
of about 1.9% of mineral elements in the form of
macro and micro nutrients. These elements must
be supplied regularly through diet [4,5].
Deficiency of mineral elements in the human
body can lead to serious diseases such as
hemoglobin synthesis disorders, inflammatory
anemia, fatigue, growth retardation, neural tube
defects, immune depression, osteoporosis,
muscle spasms, nervous disorders etc. [6].
2. MATERIALS AND METHODS
2.1 Materials
The leaves of M. expansa (green and color) and
A. albovialaceum were collected in Kinshasa,
precisely in the commune of Mont-Ngafula in
March 2019 (DRC). These samples were
identified and authenticated at the Herbarium of
the Institut National d'Etudes et de Recherches
Agronomiques (INERA) at the Faculty of
Sciences of the University of Kinshasa. The
leaves of these plants were dried in the open air
and protected from sunlight for two weeks, and
then ground to powder using an electric grinder
(Sinbo).
2.2 Methods
The main objective of the present study is to
enhance the use of medicinal plants in the diet
and in the management of certain diseases. To
do this, a particular choice was made on
Manotes expansa Sol. ex Planch. and
Aframomum alboviolaceum (Ridl.) K.Schum.
2.2.1 Chemical screening in solution
The phytochemical screening in solution was
carried out using the method described by Békro
[10].
58
Kabengele et al.; ARRB, 37(11): 57-63, 2022; Article no.ARRB.93589
leaves show the presence of polyphenolic
compounds (flavonoids, Anthocyanins, leucoanthocyanins, Tannins, saponins, steroids and
free quinones) while the triterpenoids, alkaloids
and bound quinones are absent in A.
alboviolaceum leaves. For M. expansa green and
red leaves, a similar phytochemical profile was
found regarding the presence of polyphenolic
compounds. The triterpenoids are also present,
while the free alkaloids and quinones are absent
in red leaves.
2.2.2 Thin layer chromatography (TLC)
The standard protocol of Wagner was used in
order to highlight certain secondary metabolites
by spots of different colors on chromatograms
[11]
2.2.3 Determination of secondary metabolites
2.2.3.1 Determination of total polyphenols
The content of total polyphenols was determined
by the method of Folin-Ciocalteu [12]. Briefly,
200µL of the extract was mixed with 1mL of
freshly
prepared
Folin-Ciocalteu
reagent
(previously diluted 10-fold with distilled water)
and 0.8 mL of 7.5% sodium carbonate. The
whole set was incubated at room temperature for
30 minutes and read against a blank using a UVvisible spectrometer type JENWAY 7315 at 760
nm. A calibration curve of gallic acid at different
concentrations (50µg/mL to 350µg/mL in 80%
methanol), prepared under the same conditions
with the extract was plotted for the calculation of
the total polyphenol concentration expressed in
milligrams of gallic acid equivalent per gram of
dry plant matter (mgEAG/g).
3.1.2 Chemical screening by TLC
The result of the chemical screening by TLC of
leaves of A. alboviolaceum and M. expansa
confirmed
the
presence
of
triterpenes,
anthracene derivatives, alkaloids and flavonoids
as presented in Figs. 1, 2, 3 and 4.
2.2.3.2 Determination of flavonoids and tannins
The percentages of flavonoids and tannins in the
samples of plant leaves were determined
following the experimental protocol described by
Dohou et al. [13].
2.2.3.3 Determination of anthocyanins
The determination of anthocyanins was done
according to the methodology of Lebreton et al.
[14].
2.2.4 Determination of minerals by x-ray
fluorescence spectrometry
Minerals content was determined done using an
X-ray fluorescence spectrophotometer. The
preparation of samples and measurements for
the quantification of the mineral elements by Xray fluorescence were carried out following the
procedure described by Kabengele et al. [15].
Fig. 1. Chromatogram of the methanolic
extract of A. alboviolaceum and M. expansa
for anthraquinons Mobile phase: Ethyl
acetate/Methanol/Water (50 :8,5 :6,5).
Detection: UV at 366nm
3. RESULTS AND DISCUSSION
The TLC results presented in Figs. (1, 2, 3, 4)
above show the presence of phenolic
compounds
(flavonoids,
anthraquinones,
terpenes) and alkaloids. The anthracene
compounds revealed by the presence of red
spots on Fig. 1 after revelation at 366 nm and
3.1 Chemical Screening
3.1.1 Chemical screening in solution
The results of phytochemical screening in
solution of A. alboviolaceum and M. expansa
59
Kabengele et al.; ARRB, 37(11): 57-63, 2022; Article no.ARRB.93589
Manotes longiflora are similar to the one
conducted by Kablan in 2008 [17,18].
10% ethanolic KOH. The terpenoids are
identified by the blue spots on the chromatogram
at Fig. 2 after revelation with sulfuric
anysaldehyde and heating at 100°C for
10minutes. Fig. 3 shows the spots corresponding
to the presence of alkaloids which are yellow in
color after revelation with a 5% NaNO2 solution.
The blue fluorescence on the chromatogram of
Fig. 4 confirms the presence of flavonoids in the
3 samples after spraying with Neu reagent and
UV lamp at 366 nm.
Fig. 3. Chromatogram for alkaloids
Mobile phase : Toluene/ ethyl acetate/
dietthylamine (35 : 10 : 5).
Détection : NaNO2 5%.
Fig. 2. Chromatogram for terpenes Mobile
phase : Toluene/ Ethyl acetate (31 :2,5).
Detection : Sulfuric anysaldehyde
The results of the chemical screening in solution
and TLC prove that the leaves of these two
plants are rich in phenolic compounds. It is worth
mentioning that, although being part of the same
plant (M. expansa), the green and red leaves
revealed some differences in the presence or not
of some metabolites and their TLC profile is
slightly different. These observed differences in
the composition of M. expansa leaves are the
results of the evolution and distribution of
metabolites as a function of the maturity of
different parts of the plant [16]. The comparison
of result of this study with the one conducted
by Inkoto et al. [17] on A. Alboviolaceum shows
a similar phytochemical profile except for
alkaloids. The results obtained from this study for
Fig. 4. Chromatogram for flavonoids. Elution
system: ethyl acetate/ formic acid/ glacial
acetic acid/ water (50: 6.5: 6.5: 13.5)
Detection: Neu reagent and UV at 366 nm
60
Kabengele et al.; ARRB, 37(11): 57-63, 2022; Article no.ARRB.93589
S
and
Cl).
Indeed,
potassium
is
the most abundant element in A. alboviolaceum,
which was also confirmed by the study
result by Latham & Kumbuta (2010).
Ca is the most abundant element in the
green part of M. expansa and K in the red
part.
3.2 Secondary Metabolite Determination
3.2.1 Total polyphenol content
The total polyphenol content expressed as
milligram gallic acid equivalent per gram of dry
matter (mgEqAG/g) in leaves of two species was
determined from the linear regression equation of
the gallic acid calibration curve. The results
obtained show that A. alboviolaceum leaves
have the highest total polyphenol content of
442.2mgEqAG/g. 370.64mgEqAG/g for red
leaves and 282.64mgEqAG/g green leaves of M.
expansa.
3.2.2 Flavonoid,
contents
tannin
and
The comparison of the results of this study with
the one carried out by Enzonga et al. [19] in
Congo Brazzaville and the one carried out by
Herzog et al. [20] in Ivory Coast on A.
alboviolaceum seeds reveals huge discrepancies
in the concentration values of elements such as
Mg, Fe, Ca, P.
anthocyanin
The concentrations of mineral elements
such as K, Ca, Zn, Cu, Br, Mn, Ni found in the
study of Agbo et al. [21], on the leaves of M.
expansa in Ivory Coast are far lower than those
found in the same plant harvested in DRC.
This may be attributed to the different
chemical composition of the harvest soil. It
should be noted that the element Sr was not
detected in A. alboviolaceum and the element
silver was not identified in the green part of M.
expansa.
The flavonoid, tannin and anthocyanin contents
expressed in % are shown in the following
Table 1.
3.3 Determination of Minerals by X-ray
Fluorescence Spectrometry
X ray fluorescence spectrometry analysis on
powders of A. alboviolaceum and M. expansa
(red and green part) allowed the quantification of
several mineral elements. The results are
presented in Table 2.
Manotes expansa leaves are very rich in mineral
elements, especially Iron which is found in high
content in both red and green parts with
concentrations of 236.0 and 271.0 ppm
respectively. Iron is one of the constituents of
hemoglobin and it is also involved in oxygen
transport in the cell; thus M. expansa can be
used in anemia cases because of its high iron
content. Consumption of M. expansa leaves can
be considered as an alternative solution to this
problem of deficiency of iron element. High
concentration of Zinc in red leaves of M. expansa
and A. alboviolaceum confirms their use in
strengthening
the
immune
system
and
preventing some diseases of microbial origin
[21].
The mineralogical study carried out by the
X-ray fluorescence method allowed the
characterization of 20 elements including calcium
(Ca), sodium (Na), potassium (K), phosphorus
(P), magnesium (Mg), sulfur (S), Chlorine (Cl),
Aluminum (Al), Manganese (Mn), Iron (Fe),
Zinc (Zn), Copper (Cu), Strontium (Sr),
Rubidium (Rb), Bromine (Br), Silicon (Si),
Neodymium (Nd), Nickel (Ni), Titanium (Ti) and
Silver (Ag).
This Table 2 shows that all three samples
contain the 7 macroelements (K, P, Ca, Na, Mg,
Table 1. Concentrations of flavonoids, tannins and anthocyanins in the three leaf samples
Métabolites
Flavonoïds
Anthocyanins
Hydrolysable Tanins
condensed Tanins
Concentration (%)
M. expansa
(red)
6.89
0.36
1.87
0.58
M. expansa
(green)
7.55
0.26
2.14
0.65
61
A. alboviolaceum
3.29
0.68
1.67
0.30
Kabengele et al.; ARRB, 37(11): 57-63, 2022; Article no.ARRB.93589
Table 2. Concentration of mineral elements in the samples
Eléments
Potassium (K)
Phosphore (P)
Calcium (Ca)
Sodium (Na)
Magnésium (Mg)
Soufre (S)
Chlore (Cl)
Manganèse (Mn)
Aluminium (Al)
Neodymium (Nd)
Fer (Fe)
Zinc (Zinc)
Cuivre (Cu)
Strontium (Sr)
Rubidium (Rb)
Brome (Br)
Argent (Ag)
Silicium (Si)
Titane (Ti)
Nickel (Ni)
M. expansa (Red)
18360.2 ±103.8
3769.0 ±73.2
3594.3 ±92,1
4570.0 ±101.4
556.0 ±29.1
3655.3 ±142,8
231.7 ±8.7
179.9 ±17.1
380.2 ±12.8
18.7 ±2.8
236,0 ±21,2
38,8 ±3.8
15.7 ±2.1
6.3 ±0.2
99.8 ±23.9
225.9 ±42.2
5.7 ±0.6
1129.0 ±179.2
19.7± 2.4
12.9 ±2.1
Concentration (mg/Kg)
M. expansa (green)
5898.1 ±289,1
1238.0 ±56.1
11480.0 ±102,3
5840.8 ±122.9
1465.0 ±32.2
3226.0 ±207,1
178.8 ±11.6
886.2 ±34.8
414.4 ±13.0
8.6 ±2.1
271,0 ±27,8
8,3 ±3.2
7.5 ±0.6
41.2 ±6.2
22.8 ±9.1
66.0 ±2.1
1532.0±186.3
32.6 ± 5.3
13.4 ±3.2
A. aboviolaceum
28830.0 ±203.7
3862.4 ±43.8
794.0 ±12.7
590.0 ±11.8
576.7 ±19.1
3683.0 ±192.8
1410.2 ±63.4
64.8 ±7.7
248.9 ±17.5
28.6 ±5.2
90.0 ±8.2
52.8 ±3.4
20.4 ±1.3
111.8 ±12.3
7.6±0.9
8.9 ±2.1
1386.0±207.9
11.6 ±1.2
3.5 ±0.8
this can justify their multiple uses in the treatment
of several diseases.
4. CONCLUSION
This work focused on the phytochemical profile
of the leaves of A. alboviolaceum and M.
expansa. The aim was to identify and quantify
the mineral elements and secondary metabolites
present in the leaves of these two plants. The
results of chemical screening by TLC and in
solution revealed that the leaves of A.
alboviolaceum and M. expansa are rich in
secondary metabolites including polyphenols
(flavonoids, saponins, tannins, anthocyanins,
leuco-anthocyanins),
alkaloids,
terpenoids,
steroids and free quinones. Quantitative analysis
of the different secondary metabolites present in
the leaves of these two plants allowed the
determination of different concentrations of
polyphenolic compounds. The results showed
that the leaves of A. alboviolaceum are very rich
in total polyphenols compared to the leaves of M.
expansa. A high level of flavonoids was obtained
in the green colored leaves of M. expansa;
anthocyanins and saponins were found in high
amounts in the leaves of A. alboviolaceum.
Mineralogical determination on the powder of
each sample revealed the presence of 20
mineral elements, namely Ca, Na, K, P, Mg, S,
Cl, Al, Mn, Fe, Zn, Cu, Sr, Rb, Br, Si, Nd, Ni, Ti
and Ag. It appears from these results that the
leaves of these two plants are very rich in
mineral elements and secondary metabolites,
COMPETING INTERESTS
Authors have
interests exist.
declared
that
no competing
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