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Medicinal Plants-Nature's Pharmacy

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Chapter 2 Medicinal Plants--Nature's Pharmacy*

Ram J. Singh, Ales Lebeda, and Arthur O. Tucker

Contents

2.1 Introduction............................................................................................................................. 13 2.2 Medicinal Plants, Herbs, and Crops: Concept and Issue........................................................ 16 2.3 Medicinal Plants of Asia......................................................................................................... 18 2.4 Medicinal Plants of Australia and New Zealand.................................................................... 19 2.5 Medicinal Plants of Oceania................................................................................................... 19 2.6 Medicinal Plants of Europe.....................................................................................................20 2.7 Medicinal Plants of Africa......................................................................................................20 2.8 Medicinal Plants of the Middle East and North Africa.......................................................... 23 2.9 Medicinal Plants of the Americas...........................................................................................24 2.10 Modern Plant-Based Medicine................................................................................................25 2.11 Looking Forward.....................................................................................................................26 Acknowledgments. ........................................................................................................................... 44 References. ....................................................................................................................................... 44

2.1 Introduction

Plants are an integral part of all living organisms of the earth, and medicinal plants are widely distributed worldwide (Figure 2.1). Since time immemorial, humans from all the cultures of the world have independently selected plants for food, shelter, clothing, and medicine. Plants were identified, according to their therapeutic properties and through trial and error, by the priests, shamans, herbalists, spiritual leaders and medicine men, and this practice is still a routine in many countries of Asia, Africa, the Middle East, Australia, and Latin America. Indeed, the widespread use of natural herbs and medicinal plants for curing and preventing diseases (nature's pharmacy) has been described in the ancient texts of the Vedas and the Bible (Hoareau and DaSilva 1999) and the Qur'an and the Ahadith (Ahmad et al. 2009). Duke, Duke, and duCellier (2008) even wrote a book entitled Duke's Handbook of Medicinal Plants of the Bible and cataloged "faith-based farmaceuticals."

* This chapter is dedicated to the memory of the late Professor Edgar J. DaSilva, who suggested the inclusion of the topic of this chapter in this book.

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Genetic Resources, Chromosome Engineering, and Crop Improvement

FOXGLOVE

WESTERN YEW CASCARA SAGRADA

IPECAC

WILLOW

MAYAPPLE WILD YAM

VALERIAN

VISNAGA

BLOODROOT

AUTUMN CROCUS

CURARE CACAO

JABORANDI

HOT PEPPER

YOHIMBE

COCA ORDEAL BEAN

BELLADONNA

SWEET ANNIE

INDIAN SNAKEROOT MARIJUANA

TRAGACANTH GINKGO

OPIUM POPPY

SENNA

BLACK DOT PSYLLIUM

MA HUANG

CROTON

QUININE

PAPAYA

CASTOR BEAN

ALOE

ROSY PERIWINKLE

EUCALYPT VELVET BEAN

BLACK BEAN

PITURI

Figure 2.1Centers of origin for some medicinal plants. Medicinal plants include some herbs, spices, vegetables, fruits, and agronomic crops--legumes and oilseed crops--from herbs to trees. (Duke, J. A. 2002. Handbook of medicinal herbs, 2nd ed. Boca Raton, FL: CRC Press. With permission.)

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Medicinal Plants--Nature's Pharmacy

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The rapid explosion of human population, migration, urbanization, and deforestation created many diseases for humans as well as for domesticated animals during the nineteenth century. During this time, the systematic study of plants with medical properties was begun worldwide with advances in chemistry.

Some believe that natural medicines have been overly studied, but, in fact, we have hardly begun to tap the reservoir of potential therapeutics from plants. One study estimates that around 422,000 plant species exist worldwide (Marinelli 2005). These plants are a potentially rich source of medicinal compounds, curing everything from the common cold to cancer and HIV/AIDS. Schultes (1972) described chemical compounds of medicinal properties that are scattered throughout the plant kingdom--250,000?350,000 species: 18,000 algaes; 90,000 fungi (including bacteria); 15,000 lichens; 14,000?20,000 bryophytes; 6,000?9,000 pteridophytes; 675 gymnosperms; and 200,000 species of angiosperms in some 300 families. These are an untapped reservoir for future wonder drugs. Medicinal treasures from the wild may be available for future generations, but today only 50,000?80,000 flowering plants are used medicinally worldwide (Marinelli 2005).

Different medicinal plants have antibiotic, antidiabetic, antihyperglycemic, and hyperlipidemic properties (Mentreddy 2007). We present here some recent studies and reviews on the role of medicinal plants in treating human diseases and promoting healing:

Alzheimer's: Tucci (2008) reviewed herbal treatments for slowing the onset of Alzheimer's and remarked that "herbal medicines...have been used for centuries as cognitive activators in traditional cultures, and their consideration in the Western medical regime may eventually lead to greater options in the treatment of Alzheimer's." Zhang (2005) listed on-compound multiple-target strategies to combat Alzheimer's, both from natural and synthetic sources.

Cancer: Graham et al. (2000) listed 350 plant species used to fight cancer. These plants are native or domesticates from Asia, Europe, South America, the Caribbean, Africa, and Australia. Ionkova (2008) looked at several anticancer compounds from in vitro cultures of rare medicinal plants and focused upon two genera: Astragalus and Linum. Mahady et al. (2003) found that the isoquinoline alkaloids from Sanguinaria canadensis L. and Hydrastis canadensis L. were effective against Helicobacter pylori, the cause of stomach ulcers and linked to stomach cancer. O'Sullivan-Coyne et al. (2009) found that curcumin (the principal component in turmeric, Curcuma longa L.) induces apoptosis-independent death in esophageal cancer cells. In regard to the role of dietary herbs and spices in cancer prevention, Kaefer and Milner (2008) remarked:

While culinary herbs and spices present intriguing possibilities for health promotion, more complete information is needed about the actual exposures to dietary compounds that are needed to bring about a response and the molecular agent(s) for specific herbs and spices. Only after this information is obtained will it be possible to define appropriate intervention strategies to achieve maximum benefits from herbs and spices without eliciting ill consequences.

Conjunctivitis: Sharma and Singh (2002) listed 169 species of the 66 families used during 1933?2000 for treating conjunctivitis; the maximum number (17) of species was from the family Asteraceae, followed by Euphorbiaceae (11) and Mimosaceae (8). These plant species are from Asia, Africa, the Middle East, Europe, the South Pacific Islands, and South America.

Diabetes: Yadav et al. (2007) listed 17 species of commonly used plants for treating diabetes (Table 2.1). Garg and Garg (2008) listed 113 species used for treating diabetes worldwide but emphasized that these must be used in conjunction with diet and exercise.

Immunomodulation: Sagrawat and Khan (2007) listed 18 plant species from India with immunomodulatory activity. Withania somnifera (L.) Dunal has immunomodulatory effects and could be useful in the treatment of colon cancer (Muralikrishnan, Donda, and Shakeel 2010).

Sexual dysfunction: Yakubu, Akanji, and Oladiji (2007) reviewed the 10 leading plants used to alleviate male sexual dysfunction. Yohimbe bark (Pausinystalia yohimbe Pierre ex Beille) contains tryptamine alkaloid yohimbine and is widely distributed over the counter as an herbal aphrodisiac

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Genetic Resources, Chromosome Engineering, and Crop Improvement

Table 2.1Medicinal Plants with Antidiabetic Properties

Botanical Name

Momordica charantia L. Swertia chirayita (Roxb.) H. Karst. Gymnema sylvestre (Retz.) Schult. Trigonella foenum-graecum L. Plumbago zeylanica L. Syzygium cumini (L.) Skeels (Eugena jambolana Lam.) Aegle marmelos (L.) Corr?a Terminalia chebula Retz. Terminalia bellirica (Gaertn.) Roxb. Phyllanthus emblica L.

(Emblica officinalis Gaertn.) Curcuma longa L. Pterocarpus marsupium Roxb. Berberis aristata DC. Citrullus colocynthis (L.) Schrad. Cyperus rotundus L. Piper longum L. Zingiber officinale Roscoe

General Indian Name Karela Chirayata Gudmar patra Methi dana Chitrak mool Jamun

Bilva patra Harad Baheda Amla

Haridra Vijaysar Daru harida Indrayan mool Nagarmotha Pippali Adrak

Family Cucurbitaceae Gentianaceae Plumbaginaceae Fabaceae Plumbaginaceae Myrtaceae

Rutaceae Combretaceae Combretaceae Euphorbiaceae

Zingiberaceae Fabaceae Berberidaceae Cucurbitaceae Cyperaceae Piperaceae Zingiberaceae

Source:Adapted from Yadav, H. et al. 2007. Journal of Pharmacological Sciences 105:12?21.

(Adeniyi et al. 2007). Yohimbe is native to western Africa, including Nigeria, Cameroon, Congo, and Gabon (Barceloux 2008). Wound healing: Habbu, Joshi, and Patil (2007) reviewed potential wound healers of plant origin. They listed 81 plant species with potential to promote wound healing and stated that they "could be of enormous help in managing and treating various types of wounds."

The last detailed survey of the medicinal plants industry was 20 years ago (Wijesekera 1991). The main objective of this chapter is to update briefly the story of medicinal plants, nature's pharmacy, from time immemorial to the present day, where scientists have been and are desperate to find cures for illnesses such as Alzheimer's, cancer, cardiovascular diseases, diabetes, HIV/AIDS, malaria, and many others. The popularity of and demand for plant-based health food and cosmetics have been increasing over that for allopathic medicines. The collection, preservation, and maintenance of germplasm resources of the few medicinal plants described here will set the stage for the conservation of plants from the unexplored regions of the world before they become extinct.

2.2 Medicinal Plants, Herbs, and Crops: Concept and Issue

Not only botany, chemistry, and pharmacology, but also anthropology, archeology, linguistics, history, sociology, comparative religion, and numerous other specialties have contributed appreciably to the search for new biodynamic plants (ethnobotany, or with respect to drug plants, ethno pharmacology or pharmacognosy; see, for example, Lewis and Elvin-Lewis 2003; Samuelsson and Bohlin 2010; Tyler, Brady, and Robbers 1988).

Medicinal plants are mostly wild, and few have been domesticated or are currently being cultivated. Based on reviewing studies from eight countries (Mexico, Guatemala, Spain, Bulgaria, Ethiopia, Uganda, the Philippines, and Nepal) in four regions of the world, Aguilar-St?en and

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