Irfan Sajid, Shoaib Ahmed et al. Science Reviews - Biology, 2025, 4(1), 8-14

Antioxidant effects following oral administration of

Foeniculum vulgare

in male rats

Irfan Sajid, PhD

*, Shoaib Ahmed, PhD

, Lubna Anis, M.Phil.

, Hafsah Khan,

M.Phil.

, Syed Ikhlaq Hussain, PhD

Department of Biochemistry, Federal Urdu University of Arts, Science and Technology, Karachi

Department of Zoology, Federal Urdu University of Arts, Science and Technology, Karachi

*Corresponding Author: Irfan Sajid (irfan.sajid@fuuast.edu.pk)

https://orcid.org/0000-0002-5547-3492

https://doi.org/10.57098/SciRevs.Biology.4.1.2

Received November 27, 2024. Revised January 04, 2025. Accepted January 07, 2025.

Abstract: Fennel (Foeniculum vulgare), a perennial herb belongs to the carrot family and comprises of

yellow flowers and feathery leaves. Due to highly fragrance, it is widely used in cooking and is one of the

primary components of absinthe. Fennel has become established along roadsides, in pastures, and in various

open areas around the world. Present study was carried out to evaluate the antioxidant effects following fennel

seeds administration in male albino rats. Twelve albino rats were divided into control and tests. Control was

treated with normal saline while treatment was given at concentration of 200 mg/kg/ml of fennel seeds aqueous

solution in oral form for three weeks. Antioxidant activities were evaluated by measuring the levels of

Malondialdehyde, Catalase, Glutathione peroxidase and Glutathione reductase levels in blood. The

administration of fennel seeds significantly enhanced the antioxidant activity showing active action against free

radicals in body. It is suggested that fennel seeds can be used as a functional health boosting meal. Further

neurochemical research is needed to confirm the mechanism at molecular level.

Keywords: Fennel seeds, Catalase, Malondialdehyde, Glutathione peroxidase and Glutathione reductase

Introduction

Herbs have been used as medicine for a long

time; either parts or seeds of plants as phyto-constit-

uents, specifically as medications and other phar-

maceutical products. Different herbs like fennel,

curcumin, black seeds and cardamom are widely

used as medicinal substances (Yang and Shin, 2015).

Cytokines involved in inflammatory reactions are

produced in a sequential order of events. Addition-

ally, its antioxidant characteristics might reduce

stress and stress-related disorders (Koppula & Ku-

mar, 2013). Fennel, Foeniculum vulgare is a medic-

inal plant which has a significant smell, belongs to

the Apiaceae family. It shows properties such as

liver protection, blood clot prevention, antioxidant

defense, bacterial fighting, inflammation reduction,

and fungus inhibition (Rather et al 2016). Several

macromolecules like carbohydrates, protein, fats,

vitamins and minerals are rich in fennel seeds (Bu-

khari et al 2014).

Fennel seeds are found to help reduce neuronal

damage by maintaining stable levels of amyloid pre-

cursor proteins isoforms and oxidative stress markers

(Bhatti et al 2018). It has been observed that fennel ex-

tract has an anti-cholinesterase property and may help

improve memory impairments in Alzheimer's disease

and dementia (Joshi & Parle, 2006). Fennel in the diet,

along with other dietary spices, can lead to a notable

decrease in food transit time, and promote a healthy

appetite and digestion. It contains high levels of ane-

thole spread evenly throughout the plant, but mainly

concentrated in the seeds (Patel and Srinivasan 2001).

The reason for fennel's digestive and carminative ef-

fects is due to this compound, while its delightful fla-

vor and unique scent make fennel a tasty vegetable to

incorporate into dishes. Vegetable charcoal has been

known for its capacity to easily absorb liquid and gases

in the intestines, as well as aiding healthy intestinal

bacteria that enhance proper digestion (Patel and Srini-

vasan 2001; Noreen et al 2023). Some scientists reported

Science Reviews - Biology, 2025, 4(1), 8-14 Irfan Sajid, Shoaib Ahmed et al.

that fennel could remove gas from the digestive system,

releasing the respiratory system and providing a

soothing impact on respiratory disorders; anethole and

fenchone, the key components of its essential oil, have

been proven to have a mucous-eliminating effect on

the respiratory system (Noreen et al 2023). Of medicine,

fennel seeds are boiled in syrups to alleviate cough and

breathing difficulties (Razieh et al 2022). Fennel essen-

tial oil is considered beneficial for treating obesity

(Hossein et al 2016). The weight loss effects of fennel are

thought to be due to appetite suppression. Anetholes

found in fennels could possibly be utilized for the pre-

vention and treatment of cancer (Anand et al., 2008).

Anethole can disrupt TNF signaling, causing activa-

tion of necrosis factors including NF-κB and pro-

grammed cell death. Researchers explained that ane-

thole might inhibit NF-κB-dependent gene expression

triggered by TNF, which regulates the expression of

certain genes related to cancer development and in-

flammation according to (Chainy et al., 2000).

It has been observed that plants that mostly con-

tain hydroxyl groups and isoprene units in their struc-

ture contain antioxidants properties (Manzoor et al.

2022; Süntar 2020). The fennel fruits yield products are

important and contain antioxidant properties (Mata et

al., 2007). Previous studies showed that flavonoids pre-

sent in fennel plants, recognized for their ability to

combat free radicals with antioxidant properties

(Anwar et al 2009). It has been well documented that

significant amounts of overall phenolic compounds

flavonoids present in plant have a capacity of radical

scavenging that can inhibit peroxidation. It has been

reported that reactive oxygen species (ROS) can be

generated in the skin through chemical ionization

and/or UV radiation, as well as enzymatically by pol-

ymorphonuclear leukocytes at infection sites (Goto et

al 2002). Furthermore, it has been found that fennel

seeds enhance catalase activities and increase the levels

of plasma superoxide dismutase, along with an in-

crease in high density lipoprotein-cholesterol level

while the level of malondialdehyde as an indicator of

lipid peroxidation was notably reduced in fennel

treated individuals as compared to control (Eun and

Hwang 2004).

The present study was designed to find out the

antioxidant properties of fennel in albino rats espe-

cially to know the mechanism of action of fennel

against reactive oxygen species that are commonly in-

corporated with environment which could elaborate

about fennel and its beneficial effects in the

development of various medications that are essential

for preserving human health.

Materials and Methods

Fennel seeds used in current study are locally

purchased. Fennel seeds known amount 200mg

soaked in water overnight, and the extract was col-

lected which was used as dose given to the rats follow-

ing the protocol of Sajid et al (2017). Twelve locally

bred Albino Wister rats (150-180g) purchased from

Dow University Ojha Campus. All animals were kept

individually and provided standard conditions with

free access to a rodent diet. Animals were divided into

two groups control and test. Control was given saline

while test animals were given fennel seeds extract and

administered orally for 23 days and were sacrificed at

day. Blood was collected in heparinized tubes to

obtain plasma and immediately was stored for antiox-

idant analysis. All experiments were conducted ac-

cording to a protocol approved by the Institutional

Ethical Care Committee.

Determination of Antioxidant Enzyme Activities

Estimation of activity of catalase, malondialde-

hyde, glutathione peroxidase and glutathione was per-

formed following the protocol as described by Sajid et

al (2017).

Data Analysis

The data was analyzed using by Student’s t-test.

The results are represented as mean ± S.D, and signifi-

cant values are indicated when p<0.05.

Results

The effect of fennel extract on catalase antioxi-

dant enzyme is shown in Fig. 1. Data analyzed by the

t-Test reveals the significant effect on administration of

fennel extract significantly increased (t=-5.61, df=10)

catalase enzyme as compared to control. Malondialde-

hyde (MDA) is a marker of lipid peroxidation showing

oxidative stress and redox signaling studies. A signifi-

cant decrease was found (t=1.45, df=10) under the ad-

ministration of MDA when content LPO had a signifi-

cant effect (Fig. 2). The current findings showed that

fennel administration could be beneficial for mem-

brane structure and helps in more protection against

oxidative damage by free radicles. Similarly, Glutathi-

one Peroxidase; an intracellular antioxidant enzyme

was found significantly increased (t=-2.17, df=10) as

compared to control (Fig. 3). Glutathione reductase en-

zyme was found non-significantly increased (t=-0.42,

df =10) as compared to control (Fig. 4).

Irfan Sajid, Shoaib Ahmed et al. Science Reviews - Biology, 2025, 4(1), 8-14

Figure 1: Catalase enzyme activity in Blood Plasma

Mean ± SD (n=6) analysis by student’s t-test revealed a significant effect (**P<0.01vs control)

Figure 2: Malondialdehyde (MDA) levels in Blood Plasma

Mean ± SD (n=6) analysis by student’s t-test revealed a significant effect (*P<0.05vs control).

Control Test

Plasma Catalase level in mol/ml

Groups

Catalase Activity

Control Test

Malondialdehyde levels in Plasma

Groups

Lipid Peroxidation

Science Reviews - Biology, 2025, 4(1), 8-14 Irfan Sajid, Shoaib Ahmed et al.

Figure 3: Peroxidase Enzyme levels in Blood plasma

Mean ± SD (n=6) analysis by student’s t-test revealed a significant effect (*P<0.05vs control)

Figure 4: Reductase levels in Blood Plasma

Mean ± SD (n=6) analysis by student’s t-test revealed a non-significant effect (P>0.05vs control)

Discussion

The current study revealed that fennel seeds

have a notable effect on catalase, MDA content, and

glutathione peroxidase, while showed no significant

effect on glutathione reductase.

Studies reported that free radicals are reactive

oxygen species (ROS) that can damage cells and are re-

sponsible for many diseases infertility, different carci-

nomas, diabetes, and cardiovascular issues, illness,

getting older, and neurodegenerative diseases (Mata et

al., 2007). The fennel fruits yield essential oil, water,

and ethanol extracts that are important and contain an-

tioxidant properties (Noreen et al., 2023). Furthermore,

it has also been reported that water and ethanol ex-

tracts of fennel show 99.1% and 77.5% peroxidation in-

hibiting in the linoleic acid system, respectively and α-

tocopherol, a natural antioxidant (Ahmed et al 2019).

Both samples demonstrate strong abilities in scaveng-

ing free radicals, superoxide anion radicals, hydrogen

100

120

140

160

180

Control Test

GPx levels in Plasma in nmol/ml

Groups

GPx levels

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Control Test

Enzume levels in Plasma

Groups

Glutathione reductase

Irfan Sajid, Shoaib Ahmed et al. Science Reviews - Biology, 2025, 4(1), 8-14

peroxide, and chelating metals, all of which are closely

related (Oktay et al 2003). The level of concentration

suggests that fennel seeds have the possibility to be a

source of antioxidants that occur naturally. The

present study showed significant effects of fennel on

antioxidant enzyme levels that can be attributed with

the beneficial and protective effect of seeds as reported

in different previous studies to assess the antioxidant

activity of fennel seeds by administering in rats 200

mg/kg/day. Previously it has been shown with a sig-

nificant effect on SOD and catalase levels, while lipid

peroxidation was significantly decreased (Hassan et al

2023). Effects on antioxidant enzymes levels and could

be attributed to a decrease in harmful impact from the

buildup of oxygen radicals that might produce posi-

tive impact on pathological changes, particularly in in-

flammatory conditions. Hassan et al (2023) noted an in-

crease in HDL-cholesterol levels in fennel seeds ad-

ministered group. This HDL effect could be occurring

because it inhibits the oxidative alteration of LDL.

Ragaa et al (2011) identified that fennel seed extract ef-

fectiveness in albino mice for its protective mechanism

in cell and as a non-toxic radioprotector. After admin-

istration of fennel seeds extract, the improvement has

been noticed in liver and tumor tissue of mice with as-

cites carcinoma due to notable rise in MDA levels and

reduction in catalase activity and glutathione Consist-

ently the current findings showed a decrease in MDA

participate in maintaining integrity of membranes of

cell. In recent study glutathione peroxidase has crucial

effect so that the oxidative stress can be reduced by

scavenging of free radicals and conversion of hydro-

gen peroxide radical into water or alcohols fennel

seeds contain these natural antioxidants in large quan-

tity. Due to its high contents of polyphenols and flavo-

noids, this plant can help in inhibiting the production

of free radicals (Parejo et al., 2004b). In the body differ-

ent antioxidants like molecules are involved that can

neutralize reactive molecules. Moreover, Sura et al

(2024) showed a notable increase in Glutathione perox-

idase levels in chicks that consumed fennel seeds,

along with a significant decrease in malondialdehyde;

these alterations may be attributed to fennel's effective

radical scavenging properties. A notable increase in the

functions of antioxidant enzymes was seen in diets that

included fennel (Nickavar and Abolhasani, 2009). Fur-

thermore, Rezq (2013) indicated in past research that

providing diets enriched with varying amounts of

fennel seeds markedly enhanced the serum levels of

Superoxide dismutase (SOD) and Glutathione peroxi-

dase enzyme relative to the control group. Further-

more, it has been reported that dieting chicks with a

high-fat diet enriched with fennel seeds notably low-

ered serum MDA levels in comparison to the positive

control (Rezq, 2013). Flavonoid and phenolic com-

pounds contain antioxidants with a radical scavenging

mechanism, which can potentially change the physio-

logical antioxidant status by increasing GSH-Px and

decreasing malondialdehyde, according to current

findings (Zayachkivska et al., 2005). The current results

also explained beneficial effects of fennel seeds admin-

istration as enhancing activities of antioxidant levels in

blood sample (Mohamad et al 2011). They further con-

cluded in their research that fennel seed extract might

diminish oxidative stress and safeguard mouse cells

from harm induced by reactive oxygen species, and it

may serve as a secure, efficient, and readily available

source of natural antioxidants to enhance the oxidative

stability of fatty foods while in storage. Extracts pos-

sess an antitumor effect by influencing lipid peroxida-

tion and enhancing the antioxidant defense system in

EAC-bearing mice, whether they were exposed to ra-

diation or not. Mohammad et al. (2011) found that the

activities of superoxide dismutase and catalase and

MDA and GSH were enhanced. The current study in

consistence to the findings of Choi et al (2004) revealed

a decrease in MDA contents. Body has its own antiox-

idant defenses to keep free radicals in check and cur-

rent study provides a concept that fennel seeds

strengthen defense system of body.

Conclusion

Present research showed that fennel seeds serve

as excellent sources of vital phytonutrients and phyto-

chemicals as fennel seeds have significant effect on cat-

alase, MDA and glutathione peroxidase levels. Fennel

seeds, thus, can be used as a functional, health boosting

meal. Synthetic drugs possess several side effects that

could be harmful for body, so knowledge of using nat-

ural plants as an alternative medicine for diseases has

been raised. However, the use of fennel seeds as natu-

ral medicine for many years has been acknowledged.

Further neurochemical research is needed to confirm

the mechanism of fennel at molecular level.

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