Antioxidant Activity of Selected Wild Orchids of Nepal

Table of Contents

CHAPTER ONE: INTRODUCTION

1.1. Background

1.1.1. Antioxidants and antioxidant activity

1.1.2. Preliminary phytochemical screening

1.1.3. Determining plant phenolics content and antioxidant activity

1.2. Wild Orchids and their medicinal properties

1.3. Hypothesis

1.4. Objectives

A. General objective

B. Specific objectives

1.5. Rationale of the study

1.6. Limitations of the study

CHAPTER TWO: LITERATURE REVIEW

2. 1. Phytochemical constituents

2. 2. Total polyphenols and total flavonoids contents

2. 3. Antioxidant activity by DPPH assay

CHAPTER THREE: MATERIALS AND METHODS

3.1. Materials

3.1.1. Selected wild orchids

3.1.2. Chemicals used

3.1.3. Orchid samples

3.1.4. Glassware and instruments

3.2. Methods

3.2.1. Collection and identification of plant materials

3.2.2. Drying and extraction

3.2.3. Estimation of dry powder yield

3.2.4. Estimation of extract yield

3.2.5. Reagent preparation

3.2.6. Preliminary phytochemical screening

A. Test for tannins

B. Test for saponins

C. Test for steroids and terpenoids

D. Test for flavonoids

E. Test for alkaloids

3.2.7. Estimation of total flavonoid content

3.2.8. Estimation of total polyphenols content

3.2.9. Antioxidant activity

3.2.10. Statistical analysis

CHAPTER FOUR: RESULTS

4.1. Estimation of dry powder yield

4.2. Extract yield from powdered materials

4.3. Dry extract yield in comparison to fresh material

4.4. Preliminary phytochemical screening

A. Alkaloids

B. Flavonoids

C. Saponins

D. Steroids and terpenoids

E. Tannis

4.5. Total flavonoids content

4.6. Total polyphenols content

4.7. Antioxidant activity

4.8. Relationship of antioxidant activity with total polyphenolics and flavonoids content

CHAPTER FIVE: DISCUSSION

5.1. Preliminary phytochemical screening

5.2. Total flavonoids content

5.3. Total polyphenols content

5.4. Antioxidant activity

5.5. Relationship of antioxidant activity with total polyphenolics and flavonoids content

CHAPTER SIX: CONCLUSION

CHAPTER SEVEN: RECOMMENDATIONS

Research Objectives and Themes

The primary research objective of this dissertation is to evaluate the antioxidant activity of selected wild orchids found in Nepal. By examining their biochemical properties, the study aims to correlate their phytochemical composition, specifically total polyphenolics and flavonoids content, with their free radical scavenging capabilities. The research explores the medicinal potential of these species, many of which have been used in traditional folklore for treating various ailments, while providing a scientific basis for their pharmacological utility.

• Phytochemical screening of various orchid species to detect presence of alkaloids, tannins, flavonoids, saponins, and steroids.
• Estimation of total flavonoids and total polyphenolics content in various orchid parts (leaf, stem, root, pseudobulbs).
• Assessment of antioxidant activity using DPPH (2, 2-diphenyl-1-picryl hydrazyl) radical scavenging assay.
• Statistical correlation between antioxidant capacity and phenolic/flavonoid concentration in the tested extracts.

Excerpt from the Book

Summary of Chapters

CHAPTER ONE: INTRODUCTION: This chapter provides the theoretical foundation regarding antioxidants and their function in plants, specifically focusing on the medicinal properties of wild orchids in Nepal.

CHAPTER TWO: LITERATURE REVIEW: This section surveys existing knowledge on phytochemical constituents in orchids and evaluates previous studies regarding the measurement of polyphenols, flavonoids, and DPPH-based antioxidant activities.

CHAPTER THREE: MATERIALS AND METHODS: This chapter details the plant sample collection sites, specific laboratory protocols for extraction, and the analytical methods used for qualitative and quantitative biochemical assessment.

CHAPTER FOUR: RESULTS: This section presents the empirical data derived from dry powder yield calculations, phytochemical screening, and the concentration-dependent measurements of flavonoids, polyphenols, and antioxidant activity.

CHAPTER FIVE: DISCUSSION: This chapter interprets the experimental findings, comparing the antioxidant efficiency and phytochemical content of the studied orchids against known medicinal standards and prior research.

CHAPTER SIX: CONCLUSION: The study concludes that the selected Nepalese orchids exhibit significant antioxidant potential, which is positively associated with their phenolic and flavonoid content, suggesting future pharmacognostical relevance.

CHAPTER SEVEN: RECOMMENDATIONS: This chapter suggests that future research should focus on isolating biologically active compounds from the most promising species and conducting clinical studies to validate their medicinal claims.

Keywords

Antioxidant activity, Wild orchids, Nepal, DPPH assay, Total flavonoids content, Total polyphenolics content, Phytochemical screening, Ethanolic extract, Radical scavenging, Pharmacognosy, Trudelia cristata, Gastrochilus acutifolius, Medicinal plants, Secondary metabolites, Biochemical evaluation

Frequently Asked Questions

What is the core focus of this research?

The research focuses on assessing the antioxidant activity and phytochemical profile of nine wild orchid species native to Nepal, aiming to understand their potential medicinal value.

What are the primary themes of the study?

The themes include the identification of phytochemical classes (like alkaloids and tannins), the quantification of total phenolic and flavonoid contents, and the evaluation of the free radical scavenging capacity of ethanol-based extracts.

What is the primary objective of this dissertation?

The primary objective is to evaluate the antioxidant activity of selected wild orchids and to determine if there is a correlation between this activity and the concentration of total polyphenols and flavonoids.

Which scientific method is employed for testing?

The study utilizes Soxhlet extraction for obtaining crude extracts, the aluminium chloride method for flavonoid estimation, the Folin-Ciocalteu method for polyphenolic estimation, and the DPPH free radical scavenging assay for antioxidant evaluation.

What does the main body of the work cover?

The main body covers the detailed materials and methods, the analytical results for different orchid parts, and a comprehensive discussion comparing these findings with existing literature on medicinal plants.

Which keywords characterize this work?

Key terms include antioxidant activity, wild orchids, total flavonoids content, total polyphenolics content, DPPH assay, and ethnobotanical studies of Nepalese flora.

How do the results from this study compare to the reference compound?

The study notes that while the orchid extracts show significant radical scavenging activity, none of the tested extracts were as effective as the reference compound, Quercetin.

What relationship was found between total polyphenols and antioxidant activity?

The study found a negative association between IC50 values and phenolic/flavonoid content, indicating that higher concentrations of these phytochemicals lead to a lower IC50 value, which corresponds to higher antioxidant activity.