Introduction

Natural products attained from various terrestrial and marine plants were being exploited as a source of classical medicines since archaic times [1,2]. Medicinal plants play an active role as one of the sources of natural products for the treatment and management of debilitating diseases [3]. The use of plant extracts and isolated pure compounds has provided the basis for the production of herbal medicines and phytopharmaceutical compounds [4,5].

Phytochemicals in plant extract encompass several bioactive compounds which exhibits propitious pharmacological activities. These phytochemicals notably cure affliction pertinent to free radicals induced stress, renal, and cardiac complaints and also, function as anti-oxidant, anti-inflammatory, anti-hyperlipidemic and hepatoprotective [6,7]. Moreover, many phytochemicals are naturally materializing antioxidants which are promising reason behind their underlying mechanism in the therapeutic action on various diseases and disorders [8,9]. Advancement of powerful antioxidant molecule is clinching consequence in recent years as it plays the pivotal role in preventing or detaining the onslaught of certain diseased consequences such as nephrotoxicity, hepatotoxicity, and cancer. 

“Medicinal plants functions as eminent antioxidant to scavenge free radicals and have immense importance as therapeutic agent in combating oxidative stress related degenerative ailments” [10,2]. Jasminum auriculatum (F:Oleaceae), is a medicinal plant which is valued for its benefits in the management of various ailments in traditional medicine. Roots are used as regimen in distinct ailments including skin infections especially for ringworm, eye diseases, headache, leprosy, mouth ulcers, renal calculi, burning micturition, wound healing [11]. The roots of the plant were claimed for good ethnomedicinal benefits, however till date there were no reports on phytochemical analysis and in vitro and in silico antioxidant screening roots of Jasminum auriculatum. Hence, the current study is focused to identify the phytoconstituents using HPLC and GC-MS analysis and evaluation of antioxidant activity of roots of Jasminum auriculatum.

Materials and methods

Collection & authentication of plant material

The roots of Jasminum auriculatum were collected from Thalkona forests of Chittoor dist. The collected plant material was authenticated by Dr. Madhavachetty (Botanist). A specimen (Voucher no. 0743) was deposited in herbarium at “Sri Venkateswara University, Tirupati, Andhra Pradesh, India”. The roots were initially washed, shade dried, and grounded in Wiley mill.

Preparation of extract

After collecting of plant material, the roots are separated from it and washed under tap water for 3-4 times and shade was dried. The dried roots were powdered in Wiley mill. The extract was prepared by maceration with ethanol followed by hot extraction for 3 hours. The filtrate was separated and the same procedure was repeated twice. Three filtrates were amalgamated and distilled. The obtained extract was finally stored in desiccator.

Preliminary phytochemical studies

The prepared root extract was examined for active secondary metabolites like alkaloids, tannins, phenolic compounds, steroids, carbohydrates, flavonoids, and glycosides according to the standard methods [12].

HPLC analysis

HPLC qualitative analysis was performed for Ethanol extract of roots of Jasminum auriculatum (EEJA) using C₁₈ Phenomenox 5u, 4.6×250 mm column. Methanol: Water is used as mobile phase. The sample was dissolved in ethanol and injected at volume of 20 μl. Flow rate at 1 mL/min is maintained and detection is carried at 254 nm.

GC-MS analysis

GC-MS analysis of EEJA was performed using Clarus 680 GC. “Gas chromatograph was equipped and coupled to a mass detector Turbo mass gold-Perkin Elmer with turbomass version 5.2.0 spectrometer with an Elite-5MS (5% Phenyl 95% dimethyl Polysilioxane), 30 m x 500 μm id capillary column”. The instrument adjusted to the initial temperature 60 °C. Then, the oven’s temperature was increased to 300 °C at the inclination rate is 10 °C/min, and sustained for 6 min. Helium flow rate was -1.0 mL/min and ionization voltage was –70 eV. The samples at 1:10 were injected at split mode. The compounds’ spectrums were compared with GC-MS NIST (2008) library. Further bioactivity of the compounds was predicted based on Dr.Dukes ethnomedicinal database.

In vitro antioxidant activity

DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay

EEJA in concentrations of 1 to 5 mg/mL was taken and 195 µL of 0.004% (w/v) DPPH was affixed. The mixture then was incubated for 30 min at room temperature in a relatively dark place and absorbance was measured at 517 nm. Ascorbic acid (Vitamin C) was used as the standard. The percentage inhibition is calculated as per the standard methods [13].

ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity:

The working solution was processed by blending 25 mL of ABTS with 0.1 mL of potassium persulfate solution. The mixture was confirmed to revert for 12 h in dark at room temperature. The solution was diluted by combining it with ethanol to attain absorbance of 0.706±0.001 at 734 nm employing spectrophotometer. To 1 mL of the plant extract, 3 mL of ABTS solution was put inside and permitted to react for 6 min. Absorbance was scaled at 734 nm. The ABTS scavenging ability of EEJA was correlated accordingly with ascorbic acid’s and percentage inhibition assessed [14].  

Nitric oxide scavenging assay

EEJA at a concentration of 1 to 5 mg/mL was taken and 1 mL of sodium nitroprusside solution and phosphate buffer was added. The mixture was then incubated for about 2 hrs at 27 °C. This reaction mixture was treated with 1.2 mL Griess reagent. Absorbance was measured at 550 nm and compared with the standard (Ascorbic acid). Using standard formula percentage inhibition was calculated [15].

In silico molecular docking studies

Ligand preparation

The 2D structures of the draw up ligand were computerized in the SDF set out from online data base (Pubchem). These molecules were then processed in Schrodinger Ligprep wizard as per the standard methods and ultimately, ligand directory files were constructed.

Protein preparation

The protein structural codes for the NADH oxidase (NOX 4) (3A1F) and superoxide dismutase (SOD1) (5YTO) were attained out of the protein data bank. The construction of proteins was accomplished by adopting the standard methods [16].

Grid preparation & molecular docking

Using Maestro search grid was prepared for each protein and ligands were docked and the docked conformers were evaluated by availing Glide Score (G).

Results and discussion

Preliminary phytochemical studies

The preliminary phytochemical assessment divulged the presence of varied bioactive phytoconstituents namely flavonoids, tannins, glycosides, steroids, and terpenoids which were immensely beneficial for assessing the pharmacological activity of these roots.

HPLC analysis

HPLC was used for characterization of secondary metabolites in plant extracts [17]. EEJA was subjected to HPLC analysis in solvent system Chloroform: Methanol (7:3). A peak at R_t of 5.189 was identified and it found to be matched with retention time of rutin (Table 1 and Figure 1).

GC-MS analysis of ethanol root extract of Jasminum auriculatum

The identification of 15 phytoconstituents in EEJA by GC-MS analysis confirmed the presence of notable amounts of phytoconstituents which may contribute to various pharmacological activity of EEJA extract (Figure 2 and Table 2).

In vitro antioxidant studies

In pathological states like hypoglycemia, cancer, autoimmune and cardiovascular maladies the fructification of free radicals is overwhelmed [18,19]. These awfully instinctual radicals can oxidatively amend an array of biomolecules, induce to cellular oxidative strain and demise. At these pathological conditions, the endogenous antioxidants will not be sufficient to scavenge the produced free radicals and thus the exogenous antioxidants are required [20,21]. Phytochemicals are naturally befalling antioxidants which could be contemplated as one of the optimistic materials used in indiscriminate pathological conditions with underlying free radicals production [22]. The antioxidant activity of root extract of Jasminum auriculatum was assessed by three different assays and the results are given in Figure 4 and Table 3. The IC₅₀ of EEJA in DPPH was found to be 4.26 mg/mL, in NO scavenging activity 1.35 mg/mL and in ABTS 1.009 mg/mL.

In silico screening

“In silico prediction is a valid alternate to the experimental studies and plays a vital role in selecting hit molecules from huge library in drug discovery process” [23,24]. Molecular docking was carried out to predict the preferred orientation and binding affinity of molecules to a receptor/a binding site/an enzyme. The compounds identified in GC MS and HPLC analysis were docked against two targets (proteins) namely; NADPH oxidase and Super oxide dismutase (SOD). These two selected proteins i.e. NADPH oxidase and SOD play a crucial role in cellular antioxidant complex by aiding in further reducing the oxidized antioxidant molecules and scavenging the free radicals (super oxide anion), respectively. The binding affinity of ligand with proteins was represented in the terms of Glide docking score and mentioned in Tables 4 and 5. The ligand interactions are illustrated in Ligand interaction tool of maestro and it was noticed that with both targeted some compounds exhibiting potent score which were contrasted with the standard. Many compounds demonstrated both hydrogen bond and strong hydrophobic interactions at the active site of proteins. The more negative values of the glide docking score represented tighter binding to the targets. Among all the compounds “Rutin and Trimethyl [4-(2-methyl-4-oxo-2pentyl) phenoxy] silane” displayed the admirable G score with both the proteins (Figure 3).

Conclusion

The findings of the study clearly evidenced potent antioxidant activity in both in vitro and in silico screening which may be due to the presence of bioactive phytoconstituents and the desired antioxidant properties in roots of Jasminum auriculatum. Furthermore, it supports the ethnomedicinal usage of these roots in various diseases associated with the oxidative stress.

Acknowledgements

We like to extend the sincere gratitude to the University authorities of Sri Padmavati Mahila Visva Vidyalayam for providing seed money grant to perform the research activity.

Orcid:

Adikay Sreedevi: https://www.orcid.org/0000-0001-7330-5612

Yellamandayya Vadlamudi: https://www.orcid.org/00000000330537151

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How to cite this article: Adikay Sreedevi*, Sravana Sangeetha, Kamsali Murali Mohan Achari, Kaveripakam Sai Sruthi, Yellamandayya Vadlamudid. Phytochemical, in vitro and in silico screening of roots of Jasminum auriculatum for antioxidant activity. Eurasian Chemical Communications, 2022, 4(8), 768-777. Link: http://www.echemcom.com/article_147984.html

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