Ethnobotany. Lecture 15

Alexey Shipunov

Minot State University

February 25, 2015

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Outline

1 Centers of cultivated plants origin

2 Sugar plantsSugarsSweeteners

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Outline

1 Centers of cultivated plants origin

2 Sugar plantsSugarsSweeteners

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Centers of cultivated plants origin

Harlan’s centers of agricultural beginnings

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Sugar plants Sugars

Sugar plantsSugars

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Sugar plants Sugars

Ethanol

Immediate product of yeast fermentation of glucosePre-adaptation to alcohol from frugivoresBind to GABA (gamma-aminobutyric acid) receptorsConverted into acetaldehyde (toxic!) by alcohol dehydrogenaseand then into acetic acid by acetaldehyde dehydrogenase“Asian flush” (result of acetaldehyde dehydrogenase deficiency)and alcoholism are related to the genetic diversity of alcoholdehydrogenases

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Sugar plants Sugars

Downsides of sugars

Obesity, because sugars are easily convert into fatsDiabetes, because insulin cannot deal with large quantities ofsugarsDental diseases, especially dental caries (caused by lactobacteriataking sugars for their growth)Multiple sweeteners have been developed to avoid side-effects ofsugars: heterocyclic saccharine (in “Sweet’N Low”), amino acidderivative aspartame (in “Equal”), chlorine hexose sucralose (in“Splenda”, “Altern”). All are controversial.

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Sugar plants Sweeteners

Sugar plantsSweeteners

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Sugar plants Sweeteners

Stevia rebauldiana, the natural sweetener

Belongs to aster family, CompositaeOriginated in South AmericaLeaves contain the group of sweet glycosides, derivatives ofsteviolThey are 100–150 times sweeter than sucrose (on the weightconcentration basis)Despite of multiple controversies (not approved in EU, banned inNorway and Singapore) used by Coca-Cola and PepsiCo in their“zero calories” drinks

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Sugar plants Sweeteners

Stevia flowers

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Sugar plants Sweeteners

Steviol

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Sugar plants Sweeteners

Our native natural sweeteners

North Dakotan wild licorice (Glycyrrhiza lepidota) belongs tolegume family, LeguminosaeContains natural sweetener glycyrrhizin, about 50 time sweeterthan sucroseSide-effects are hypertension and lowering of testosterone level inmales

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Sugar plants Sweeteners

American licorice, Glycyrrhiza lepidota

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Sugar plants Sweeteners

Glycyrrhizin

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Sugar plants Sweeteners

What is sweetness?

Nature of sweetness is not yet fully discoveredProbably due to specific Van der Waals forces occurring in varietyof moleculesThese molecules have an effect on sweet receptors—largeproteins from G protein-coupled receptors (GPCRs) group

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Sugar plants Sweeteners

GPCR, sweetness receptor

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Sugar plants Sweeteners

Miracle fruit, Synsepalum dulcificum, thesuper-sweetener

West African tree, belongs to tropical Sapotaceae familyBerries convert sour tastes into sweet tastes (!), effect lasts for ≈1hourThe effect is due to glycoprotein miraculin which is binding tosweet receptorsCultivation is now starting in Florida, approval as food additive ispending—it is heat-resistant and may be used as a “sweetener”;there are genetically modified lettuce plants which producemiraculin

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Sugar plants Sweeteners

Miracle fruit

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Sugar plants Sweeteners

Miraculin glycoprotein

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Sugar plants Sweeteners

Other plants super-sweeteners

Curculin from Curculigo latifolia (“lumbah-lumbah”), Malaysianherb from Hypoxidaceae family, has the same effect + it is alsosuper-sweet by itself (500–2000 times sweeter on weight basisthan sucrose).Thaumatin from Thaumatococcus daniellii (“miracle berry”), WestAfrican herb from Marantaceae, is 3000 times sweeter thansucrose.Monellin from Dioscoreophyllum volkensii (“serendipity berry”),West African Menispermaceae vine, is 800–2000 times sweeterthan sucrose but only to Old World monkeys including humans.

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Sugar plants Sweeteners

Lumbah-lumbah

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Sugar plants Sweeteners

Miracle berry (not “miracle fruit”!)

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Sugar plants Sweeteners

Thaumatin, the most sweet protein

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Sugar plants Sweeteners

Anti-sweeteners

Several plants contain chemicals which are able to suppresssweet receptorsIndian herbaceous vine Gymnema sylvestris from a dogbanefamily (Apocynaceae) contain gymnemic acids which suppresssweet taste for ≈10 minIn addition, plant has an unrelated (?) effect in lowering bloodsugarsUsed as a drug for curing Type 2 diabetes and different forms ofmetabolic disorders

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Sugar plants Sweeteners

Gymnema sylvestre

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Sugar plants Sweeteners

Gymnemic acid

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Sugar plants Sweeteners

Summary

Sugar is highly used but controversial source of energySweet taste still has undiscovered nature

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Sugar plants Sweeteners

For Further Reading

A. Shipunov.Ethnobotany [Electronic resource].2011—onwards.Mode of access:http://ashipunov.info/shipunov/school/biol_310

P. M. Zhukovskij.Cultivated plants and their wild relatives [Electronic resource].Commonwealth Agricultural Bureaux, 1962. Abridged translationfrom Russian.Mode of access:http://ashipunov.info/shipunov/school/biol_310/zhukovskij1962_cultivated_plants.djvu.

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