A comparative study of effects of extraction solvents/techniques on percentage yield, polyhenolic composition, and antioxidant potential of various extracts obtained from stems ofNepeta leucophylla: RP-HPLC-DAD assessment of its polyhenolic constituents

Abstract

In the present study, the methanol, chloroform, and hexane extracts were isolated from the stems of Nepeta leucophylla using maceration method, soxhlet extraction method, and ultrasonic assisted extraction method. These extracts were analyzed for their total flavonoids content (TFC), total polyphenolic content (TPC), and antioxidant potential using nitric oxide scavenging (NOS), DPPH˙ (2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging), total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP) assays. The results of percentage yield, TPC, and TFC for various extracts varied from 0.99 to 12.16%, 0.34 to 133.7 mg GAE/g DPE, and 20.21 to 282.74 mg RE/g DPE, respectively, whereas the results of antioxidant potential of TAC, FRAP, percentage inhibition of NO and DPPH˙ scavenging activity ranged from 0.11 to 40.74 mg AAE/g DPE, 4.41 to 148.65 mg Fe (II) E/g DPE, 1.29 to 35.56%, and 14.93 to 90.43%, respectively. Practical applications N. leucophylla is an important wild Himalayan aromatic plant. Traditionally, it is used for the cure of malarial fever and its leaves are consumed as herbal tea. It is also known to have antifungal and antibacterial activity. The present results indicate that the SEM is the best technique for the isolation of naturally occurring antioxidants (NOAs) using methanol as a solvent from the powdered stem of N. leucophylla. Our research findings also indicate that the various extracts obtained from the stem of N. leucophylla show high antioxidant potential (FRAP, TAC, NO, and DPPH˙ radical scavenging activity) and are rich source of different NOAs viz. polyphenolics, flavonoids, coumarins, steroids etc. These classes of NOAs are also well known for their therapeutic potential like antitumor, anti‐inflammatory, antiviral, antimicrobial, and antifungal properties. Hence, the stem of N. leucophylla may play a promising role in health benefits, pharmaceutical, nutraceutical, and functional foods development.

Phytochemical Screening and Antioxidant Activity Study of Methanol Extract of Stems and Roots of Codonopsis clematidea from Trans-himalayan Region

“…alkaloids, glycosides, proteins, phenols, carbohydrates, diterpenoids, triterpenoids and flavonoids using standard qualitative tests. 26 The results were represented as + or -which indicate the presence or absence of classes of compounds in the extracts.…”

“…where: C = total phenolic content in mg GAE/g dry powdered extract, c = concentration of reference standard in mg/mL obtained from calibration curve, v = volume of extract in mL, m = mass of extract in gram. 26…”

“…The flavonoid content was evaluated by aluminium chloride method with slight modifications. 26 One hundred fifty micro liters of different concentrations of standard solution (Rutin trihydrate; 3.906-2000.000 µM) and two extracts were mixed with 600 µL of deionized water respectively, followed by addition of 45 µL of sodium nitrite solution (0.724 M) and incubated for 5 min at RT. Successively, 45 µL of aluminium chloride(0.749 M) was added to each reaction mixture and incubated for 6 min .Further, 300 µL of sodium hydroxide (1 M) was added to each reaction mixture.…”

“…Soxhlet extraction produced the maximum yield as it reduces the viscosity and surface tension of the solvents at high temperature leading to higher perforation of solvent and increases the extraction efficacy of solvents. 26 Though the yield percentage of sonication is lower to maceration the efficacy of sonication is more than maceration technique which can be the effect of acoustic cavitation phenomenon of sonication waves due to which the cell wall disrupts and allows the solvent to penetrate deeply. 42 Phenols are found to be the most widely spread secondary metabolites in the plant kingdom with great recognition as potential natural antioxidants since they were found to have the ability to act as an efficient radical scavenger, metal chelator, reducing agent, singlet oxygen quencher, a hydrogen donor and in other activities of the plant which are associated with the redox properties of these components.…”

Antioxidant Evaluation and Polyphenol Contents of Hydro Ethanolic Extract’s Fractions from Ephedra nebrodensis

“…Medicinal plants are the main source of a variety of biochemicals, i.e. phenolic compounds, flavonoids, terpenoids, and vitamins which are important free radical scavengers 6,7,8 .…”