Antioxidants natural products

Supercritical fluid extraction (SFE) has been widely used to the extraction processes in pharmaceutical industries. Besides application of SFE in phannaceuticals, it has been applied on a wide spectmm of natural products and food industries such as natural pesticides, antioxidants, vegetable oil, flavors, perfumes and etc [1-2]. 

In nearly every pharmacy, supermarket, and health food store, you can find bottles of antioxidants and antioxidant-rich natural products, such as fish oils, Gingko biloba leaves, and wheat grass. These dietary supplements are intended to help the body control its population of radicals and, as a result, slow aging and degenerative diseases such as heart failure and cancer. 

The most common natural antioxidants are tocopherols, ascorbic acid and P-carotene (more often synthetic nature-identical compounds than natural products). Their changes were studied in detail in model systems, fats and oils, but experimental evidence is mainly lacking on more complicated systems, such as natural foods and ready dishes. Still less is known on different antioxidants from spices and from essential oils. These data will probably be obtained gradually. Very little is known about synergism of antioxidants in food products other than edible fats and oils or their regeneration from the respective free radicals and quinones. In mixtures, some antioxidants are preferentially destroyed and others are saved. Some data have already been published, but these complex changes should be studied in more detail. 

Natural products have been noted for their potential health benefits from time immemorial and are the basis of Ayurveda, an ancient Indian medical practice (Bushkin and Bushkin, 2002). However, the potential benefits of several natural products reside in one or two active ingredients. For example green tea stands for polyphenols, soy for soy estrogens, broccoli for isothiocyanates and grape seed for polyphenols. The beauty of rice bran is that there are more than 100 antioxidants, several categories of bioactive phytonutrients, such as IP6, polyphenols, phytosterols, tocotrienols, y-oryzanol, B vitamins, minerals and trace minerals in addition to fat, protein, fiber, polysaccharides and other nutrients. These phytonutrients and antioxidants of rice bran are believed to act at the cellular level, and their synergestic function is responsible for the positive health benefits. 

Trott, A. West, J. D. Klaic, L. Westerheide, S. D. Silverman, R. B. Morimoto, R. I. Morano, K. A. Activation of heat shock and antioxidant responses by the natural product celastrol transcriptional signatures of a thiol-targeted molecule. Mol. Biol. Cell2008,19, 1104-1112. 

On-line SFE-pSFC-FTIR was used to identify extractable components (additives and monomers) from a variety of nylons [392]. SFE-SFC-FID with 100% C02 and methanol-modified scC02 were used to quantitate the amount of residual caprolactam in a PA6/PA6.6 copolymer. Similarly, the more permeable PS showed various additives (Irganox 1076, phosphite AO, stearic acid - ex Zn-stearate - and mineral oil as a melt flow controller) and low-MW linear and cyclic oligomers in relatively mild SCF extraction conditions [392]. Also, antioxidants in PE have been analysed by means of coupling of SFE-SFC with IR detection [121]. Yang [393] has described SFE-SFC-FTIR for the analysis of polar compounds deposited on polymeric matrices, whereas Ikushima et al. [394] monitored the extraction of higher fatty acid esters. Despite the expectations, SFE-SFC-FTIR hyphenation in on-line additive analysis of polymers has not found widespread industrial use. While applications of SFC-FTIR and SFC-MS to the analysis of additives in polymeric matrices are not abundant, these techniques find wide application in the analysis of food and natural product components [395]. 

Figure 11.3. Effect of natural product treatment (methyl jasmonate MJ 22 ptg/liter, ethanol ETOH 400 pl/liter, methyl jasmonate-ethanol (MJ-ETOH) on (I) total antho-cyanins (mg/100 g FW), (II) total phenols (mg/100 g FW), and (III) antioxidant capacity measured as ORAC (p.mol TE/g FW) of strawberry fruit (cv. Chandler) stored at 5°C. Bars show the final values after treatments. Different letters on top of the bars indicate statistical differences among treatments (p < 0.05).

D-Ascorbic acid (lAA) is not present in natural products, but it is present in vitamin C-enriched foods or as an antioxidant. Therefore, it is important to distinguish between AA and lAA [417]. 

Kinoshita, T., Tamura, Y., and Mizutani, K., Isolation and synthesis of two new 3-arylcoumarin derivatives from the root of Glycyrrhiza glabra (licorice), and structure revision of an antioxidant isoflavonoid glabrene, Natural Product Letters, 9, 289, 1997. 

Another processing procediue that could involve supercritical fluid extraction with CO2 is the preparation of flavor concentrates from meat lipids for use in mixtures of other natural precursors for the preparation of tynthetic meat flavor additives that serve bofii as antioxidants that prevent warmed-over flavor (WOF) in cooked meat diuing storage and enhance the flavor of the natural products. 

Takamatsu S, Hodges TW, Rajbhandari I, Gerwick WH, Hamann MT, Nagle DG (2003) Marine Natural Products as Novel Antioxidant Prototypes. J Nat Prod 66 605... 

Currently pest control by natural plant extracts is practiced primarily by subsistence farmers in those less developed part of the world where it is still an economic necessity.(ref. 3). Of the approximately 2000 plant species with known insecticidal properties (ref. 4), few have been developed commercially. These include the pyrethrins, rotenones and some of the alkaloids. Pyrethrins were the most important natural plant extracts in the early commercial insecticide formulations and were already in use in Persia and Yugoslavia during the early 1800s. By 1939 pyrethrum imports to the United States were 13-5 million lbs, declining from this peak as the synthetic analogs (e.g., the allethrins) appeared on the market. The addition of stabilizers (antioxidants) and synergists to the original pyrethrum formulations saved the natural product from commercial extinction. Currently the demand for pyrethrum flowers is still over 25,000 tons per annum—met by hand-harvested crops from Ecuador, Kenya and Tanzania (ref. 5) ... 

Recovery of valuable bioactive compounds by nanofiltration, from natural products or streams resulting from the processing of natural products, is also gaining an increasing interest. Recent examples include the production of natural extracts from olive oil subproducts, which are rich in the most potent natural antioxidant compound identified so far (hydroxytyrosol) as well as the production of natural extracts from grape pomace residues, which are rich in a number of high-value compounds. 

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