The History Of Plants Biology Essay

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Prehistoric people primarily depend on plants for their survival including food, medicine and shelter but with the passage of time and advancements in science, man explored the potential of plants for a number of other purposes thus increasing their dependency on plants both directly and indirectly. Wild plants have always been the matter of high concern and used for their potential of human beings [1]. Initially, the knowledge of plants is based on error and trial and the authentic knowledge of the uses of medicinal plants passed on after refining and additions from one generation to the other [2]. Medicinal plants provide a real alternative for primary health care system in the developing countries [3]. Products from hundreds of species are being collected from meadows and remote forests and which is later on traded to international markets and consumed [4]. These practices provide an important source of income to the huge number of rural households. About world's 70- 80% population use medicine for curing different ailments and illness [5].In developed countries, the percentage of people using traditional medicine have been decreased due to the availability of health facilities [6]. Certain areas in Himalayan Mountains are yet to be documented in the indigenous uses of the medicinal plants [7].

According to World Health Organization (WHO) "a medicinal plant is a plant which contains substance in one or more of its organs and that can be used for therapeutic purposes, or which are precursors for chemo-pharmaceutical semi-synthesis" [8]. According to the National Cancer Institute (NCO), in the last 25 years at least 70 percent of new drugs introduced in the United States are derived from natural sources [9]. It has been estimated from the literature that there are about 35,000 to 70,000 plant species that have been used in one or another culture for medicinal purposes at one or the other time in the world. At least 6,500 plant species are used alone for various ailments as home remedies in Asia [10].

1.2 Medicinal Plants in Pakistan Pakistan is a rich source of herbs due to variety of its climate and that are distributed over a wide range and used for medicines.. About 600 plant species have been identified as having medicinal values [11]. In Pakistan, primarily medicinal plants are used by Tibbia Dawakhana (herbal medical centers of indigenous physicians known as "Hakims"). In ayurvedic system of herbal treatment, pharmaceutical industries are being used for the extraction of various ingredients commercially [12].

Medicinal plants in Pakistan are considered to be of two broad categories.

Firstly, those plants which are used in various formulations by local physicians in order to provide some relief to the local population in the developing countries.

Secondly, those plants which are in demand for their active ingredients by pharmaceutical companies [13].

Plants have been used to cure diseases for a very long time. The use of commmonly available medicinal plants remains an important for human health care, especially for the people living in rural areas due to their inability to afford the costly and synthetically prepared medicines. Since the ancient times, forests have been an important source of medicinal plants when people felt the medicinal properties of plants thus started using them for human health care. The Indian systems of medicine (ISM) is one of the most ancient medicine practices and derives most of the materials from plants found in forests. Out of these about 400 plants are used in regular production of Unani, , Siddha, Ayurvedic and tribal medicine and about 25% are from temperate and 75% from tropical forests. 14% of formulations are derived from bark, 7% seeds, 6% stems, 16% whole plants, 10% fruits, 6% leaves, 4% rhizomes, 3% woods, 6% stems, 30% roots and only less than 20% species used are cultivated [14].

1.3 Natural Products

Natural products can be defined as "Chemical substances derived from living systems e.g. plants, microbes and animals have been used in traditional medicinal system in order to prevent and treat various human disorder". From 1970-1980, the investigation of natural products reached its apex as a human therapeutic source in the Western pharmaceutical industry. Between 1981-2002, out of 877 molecules New Chemical Entities (NCEs) introduced roughly half were natural compounds, synthetic compounds and semi-synthetic natural compounds analogues [15].

Natural products including minerals, plants and animals have been the basis of human disease treatment. Practically history of medicine gives us information about the existence human civilization and over the years by observational and scientific efforts of scientists, the current accepted modern medicine has gradually developed but its development is based on the traditional therapies and medicine. Nevertheless, modern medicine based on ancient wisdom and will remain as an important source of future therapeutics, medicines but the future of natural products drug discovery will be more holistic and personalized including wide use of modern and traditional therapeutic skills in a parallel manner in order to provide maximum benefits to the community and patients [16].

The foundations of the modern pharmaceutical industry were laid when techniques to produce synthetic replacements for many of the medicines were developed that had been derived from the forests. Natural products chemistry actually began with the work of Serturner, who isolated first morphine from opium. This, in turn, was derived from opium poppy by various processes that have been used for over 5000 years [17].

Table 1.1: Plant-derived Medicines

Drug

Medicinal Use

Source

Structure

Reference

Aloe

Treatment of burns

and wounds

Aloe species

[18]

Aspirin

Pain relief, promotion

of heart-health, blood

thinning

Salix species

[19]

Camphor

Rheumatic pain relief

Cinnamomum camphora

[19]

Codeine

Pain relief, cough

suppression

Papaver somniferum

[20]

Pseudoephedrine

Bronchodilation, nasal

decongestion, allergies

Ephedra sinica

[19]

Quinine

Malaria and heart disease

treatment

Cinchona species

[19,20]

Taxol

Treatment of breast

and other cancers

Taxus species

[21]

Topotecan

Ovarian and lung

cancer treatment

Camptotheca

acuminata

[22]

1.4 Antioxidant Activity

Free radicals are reactive, unstable species and have potential to damage chemical species (transient) possessing one or more unpaired electrons and extract electrons, thus damaging other molecules in order to attain stability. These free radicals are formed continuously inside the human body or any other system because they are essential for energy supply, detoxification, chemical signaling and immune system. These free radicals are regulated by endogenous antioxidant enzyme system but due to over production of these radicals as by exposure to UV radiations, cigarette smoking, etc or a failure in antioxidant defense mechanism or damage to cell structure, the risk for many chronic diseases increases such as atherosclerosis, cancer, arthritis, inflammatory diseases, pulmonary dysfunction, renal disease, diabetes, shock, ischemia, trauma, multiple sclerosis, hemodialysis etc.

Interestingly, human body possesses defense system against oxidative stress induced by free radicals which involve repair and preventive mechanism [23]. Antioxidants may enhance the human immune defense system therefore, low the risk of infection and cancer and protect body against the development of chronic disorders.

A number of assays of the plant extract and their purified constituents for the measurement of total antioxidant activity have been introduced [24]. There are two types of assays taken:

The inhibition assay in which the extent of scavenging by electron donation of pre-formed free radicals or hydrogen is the marker of antioxidant activity.

Assays during the generation of free radical involving the presence of antioxidant activity.

1.4.1 Reactive Oxygen Species (ROS)

ROS cause damage to bio-molecules including lipids and nucleic acids by reacting and depleting the body of natural and synthetic antioxidants which act as scavengers of free radicals thus take part in the process of oxidation including preventing and repairing the demages caused by free radicals and removing damaged bio-molecules by oxidation etc. [25, 26]

Table 1.2: Various ROS and Corresponding Neutralizing Antioxidants

ROS

Neutralizing Antioxidants

Reference

Hydroxyl radical

Vitamin C, glutathione, flavonoids, lipoic acid.

[27]

Superoxide radical

Vitamin C, glutathione, flavonoids.

[27]

Hydrogen peroxide

Vitamin C, glutathione, beta carotene, vitamin E.

[27]

Lipid peroxides

Beta carotene, vitamin E, ubiquinone, flavonoids.

[27]

hus ng sease,sease

1.4.2 Action of Antioxidants

Antioxidants by preventing the propagation reaction restrict process of oxidation given below:

1.4.2.1 Propagation Reaction:

The removal of hydrogen by peroxyl radical from any primary antioxidants, which are designed in order to make free radicals relatively ineffective and inert towards oxidation process is rapid than removal of it from any other substrate.

1.4.2.2 Inhibition Reaction:

Primary antioxidants such as hindered phenol and alkylated diphenylamine are often used with secondary antioxidants as a peroxide scavenger thus avoiding the chain branching reactions and resistance to oxidation processs [28]

DPPH is a stable free radical on reaction with antioxidants, is reduced to DPPH-H from DPPH., absorbance decreased and the degree of color discharge indicates the inhibition potential of the extract or compound in terms of hydrogen transfer from substrate to the free radical. The inhibition reaction between an antioxidant (RH) and DPPH. is written as:

Fig 1.1 DPPH Mechanism

1.4.3 Types of Antioxidants

Antioxidants are divided into two broad categories;

Synthetic antioxidants

Natural antioxidants

1.4.3.1 Synthetic Antioxidants

Butylated hydroxytoluene, tertiary butylated hydroquinone and propyl gallate are some of the synthetic antioxidants, used commonly for preservation in various companies e.g. food, cosmetic and pharmaceutical etc but are also investigated to be responsible for various disorders so there is increasing interest to replace it with safer compounds that can protect living system and can protect it from various chronic disorders due to free radicals.A large number of medicinal plants containing chemical compounds show antioxidant properties. [29].

Fig 1.2 Structures of Synthetic Antioxidants

1.4.3.2 Natural antioxidants

Plants are a big source of antioxidants including beta carotene, lycopene, selenium, ascorbic acid, α-tocopherol, lutein and polyphenols which are important in various reactions such as they neutralize and adsorb free radicals, decompose peroxide or quench oxygen (singlet and triplet) but on the other hand plant's secondary metabolites include triterpenoids, and flavonoids are important in defence system against free radicals. Therefore, consumers should increase their intake of rich foods in antioxidant compounds in order to reduce the risk of chronic health problems associated with various diseases. It has been estimated from the studies that medicinal plants are a big source of natural antioxidants such as tannins and phenolic compounds that contains pronounced antioxidant activity than other plants and such compounds can be separated and used for the treatment of various diseases caused by unstable radicals.

Beta Carotene

Fig 1.3 Structures of Natural Antioxidants

1.4.4 Sources and Origin of Antioxidants

Antioxidants occur in vegetables, fruits and foods such as nuts, grains, meats and fish.

Table 1.3: Sources and Origin of Antioxidants

Antioxidant

Source

Reference

βcarotene

Present in various foods that may be green and orange in color i.e., carrots, squash, pumpkin, potatoes, apricots, vegetables (leafy) and cantaloupe, spinach etc.

[30]

Lutein

Found in vegatables(leafy and green) e.g. kale and spinach and is good for healthy eyes.

[31]

Lycopene

Abundant in watermelon, apricots, oranges, tomaroes, papaya, grapefruit (pink) etc.According to the estimates, tomato products are a big source (about 85%) of diet in America.

[32]

Vitamin A

Abundant in foods like carrots, potatoes, milk, and cheese ets.

[33]

Vitamin C

Known in various vegetables, fruits and poultry, cereals and fish etc.

[34]

Vitamin E

Abundant in nuts, almonds, mangoes, and in oils ( safflower. wheat germ and corn oils).

[35]

1.5 Ficus variegata

Ficus variegata belongs to Moraceae, is the Mulberry family, consist of over 53 genera and 1400 plant species, most of which are located in the tropical area about, includes mostly wild trees and has a thorn [36]. There are about 132 Ficus species occur in central and South America, 112 occur in Africa South of Sahara and Mudagascar and 511 Ficus trees existed in Asia, Malaysia, Pacific Island and Australia. The existence of Ficus is affected by the factors, humidity and temperature [37].There are a great variety of wild Ficus trees in Malaysia, some of which are bushes and climbing plants and also bear figs (also called as Ficus) of varying sizes.

Table 1.4: Economic Importance of Moraceae

Plant Name

Part of Plant

Economic Importance

Reference

B. gulanensis

Tree

Valuable Timber Source

[38]

B. rebescens

Tree

Valuable Timber Source

[38]

C. elastica

Plant

Rubber Source

[38]

M. tinctoria

Plant

Yellow Dye Source

[38]

B. alicastrum

Seed

Starch Food Source

[38]

F. inspida

Latex

Against Intestinal Worm Infections

[38]

M. tinctoria

Plant

Extract Inflicted Teeth

[38]

P. armata

Bark

Preparing Bark Cloth

[38]

Table 1.5: Medicinal Importance of Ficus Species

Plant Name

Part of Plant

Medicinal Use

Reference

F. arnottiana and F. hispida

Bark

Shows hypoglycaemic activity.

[39,40]

F. bengalensis

Roots

Shows anthelmintic activity.

[41]

Extract

Inhibit insulinase activity from liver and kidney.

Fruit extract

Exhibits anti-tumour activity.

F. exasperata

Leaf extract

Shows anti-bacterial activity.

[42]

Leaves

Exhibit hypotensive activity.

[43]

F. glomerata

Wood extract

Shows Anti-HIV- 1 integrase activity.

[44]

F. religiosa

Leaf juice

Used in treatment of diarrhea, rea-ache, eye troubles, tooth-ache, and gastric problems.

[45]

Leaf decoction

Used for toothache.

[45]

Fruits

Used in respiratory disorders, asthma and shows anti bacterial and anti tumerous activity.

[45,46]

Stem bark

Treatment of paralysis, fracture of bone, diabetes, antiseptic, diarrhea and astringent etc.

[45]

F. carica

Fresh and dried fruit

Treatment of Cancer, carcinoma, ulcers, hepatomegaly, spleenomegaly.

Shows spasmolytic activity, mediated through the activation of K+-ATP channels along with anti platelet activity. Hence, it can be used in gut motility and inflammatory disorders.

[47]

Latex

Used in Ulcers and gout.

[47]

Leaves

Used in Cancer, tumors, dermatitis.

[47]

F. racemosa

Latex

Used as Aphrodisiac

[47]

Leaves

Treat gastrointestinal problems

[48]

Bark powder

Used in Diabetes, ulcers, hiccups, gonorrhea

[47]

Fruits

Used as laxative and digestive.

[47]

Fig 1.4 Chemical Constituents Isolated from Ficus Species

1.6 Conocarpus erectus

Conocarpus erectus belongs to Combretaceae is one of the prominent family in Southern Africa, consists of some 19 genera and 600 species.It is family of tropics and subtropics and found in southern and south western areas, its members are widespread in South Africa. Members of this include creepers and attractive creepers [49]. The Combretum is the largest genus in the Combretaceae, comprises of some 180 species of shrubs, trees and climbers and out of which 33 species occur in South Africa, used for many medicinal purposes such as treatment of abdominal pains, colds, fattening babies, fever, conjunctivitis, headache, infertility in women, snake bite, toothache, scorpion bite, pneumonia, general weakness, chest coughs, abdominal disorders and swelling caused by mumps [50-53].

Conocarpus erectus L. is one of two species in the genus Conocarpus growing in tropical and subtropical regions on shorelines around the world. It is commonly called as button mangrove or buttonwood; is an evergreen tree [54]. It is used in some countries as folk remedy for conjunctivitis, diabetes, anemia, catarrh, fever, diarrhea [55].

Table 1.6: Traditional Medicinal Uses of Combretaceae

Combretum species

Traditional uses

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