© The Authors, 2025, Published by the Universidad del Zulia*Corresponding author: guillermo.ninomd@uanl.edu.mx
Keywords:
Grape
Phytochemicals
Resveratrol antioxidant
Catechins
Antimicrobial
Health benets
Local grape cultivars in Egypt: exploring their potential health benets
Cultivares de uva locales en Egipto: explorando sus posibles benecios para la salud
Cultivares de uvas locais no Egito: explorando seus potenciais benefícios para a saúde
Abeer A. Dahab
1*
Rania A. Mahmoud
2
Hemat S. Abd El-Salam
3
Gehan A. Mahmoud
4
Eman S. H. Ibrahim
5
Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225
ISSN 2477-9407
DOI: https://doi.org/10.47280/RevFacAgron(LUZ).v42.n2.IX
Food technology
Associate editor: Dra. Evelyn Pérez Pérez
University of Zulia, Faculty of Agronomy
Bolivarian Republic of Venezuela
1
Medicinal and Aromatic Plants Research Department,
Biotechnology Central Lab, Horticulture Research Institute
(HRI), Agricultural Research Center (ARC), Egypt.
2
Deciduous Fruits Research Department, Biotechnology
Central Lab, HRI, ARC, Egypt.
3
Medicinal and Aromatic Plants Research Department,
Chemical Analysis Central Lab, HRI, ARC, Egypt.
4
Fruit Crops Handling Research Department, Chemical
Analysis Central Lab, HRI, ARC, Egypt.
5
Microbiology Department, Egyptian Drug Authority
(EDA), Egypt.
Received: 20-01-2025
Accepted: 14-04-2025
Published: 20-05-2025
Abstract
The biological activities of phytochemical compounds in
grapes have recently attracted increasing attention due to their
potential health benets for humans. In this study, seven local grape
cultivars of Egypt (Gharibi, Fayoumi, Bez El-Naka, Romy Ahmer,
Edkawy, Matrouh Eswid and Baltim Eswid) were investigated
to determine their phytochemical composition, antioxidant and
antimicrobial activities. Tannins, total phenols, total avonoids and
resveratrol content of grape pulp and seed extract were measured.
The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging
and the ferric reducing antioxidant power (FRAP) assays were
used to determine the level of antioxidant activity. Polyphenolic
compounds were identied using Liquid Chromatography-Tandem
Mass Spectrometry Technique (LC-MS/MS). The ndings revealed
that, the Edkawy and Baltim Eswid cultivars presented the highest
content of tannins in the seeds (0.68 and 0.65 %, respectively), and
total avonoids in the pulp and seeds (0.06 and 0.08 %, respectively).
Baltim Eswid showed the best total phenols content (0.11 %) in
the pulp. Overall antioxidant capacity of grape seed extracts was
extremely superior to that of the pulp, where Baltim Eswid was
the best in this concern. The maximum values of resveratrol for
pulp and seed (46.24 and 307.12 mg.100 g
-1
, respectively), were
observed in Baltim Eswid. The main compounds found in the seed
extract were the catechins, ranging from 26.51 % in Fayoumi to
35.8 % in Bez El-Naka. The study demonstrated that grape seed
extract has antimicrobial properties with potential application as
an antimicrobial agent in the industrial area and as an alternative
treatment in the medical sector.
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225 April-June. ISSN 2477-9409.
2-7 |
Resumen
Las actividades biológicas de los compuestos toquímicos
presentes en la uva han atraído recientemente una creciente atención
debido a sus posibles benecios para la salud humana. En este
estudio, se investigaron siete cultivares locales de uva de Egipto
(Gharibi, Fayoumi, Bez El-Naka, Romy Ahmer, Edkawy, Matrouh
Eswid y Baltim Eswid) para determinar su composición toquímica
y sus actividades antioxidantes y antimicrobianas. Se midieron los
taninos, fenoles totales, avonoides totales y resveratrol en la pulpa
de uva y el extracto de semilla. Se utilizaron ensayos de eliminación
de radicales 2,2-difenil-1-picrilhidrazilo (DPPH) y de potencia
antioxidante reductora férrica (FRAP) para determinar el nivel de
actividad antioxidante. Los compuestos polifenólicos se identicaron
mediante cromatografía líquida-espectrometría de masas en tándem
(LC-MS/MS). Los resultados revelaron que los cultivares Edkawy
y Baltim Eswid presentaron el mayor contenido de taninos en las
semillas (0,68 y 0,65 %, respectivamente) y de avonoides totales en
la pulpa y las semillas (0,06 y 0,08 %, respectivamente). Baltim Eswid
presentó el mayor contenido de fenoles totales (0,11 %) en la pulpa.
La capacidad antioxidante general de los extractos de semilla de uva
fue extremadamente superior a la de la pulpa, siendo Baltim Eswid
el mejor en este aspecto. Los valores máximos de resveratrol para la
pulpa y la semilla (46,24 y 307,12 mg.100 g⁻¹, respectivamente), se
observaron en Baltim Eswid. Los principales compuestos presentes
en el extracto de semilla fueron las catequinas, con concentraciones
que oscilaron entre el 26,51 % en Fayoumi y el 35,8 % en Bez El-
Naka. El estudio demostró que el extracto de semilla de uva tiene
propiedades antimicrobianas con potencial aplicación como agente
antimicrobiano en el área industrial y como tratamiento alternativo
en el sector médico.
Palabras clave: uva, toquímicos, resveratrol, antioxidante,
catequinas, antimicrobiano, benecios para la salud.
Resumo
As atividades biológicas dos compostos toquímicos presentes
nas uvas têm atraído cada vez mais atenção devido aos seus potenciais
benefícios à saúde humana. Neste estudo, sete cultivares de uva
locais do Egito (Gharibi, Fayoumi, Bez El-Naka, Romy Ahmer,
Edkawy, Matrouh Eswid e Baltim Eswid) foram investigadas para
determinar sua composição toquímica e atividades antioxidantes e
antimicrobianas.Foram medidos os teores de taninos, fenóis totais,
avonoides totais e resveratrol da polpa de uva e do extrato de
semente. Os ensaios de sequestro de radicais 2,2-difenil-1-picril-
hidrazila (DPPH) e de poder antioxidante redutor de ferro (FRAP)
foram utilizados para determinar o nível de atividade antioxidante.
Os compostos polifenólicos foram identicados pela técnica de
cromatograa líquida-espectrometria de massas em tandem (LC-MS/
MS). Os resultados revelaram que as cultivares Edkawy e Baltim
Eswid apresentaram os maiores teores de taninos nas sementes (0,68 e
0,65 %, respectivamente) e avonoides totais na polpa e nas sementes
(0,06 e 0,08 %, respectivamente). A cultivar Baltim Eswid apresentou
o melhor teor de fenóis totais (0,11 %) na polpa. A capacidade
antioxidante geral dos extratos de sementes de uva foi extremamente
superior à da polpa, sendo o Baltim Eswid o melhor nesse aspecto. Os
valores máximos de resveratrol para polpa e semente (46,24 e 307,12
mg.100 g
-1
, respectivamente), foram observados no Baltim Eswid.
Os principais compostos encontrados no extrato de semente foram as
catequinas, variando de 26,51 % em Fayoumi a 35,8 % em Bez El-
Naka. O estudo demonstrou que o extrato de semente de uva possui
propriedades antimicrobianas com potencial aplicação como agente
antimicrobiano na área industrial e como tratamento alternativo no
setor médico.
Palavras-chave: uva, toquímicos, resveratrol, antioxidante,
catequinas, antimicrobiano, benefícios para a saúde.
Introduction
The need for “healthier” or “functional foods” is always rising,
as maintaining health and preventing diseases that go beyond the
requirements of basic nutrition are the main factors inuencing
consumer food choices today (Adefegha, 2017). Grape (Vitis vinifera
L.) and products made from grapes are among the most important
horticultural products in the world. Numerous nutrients and health-
promoting substances are found in grape berries. The biological
activities of grape phenolic compounds that link to human health
advantages, such as antioxidant, cardioprotective, anti-cancer, anti-
inammation, antiaging, and antibacterial characteristics, have
recently attracted increased attention (Xia et al., 2010). Many factors,
including genotype, cultivation techniques, vineyard characteristics
(soil, sanitary stage), and climate, inuence the content of polyphenols
in grapes (Paredes-López et al., 2010). A member of the viniferins
family of polyphenols, resveratrol (3,5,4′-trihydroxystilbene),
a phytoalexin with a variety of physiological and biochemical
characteristics, has anti-inammatory, antiplatelet, and estrogenic
eects, providing a range of health advantages (Perrone et al., 2017).
Antimicrobial resistance has become one of the major public
health burdens in the 21
st
century and threatens the eective
prevention and treatment of a variety of infections (Prestinaci et
al., 2015). Antimicrobial compounds may be found in plants, and
numerous researchers worldwide are examining the antimicrobial
abilities of medicinal plants that are used in conventional or alternative
healthcare systems (Vaou et al., 2021). Because of its antibacterial and
antioxidant properties, grape extract is widely accepted as a safe food
additive. The partial hydrophobicity of their phenolic components is
what gives them their antibacterial properties (Rababah et al., 2004).
The genetic resources of local grapes vary across Egypt’s
governorates, demonstrating their ability to adapt to a wide range
of environmental conditions; among these are black ones that have
long been widespread along the Mediterranean coast under rain-fed
conditions. The country has a rich history of grape cultivation, and
local varieties are often tied to ancient agricultural practices and
traditions. Dierent grape varieties may have unique nutritional
proles, including varying levels of antioxidants (resveratrol and
avonoids), vitamins, and minerals. Understanding how local
grape varieties aect human health help highlight specic varieties
that oer superior health benets compared to others and could
inspire innovative food products, supplements, or functional foods
tailored to both local and global markets. Thus, the aim of this
study was to investigate seven local grape cultivars to determine
their phytochemical composition and antioxidant and antimicrobial
activities and explore their potential application as antimicrobial
agents in industrial and medical sectors.
Materials and methods
Plant Material
Matures berry of seven local grape cultivars in Egypt (Gharibi,
Fayoumi, Bez El-Naka, Romy Ahmer, Edkawy, Matrouh Eswid
and Baltim Eswid) were collected from Kaha Horticulture Research
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Dahab et al. Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225
3-7 |
Station (Kaluobia Governorate, Egypt) in the seasons of 2023 and
2024, and data were recorded as average of the two seasons. There
were three grapevines (three years) for each cultivar. Standard
fertilizer, irrigation, trimming, and disease and pest control were
applied to every vine. From each vine, about 100 representative
berries were taken. Before each sample was frozen and kept at -80 °C
for additional processing, several measurements were conducted on
grape berry included:
-Fresh weight of berry (g) as average of 100 berries.
-Seed yield % per berry as average of weighted 100 berries.
-Seed oil content (%): Fixed oil extraction was performed with a
Soxhlet apparatus using n-hexane as the solvent (Gómez et al., 1996).
Phytochemical Assays
Grape pulp and seed were extracted by cold maceration (3 times,
24 hours) in ethanol (70 %). The extracts were vacuum-ltered and
stored at -20
°
C for further analysis.
Quantitative determination of tannins was performed by titrating
the sample with a standardized solution of potassium permanganate in
the presence of indigo carmine indicator (Atanassova & Christova-
Bagdassarian, 2009). Total phenols content of grape pulp and seed
extract were measured as described by McDonald et al. (2001) with
minor changes, using the Folic Ciocalteu reagent assay with gallic
acid as a reference standard. With little alterations, a colorimetric
assay (Zhishen et al., 1999) was used to determine the total
avonoid concentration, catechin was used as a standard for the
calibration curve. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical
scavenging technique was performed according to Blois (1958), with
little modications. The scavenging eect of DPPH was reported as a
percentage decline of absorbance in the presence of the tested extracts
compared to the control reaction. The ferric reducing antioxidant
power (FRAP) assay was used to determine the overall level of
antioxidant activity (Quisumbing, 1978), the reducing power of the
samples was compared with that of ascorbic acid used as standard.
Identication and Quantitative of Resveratrol by High
Performance Liquid Chromatography
Identication of resveratrol (Nour et al., 2012) by High
Performance Liquid Chromatography (HPLC) was carried out in the
reverse phase mode. Separation was done after direct injection using
C18 column (250 × 4.6 mm) with gradient elution (solvent (A): 2 %
acetic acid, solvent (B): acetonitrile). Resveratrol was detected at a
wavelength of 306 nm.
Phytochemical Analysis using Liquid Chromatography–
Tandem Mass Spectrometry (LC–MS/MS) Technique
Identication of phytochemical compounds by LC -MS/MS was
carried out in the reverse phase mode with C18 column. Separation was
performed as follows; solvent A; 99 % water, 1 % acetonitrile and 0.1
% formic acid and solvent B; 99 % acetonitrile, 1 % water and 0.1 %
formic acid. The ow rate was set to 0.4 mL.min
-1
,
column temperature
at 20 °C and the injection volume of 3 µL (Jaitz et al., 2010).
Anti-Microbial Activity
For sample preparation, fresh grape seeds were ground to be
powder. An amount of 5 g of dried powder of each cultivar separately
was soaked in 10 mL of 95 % ethyl alcohol for 2 h with intermittent
shaking and then ltered. The residue was re-extracted with addition of
95 % ethanol, and after 4 h it was ltered again. Combined ltrates were
concentrated on a rotary evaporator at 45 °C for ethanol elimination,
and the supernatant was collected and dried to be powder, 0.25 g of
dried powder was dissolved in 1 mL serial water (solution) to be tested
for the anti-microbial activity and to determine the most active extract.
Cultures of E. coli (ATCC 8739), Staphylococcus aureus (ATCC
6538), Bacillus subtilis (ATCC 6633), Pseudomonas aeroginosa
(ATCC 9027) and Candida albicans (ATCC 10231) were prepared
in accordance with the method of Wiegand et al. (2008), using a
concentration of 100 cfu.mL
-1
.
Screening of antimicrobial activity against grape seeds
Anti-microbial activity was screened using the agar well diusion
method as described by the National Committee for Clinical
Laboratory Standards (NCCLS) according to Clinical and Laboratory
Standards Institute (CLSI) (2008). The antibacterial activity was
evaluated by measuring the zone of inhibition for each bacterial
culture by the agar disk-diusion method, as described previously
(Balouiri et al., 2016). At the end of incubation period, diameter of
inhibition zones (clear zone in the agar) was measured to the nearest
millimetre.
Determination of minimum inhibitory concentration (MIC)
Determination of MIC was carried out using resazurin-based
96-well plate microdilution method (Karuppusamy & Rajasekaran,
2009). The MIC value was dened as the lowest concentration at
which color change was observed.
Statistical analysis
The data were statistically analyzed in a complete randomized
design (CRD) with three replicates using CoStat version 6.45
software. Dierence within mean values was assessed using the
Duncan multiple range test with a 0.05 probability (Waller & Duncan,
1969). The average means were reported, along with their standard
errors (SE).
Results and discussion
Physico-chemical characteristics
There were signicant dierences between all the cultivars under
study in berry weight, seed yield percentage, and seed oil content
(table 1). Matrouh Eswid gave the heaviest berry weight (4.617 g),
Gharibi exhibited the highest seed yield percentage (3.878 %) and
both Baltim Eswid and Edkawy had the best seed oil content (5.787
and 5.701 %, respectively). On the contrary, the lowest values of
berry weight (3.339 g), seed yield percentage (1.401 %) and seed oil
content (1.696 %) were recorded with Gharibi, Matrouh Eswid and
Romy Ahmer, respectively. The obtained results agreed with other
studies for dierent grape cultivars (Gaser et al., 2023; Ahmed & Abd
EL-Aziz, 2021; Martin et al., 2020).
Phytochemical composition of grapes pulp and seed extract
Gharibi cultivar exhibited high tannin content in the pulp (0.08
%), and Edkawy and Baltim Eswid cultivars gave high tannin content
in the seed (0.68 and 0.65 %, respectively). Signicant dierences
between the total phenols content (TPC) in the pulp extracts were
observed and there were no appreciable variations in the seed extracts,
which ranged from 1.38 to 1.45 %. The highest TPC in the pulp (0.11
%) was recorded with Baltim Eswid, on the contrary, Romy Ahmer
gave the lowest TPC (0.03 %). Compared to pulp extracts, the total
avonoid content (TFC) was greater in the seed. The highest value
for the TFC in the pulp and seed was found in the Edkawy and Baltim
Eswid (0.058 and 0.08 %, respectively) (Table 2). This result agrees
with those obtained by Wongnarat & Srihanam (2017) who reported
that grape seeds are richer in phenolic compounds than the grape pulp.
This may be due to the seeds acting as a reservoir for the development
of the sprouts (Pająk et al., 2014).
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225 April-June. ISSN 2477-9409.
4-7 |
Table 1. Berry weight, seed yield percentage and seed oil content
for seven local grape cultivars.
Grape cultivars Berry weight (g) Seed yield (%) Seed oil (%)
Gharibi 3.339±0.058d 3.878±0.069a 4.177±0.070d
Fayoumi 3.702±0.115c 2.359±0.023c 4.930±0.069c
Bez El-Naka 4.171±0.068b 2.823±0.064b 5.215±0.058b
Romy Ahmer 3.435±0.029cd 2.799±0.058b 1.696±0.060e
Edkawy 3.675±0.173c 2.454±0.075c 5.701±0.144a
Matrouh Eswid 4.617±0.052a 1.401±0.115e 5.003±0.002bc
Baltim Eswid 4.361±0.058ab 2.123±0.006d 5.787±0.063a
Data are mean value ± SE, dierent letters in the column indicate signicant dierences
(p<0.05).
Generally, antioxidant capacity, represented by DPPH scavenging
activity and ferric reducing antioxidant power (FRAP), of grape seed
extracts was extremely superior comparable to that of the pulp (Table
2). Among all of the cultivars, Baltim Eswid exhibited the highest
antioxidant potential for pulp and seed (0.13 and 48.36 % for DPPH,
0.48 and 51.48 mg.g
-1
for FRAP, respectively), while Gharibi gave the
lowest values for pulp (0.01 % and 0.12 mg.g
-1
for DPPH and FRAP,
respectively), whereas Romy Ahmer was the least for seed (17.92 % and
12.02 mg.g
-1
for DPPH and FRAP, respectively).
Our results agreed with those reported by Wongnarat & Srihanam
(2017) who indicated that, the grape seed extracts contained higher
amounts of total phenol contents than the pulp. Moreover, red grape
cultivars had the highest phenols content followed by white grape
cultivars. Elejalde et al. (2024) concluded that, among the phenolic
compounds, grape seed contains mainly gallic acid, catechin,
epicatechin, procyanidins and proanthocyanidins or condensed
tannins, which are known for their antioxidant activity.
Resveratrol content
The results of HPLC chromatographic of resveratrol content in various
local grape cultivars pulp and seed are presented in Figure (1 A and B).
In general, the grape seed ethanolic extracts showed higher resveratrol
values, which were approximately 12 times (on average) higher than all the
grape pulp extracts. Baltim Eswid gave the highest resveratrol content for
pulp and seed (46.235 and 307.119 mg.100 g
-1
, respectively). On the other
hand, Bez El-Naka and Gharibi showed the lowest values for pulp (7.432
mg.100 g
-1
) and seed (55.271 mg.100 g
-1
). In this regard, Mohammadparast
et al. (2024) concluded that, resveratrol is primarily present in grapes, and
their concentrations can vary depending on grape cultivar.
Phytochemical analysis of grape cultivars seed ethanolic
extract by LC-MS/MS
The proportional composition of the analyzed phytochemicals of
the grape seeds extract (Table 3) revealed many dierences between
the samples in the percentage of polyphenols. Catechins (ctechin and
epicatechin) were the main polyphenolic phytochemicals found in the
ethanolic extract of grape seeds, whose values ranging between 26.51
% in Fayoumi and 35.8 % in Bez El-Naka. According to the standards
used; catechin was higher in Gharibi, Bez El-Naka, Edkawy, Matrouh
Eswid and Baltim Eswid representing 23.2, 22.2, 21.9, 22.1 and 18.0 %,
respectively, while epicatechin was the most in Fayoumi and Romy
Ahmer with 21.7 and 25 %, respectively. Other main compounds
following catechins were caeic in Fayoumi (25.3 %) and Gharibi
(20 %), Narirutin in Bez El-Naka (22.2 %), Edkawy (21.9 %) and
Baltim Eswid (21.3 %), and Rutin only for Romy Ahmer with 18.8 %.
Results are corroborated by earlier studies (Karageçili et al., 2023).
Table 2. Phytochemical composition of grapes pulp and seed extract.
Grape cultivars Tannins (%) TPC (%) TFC (%) DPPH (%)
FRAP (mg.g
-1
)
Pulp
Gharibi 0.08±0.060a 0.05±0.002d 0.004±0.001e 0.01±0.001e 0.12±0.011e
Fayoumi 0.02±0.001ab 0.08±0.006b 0.001±0.001f 0.12±0.002c 0.36±0.017c
Bez El-Naka 0.01±0.001b 0.06±0.001c 0.006±0.002d 0.12±0.001c 0.26±0.013d
Romy Ahmer 0.02±0.001ab 0.03±0.001e 0.006±0.001d 0.04±0.002d 0.14±0.011e
Edkawy 0.02±0.001ab 0.08±0.003b 0.058±0.003a 0.13±0.002b 0.43±0.007b
Matrouh Eswid 0.04±0.001ab 0.09±0.001b 0.031±0.002b 0.13±0.001b 0.43±0.009b
Baltim Eswid 0.02±0.001ab 0.11±0.010a 0.024±0.001c 0.13±0.003a 0.48±0.009a
Seed
Gharibi 0.49±0.012c 1.38±0.045a 0.07±0.001b 29.09±0.36f 25.48±0.44f
Fayoumi 0.33±0.005d 1.44±0.052a 0.05±0.001d 31.41±0.31e 33.47±0.37e
Bez El-Naka 0.45±0.013c 1.41±0.009a 0.07±0.003b 38.50±0.43d 35.74±0.04d
Romy Ahmer 0.34±0.024d 1.42±0.033a 0.05±0.001c 17.92±0.13g 12.02±0.03g
Edkawy 0.68±0.017a 1.38±0.017a 0.07±0.001b 41.78±0.19b
41.65±0.11c
Matrouh Eswid 0.56±0.011b 1.40±0.065a 0.07±0.001b 40.83±0.12c 44.32±0.36b
Baltim Eswid 0.65±0.023a 1.45±0.035a 0.08±0.001a 48.36±0.36a 51.48±0.35a
TPC; Total phenol content. TFC; Total avonoid content. Data are mean value ± SE, dierent letters in the column indicate signicant dierences (p<0.05).
Figure 1. Resveratrol content in local grape genotypes pulp (A)
and seed (B). Bars with dierent letters are signicantly
dierent at p ≤ 0.05.
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Dahab et al. Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225
5-7 |
Table 3. Names, molecular ions, fragment ions and proportional composition of the phytochemicals (%) in ethanolic extract of grape
seeds by LC-MS/MS analytical method.
Analytes %
MI (m/z)
FI (m/z)
Gharibi
Fayoumi
Bez El-Naka
Romy Ahmer
Edkawy
Matrouh Eswid
Baltim Eswid
Maleic
115.2 71.1 2.10 4.81 6.17 6.25 3.29 4.42 4.09
Coumarin
146.5 103 6.31 12.0 2.46 12.5 2.19 5.30 2.45
Gallic
169.2 125 13.7 1.20 2.46 6.25 6.6 5.30 7.37
Caeic 179.3 59 20.0 25.3 14.8 12.5 18.7 18.6 12.3
Catechin
289.2 203 23.2 4.82 22.2 6.25 21.9 22.1 18.0
Isorhamnetin-3-o
D-glucoside
349.3 315 4.21 1.20 9.87 6.25 9.89 13.3 5.73
Epicatechin gallate
439.5 289 5.26 21.7 13.6 25.0 6.59 6.19 12.3
Narirutin 577.7 271 12.6 20.5 22.2 6.25 21.9 12.4 21.3
Rutin 609.5 301 12.6 8.43 6.17 18.8 8.79 12.4 16.4
MI (m/z); molecular ions of the standard analytes (m/z ratio). FI (m/z); fragment ions.
Anti-microbial evaluation
Screening of antimicrobial activity against grape cultivars seed
In the current study, the evaluation of antimicrobial activity by
the agar-well diusion method indicated that all the tested organisms
showed growth inhibition towards the grape seed extract, with
diering sensitivity. Among the bacterial pathogens, B. subtilis is more
sensitive when compared to other bacteria. Gram-positive bacteria
exhibited more sensitiveness to grape seed extracts when compared
to Gram-negative bacteria. The diameters of the inhibition zones
of the microbial growth by the ethanolic extract of dierent grape
seeds presented in table 4 revealed that, the investigated extracts were
potentially eective in suppressing the growth of selected strains
within the range of 11-25 mm.
Baltim Eswid seed extract had the highest growth-inhibitory
action against all tested micro-organisms, with the highest activity
being observed against Candida albicans with an inhibition zone
diameter of 25 mm. On the other hand, Romy Ahmer seed extract
had the lowest growth-inhibitory action against all tested micro-
organisms. In our study the results were similar to those obtained by
Ranjitha et al
. (2014) in grape seed extracts. They reported that, grape
seed extracts inhibited Gram-positive bacteria, such as S. aureus and
B. cereus more easily than Gram-negative ones, such as E. coli.
The partially hydrophobic phenolic contents in grape seeds are
thought to interact with the lipopolysaccharide and bacterial cell wall
interfaces by reducing membrane stability (Shrestha et al., 2012). The
antibacterial capabilities of grape seed extract have been found to be
directly associated with its phenolic content (Baydar et al., 2006).
Minimum Inhibitory Concentration (MIC)
After 18 hours of incubation at 37 °C, the MIC, which is the lowest
concentration of the test substances that prevented observable growth,
was visually ascertained. The results recorded in table 5 showed that,
the MIC of Gram-positive bacteria ranged from 4 - 64 mg.mL
-1
, while
Gram- negative bacteria was 8 - 128 mg.mL
-1
. Baltim Eswid seed
extract was the highest eect on all tested microorganisms with lowest
MIC (4 - 8 mg.mL
-1
). Numerous investigations have demonstrated
the antibacterial action of avan-3-ols. It is possible for catechins to
bind to synthetic lipid bilayers (Caturla et al., 2003). Additionally, it
has been found that epicatechin gallate and epigallocatechin gallate
reduced β-lactam MICs to the antibiotic break point and functioned as
norA gene suppressors, enhancing the antibacterial ecacy of those
antibiotics (Stapleton et al., 2004).
Table 4. Antimicrobial screening of seed ethanolic extract of dierent grape cultivars.
Grape cultivars seed
alcoholic extract
Inhibition zone diameter (mm)
Gram-positive bacteria Gram-negative bacteria Fungi
S. aureus
B. subtilis E. coli
P. aeruginosa
C. albicans
Gharibi
14±0.577c 16±0.58c 11±0.577c 18±0.58ab 15±0.87c
Fayoumi
14±0.289c 18±1.15bc 12±0.578c 19±1.15a 14±0.58c
Bez El-Naka
14±0.577c 19±0.57b 12±0.289c 16±0.57bc 14±1.2c
Romy Ahmer 14±1.155c 16±0.29c 11±0.433c 15±0.29c 13±0.57c
Edkawy
22±1.15ab 22±0.58a 17±0.462b 18±1.2ab 21±1.2b
Matrouh Eswid
20±0.577b 20±1.2ab 16±0.577b 18±0.43ab 20±0.29b
Baltim Eswid 23±0.289a 22±0.87a 21±0.434a 20±0.28c 25±0.58a
S. aureus (Staphylococcus aureus), B. subtilis (Bacillus subtilis), E. coli (Escherichia coli), P. aeruginosa (Pseudomonas aeruginosa) and C. albicans (Candida albicans). Data are mean value ±
SE, dierent letters in the column indicate signicant dierences (p<0.05).
This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2025, 42(2): e254225 April-June. ISSN 2477-9409.
6-7 |
Conclusion
The current study demonstrated that the main phytochemical
components found in the seeds of seven local grape cultivars
-phenols, avonoids, and resveratrol in particular- are superior
to those found in the pulp. The grape seeds showed a high rate of
antioxidant activity in both DPPH radical scavenging and Ferric
Reducing Antioxidant Power assays. The main compounds found
in the ethanolic extract of grape seeds were catechins polyphenolic
phytochemicals. Gram-positive bacteria exhibited more sensitiveness
to grape seed extracts compared to Gram-negative bacteria. Finally,
Baltim Eswid seed extract had the highest growth-inhibitory action
against all tested microorganisms comparing to other tested local
grape cultivars. This study highlights the potential of grape fruits
as a sustainable source of bioactive molecules that contribute to
the health benets. The outstanding antioxidant activity observed
in these local grape cultivars suggests they could play a signicant
role in combating oxidative stress-related diseases. Furthermore, the
antimicrobial properties identied may oer promising avenues for
natural preservative applications and alternative therapeutic options
in food safety and health management.
Funding source
This work was supported by STDF “Science, Technology &
Innovation Funding Authority”, grant number “Prima”, within the
framework of the project freeclimb “Fruit crops resilience to climate
change in the mediterranean basin”.
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