The inhibitory or delaying action of both the synthetic chemicals and naturally occurring phytochemicals against oxidative damage to tissues by free radicals produced in biological system of living organisms is known as antioxidant activity. Since some phytochemicals are responsible for biological as well as medicinal activities, nine wild orchids of Nepal were assessed for total polyphenolics and flavonoids content along with the antioxidant activity.
The ethanolic extract of Eria graminifolia pseudobulbs, Gastrochilus acutifolius leaf and root, G. distichus whole plant, Luisia trichorhiza leaf and root, Otochilus albus pseudobulbs, Papillionanthe uniflora whole plant, Pholidota articulata leaf and pseudobulbs, Rhynchostylis retusa leaf, and Trudelia cristata leaf and stem were prepared by Soxhlet extraction.
Phytochemicals were detected by previously established protocols with minor modifications. The total flavonoids were estimated with aluminium chloride method and total polyphenolics content with Folin-Ciocalteu phenol reagent method. Antioxidant activity was assessed by DPPH (2, 2-diphenyl-1-picryl hydrazyl) free radical scavenging assay. There was significant variation of total flavonoids, total polyphenolics content and antioxidant activity among the orchid extracts at P = 0.05. The total flavonoids varied with highest in Rhynchostylis retusa leaf (110.68 ± 4.52 mg QE/g) and lowest content in Gastrochilus acutifolius root (22.32 ± 1.10 mg QE/g); total polyphenolics with highest in Trudelia cristata stem (69.68±2.78 mg GAE/g) and lowest content in Gastrochilus acutifolius leaves (11.89±0.64 mg GAE/g). Also, the antioxidant activity varied with highest in Trudelia cristata stem (IC50 79.69 μg/ml) and lowest DPPH radical scavenging activity in Gastrochilus acutifolius leaf (IC50 341.79 μg/ml). However, none of the orchid extracts were as effective as quercetin – the reference compound – in radical scavenging activity (IC50 32.90 μg/ml). Total polyphenolics and flavonoids content and antioxidant activity of selected
orchid extracts in this study were higher or lower than medicinal plant and orchid extracts of previous studies with considerable margin. Again, their antioxidant activity was positively associated with total flavonoids and total polyphenolics content. [...]
Inhaltsverzeichnis (Table of Contents)
- ABSTRACT
- INTRODUCTION
- REVIEW OF LITERATURE
- Oxidative Stress
- Antioxidants and their Sources
- Mechanism of Antioxidant Action
- Antioxidant Activity of Orchids
- MATERIAL AND METHODS
- Plant Materials
- Chemicals and Reagents
- Preparation of Extracts
- Phytochemical Analysis
- Total Flavonoids Content (TFC)
- Total Polyphenolics Content (TPC)
- Antioxidant Activity
- DPPH Radical Scavenging Assay
- Statistical Analysis
- RESULTS AND DISCUSSION
- Phytochemical Screening
- Total Flavonoids Content (TFC)
- Total Polyphenolics Content (TPC)
- Antioxidant Activity of Extracts
- DPPH Radical Scavenging Activity
- Correlation Studies
- CONCLUSION
- REFERENCES
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This dissertation aims to investigate the antioxidant activity of nine wild orchid species found in Nepal. The study explores the relationship between the total flavonoids and polyphenolics content in these orchids and their antioxidant properties.
- Investigate the antioxidant activity of selected wild orchids of Nepal.
- Determine the total flavonoids and polyphenolics content in the orchid extracts.
- Assess the correlation between antioxidant activity and the levels of flavonoids and polyphenolics.
- Compare the antioxidant activity of the orchid extracts to established reference compounds.
- Explore the potential of these orchids as sources of natural antioxidants.
Zusammenfassung der Kapitel (Chapter Summaries)
The introduction provides an overview of oxidative stress, antioxidants, and their sources. The review of literature delves into the mechanism of antioxidant action and explores previous research on the antioxidant activity of orchids. The material and methods section outlines the experimental procedures, including plant collection, extraction methods, and analysis techniques. Results and discussion present the findings of the study, focusing on the phytochemical analysis of the orchid extracts, their antioxidant activity, and the correlation between these factors. The conclusion summarizes the major findings and discusses the potential applications of the study's results.
Schlüsselwörter (Keywords)
The key focus areas of this dissertation are antioxidant activity, wild orchids, flavonoids, polyphenolics, DPPH assay, Nepal, and ethanolic extracts.
- Quote paper
- Mukesh Babu Chand (Author), 2015, Antioxidant Activity of Selected Wild Orchids of Nepal, Munich, GRIN Verlag, https://www.grin.com/document/379531
