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ISSN 2449-8955 
European Journal  

of Biological Research 
Research Article 

 

European Journal of Biological Research 2022; 12(3): 282-293 

DOI: http://dx.doi.org/10.5281/zenodo.7274997  

Phenolic profile and biological activities of Aloe 

barbadensis (Miller) from western Algeria 

Firdaous Faiza Fedoul 1*, Boumediene Meddah 1, Mohammed Larouci 1, Aicha Tir Touil 1,                       

Yahya Merazi 2, Yavuz S. Cakmak 3 

1 Bioconversion, Microbiological, Engineering, and Health Safety Laboratory, Department of Biology, Faculty of Nature 

and Life Sciences, University of Mustapha Stambouli Mascara, 29000 Mascara, Algeria 
2 Department of Biology; Faculty of Nature and Life Sciences, University Abdelhamid Ibn Badis Mostaganem, Algeria 
3 Department of Biotechnology and Molecular Biology, Faculty of Science and Letters, Aksaray University, Aksaray, 

Turkey 

* Corresponding author e-mail: firdaous.fedoul@univ-mascara.dz 

Received: 03 April 2022; Revised submission: 15 August 2022; Accepted: 12 October 2022 

 

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ABSTRACT: Aloe vera is widely used in conventional medicine in Algeria to treat various diseases. This study 

aims to evaluate the chemical composition and biological activities of Aloe vera collected from western Algeria. 

Two extracts of ethanolic (EEA) and aqueous (AEA) were used to determine the total phenolic and flavonoid 

content. HPLC was applied to determine the amount of 15 compounds they contain, while the antioxidant 

activity was determined by the DPPH method. The antimicrobial activity experiment was conducted against 

five selected bacterial strains. Finally, an in vivo study on Swiss albino mice was conducted to discover the 

toxicity using Lorke’s method and anti-inflammatory activity using the Carrageenan method. The EEA extract 

shows the highest total phenol content of 37.00±0.37mg GAE/g and total flavonoid content of 9.14±0.19 mg 

CE/g. The AEA contains hydroxybenzoic and benzoic acid with other ingredients (0.84 and 0.82 mg/g, 

respectively). The EEA contains 0.93 mg/g of benzoic acid. Aloe vera has antioxidant activity with IC50 values 

equal to 0.821 mg/ml for EEA and 1.993 mg/ml for AEA. The AEA inhibits E. coli and S. aureus with a 

bacteriostatic effect; EEA is the best inhibitor of S. aureus and S. mutans with the bactericidal effect. Aloe vera 

is practically nontoxic (LD50 is 3800 mg/kg of the AEA and superior to 5000 mg/kg of EEA). The AEA gives 

the best inhibition of edema, 85.96% at (100 mg/kg). Aloe vera leaves are an important resource of polyphenols, 

which have interesting antioxidant power, and antimicrobial and anti-inflammatory activities. 

Keywords: Aloe vera; Antimicrobial; Antioxidant; Anti-inflammatory; HPLC. 

1. INTRODUCTION 

Finding natural and biologically active compounds has always been the goal of the food, 

pharmaceutical and cosmetic industries because of their therapeutic and commercial properties. Many studies 

have proven the existence of various herbals with pharmaceutical effects, but Aloe plants, specifically Aloe vera 

(Aloe barbadensis Miller), are the most commonly applied medicinal plant worldwide. Aloe vera has long been 

utilized in traditional medicine for its curative and therapeutic properties [1]. Aloe vera gel contains over 75 



Fedoul et al.   Phenolic profile and biological activities of Aloe barbadensis 283 

European Journal of Biological Research 2022; 12(3): 282-293 

different bioactive compounds [2], sugar, vitamins and amino acid [3]. It has been an important medicine for 

centuries and is still a common household remedy [4]. 

Moreover, it is an important medicinal plant in the Indian system of medicine [5], the Yemeni culture 

[1] and the Egyptian civilization since ancient times [4]. Thanks to its anti-inflammatory, antimicrobial, and 

cicatrizing properties, A. vera has been traditionally used to cure skin injuries (burns, insect bites, cuts and 

eczemas) and digestive disorders [6]. It is an antioxidant [2] with hypoglycemic agents, hypolipidemic effects 

[7], photoprotective activities and cytotoxic effect [8]. A. vera extract improves insulin secretion and pancreatic 

β-cell function by restoring pancreatic islets [9]. 

A. vera also exhibits anticoccidial activity [10]. It has shown other therapeutic properties, including 

anticancer [6]. Most of the diseases treated with Aloe vera are symptoms of inflammation, microbial infection, 

or the accumulation of oxidants in the organism. 

Thus, it is important to test the antimicrobial activity against five selected microbial strains that cause 

an infection disease and in vivo study of plant toxicity and anti-inflammatory activity. To our knowledge, there 

are no prior reports about an in-depth and sequential study of Aloe vera original in western Algeria. Therefore, 

this study aims to estimate the biological activities, total phenolic contents, and total flavonoid contents into 

ethanolic extracts (EEA) and aqueous (AEA) of A. vera. To consider if a natural composite has an antioxidant 

substance, antibacterial and anti-inflammatory properties, it is important to investigate these activities in vitro 

and in vivo. Our study adopts this approach and it aims at showing the value of TPC, TFC, IC50, MIC, MBC, 

LD50 and inhibition capacity of edema inflammation. Despite the value of this medicinal plant, its high 

biological activity, and its availability, it is not utilized in Algeria as it should be. 

2. MATERIALS AND METHODS 

2.1. Collection of samples 

 The Aloe vera plant was harvested in July 2019 in Sfisef, Sidi Bel Abbes, located in western Algeria 

(35.22683683211121, - 0.3025574118455309) and (latitude 35°13’36.61“ North, longitude 0°18’9.21” West). 

Botany experts at the University of Mascara confirmed the plant. The plant’s aerial part (leaves) was washed 

with distillate water and then shade-dried at 25–35°C for 21 days. Afterward, it was ground in mills (SM-

450TR), then sieved (size 125 μm < ø < 1 mm) to become a fine powder. 

2.2. Extraction 

Ethanolic extract (EEA): Ten grams of powder of dried leaves were extracted with 80% ethanol (1:10 

w/v) (Sigma-Aldrich) and macerated for 24 h in obscurity. The output was then filtered and evaporated with 

rotavapor [11]. 

Aqueous extract (AEA): The aqueous extract was in the form of decoction. A quantity of 50 g of 

powdered leaves was boiled in 500 ml distilled water for 20 min at 80°C [12] (at a 1:10 w/v sample to solvent 

ratio) and followed by filtration and lyophilization to produce a dark brown powder. The yield was calculated 

and stored at 4°C [11]. 

2.3. Determination of total polyphenol concentration (TPC) 

The concentration of total phenolics in the extracts was determined according to the modified method 

of Singleton [13]. Briefly, 100 µl of various concentrations of extracts solutions was added to 500 µl of Folin-

Ciolcalteu (10% v/v) (Sigma-Aldrich), supplemented with 400 ml of 7.5% (p/v) Na2CO3 after 4 min. The 

mixture was agitated for 2 h at room temperature, and the absorbance was recorded at 765 nm. Gallic acid was 



Fedoul et al.   Phenolic profile and biological activities of Aloe barbadensis 284 

European Journal of Biological Research 2022; 12(3): 282-293 

also used as a standard. The concentration of total phenolic compounds in these extracts was determined as mg 

of gallic acid equivalent per 1 g of extract (mg GAE/g extract). All experiments were conducted in triplicate. 

2.4. Determination of flavonoid concentration (TFC) 

The total flavonoid concentration in these extracts was determined according to Zhishen et al. [14]. 

Briefly, 1 ml of 2% AlCl3 in ethanol was added to 1 ml of the extracts (2 mg/ml). After 10 min of incubation at 

room temperature, the absorbance was measured at 430 nm. The catechin (Sigma-Aldrich) was used as a 

standard. In this study, the total flavonoid content is indicated as mg of catechin equivalent per 1 g of extract 

(mg CE/g extract).  

2.5. Determination of antioxidant activity using the DPPH method 

The antioxidant activity was measured through DPPH free radical scavenging assay. The method was 

carried out as described [15]. First, the DPPH solution was prepared by the solubilization of DPPH (Sigma-

Aldrich) (2.4 mg) in methanol (100 ml). Next, 0.05 ml of concentration of each extract (0.01 to 2 mg/ml) (w:v) 

was removed and mixed with the DPPH solution (1.95 ml) in a test tube. After 30 min in a dark room, the 

absorbance of these solutions was read at 517 nm. A duplicate reading was performed for each concentration 

using ascorbic acid as a positive control. The radical scavenging activity was calculated using the following 

formula: the radical scavenging activity (%) = Ac–As/Ac × 100, where Ac is the absorbance of the control 

(DPPH without the addition of test solution), and as the absorbance of the sample. The IC50 value was 

determined graphically from the sigmoidal-shaped curve of antioxidant concentration (µg/ml) versus % 

inhibition. For comparison purposes, the reciprocal 1/IC50 values were used [16]. 

2.6. High-pressure liquid chromatography- diode-array detection (HPLC-DAD) 

The phenolic composition analysis of different extracts was made [17] with slight modifications and 

performed using an HP-Agilent 1290 Infinity HPLC equipped with a C18 column and diode array detector 

DAD. As a mobile phase, 3% acetic acid in (A) water and methanol (B) was used. The injection volumes were 

1 µl, and the extract concentrations were 20 mg/ml. The eluates were detected at 278 nm. The tested samples 

were prepared in methanol, and 20 µl was the injecting volume. The elution gradient was applied at a flow rate 

of 0.8 ml/min is: 93% A-7% B (0.1 min), 72% A-28% B (20 min), 75% A-25% B (8 min), 70% A-30% B (7 

min); and the same gradient for 15 min was 67% A-33% B (10 min), 58% A-42% B (2 min), 50% A-50% B (8 

min), 30% A-70% B (3 min), 20% A-80% B (2 min), and 100% B in 5 min until it reached the end of the run. 

In addition, the standards used were gallic acid, catechin, chlorogenic acid, caffeic acid, hydroxybenzoic acid, 

epicatechin, syringic acid, coumaric acid, trans-ferulic, sinapic acid, benzoic acid, acid hesperidin, rosmarinic 

acid, cinnamic acid and quercetin. In this study, the identification and quantitative analysis are presented by 

comparison to these standards. The quantity of each phenolic compound is expressed as mg per gram of extract 

by external calibration curves, which were evaluated for each phenolic standard [18]. 

2.7. Antimicrobial activity assay and serial microdilution assay 

 Minimal inhibitory and minimal bactericidal concentrations (MIC and MBC) were determined by a 

broth microdilution assay [19] using a 96-well polypropylene plate and Mueller-Hinton broth. After 24 h at 

37°C, the MIC was the lowest substance concentration that inhibited visible bacterial development in the well. 

Similarly, the MBC was defined as the lowest concentration yielding negative subcultures for 24 h of a 10 µl 

aliquot withdrawn from each well that expresses no bacterial growth. They were subcultured in MH agar. The 

experiment was carried out in triplicate. The MBC/MIC report of extract provides information on the 



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European Journal of Biological Research 2022; 12(3): 282-293 

antimicrobial power. Indeed, when this ratio is equal to or less than 4, the extract is bactericidal while when it 

is greater than 4, the extract is bacteriostatic. 

2.8. Bacteria and growth conditions 

Five microorganism species were employed as test organisms: Escherichia coli ATCC 25922, 

Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25175, Bacillus cereus  ATCC 6633 and 

Candida albicans ATCC 10231 (Laboratory for Research on Local Animal Products, Ibn Khaldoun Tiaret). The 

strains were in Eppendorf tubes, each containing a bacterial culture preserved in nutrient broth supplemented 

with 30% glycerol and maintained at -20°C. A volume of 100 μl of each tube was transferred into the BHI broth 

(Brain heart infusion) and then incubated at 37°C. After 24 to 48 h, the referenced strains developed, indicating 

their reactivation and that they were ready for use.  

2.9. In vivo study 

2.9.1. Experimental animals 

 Swiss Albino mice were left at room conditions in polypropylene cages for acclimatization within 7 

days [20] (T 25 ± 2°C) and a 12 h light/dark cycle, with liberated access to standard pellet diet and water 

throughout breeding. The weight of the mice used was between 25–30 g. The animals fasted for 16 h before 

each experiment with free access to water. All the experimental protocols were prepared and performed based 

on the ethical guidelines of the Institutional Animal Ethical Committee of Mascara University, Mustapha 

Stambouli (ARECM), according to the Adelaide University Animal Ethics Committee (Ethics number 

M/76/98). 

2.9.2. Extract toxicity 

 Lorke’s method was used to determine the extract toxicity in two phases. During the first phase, nine 

animals were divided into three groups, i.e., three animals per group (n=3). Afterward, each group was 

administered a different dose intra-peritoneal (10, 100 and 1000 mg/kg) of extract mixed with a saline solution 

of 0.9%. Subsequently, they were put under observation for 24 h to scrutinize their comportment and mortality. 

The second phase involved using six animals, distributed into three groups of two animals each [21]. Then, we 

applied to each group different doses of intra-peritoneal (1600, 2900 and 5000 mg/kg) extract mixed with a 

saline solution of 0.9%. After that, the animals were inspected every 10 mins, followed by 24, 48, and 72 h 

observations of any changes in motor activity, respiration, writhing, and piloerection. The LD50 was calculated 

using the basic formula of Lorke: 

LD50=√axb, where a=highest non-lethal dose, b= least lethal dose. 

2.10. Anti-inflammatory activity 

Carrageenan (Sigma-Aldrich Co. (St. Louis, MO, USA) induced hind paw edema exemplar was used 

for the anti-inflammatory activity [22]. It is a useful model to detect the action of anti-inflammatory agents. The 

animals, Swiss albino mice (25–30 g), were divided into 4 groups (n = 6) and treated by intraperitoneal injection 

with saline 0.9% (control group), aqueous extract with (100 mg/kg), ethanolic extract (100 mg/kg) and 

(experimentation groups) 60 min after the administration of a test sample. Each mouse was injected with the 

freshly prepared suspension of carrageenan (1%) in physiological saline into the subplantar tissue of the right 

hind paw. After the control was injected (group control), the measure of paw edema was achieved every 60 min 

for 6 h after the induction of inflammation. Diclofenac (10 mg/kg) (Saidal, Algeria) was used as the reference 

drug [23]. The difference in foot-pad thickness was scaled by a gauge caliper (Fischer Darex). The mean values 



Fedoul et al.   Phenolic profile and biological activities of Aloe barbadensis 286 

European Journal of Biological Research 2022; 12(3): 282-293 

of treated groups (six animals in each group) were compared with those of a control group and analyzed using 

statistical methods. 

2.11. Statistical analyses 

The data are presented as the mean ± SEM (standard error of the mean) or mean ± SD (standard 

deviation). The differences between the means were evaluated through the analysis of variance (ANOVA), 

followed by Dunnet’s test. The statistical differences are considered significant, with P <0.05 [24]. 

3. RESULTS AND DISCUSSION 

Table 1 lists the results of extraction yield water extracts and ethanolic extract of A. vera leaves. 

Accordingly, the extraction procedure using the ethanol solvent shows that the crude extract of the A. vera 

leaves (11.11 ± 0.16%) is superior to the one obtained by aqueous extract (9.11±1.19 %) AEA<EEA. In the 

study [8], the yield of the aqueous extract is 13.56 ± 0.78%, and solvent extraction is 20.56% ± 0.38. Ethanol 

is still considered the best solvent for the extraction of A. vera [25]. The reasons why ethanol extraction gives 

superior yields may be attributed to the followings: (i) the use of an organic solvent that can easily be evaporated 

than water, (ii) the high concentration used (80% ethanol) and (iii) most components of this plant are organic 

compounds that easily dissolves in an organic solvent.  

The total phenolic contents of plant extracts are observed to be a maximum of 37.00±0.37 mg GAE/g 

of EEA. However, the TPC of AEA is 16.23±0.47 mg GAE/g (Table 1), AEA<EEA. The ethanolic extract of 

Tunisia Aloe showed the highest total phenolic (40.500 ± 0.041 µg GAE/g of extract) [26]. The value of total 

flavonoids is observed to be higher, that is, 9.35 mg CE/g obtained from ethanolic A. vera extract. The aqueous 

extract gives 4.06±0.07mg CE/g. (Table 1) AEA<EEA. The results obtained in Nepal [12] show that TPC is 

equal to 54.95±2.46 (mg GAE/g), and TFC equals 1.13±0.19 (mg QE/g) in ethanolic extract. The Yemeni AVG 

contains a total phenolics of 97.2±12.0 mg/g; total flavonoids of 9.27±1.07 mg/g [1]. 

 

Table 1. The yields, total phenolic, total flavonoid contents, total antioxidant activities, IC50 and the equations of the 

graphics. 

Aloe vera (A. barbadensis Miller) 

Type of extract AEA EEA 

Yield % 9.11±1.19 11.11±0.16 

TPC (mg GAE/g extract) 16.23±0.47 37.00±0.37 

TFC (mg CE/g extract) 4.06±0.07 9.14±0.19 

Total antioxidant activity% 29.33±0.57 58.38±1.99 

IC50 µg/ml 199.305 82.107 

1/IC50 µg/ml-1 0,00501744 0,0121792 

Y=ax+b 0.19x+12.238 0.3018x+25.22 

R2 0.9827 0.987 

The results are the average of three determinations± standard deviation. AEA: Aqueous Extract of Aloe vera. EEA: Ethanolic Extract of 

Aloe vera. TPC: Total phenolic content (mg GAE/g extract). TFC: Total flavonoid content (mg CE/g extract) Total antioxidant activity % 

at 100 µg of extract. IC50: The concentration of drug required for 50% inhibition. GAE/g: Gallic acid equivalents/g of extract. CE/g: 

Catechin equivalent/g. 

 

 



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3.1. DPPH radical scavenging activity assay 

The results show a considerable diversity of the capacity to scavenge free radicals between extracts and 

ascorbic acid when its capacities show the strongest DPPH scavenging capacity is 98.39% at 2 mg/ml, with 

IC50 of 0.42 mg/ml and (R²=0,9973). The extract exhibited DPPH scavenging capacity assay demonstrates that 

the maximum inhibition is the EEA (58.38±1.99%) at 2 mg/ml, with IC50 of 0.821g/ml and (R²=0.987). On the 

other hand, the minimum inhibition showed by AEA (29.33±0.57%) at 2 mg/ml with IC50 values equal to 1.993 

mg/ml. The rapport (1/IC50) is present in Table 1. 

The ethanolic extract of Tunisia Aloe showed an antioxidant capacity (471.3± 0.013µg/ml) [26], which 

means that it has a higher antioxidant capacity than Algeria Aloe. Therefore, it explains that the high amount 

(37.00±0.37mg GAE/g) of polyphenols positively affected the antioxidant capacity. The antioxidant activity of 

plant materials is closely related to the content of their phenolic compounds [27]. If a bad inhibition of radicals 

happens, the phenomenon of transient cavitation initiates chemical reactivity through thermolysis, supercritical 

water oxidation and free radical oxidation. The impact of thermolysis but also the generation of hydrogen ions 

(H+), free radicals (O−, OH− and HO2−) and hydrogen peroxide (H2O2) [28]. The radical scavenging activity of 

the extracts could be related to the nature of phenolics and their hydrogen-donating ability. 

3.2. High-pressure liquid chromatography-diode-array detection (HPLC-DAD) 

The analysis of HPLC of the extracts of 15 compounds (gallic acid, catechin, chlorogenic acid, caffeic 

acid, hydroxybenzoic acid, epicatechin, syringic acid, coumaric acid, trans ferulic acid, sinapic acid, benzoic 

acid, hesperidin, rosmarinic acid, cinnamic acid and quercetin) was investigated for each extract. Table 2 lists 

the amount of each phenolic compound expressed as mg per gram. The results show that 14 of these 15 

compounds are identified in the aqueous extract of Aloe vera (Table 2, Figure 1). Hydroxybenzoic acid and 

benzoic acids are the most abundant components accounting for 0.84 mg/g and 0.82 mg/g extract, respectively. 

 

Table 2. Chemical composition of aqueous extract of Aloe vera ( AEA) from Algeria. 

Peak Ret Time (min) Area [mAU.s] 
Quantity 

(mg/g of extract) 
Identification 

1 4.359 802.10480 0.84 Hydroxybenzoic Acid 

2 3.436 1578.86145 0.82 Benzoic Acid 

3 13.197 1114.65344 0.46 Catechin 

4 80.963 107.76672 0.27 Gallic Acid 

5 3.973 304.65063 0.20 Chlorogenic  Acid 

6 7.762 1143.38696 0.17 Coumaric acid 

7 12.743 313.83231 0.15 Epicatechin 

8 79.919 672.40771 0.15 Rosmarinic acid 

9 4.494 499.51447 0.14 Syringic Acid 

10 24.267 199.43004 0.12 Trans-Ferrulic Acid 

11 15.935 246.26178 0.11 Quercitin 

12 35.461 1223.61169 0.10 Cinamic Acid 

13 16.961 29.27682 0.08 hesperidin 

14 77.218 274.47412 0.02 Sinapic Acid 

Total identified 
Total of phenolic acids 

Total of flavonoids 
Total of phenolic compound 

14 compounds 
3.63 mg/g of extract 
0.80 mg/g of extract 
2.83 mg/g of extract 

 



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Figure 1. HPLC chromatogram of aqueous extract of A. vera (AEA). 

 

In the ethanolic extract (Table 3, Figure 2), 14 components are determined, and benzoic acid is the most 

abundant compound in this extract at 0.93 mg/g. Compared to previous studies, the GC MS analysis of Aloe 

vera results in some important constituents, such as benzoic acid [29]. The HPLC-UV and LC-MS of the Yemeni 

Aloe vera show anthrones and chromones as the main components [1]. With reversed-phase high-performance 

liquid chromatography (RP-HPLC), A. vera extracts are characterized by the abundance of catechin, sinapic 

acid and quercitrin. Gentisic acid, epicatechin and quercitrin are the most prominent phenolic compounds of 

the flowers [30].  

Table 3. Chemical composition of ethanol extract of Aloe vera from Algeria. 

Peak Retention Time (min) Area [mAU.s] 
Quantity 

(mg/g of extract) 
Identification 

1 3.826 750.39935 0.93 Benzoic Acid 

2 15.454 85.55801 0.29 Quercitin 

3 4.285 323.12646 0.27 Hydroxybenzoic Acid 

4 85.891 1066.77112 0.25 Trans-Ferrulic Acid 

5 79.784 257.47772 0.20 Rosmarinic acid 

6 16.962 43.45979 0.15 Hesperidin 

7 24.331 881.78558 0.14 Chlorogenic  Acid 

8 12.764 18.22491 0.09 Catechin 

9 4.368 374.07138 0.08 Syringic Acid 

10 77.222 251.01648 0.07 Sinapic Acid 

11 80.250 127.87583 0.07 Coumaric acid 

12 83.895 121.82565 0.03 Gallic Acid 

13 82.455 108.61681 0.03 Cinamic Acid 

14 74.372 13.50143 0.02 Caffeic acid 

Total identified 
Total of phenolic acids 

Total of flavonoids 
Total of phenolic compound 

14 compounds 
2.62 mg/g of extract 
0.53 mg/g of extract 
2.09 mg/g of extract 

 



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European Journal of Biological Research 2022; 12(3): 282-293 

 
Figure 2. HPLC chromatogram of ethanolic extract of A. vera (EEA). 

3.3. Antibacterial activity assay 

Antibacterial activity assay  and serial microdilution assay. The antimicrobial activity of all plant 

extracts is evaluated against four pathogenic bacterial strains and one fungal strain. The antimicrobial effect of 

herbal plant extracts is evaluated in terms of MIC and MBC of microbe’s development, as presented in Table 

4. Results revealed that aqueous extracts are more effective against microbes than ethanolic extracts. All the 

extracts of Aloe show better antibacterial and antifungal activity. The AEA inhibits E. coli ATCC 25922, S. 

mutans ATCC 25175 and C. albicans ATCC 10231, with MIC ranging from 12.5 to 100 µl/ml with bacteriostatic 

effect against E. coli and bactericidal effect against other strains (Table 4). EEA is the best inhibitor of S. aureus 

ATCC 25923. The same result was reported [5]. The aqueous extract effectively inhibits the growth of B. 

subtilis, S. aureus, and C. albicans.  

 

Table 4. The minimal inhibitory concentrations (MICs) and  (MBCs) of extracts against bacteria and yeast. 
 

MIC μl/ml MBC μl/ ml MBC/MIC ratio 

AEA EEA AEA EEA AEA EEA 

Escherichia coli ATCC 25922 25 12.5 100 50 4 4 

Staphylococcus aureus  ATCC 25923 12.5 50 50 100 4 2 

Streptococcus mutans  ATCC 25175 50 25 100 25 2 1 

Bacillus cereus ATCC 6633 100 6.25 200 50 1 8 

Candida albicans  ATCC 10231 100 100 200 100 2 1 

MIC: Minimal inhibitory concentrations MBC: Minimal bactericidal concentrations. MBC/MIC ratio ≤2: bactericidal effect. MBC/MIC 

ratio ≥ 4: bacteriostatic effect. AEA: Aqueous Extract of Aloe vera. EEA: Ethanolic Extract of Aloe vera. 

 

The EEA is the best inhibitor of S. aureus ATCC 25923 with a MIC of 50 µl/ml and a bactericidal effect 

(Table 4). In the study [31], Aloe has an effect on the three bacterial organisms, S. pyogenes, S. aureus and E. 

coli. A. vera leaf gel can relates the development of the Gram-positive bacteria. A. vera gel inhibited (79%) in 

vitro growth of E. faecalis [4]. 

The fresh ‘juice’ from cut leaves down S. aureus, but the activity is unstable unless the extract is 

refrigerated, heated, and then freeze-dried. The freeze-dried extract inhibited some species of Staphylococcus 

and Streptococcus [4]. Aloe vera contains six antiseptic agents (sulfur, lupeol, salicylic acid, cinnamic acid, urea 

nitrogen and phenol), which act as a team to provide antimicrobial effects [5]. Specific plant compounds such 

as anthraquinones, dihydroxy anthraquinones, and saponins have been suggested to have direct antimicrobial 



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European Journal of Biological Research 2022; 12(3): 282-293 

activity [6, 23]. This effect may be due to the existence of benzoic acid and hydroxybenzoic acid in these extracts 

because the benzoic acid and hydroxybenzoic acid showed an inhibition for all the microorganisms tested: 

Bacillus subtilis, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and 

Candida albicans [32]. 

3.4. Toxicity of extracts 

In the acute extract toxicity study, no mortality was observed in all mice 24 h after testing extracts at 

600 mg/kg, and 1000 mg/kg and no mortality was recorded in mice tested at 5000 mg/kg EEA. One mouse died 

at doses from 5000 mg/kg of the AEA. The lethal dose is 5000 mg/kg. The LD50 is equal to 3800 mg/kg of the 

AEA, and the lethal dose of the EEA is superior to 5000 mg/kg. Aloe vera caused moderately adverse effects 

[4]. These extracts are practically nontoxic according to Hodge and Sterner toxicity scale. 

3.5. Anti-inflammatory activity 

The anti-inflammatory activity of AEA and EEA against carrageenan-induced paw thickness is 

represented in Table 5, and the inhibition of edema is presented in Figure 3. In the control group of this study, 

the edema volume increased progressively depending on the number of hours (Figure 4), reaching its peak at 4 

h after the carrageenan injection. Besides, the AEA at 100 mg/kg gives the best inhibition of 85.96% of edema 

after 6 h of induced carrageenan. The EEA inhibits 83.51% of edema. All inhibitions are less than the standard 

of 10 mg/kg, inhibiting 90.87% of edema paw. 

 

Table 5. Anti-inflammatory of extracts on paw edema induced by carrageenan in mice. 

 
Paw Thickness (mm) 

h0 h1 h2 h3 h4 h5 h6 

Control 1.91±0.04 2.07±0.09 3.24±0.24 3.37±0.25 3.57±0.06 3.89±0.11 3.88±0.07 

Standard 1.92±0.02 2.05±0.08 2.85±0.10* 2.78±0.15*** 2.73±0.17*** 2.49±0.08*** 2.10±0.06*** 

AEA 1.89±0.05 2.02±0.10 2.92±0.10* 2.67±0.24*** 2.52±0.29*** 239±0.26*** 2.17±0.16*** 

EEA 1.93±0.05 2.04±0.05 2.84±0.17* 2.74±0.29*** 2.51±0.37*** 2.34±0.43*** 2.25±0.42*** 

Mean ± SEM (n = 6); Control: vehicle (NaCl, 0.9%); Standard: Diclofenac 10 mg. h: hour. *p<0.05;***p< 0.001 significance (comparison 

with control group). AEA: Aqueous Extract of Aloe vera. EEA: Ethanolic Extract of Aloe vera. 

 

The AEA and EEA (100 g/kg) give a good inhibition of edema better than diclofenac (10 mg/kg) from 

the 3rd hour (2.67±0.24 mm, 2.74±0.29 mm and 2.78±0.15 mm, respectively) to the 5th hour (2.39±0.26 mm, 

2.34±0.43 mm and 2.49±0.08 mm, respectively) after inducing the carrageenan (Figure 4). The treatment of 

mice with the two extracts at a dose of 100 mg/ml show a highly significant decrease in edema (p< 0.001) from 

3 h compared with the control. Meanwhile, the same could be observed for diclofenac compared with the 

control. This indicates that it has a faster effect, whereas diclofenac has a good effect when it reaches the 6th 

hour. 

This significant activity of all the extracts and standard drugs highlighted in this study may be due to 

the inhibition of mediators of inflammation such as histamine, serotonin, and prostaglandin. The extracts’ anti-

inflammatory activity results can be attributed to their main compounds: hydroxybenzoic and benzoic acids. 

Plant benzoic acids [11] and their derivatives are common and widespread mediators of plant responses to biotic 

and abiotic stress [33]. The biosynthesis of all plant benzoic acids and their products ultimately starts from the 

shikimate pathway [34]. Benzoic acid converts to salicylic acid in plants [35]. Many natural products obtained 

from plant benzoic acids or have benzoyl/benzyl moieties are also of medicinal or dietary value to humans [34]. 



Fedoul et al.   Phenolic profile and biological activities of Aloe barbadensis 291 

European Journal of Biological Research 2022; 12(3): 282-293 

Carrageenan-induced paw edema is a usually utilized experimental model of acute inflammation represented 

by a biphasic development of edema. The first phase (1–2 h) depends on mediator release, e.g., histamine, 

serotonin, and bradykinin [36]. At the same time, the second phase (3–6 h) is sustained by the release of 

prostaglandins, leukotrienes, lysozymes, proteases, nitric oxide and by local infiltration by neutrophils 

producing free oxygen radicals, e.g., O2- and OH [37]. 

In a carrageenan-inflamed synovial pouch model of inflammation, a 10% A. vera treatment of synovial 

pouches reduces vascularity by 50% and the number of mast cells in synovial fluid by 48%. However, the aloin 

and aloe-emodin, two anthraquinones present in the exudate, are pronounced to cause anti-inflammatory effects 

by inhibiting inducible nitric oxide synthase (iNOS) and COX-2 expression [4].  

4. CONCLUSION 

The study demonstrates that the yield, total phenolic content, total flavonoid continent and antioxidant 

activity are higher in the ethanolic extract of Aloe vera compared to the aqueous extract of Aloe vera. 

Nevertheless, the aqueous extract is the best antimicrobial, so four of five bacteria are sensitive to the aqueous 

extract (diameter greater than 15 mm) and anti-inflammatory based on the percentage of edema inhibition. Our 

results confirm the correlation between phenolic content and antioxidant activity. This plant could treat various 

infections caused by microbes and reduce inflammation. 

Authors' Contributions: FFF practiced laboratory experiments and wrote the article. MB, ML and AT elaborate on a 

research plan and correct the article. MY performed the antimicrobial activity. YSK analyzed and interpreted the HPLC of 

extracts. All authors read and approved the final version of the manuscript. 

Conflict of Interest: The authors declare no conflict of interest.  

Acknowledgement: We thank Pr Benhassaini Hachemi of the University of Sidi-Bel-Abbes, Algeria, for the plant 

identification. We also want to thank Dr. Hamed Djahira, engineer of the research laboratory of the University of 

Mostaganem, Algeria. 

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