Plant compounds, flavonoids

Polyphenols, as one of the largest and most widespread class of plant compounds, are also present in saffron stigma. In the mass spectrum of the flavonoid fraction of the methanolic extract from saffron there were ions at m/z 611 and 633 which may be attributed to protonated and sodiated quasi-molecular ions of kaempferol diglycoside. [22] Flavonoids from the water extract can be isolated and concentrated... 

Most flavonoids are potent antioxidant compounds. Several flavonoids possess anti-inflammatory, antihepatotoxic, antimmour, antimicrobial and antiviral properties. Many traditional medicines and medicinal plants contain flavonoids... 

Marked variations in the stability of 21 tinctures and 13 related singleentity plant compounds were noted (26). Bilia et al. (27) investigated the stability of 40% and 60% v/v tinctures of artichoke, SJW, calendula flower, milk thistle fruit, and passionflower. The investigation showed a very low thermal stability of the constituents from accelerated and long-term testing as determined by HPLC iode array detector and MS analyses. Stability was related both to the class of flavonoids and water content of the investigated tinctures. Shelf life at 25° C of the most stable tincture (passionflower 60% v/v) was about six months, whereas that of the milk thistle tinctures was only about three months. The stability of artichoke and... 

Flavonoids are widely distributed colored phenolic derivatives. Related compounds include flavones, flavonols, flavanonols, xanthones, flavanones, chalcones, aurones, anthocyanins, and cat-echins (see Chapter 29). Plants containing flavonoids with anticancer properties include ... 

Another Streptomyces sp. obtained from black anaerobic intertidal sediment collected near Christchurch, New Zealand was fermented in a saline medium and found to produce modest antibacterial activity against Bacillus subtil is.14 The isolation of the active compound revealed it to be an actinoflavoside, a molecule of an unprecedented structure class (Structure 18.5). Actinofla-voside resembles the common plant-derived flavonoid glycosides, but this compound contains an... 

Phenylpropanoids have an aromatic ring with a three-carbon substituent. Caffeic acid (308) and eugenol (309) are known examples of this class of compounds. Phenylpropanoids are formed via the shikimic acid biosynthetic pathway via phenylalanine or tyrosine with cinnamic acid as an important intermediate. Phenylpropanoids are a diverse group of secondary plant compounds and include the flavonoids (plant-derived dyes), lignin, coumarins, and many small phenolic molecules. They are known to act as feeding deterrents, contributing bitter or astringent properties to plants such as lemons and tea. 

A number of compounds found in foods of plant origin have potentially protective effects, although they cannot be considered to be dietary essentials they are variously known as phytonutrients, phytoceuticals, or nutraceuticals. Such compounds include allyl sulfur compounds, flavonoids, glucosinolates, and phytoestrogens. 

Tables 1,2 summarise the compounds of this type so far isolated from the plant kingdom and it can be seen that there is no discernible pattern in the distribution of chromone alkaloids in the flowering plants. The flavonoidal alkaloids have been isolated from several different plant families but often only from one genus of a family. Many genera and species related to those yielding this type of alkaloid have not been investigated so further studies may enable patterns to be discerned.

Capillarisin Cirsimaritin Rhamno-citrin Artemisia Capillari Spica/Compositae Whole plant Three flavonoids and two coumarins, scoparone and scopoletin, were isolated from the ethyl acetate extract of A. capillari. These compounds have been tested for their inhibitory effect on bovine lens aldose reductase (bovine-LAR) and rabbit platelet aggregation. Increased aldose reductase activity and platelet aggregation are considered as two causes of diabetic complications. Capillarisin exhibited a potent inhibitory effect on bovine-LAR. Scoparone showed strong inhibitory effect on rabbit platelet aggregation [25],... 

Ajuga iva (L.) Schreber has examined for its hypoglycaemic effect in normal and streptozotocin-induced rats, and a significant decrease was observed in plasma glucose levels. Among other compounds, flavonoids were the major constituents of the aqueous extract of this plant [153]. 

Of the substances identified in plants, the flavonoids represent one of the most important and interesting classes of biologically active compounds. They are present in a wide variety of plants, and are especially common in leaves, flowering tissues, pollens and fruits. These compounds are also abundant in woody parts such as stems and bark, and they are an important part of human nourishment. 

Among phenolic compounds, flavonoids are of exceptional interest, as they represent one of the most ubiquitous and widely spread groups of namral products present in a majority of plants. 

Phenolic Compounds Flavonoids and their gly-coconjugates and other compounds that are synthesized by plants from amino adds phenylalanine and tyrosine and occur in most of the plant kingdom. These compounds influence color and taste of foods and have valuable properties (e.g., as antioxidants). 

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