Plant Chemistry Flashcards
Definition of Pharmacognosy
the study of the physical, chemical, biochemical and biological properties of drugs, drug substances, or potential drugs or drug substances of natural origin as well as the search for new drugs from natural sources.
Definition of Secondary Metabolites
compounds that are not directly involved in the growth, reproduction, or photosynthesis of plants. They are derived from primary metabolites (which are involved in growth, reproduction and photosynthesis).
They have a vast array of functions and are generally associated with the defense from other organisms, attraction of pollinators and other symbiotes, and protection from environmental factors such as UV radiation.
Phenolics
Aromatic (benzene) ring with an OH group
Range from simple compounds with a single aromatic ring to complex polymeric molecules.
Common Properties of Phenolic Constituents
Resonance stabilization Antioxidants Anti-inflammatories Anti-cancer Many phenolics are colorful pigments
Simple phenolics
Structure: One phenolic ring structure with varying side groups
Properties: contain a single aromatic ring, often form glycosides, varying side groups, smaller molecules are volatile
Examples: Eugenol (cinnamon, clove), Vanillin, Methyl Salicylate (wintergreen, birch)
Polyphenol
Any molecule with a phenolic ring with polyhydroxylation OR very large groups of many phenolic structures linked together.
Phenolic Glycosides
Phenolic moiety (aglycone) + sugar group (glycone) Highly antimicrobial
Example: Arbutin from Arctostaphylos uva ursi= hydroquinone +glucose
Phenolic Acids
At least one phenolic ring with an acidic carboxyl group
Examples:
- Ellagic acid (berries, grapes and pomegranate): anti-inflammatory, anticarcinogenic
- Gallic acid (grapes, berries, nuts): Anti-inflammatory, anticarcinogenic
- Salicylic acid: Anti-inflammatory, analgesic, antipyretic; Not the same effect on platelets as acetylsalicylic acid (aspirin)
Tannins Proanthocyanidins Coumarins Anthraquinones and their glycosides Naphthoquinones Phenolic Acids Chromones and Furanochromones Flavonoids Isoflavones Lignans Stilbenes
Anthraquinones
Anthraquinones and their glycosides – laxatives (and hypericin)
Examples: Emodin, frangulin, Aloin, Sennidin
Tannins
Properties: Astringent - have the ability to cross-link collagen fibers tightening tissues
Structure: Phenolic acids such as gallic acid or ellagic acid with ester linkages to a central glucose molecule.
Example: Geraniin found in Geranium maculatum and other spp
Really great in the GI! Tighten the membranes of leaky gut, diarrheas, weakened tissues, preventing infection in exposed and broken skin.
Plants high in tannins: Quercus spp. Hamammelis virginiana Aesculus hippocastanum Camellia sinensis Cinnamomum spp. Rheum spp.
Proanthocyanidins
– condensed tannins
not readily hydrolyzed to simpler molecules
Polymers and oligomers of flavan-3-ol
Contained in grapes, pine bark, hawthorn, apples, cocoa
Properties:
Related to flavonoid pigments
No sugar moiety
Oligomers and polymers of flavan-3-ol moieties
Astringent
Examples of Plants with proanthocyanidins:
Hawthorn (Crataegus spp.) Oligomeric procyanidins (OPCs)
Others: Cinnamon, Green Tea, Cocoa, Linden flower, wild cherry, grape seed and skin
Anthocyanidins
Structurally related to flavones, but carry a charge
Glycosides are called anthocyanins
antho- flower
kyanos – blue
**based on the flavylium cation (+)
pH dependent colorful pigments (acidic–> red and basic –> blue)
Anthocyanins
These are anthocyanidins + a sugar moiety (Glycosides of anthocyanidins)
Generally odorless and flavorless
Mildly astringent
Colorful red and blue compounds
Volatile Constituents
Are of LOW molecular weight… that’s why they are volatile.
They are also less stable.
Coumarins
Coumarins are derivatives of α-pyrone
They are aromatic and produce a fresh-cut-grass aroma. They are components of the essential oil.
Examples: Archangelicin, Umbelliferone, Aesculetin
