Phytochemical Screening Introduction - Lab Exam

Bioactive components

• other term for phytochemicals

Alkaloids, tannins, glycosides, formic acid, tartaric acid, flavonoids, and steroids

The screening of bioactive components indicates the presence of:

Phytochemicals

• are a large group of plant derived compounds hypothesized to be responsible for much disease protection conferred from diets high in fruits, vegetables, beans, cereals, and plant-based beverages such as tea and wine

Plant-based foods

• Hundreds of phytochemical compounds, with several different biological functions, have been identified in _______

Alkaloids

• are basic nitrogenated compounds, compromising the largest class of secondary plant metabolites

• it had been found to exhibit dramatic physiological effect, making them valuable in the field of medicine

Mayer’s

• In testing for alkaloids, a false positive result may be obtained upon the addition of heavy-metal reagents like _____

Sodium chloride

• Such effect (false positive result by the addition of heavy-metal reagents like Mayer’s) is eliminated by first treating the extract with __________ before the addition of the precipitating reagent

Anaesthetics, cardioprotective, and anti-inflammatory

• Therapeutically, alkaloids are particularly well known as:

Morphine, strychnine, quinine, ephedrine, and nicotine

• Well-known alkaloids used in clinical settings:

Steroids

• are compounds containing a 17-carbon 4-ring system and including the sterols and numerous hormones and glycosides

Cardenolides and Bufadienolides

• Two types of steroids:

Cardiac glycosides

• Cardenolides and bufadienolides are steroidal glycosides and are referred to as ________, since they have dramatic effect on the heart muscle

Cardenolides

• have a 5-membered lactone ring

Bufadienolides

• have a 6-numbered lactone ring

deoxy-sugars, steroid nucleus, unsaturated lactones

Steroids:

• The chemical test should detect the presence of the : _____

crude alcoholic extract or the partially purified extract

Steroids:

• For phytochemical screening of the plant extract, the test may be done on:

Plant-derived steroids or phytosteroids

• are bioactive compounds with significant therapeutic potential, including anti-inflammatory, cholesterol - lowering, and anti-tumor properties

diosgenin, sitosterol and stigmastrol

Examples of plant-derived steroids or phytosteroids

Anthraquinones

• form the largest group of the natural occuring quinones pigments

Anthraquinones

• commonly used as dyes and cathartics or purgatives

Flavonoids

• phenolic plant pigments generally containing the alpha benzopyrone nucleus

Flavonoids

• it gives anti-viral, anti-fungal, anti-inflammatory, and cytotoxic activities

• it includes the anthocyanines and leucoanthocyanines

Anthocyanidins

• Anthocyanines are glycosides on hydrolysis yield sugars and colored aglycones known as _______

orange-red to blue-red

The color upon boiling indicates the presence of anthocyanins:

Leucoanthocyanidins

• The leucoanthocyanines have their aglycone the ___

leucoanthocyanines

• colorless but give intense red or violet color when boiled with an acid

Saponins

• are steroids/triterpenoid glycosides that are characterized by their ability to froth when the aqueous solution is agitated

Saponins

• plant materials containing these have long been used for their detergent properties

Saponins

• they usually exert a powerful hemolytic action of the red blood cells and are high toxic when injected into the blood stream

• they are also used as fish poison, causing paralysis on the gills

Spermicidal and moluscicidal activity

Plant saponins have interesting biological activities such as:

Tannins

• have the ability to react with and precipitate proteins forming stable water insoluble copolymers

Tannins

• was first applied to plant constituents capable of transforming raw animal skin into leather because of their ability to cross-link with proteins

Tannins

• they are used in pharmaceutical preparations because of their astringent action

Tannins

• recent reports show that they may have potential value as cytotoxic and/or antineoplastic agents

Cyanogenic glycosides

• usually found in plants together with hydrolytic enzymes

• they are lost after plant harvest due to spontaneous hydrolysis

Manihot esculenta

• The roots of _____, locally known as cassave, have long been known to cause poisoning when eaten, particularly when the tubers are half-cooked or are cooked with their root peelings intact.