An Introduction to Phytomedicine

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Virtually all cultures consume drugs from psychoactive plants. Caffeine, for example, is probably the most common stimulant in the world, and many modern medicines, such as morphine and codeine, are derived from plant sources. In these cases, scientific research has revealed the composition of the plants and how they interact with the nervous system. There are also many herbal medications with reputed therapeutic value that have not yet gained acceptance into mainstream medicine, partly because there has not been enough research to support their usefulness. Instead they are regarded as "alternative medicines." This is an active research area, however, and many current studies are focusing on identifying the active components, pharmacological properties, physiological effects, and clinical efficacy of herbal medicines. This book compiles and integrates the most up-to-date information on the major psychoactive herbal medicines—that is, herbal medicines that alter mind, brain, and behavior. It focuses particularly on the effects on various areas of cognition, including attention, learning, and memory. The book covers all major classes of psychoactive drugs, including stimulants, cognitive enhancers, sedatives and anxiolytics, psychotherapeutic herbs, analgesics and anesthetic plants, hallucinogens, and cannabis.

Phytomedicine:

    1. The study or use of medicinal herbs to prevent and treat diseases and ailments or to promote health and healing.
    2. A drug or preparation made from a plant or plants and used for any of such purposes.

"My opinion, however, is that they (herbs) are superior 95% of the time to any pharmaceutical drug!" ---Dr. Robert E. Willner, M.D.

"For every drug that benefits a patient, there is a natural substance that can achieve the same effect." — Pfeiffer's Law, Dr. Carl C. Pfeiffer, M.D., PhD.

The Evolution Perspective: Why Plants Make Drugs

At first glance, it seems unusually convenient that plants would be so kind as to make drugs for human benefit. What causes plants to develop therapeutic chemicals? The answer requires a slight shift of perspective, to ask why plants manufacture chemicals in general. To understand this, one must consider it in the context of natural selection.

Evolution by natural selection was first explained by Charles Darwin in his book On the Origin of the Species (1859). Briefly stated, the theory suggests that evolution occurs through heritable propagation of adaptive traits. Nature produces a large variation in the traits of organisms. Those traits that are in some way adaptive, increasing the survival and reproductive success of the organism, are propagated to future generations. Darwin’s schema is simple but powerful, having great explanatory strength; it is a cornerstone of modern biology. The context of natural selection is essential for understanding the mutual adaptation between plants and animals that led to the manufacture of drugs by plants.

Living organisms are divided into five kingdoms: Animalia, Plantae, Fungi, Protista, and Monera. Green, multicellular plants fall under the Plantae kingdom, which originated in the Silurian period (505 to 400 million years ago) (Southwood 1984). They have the shortest evolutionary history and are the only kingdom to have completely evolved on land. Also evolving around this time were insects. Insects evolving on land found an abundant source of food in plants, provided they could adapt to eating them. This probably occurred in gradual increments, beginning with insects scavenging on pollen and spores, progressing to insects feeding on the reproductive organs of plants, and eventually leaf feeding.

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However, this newfound feast for insects was at a great cost to plant. Research indicates that plants protected from insect predators by pesticides live longer, produce more seeds, and propagate over a larger area. Thus, natural selection would favor plants that somehow deter predators from consuming them. The defenses plants have evolved fall into three categories: nutritional, physical, and chemical (Southwood 1984). Nutritional defenses involve having low nitrogen levels or balances of amino acids that are unfavourable to insect metabolism. Physical defenses involve the growth of external cuticles and epidermal hairs that make the plant mechanically difficult to hold, manipulate, and consume. The focus of this book is the chemical defenses evolved by plants, which involve the production of substances that strongly and adversely alter a predator’s physiology (either by poisoning or repelling). Also, plant defense typically are involved in life functions other than defense, so their defense advantages may well have been serendipitous. Regardless, any trait (serendipitous or not) that increases the survival and reproductive ability of a plant will propagate through natural selection. These chemical defenses alter our physiology in diverse ways. While some are outright toxic, many others can be subverted for therapeutic uses. To a large extent, this depends upon our cleverness in finding uses.

Thus, plants and predators have coevolved, reciprocally adapting to on another. Plants develop chemicals that deter predators and increase their survival advantage. Predators, in turn, adapt by developing tolerance, attraction, or even utilization of plant chemicals.

Although humans differ greatly from insects, reciprocal relationship between humans and plants exists. In the course of foraging for food, humans have serendipitously discovered plants with therapeutic effects. Over time, traditions of knowledge about the therapeutic use of plants have accumulated within cultures, even though the rationales for why such plants are effective are often incorrect. For example, Asian systems of herbal medicine are based on the theory of balancing one’s yin and yang energy. While this might have some unforeseen metaphorical value, it has no apparent basis in the actual anatomy and physiology of the human body. During the Renaissance, herbalists used the doctrine of signatures to guide the therapeutics use of plants The doctrine of signatures is the belief that the shape or color of a plant indicates its therapeutic use (e.g., if a plant contained red then it would be used to treat blood-related disorders). Although their explanations for why herbs treat an illness are inaccurate, they have still accumulated knowledge about which plants treat which illness, through trial and error discovery.

The Psychopharmacology of Herbal Medicine: Plant Drugs That Alter Mind, Brain, and Behavior. Virtually all cultures consume drugs from psychoactive plants. Caffeine, for example, is probably the most common stimulant in the world, and many modern medicines, such as morphine and codeine, are derived from plant sources. In these cases, scientific research has revealed the composition of the plants and how they interact with the nervous system.

There are also many herbal medications with reputed therapeutic value that have not yet gained acceptance into mainstream medicine, partly because there has not been enough research to support their usefulness. Instead they are regarded as "alternative medicines." This is an active research area, however, and many current studies are focusing on identifying the active components, pharmacological properties, physiological effects, and clinical efficacy of herbal medicines. This book compiles and integrates the most up-to-date information on the major psychoactive herbal medicines—that is, herbal medicines that alter mind, brain, and behavior. It focuses particularly on the effects on various areas of cognition, including attention, learning, and memory. The book covers all major classes of psychoactive drugs, including stimulants, cognitive enhancers, sedatives and anxiolytics, psychotherapeutic herbs, analgesics and anesthetic plants, hallucinogens, and cannabis.

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