CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Medicinal plants have been utilised therapeutically since human civilisation began

[1]. Medicinal plants are vital to human and community health. These plants have

therapeutic properties due to chemical compounds that affect the body

physiologically. The most important plant bioactives are alkaloids, tannins,

flavonoids, terpenes, and phenolic chemicals (Lincy et al., 2015). Plants are used

in traditional medicine and pharmaceuticals. Due to the paucity and cost of

orthodox medication, many people worldwide use traditional medicine. Medicinal

plants have given contemporary medicine several medicinal substances.

Phytopharmaceuticals, found in many plants, are significant in agriculture, human,

and veterinary medicine. Novel pharmacological leads for disease therapy and

prevention are mostly derived from natural materials (Uzer et al., 2015). Among

these, leafy vegetables such as Ipomoea batatas (sweet potato leaves) hold

significant promise. While sweet potato roots are widely consumed, the leaves are

often discarded, despite evidence that they contain an impressive range of nutrients

and phytochemicals with potential health benefits. Research indicates that sweet

potato leaves are rich in vitamins, minerals, fiber, and bioactive compounds like
phenolics and flavonoids, which have antioxidant, anti-inflammatory, and

antimicrobial properties (Islam, 2006; Truong et al., 2021).

Phytochemical analysis has become an essential tool in understanding the

nutritional and medicinal potential of plant-based foods. In particular, techniques

like Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform

Infrared Spectroscopy (FTIR) provide detailed insights into the complex chemical

composition of plant materials. GC-MS is widely used to identify volatile and

semi-volatile compounds due to its high sensitivity and specificity. This technique

allows researchers to separate and analyze the individual components in a mixture,

which is invaluable in identifying small bioactive molecules within plant matrices

(Altemimi et al., 2017).

FTIR, on the other hand, offers a complementary approach, allowing the

identification of functional groups in organic compounds through the interaction of

infrared radiation with chemical bonds. FTIR produces a molecular "fingerprint"

based on absorbance patterns, which can reveal the presence of specific bioactive

compounds, such as phenolic acids and terpenoids, that contribute to the health

benefits of leafy vegetables (Nguyen et al., 2020).

1.2 Objective of the Study

The objective of this study is to analyze and characterize the phytochemical

composition of Ipomoea batatas (sweet potato) leaves using Gas Chromatography-

Mass Spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy

(FTIR). Specifically, this study aims to:

i. To identify and quantify bioactive compounds in sweet potato leaves

through GC-MS analysis, focusing on compounds such as phenolics,

flavonoids, terpenoids, and other phytochemicals that may contribute to the

nutritional and medicinal properties of the leaves.

ii. To determine the functional groups present in the leaf compounds using

FTIR, providing insights into the chemical structure and potential health-

related functionalities of these compounds.

iii. To evaluate the potential health benefits of the identified compounds,

especially their antioxidant, anti-inflammatory, and antimicrobial properties,

which could support the use of sweet potato leaves in nutraceuticals and

functional foods.

iv. To promote the utilization of sweet potato leaves by highlighting their

nutritional value, encouraging their use in diets, and potentially reducing

food waste by incorporating this underutilized vegetable into food systems.

1.3 Significance of the Study

Underutilized leafy vegetables like sweet potato leaves have historically been

overlooked in favor of more commonly consumed parts of the plant, such as the

roots. However, recent studies highlight the potential benefits of these leaves in
enhancing dietary diversity, improving nutrition, and contributing to food security.

A study by Mbukwa et al. (2019) noted that many leafy vegetables considered

"underutilized" contain vital nutrients and bioactive compounds that could improve

health outcomes and reduce dependency on conventional food sources. Given their

accessibility and nutrient density, sweet potato leaves can be a valuable addition to

the diets of people in regions where sweet potatoes are grown but where

malnutrition remains a concern.

Despite this potential, there is limited scientific literature detailing the

phytochemical composition of sweet potato leaves, particularly using advanced

techniques like GC-MS and FTIR. This study, therefore, seeks to bridge this

knowledge gap by providing a comprehensive chemical profile of Ipomoea batatas

leaves, focusing on their bioactive compounds and functional groups. By

leveraging the strengths of GC-MS and FTIR, this research will not only contribute

to the body of knowledge on underutilized leafy vegetables but also promote the

sustainable use of plant resources (Nguyen et al., 2020; Truong et al., 2021).

The findings of this study could support initiatives aimed at reducing food waste

by encouraging the consumption of sweet potato leaves and help promote their use

in nutraceutical and functional food products, potentially benefitting public health

and nutrition.
 CHAPTER TWO

LITERATURE REVIEW

2.1 Overview of Sweet Potato Leaves (Ipomoea batatas)

Sweet potato leaves, derived from the plant Ipomoea batatas, are a valuable yet

underutilized part of the sweet potato plant. While the tubers are widely consumed

worldwide, the leaves are often overlooked, despite being nutrient-dense and

loaded with bioactive compounds. They are widely cultivated in tropical and

subtropical regions, and recent research has highlighted their nutritional benefits,
positioning them as a functional food with potential health applications (Islam,

2006; Truong et al., 2021).

Fig 2.1: Sweet Potato Leaves (Ipomoea batatas) (Truong et al., 2021)

2.2 Nutritional Composition

Sweet potato leaves are rich in vitamins such as A, C, and K, as well as essential

minerals, including calcium, iron, and potassium. Additionally, they contain a high

amount of dietary fiber, which can aid in digestive health (Islam, 2006). The leaves

are also a source of protein, making them an important dietary component in

regions with limited access to protein-rich foods. This diverse nutrient profile

suggests that sweet potato leaves can play a role in addressing micronutrient

deficiencies and promoting nutritional security.

2.3 Bioactive Compounds and Health Benefits

In addition to their macronutrient and micronutrient content, sweet potato leaves

are abundant in bioactive compounds such as polyphenols, flavonoids, carotenoids,

and anthocyanins, which have been linked to numerous health benefits.

Polyphenols and flavonoids, for example, exhibit antioxidant properties that help

combat oxidative stress in the body, which is associated with chronic conditions

like heart disease, diabetes, and cancer (Truong et al., 2021; Yahia et al., 2017).

Studies also suggest that these compounds can provide anti-inflammatory,

antimicrobial, and immunomodulatory effects, making sweet potato leave a

promising ingredient for nutraceutical applications (Sun et al., 2014).

2.4 Traditional and Potential Uses

Traditionally, sweet potato leaves are consumed in many parts of Asia and Africa,

where they are often used in soups, stir-fries, and stews. In these regions, they have
been valued for their medicinal qualities, such as promoting digestive health and

treating inflammatory conditions (Islam, 2006). Modern research supports these

traditional uses, and sweet potato leaves are now being investigated as a functional

food that could contribute to the prevention and management of various diseases.

2.5 Current Research and Underutilization

Despite their benefits, sweet potato leaves remain underutilized in many parts of

the world, particularly where the tubers are prioritized. However, increasing

awareness of their nutritional and therapeutic potential has spurred new interest in

studying their phytochemical composition using advanced techniques like Gas

Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infrared

Spectroscopy (FTIR) (Nguyen et al., 2020). This research could help position

sweet potato leaves as a valuable resource in global food systems, encouraging

their inclusion in diverse diets and potentially reducing food waste.

In summary, sweet potato leaves offer a rich nutrient profile and a variety of

bioactive compounds with health-promoting properties. As research continues to

highlight their benefits, they present a promising opportunity for improving

nutrition and health outcomes, particularly in regions where they are readily

available.

2.6 Phytochemicals in Leafy Vegetables

Leafy vegetables are a rich source of phytochemicals—bioactive compounds that

provide health benefits beyond basic nutrition. These compounds, which include

polyphenols, flavonoids, carotenoids, glucosinolates, saponins, and others, play a

significant role in promoting health by reducing the risk of chronic diseases.

Phytochemicals contribute to the antioxidant, anti-inflammatory, and anti-cancer

properties of leafy vegetables, making them valuable in diets and potential sources

for nutraceutical applications (Altemimi et al., 2017; Liu, 2013).

2.7 Types of Phytochemicals in Leafy Vegetables

1. Polyphenols: Polyphenols, including phenolic acids and flavonoids, are among

the most abundant phytochemicals in leafy vegetables. They function as

antioxidants, neutralizing free radicals and reducing oxidative stress in cells. This

oxidative stress is associated with chronic conditions such as heart disease, cancer,

and neurodegenerative disorders (Pandey & Rizvi, 2009). Examples of polyphenol-

rich leafy vegetables include spinach, kale, and sweet potato leaves.

2. Flavonoids: Flavonoids, a subgroup of polyphenols, are widely present in leafy

vegetables and are known for their powerful antioxidant and anti-inflammatory

effects. Specific types of flavonoids, such as quercetin and kaempferol, have been

linked to cancer prevention, improved cardiovascular health, and reduced

inflammation (Knekt et al., 2002). Green leafy vegetables like lettuce, parsley, and
spinach are rich in various flavonoids, which are believed to provide protective

effects against age-related diseases.

3. Carotenoids: Carotenoids, such as beta-carotene, lutein, and zeaxanthin, are

responsible for the yellow, orange, and red pigments in many vegetables. In leafy

greens, they act as antioxidants and have been shown to support eye health and

reduce the risk of age-related macular degeneration (Johnson, 2002). Carotenoid-

rich vegetables like kale and spinach are often recommended for their role in

promoting vision and protecting skin health.

4. Glucosinolates: Cruciferous leafy vegetables, such as kale, arugula, and

cabbage, contain glucosinolates, sulfur-containing compounds that have been

associated with cancer prevention. When these vegetables are chewed or chopped,

glucosinolates are converted into bioactive isothiocyanates, which have been

shown to inhibit cancer cell growth and reduce inflammation (Traka & Mithen,

2009).

5. Saponins: Saponins, which have both antioxidant and cholesterol-lowering

properties, are present in leafy vegetables like spinach and Swiss chard. They have

been studied for their potential to improve immune function and reduce the risk of

certain cancers by preventing the growth of cancer cells (Milgate & Roberts,

1995). Saponins also exhibit anti-inflammatory and antimicrobial effects, adding to

the health-promoting potential of leafy greens.

6. Alkaloids and Terpenoids: Some leafy vegetables contain alkaloids and

terpenoids, which have medicinal properties and contribute to the plant’s defense

mechanisms. Alkaloids like theophylline and caffeine in tea leaves provide

stimulant effects, while terpenoids in herbs such as basil and mint have anti-

inflammatory and antimicrobial properties (Wink, 2015).

2.8 Health Benefits of Phytochemicals in Leafy Vegetables

The phytochemicals found in leafy vegetables have been shown to play protective

roles against numerous chronic diseases. Their antioxidant properties protect cells

from DNA damage, while their anti-inflammatory effects help manage conditions

like arthritis, cardiovascular disease, and metabolic disorders (Liu, 2013). Studies

indicate that diets high in leafy greens are associated with reduced risks of various

cancers, heart disease, and age-related cognitive decline (Liu, 2013; Pandey &

Rizvi, 2009).

2.9 GC-MS and FTIR in Phytochemical Analysis

Phytochemical analysis plays a critical role in understanding the composition and

potential health benefits of plant-based foods. Two powerful analytical techniques,

Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform

Infrared Spectroscopy (FTIR), are frequently used in phytochemical research.

These methods enable the detailed characterization and identification of bioactive

compounds, helping to assess their potential applications in food, nutraceuticals,

and medicine (Altemimi et al., 2017; Rodriguez-Delgado et al., 2015).

2.10 Gas Chromatography-Mass Spectrometry (GC-MS)

GC-MS combines the separation power of gas chromatography with the detection

abilities of mass spectrometry, making it highly effective for analyzing complex

mixtures of volatile and semi-volatile compounds. The technique is widely used in

phytochemical studies to identify and quantify bioactive molecules like terpenes,

phenols, and alkaloids, which play a role in the therapeutic effects of plants (Ajayi

et al., 2017).

In GC-MS, compounds in a sample are first vaporized and separated based on their

volatility in the gas chromatography column. The mass spectrometer then detects

these separated compounds, providing a unique mass spectrum that serves as a

"fingerprint" for each compound. By comparing these spectra with known

databases, researchers can identify individual phytochemicals. GC-MS is

particularly valuable for studying essential oils and other volatile compounds

found in medicinal plants, as it offers high sensitivity and accuracy (Miyazawa et

al., 2016).

2.11 Applications of GC-MS in Phytochemical Analysis

GC-MS has been applied in various studies to analyze bioactive compounds in

plant-based foods. For example, a study by Simopoulos (2016) used GC-MS to

profile the volatile compounds in leafy vegetables, identifying compounds with

potential antioxidant and anti-inflammatory properties. This technique has also

been employed to investigate the phytochemical composition of underutilized

crops, which can help support sustainable agriculture and food security by

identifying new sources of nutrients and bioactive compounds (Altemimi et al.,

2017).

2.12 Fourier Transform Infrared Spectroscopy (FTIR)

FTIR spectroscopy is another essential tool in phytochemical analysis, as it

provides information about the functional groups within a molecule. This

technique measures the absorption of infrared light by molecular bonds, creating

an infrared spectrum that can be used to identify specific chemical groups. FTIR is

particularly useful for identifying phenolic compounds, flavonoids, terpenoids, and

other non-volatile bioactive compounds in plant samples (Dong et al., 2015).

FTIR has the advantage of being rapid, non-destructive, and requiring minimal

sample preparation. This makes it an efficient tool for analyzing plant extracts and

powders. By identifying functional groups, FTIR provides insight into the types of

compounds present, even if it does not provide the specific molecular identity that

GC-MS offers. FTIR analysis has been used effectively to analyze phenolic
content in various leafy vegetables and medicinal plants, identifying the presence

of hydroxyl, carbonyl, and carboxyl groups that indicate antioxidant activity

(Nguyen et al., 2020).

2.13 Applications of FTIR in Phytochemical Analysis

FTIR is often used alongside GC-MS to provide complementary information.

While GC-MS identifies specific compounds, FTIR helps classify compounds

based on functional groups, offering a broader view of the chemical makeup. For

example, using FTIR, Nguyen et al. (2020) were able to analyze the phenolic and

flavonoid content in sweet potato leaves, showing strong antioxidant potential.

This combined approach provides a comprehensive chemical profile, which can be

especially useful in studies of complex plant matrices.

2.14 Combining GC-MS and FTIR for Comprehensive Phytochemical

Analysis

The combination of GC-MS and FTIR provides a powerful toolset for

phytochemical analysis. GC-MS is effective for identifying individual, small-

molecule compounds, particularly volatile ones, while FTIR gives insight into

functional groups in larger or less volatile compounds. Together, they provide a

complete picture of the phytochemical profile of plant materials. This

complementary use of GC-MS and FTIR has been employed in the analysis of
numerous plant-based foods, including fruits, vegetables, and herbs, to explore

their health benefits and potential therapeutic uses (Rodriguez-Delgado et al.,

2015; Dong et al., 2015).