Pharmacognoisy I Quiz - Factors Affecting Growth

Lecture 2: Pharmacognoisy I (PHCG 111)

• Course for first-year pharmacy students
• Presented by Dr. Rafik Mounir Nassif

Chapter V: Factors Affecting Plant Growth and Drug Production

• A. Environmental Factors: Water, light, temperature, altitude, etc.
• B. Soil and Soil Contents: Soil composition (rock particles, plant roots, microorganisms, decaying organic matter), water capacity (A.W.C.), air capacity, humus content (poor, intermediate, rich).
• C. Growth Regulators (Hormones): Auxins, Gibberellins, Cytokinines, Abscisic acid, Ethylene oxide.
• D. Genetics and Plant Tissue Culture

1- Water

• Rain is the only source of fresh water.
• Water comprises about 90% of the cytoplasm of plant cells.
• Crucial for photosynthesis, biological reactions, and transformations.
• Facilitates mineral and nutrient absorption and transport within the plant.
• Regulates plant temperature via transpiration.

2- Temperature

• Plant growth rate increases with temperature up to an optimum point.
• A further increase leads to a decrease in growth rate.
• Every plant has a minimum, optimum, and maximum temperature.
• Minimum temperature is where growth rate is very low or zero.
• Optimum temperature results in highest growth rate.
• Maximum temperature is where growth rate is very low or zero.

3- Altitude

• Temperature decreases approximately 1°C for every 343 feet of elevation.
• Specific plant types have specific altitude requirements (e.g., coconut palm - maritime climate, sugar cane - low land, tea and coffee - higher elevation).
• Some plants thrive at lower elevations but produce little of the desired compounds (e.g., Cinchona succirubra).

4- Light

• Plants have differing light requirements.
• Light influences the formation of active ingredients.
• Essential for photosynthesis and chlorophyll production.
• Lack of light can lead to morphological abnormalities.
• Photoperiodism is the plant's response to day length.

5- Photoperiodism

• Day length affects plant flowering behavior.
• Categories of plants: -Short-day plants (flower in short days, like winter) -Long-day plants (flower in long days, like summer) -Day-neutral plants (uninfluenced by day length)

B. Soil and Soil Contents (Plant Nutrients)

• Soil is composed of a mixture of particles, organic materials, water and air.
• Water capacity is indicated by 'absolute water capacity' (A.W.C).
• Air capacity is inversely proportional to A.W.C. Sandy soils are highly permeable, whereas clay soils absorb water readily via capillary action
• Soil quality can be categorized based on humus content (poor, intermediate, rich).
• Humus enhances water absorption.
• Soil with high humus and low lime is acidic; conversely, having high lime makes it alkaline

Organic Manures

• Manure is a mixture of organic matter, animal waste and urine, used as a fertilizer, aiding plant growth and improving soil conditions.
• Manure increases water absorption by soil.

Humus (Organic Manures) Use

• Manures act as fertilizers.
• They help in improving soil structure and growth conditions.
• Manures reduce water loss in root zones.

Essential Nutrients (Macro and Micro)

• Major Nutrients/ Macro-elements: Nitrogen (N), Phosphorus (P), Potassium (K). Commercial fertilizers can be simple (one element) or complete (all three).
• N (Nitrogen): Crucial for chlorophyll and amino acid production; deficiency leads to chlorosis (yellowing).
• P (Phosphorus): Crucial for energy production (ATP) for plant growth; lack of P leads to smaller plant size and deeper colour.
• K (Potassium): crucial for plant growth and carbohydrate production; deficiency reduces carbohydrate synthesis.
• Micro-nutrients: Iron, boron, copper, manganese, zinc, cobalt, lead and molybdenum (needed in tiny amounts but can be hazardous in large doses)
• Active elements: Calcium (Ca) — important for flowers and apical meristem (plant tip). Deficiency in Ca may result in partial or no terminal-bud development, causing abnormal leaf margins. — Magnesium (Mg). vital for chlorophyll production & photosynthesis. Deficiency = chlorosis (yellowing or discoloration)—Sulphur (S) important for plant cell division.

C. Plant Growth Regulators

• Plant hormones, active in tiny amounts to regulate plant growth

• Growth stimulators: -Auxins: natural (IAA) and synthetic (IBA, NAA, 2,4-D). Main uses include accelerating rooting and acting as selective herbicides to increase rooting and to act as selective herbicides. -Gibberellins: Promotes flowering (earlier), increases plant height. -Cytokinines: promote cell division.

• Growth inhibitors: -Abscisic acid: Antagonizes gibberellins (counteracts their effects); essential for seed dormancy, drought resistance, and regulating stomata opening. -Ethylene: Inhibits potato shoot growth and plays a role in fruit ripening and leaf senescence (plant declines)

VI. Preparation of Drugs from Plants to Pharmaceuticals

• Collection of Crude Drugs: Medicinal plants, wild or cultivated, are collected.
• Qualitative and quantitative compositions of drugs may change during different seasons. For quality, it's crucial to select the right time of year, part of the plant, and growing stage.

Factors Affecting Collection

• Time of year: Plant composition changes seasonally. For example, rhubarb doesn't contain anthraquinones in the winter but contains anthranoles in the summer, colchicum corm is rich in starch in the fall but low in colchicine in the spring and contains little starch; and hyoscyamus has lower alkaloid levels in winter.
• Time of day: Active compound levels might fluctuate (e.g., digitalis glycosides).
• Stage of Maturity and Age: The quality and composition of the drug can change based on the stage of development (e.g. Conium fruits have the highest alkaloid levels when mature but unripe). Some plants contain the highest level of alkaloids during their blooming phase, while others have higher levels when still as buds.

General Rules for Collecting Drugs (leafs)

• Leaves should be collected when flowers are starting to open; tea leaves are collected in their bud stage; Coca leaves are collected just before they fall; and uva ursi leaves can be collected at any time of the year.
• Avoid collecting leaves when they are wet from dew or rain. Reject leaves that are discolored or damaged by insects.

General Rules for Collecting Drugs (Flowers, Seeds, Other Tissues)

• Flowers are collected in dry, clear weather conditions. Clove, red rose and wormseed flowers, should be collected when they are in bud stage; while others are collected when they are fully blossomed; and chamomile and insect flowers are collected when fully blossomed.
• Tissues like roots, tubers, bulbs should be collected in winter or autumn. Stem barks are best collected in spring when they separate more easily.
• Seeds should be collected when mature and are fully ready.
• unorganized drugs must be collected in clear weather and any plant material must be excluded.

Test your knowledge on the environmental factors, soil contents, growth regulators, and genetic aspects that influence plant growth and drug production in Pharmacognoisy I. This quiz is designed for first-year pharmacy students and covers key concepts from Chapter V presented by Dr. Rafik Mounir Nassif.