1. INTRODUCTION:

A dysregulation between the body's antioxidant defense systems and the generation of reactive oxygen species (ROS) leads to oxidative stress, which can impair cells and accelerate the onset of chronic conditions like cancer, diabetes, heart disease, and neurological disorders^1-3. Antioxidants are defined as molecules that possess the capability to neutralize free radicals through the donation of electrons, thereby alleviating oxidative damage to biomolecules such as DNA, proteins, and lipids. Given the drawbacks and possible negative consequences of synthetic antioxidants, researchers are becoming more interested in studying natural antioxidants derived from plants as safer substitutes⁴.

Medicinal plants have historically constituted a fundamental component of traditional medicinal systems and are currently undergoing rigorous scientific scrutiny to elucidate their pharmacological potential. A plethora of herbs demonstrate the presence of polyphenolic compounds, flavonoids, and various other phytochemicals, which are endowed with significant antioxidant properties⁵. Among these, Coriandrum sativum (coriander), Aloe barbadensis (aloe vera), Solanum nigrum (black nightshade), and Glycyrrhiza glabra (licorice) are extensively acknowledged for their therapeutic applications and bioactive constituents.

Coriandrum sativum is abundant in essential oils such as linalool, alongside flavonoids and phenolic acids, which have exhibited considerable antioxidant activity in vitro⁶. Empirical investigations have demonstrated that extracts derived from the seeds and leaves of C. sativum possess formidable free radical scavenging capabilities, corroborating their traditional utilization in addressing gastrointestinal and metabolic disorders⁷.

Aloe barbadensis, often known as aloe vera, is used extensively for its antioxidant, wound-healing, and anti-inflammatory properties. The gel's ability to scavenge ROS is mostly due to its bioactive components, which include vitamins C and E, flavonoids, tannins, and anthraquinones^8-10.

Solanum nigrum, a traditional herb utilized in Ayurvedic and Chinese medicine, comprises alkaloids, saponins, and polyphenols that provide hepatoprotective, anticancer, and antioxidant benefits¹¹. Numerous in-vitro assays have substantiated the pronounced free radical scavenging properties of S. nigrum extracts¹².

Glycyrrhiza glabra, commonly known as licorice, is a medicinal root recognized for its anti-inflammatory, immunomodulatory, and antioxidant properties. The flavonoids present, particularly glabridin and liquiritin, inhibit lipid peroxidation and scavenge free radicals, thereby augmenting their therapeutic efficacy in conditions mediated by oxidative stress^13-14.

While each of these herbs has exhibited considerable antioxidant capacity individually, research indicates that the amalgamation of plant extracts may reveal synergistic effects, thereby enhancing their cumulative bioactivity¹⁵. Synergism can manifest when phytochemicals interact in a complementary fashion to stabilize free radicals with greater efficacy than individual compounds can achieve in isolation¹⁶. Notwithstanding this promising trajectory, there exists a paucity of studies that have systematically appraised the combined antioxidant activity of these four herbs. The current study aims to assess the in vitro antioxidant capabilities of Coriandrum sativum, Aloe barbadensis, Solanum nigrum, and Glycyrrhiza glabra, both individually and in combination, utilizing the DPPH radical scavenging assay. This investigation aspires to ascertain whether the synergistic interaction among these herbs exceeds their capabilities and to furnish valuable data for the formulation of multi-herbal antioxidant preparations.

2. MATERIALS AND METHODS:

2.1 Plant Material:

Glycyrrhiza glabra roots, Aloe barbadensis juice, Solanum nigrum fruits, and Coriandrum sativum fruit. Glycyrrhiza glabra roots were sourced from local certified herbal markets of Moradabad (U.P.), India. Botanical identification of all plant materials was confirmed by Professor Vijai Malik, Head of Department, Botany, C.C.S. University, Meerut, Uttar Pradesh, India (Ref. No. Bot/PB/731).

2.2 Preparation of Extracts:

Approximately 30grams of powdered plant material from each sample—Coriandrum sativum (fruit), Aloe barbadensis (juice), Solanum nigrum (fruits), and Glycyrrhiza glabra (roots)—was extracted by hot percolation method using 70% ethanol as the solvent^17-18.

The plant powder was first defatted with petroleum ether to remove lipophilic impurities, then dried at room temperature^18-20. The dried powder was transferred into a Soxhlet extractor and extracted with 300 mL of 70% ethanol for 6–8hours, or until the solvent in the siphon tube became colorless, indicating exhaustion of soluble phytoconstituents.

To eliminate ethanol, the resulting extract was concentrated using a rotary evaporator at 40–45°C under decreased pressure after being filtered with Whatman No. 1 filter paper. After being dried in a desiccator, the semisolid mass was kept at 4°C in an airtight container until it was needed again. This process was carried out once again for every single plant sample²¹.

2.3 Phytochemical Screening:

A qualitative procedure called phytochemical screening is used to find out whether plant extracts contain bioactive substances. These substances, also referred to as phytochemicals, are secondary metabolites that are essential for both human health and plant defense. Alkaloids, flavonoids, tannins, saponins, phenolics, terpenoids, glycosides, and steroids are examples of common phytochemical classes. These substances play a major role in a number of pharmacological actions, including anti-inflammatory, anti-cancer, anti-microbial, and antioxidant ones^22-23.

In the present study, standard phytochemical tests were employed on ethanolic extracts of Coriandrum sativum, Aloe barbadensis, Solanum nigrum, and Glycyrrhiza glabra as recommended by Kokate (2008), and results are presented in Table 1²⁴. The screening involved specific chemical reactions that produce visible color changes or precipitates when particular classes of compounds are present.

2.4 Antioxidant Activity: DPPH Assay (2,2-diphenyl-1-picrylhydrazyl Radical Scavenging Assay):

The DPPH test was used to assess each extract's capacity to scavenge free radicals. Ascorbic acid was utilized as a standard at different concentrations (0.625-100%) and treated with 1 milliliter of buffer. The extract, which was coded AB, SN, GG, CS, and CGSA, was produced in 100 milliliters of PBS buffer. One milliliter of 0.135 mM DPPH solution was then added to this mixture, and it was thoroughly agitated. The material was incubated for 30minutes at 20°C in the dark. At 517nm, absorbance was measured following the incubation period. A freshly made DPPH solution's absorbance at 517nm served as the control^25-28. The following formula was used to compute the percentage of antioxidants or RSA:

% of antioxidant activity = [(Ac-As) ÷ Ac] ×100

Where,

Ac-Control reaction absorbance

As-Testing specimen absorbance

Different concentrations of extract were plotted against %RSA, and a trendline equation was used to calculate IC-50 concentrations for each sample.

2.4.1 Testings:

1. Standard: Ascorbic acid

2. Sample: AB (Aloe barbadensis)

3. Sample: SN (Solanum nigrum)

4. Sample: GG Glycyrrhiza glabra)

5. Sample: CS (Coriandrum sativum)

6. Sample:CGSA (Combination of four phytotherapeutic plants in a 1:1:1:1 ratio)

3. RESULTS AND DISCUSSION:

The present study evaluated the antioxidant activity of individual herbal extracts—Aloe barbadensis (AB), Solanum nigrum (SN), Coriandrum sativum (CS), Glycyrrhiza glabra (GG)—and their polyherbal extract (CGSA) using the DPPH assay, and Ascorbic acid was used as a standard antioxidant reference.

Figure 1: DPPH scavenging curve of standard Ascorbic acid

3.1 Phytochemical Screening:

Table 1 represents the qualitative results of phytochemical screening for ethanolic extracts of four medicinal plants: Coriandrum sativum, Aloe barbadensis, Solanum nigrum, and Glycyrrhiza glabra.

Table 1: Phytochemical screening of selected plants

Phytochemical	*C. sativum*	*A. barbadensis*	*S. nigrum*	*G. glabra*
Alkaloids	+	-	+	+
Flavonoids	++	++	++	++
Saponins	+	+	+	+++
Tannins	++	++	+	+++
Phenolics	+++	+++	++	+++
Glycosides	+	++	++	+
Terpenoids	+	+	+	+
Steroids	+	+	+	+

Symbols indicate the relative presence of different bioactive compounds:

"+": Present ; "++": Moderately present; "+++": Abundantly present; "-": Absent

3.2 Antioxidant Activity Results:

3.2.1 Antioxidant Activity of Ascorbic Acid:

As shown in Table 4, ascorbic acid showed the lowest IC₅₀ and has the highest antioxidant activity (Table 2), and Figure 1 shows the Antioxidant activity curve of standard Ascorbic acid (IC₅₀ = 16.15µg/mL)

Table 2: Absorbance and %RSA values of standard ascorbic acid at different concentrations

Conc. (µg/ml)	Absorbance	% RSA
100	0.209	87.24
50	0.456	72.17
25	0.698	57.41
12.5	0.845	48.44
6.25	0.997	39.17

3.2.2 Antioxidant activity of Plant Extracts:

The overall comparison of four medicinal plants with their combination is summarized in Table 3, Table 4 and Figure 2 shows comparative IC50 values of all sample extracts and standard ascorbic acid by DPPH method.

Table 3: Comparative IC₅₀ values of standard ascorbic acid and phytotherapeutic extracts

S. No	Sample/Extract	Sample Code	IC₅₀ (µg/ml)± SD
1	Ascorbic acid (Standard)	Std	16.15 ± 0.19
2	Aloe barbadensis	AB	1053.57 ± 1.03
3	Solanum nigrum	SN	867.71 ± 2.69
4	Glycyrrhiza glabra	GG	2554.25 ± 14.66
5	Coriandrum sativum	CS	846.73 ± 2.33
6	Combination (1:1:1:1, CGSA)	CGSA	819.13 ± 2.79

Figure 2: Comparative IC₅₀ values of all test samples and standard ascorbic acid by the DPPH method

Table 4: Absorbance and %RSA values of phytotherapeutic extracts at different concentrations

Conc. (µg/ml)	*Aloe barbadensis*	%RSA	*Solanum nigrum*	%RSA	*Glycyrrhiza glabra*	%RSA	*Coriandrum sativum*	%RSA	Combination	%RSA
1000	0.624	48.81	0.568	53.40	0.943	22.64	0.544	55.37	0.523	57.10
500	0.897	26.42	0.728	40.28	1.037	14.93	0.765	37.24	0.767	37.08
250	1.023	16.08	0.857	29.70	1.103	9.51	0.873	28.38	0.883	27.56
125	1.060	13.04	0.893	26.74	1.126	7.62	0.990	18.78	0.967	20.67
62.5	1.073	11.98	0.933	23.46	1.143	6.23	1.004	17.63	0.991	18.70

a) Antioxidant activity of Aloe barbadensis:

Different concentrations of the various Aloe barbadensis extracts were carefully assessed for their antioxidant activity, and the results are shown in Table 3. Figure 3(A) shows the DPPH scavenging curve of Aloe barbadensis extract (IC₅₀ = 1053.57µg/mL).

b) Antioxidant activity of Solanum nigrum:

According to Table 3, SN exhibited moderate activity, and Figure 3(B) demonstrates the Antioxidant activity curve of Solanum nigrum extract (IC₅₀ = 867.71µg/mL)

Figure 3: (A) DPPH scavenging curve of Aloe barbadensis extract, (B) DPPH scavenging curve of Solanum nigrum extract

c) Antioxidant activity of Glycyrrhiza glabra:

Table 3 presents the scavenging efficiency of GG, and Figure 4(A) shows the Antioxidant activity curve of Glycyrrhiza glabra extract (IC₅₀ = 2554.254µg/mL).

d) Antioxidant activity of Coriandrum sativum:

Different concentrations of the various CS extracts were carefully assessed for their antioxidant activity, and the results are shown in Table 3. Figure 4(B) shows the Antioxidant activity curve of Coriandrum sativum extract (IC₅₀ = 846.73µg/mL).

Figure 4: (A) DPPH scavenging curve of Glycyrrhiza glabra extract, (B) DPPH scavenging curve of Coriandrum sativum extract

3.2.6 Antioxidant activity of the polyherbal extract:

Table 3 demonstrates the combined antioxidant effect of four phytotherapeutic plants, and Figure 5 shows the curve of polyherbal combination CGSA (IC₅₀ = 819.127µg/mL).

4. DISCUSSION:

Among the individual extracts, CS and SN exhibited relatively stronger antioxidant potential with IC₅₀ values of 867.71µg/mL and 846.73µg/mL, as shown in Table 3 and Table 4, respectively. The weakest activity was observed for AB (1053.57µg/mL) as shown in Table 4. However, when these extracts were combined into a polyherbal extract (CGSA), a significantly enhanced antioxidant effect was observed, with an IC₅₀ of 819.13 µg/mL, indicating improved radical scavenging efficiency as shown in Table 4 and Figure 2.

This improvement suggests a partial or additive synergistic interaction among the phytochemicals present in the combined extract. Such interactions can potentiate each other's bioactivity by stabilizing free radicals through multiple mechanisms, including hydrogen donation, electron transfer, and metal ion chelation. This aligns with previously reported synergistic behavior observed in polyherbal extract used in conditions related to oxidative stress.

Despite not matching the potent antioxidant activity of ascorbic acid (IC₅₀ = 16.15 µg/mL), CGSA presents a promising natural alternative for antioxidant therapy, especially considering its multi-component origin and potential safety for long-term use. Further in vivo and mechanistic studies are warranted to explore its therapeutic relevance in oxidative stress–mediated disorders.

5. CONCLUSION:

The present study successfully demonstrated the antioxidant potential of individual herbal extracts—Coriandrum sativum, Aloe barbadensis, Solanum nigrum, and Glycyrrhiza glabra—using the DPPH radical scavenging assay. While each extract showed varying degrees of free radical scavenging ability, the polyherbal extract (CGSA) exhibited a notably enhanced antioxidant effect, with an IC₅₀ value lower than any of the individual components. This finding strongly supports the partial or additive synergistic interaction among the phytochemicals present in the Polyherbal extract.

The superior activity of CGSA suggests that blending these medicinal herbs could be a more effective approach for managing oxidative stress than using individual extracts alone. Such synergy offers promising potential for the development of natural antioxidant formulations in therapeutic and preventive healthcare. To confirm these results and investigate clinical applications, more research is necessary, especially in vivo studies and mechanistic analyses.

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Received on 29.08.2025 Revised on 15.12.2025

Accepted on 24.02.2026 Published on 20.05.2026

Available online from May 25, 2026

Research J. Pharmacy and Technology. 2026;19(5):2165-2170.

DOI: 10.52711/0974-360X.2026.00312

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