Glucosinolates are sulfur-rich, anionic natural products that upon hydrolysis by endogenous thioglucosidases called myrosinases produce several different products (e.g., isothiocyanates, thiocyanates, and nitriles). The hydrolysis products have many different biological activities, e.g., as defense compounds and attractants. For humans these compounds function as cancer-preventing agents, biopesticides, and flavor compounds. Since the completion of the Arabidopsis genome, glucosinolate research has made significant progress, resulting in near-complete elucidation of the core biosynthetic pathway, identification of the first regulators of the pathway, metabolic engineering of specific glucosinolate profiles to study function, as well as identification of evolutionary links to related pathways. Although much has been learned in recent years, much more awaits discovery before we fully understand how and why plants synthesize glucosinolates. This may enable us to more fully exploit the potential of these compounds in agriculture and medicine.

Biology and biochemistry of glucosinolates

Punica granatum (pomegranate) and its potential for prevention and treatment of inflammation and cancer.

Triacylglycerols produced by plants are one of the most energy-rich and abundant forms of reduced carbon available from nature. Given their chemical similarities, plant oils represent a logical substitute for conventional diesel, a non-renewable energy source. However, as plant oils are too viscous for use in modern diesel engines, they are converted to fatty acid esters. The resulting fuel is commonly referred to as biodiesel, and offers many advantages over conventional diesel. Chief among these is that biodiesel is derived from renewable sources. In addition, the production and subsequent consumption of biodiesel results in less greenhouse gas emission compared to conventional diesel. However, the widespread adoption of biodiesel faces a number of challenges. The biggest of these is a limited supply of biodiesel feedstocks. Thus, plant oil production needs to be greatly increased for biodiesel to replace a major proportion of the current and future fuel needs of the world. An increased understanding of how plants synthesize fatty acids and triacylglycerols will ultimately allow the development of novel energy crops. For example, knowledge of the regulation of oil synthesis has suggested ways to produce triacylglycerols in abundant non-seed tissues. Additionally, biodiesel has poor cold-temperature performance and low oxidative stability. Improving the fuel characteristics of biodiesel can be achieved by altering the fatty acid composition. In this regard, the generation of transgenic soybean lines with high oleic acid content represents one way in which plant biotechnology has already contributed to the improvement of biodiesel.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2008.03442.x

Plant triacylglycerols as feedstocks for the production of biofuels

The glucosinolates are a large group of sulphur-containing compounds which occur in all the economically important varieties of Brassica vegetable. Their common structure comprises a β-D-thioglucose group, a sulphonated oxime moiety and a variable side-chain derived from methionine, tryptophan or phenylalanine. When the plant tissue is damaged the glucosinolates are hydrolysed by the endogenous enzyme ‘myrosinase’ (thioglucoside glycohydrolase EC 3:2:3:1), to release a range of breakdown products including the bitter, biologically active isothiocyanates. Although these compounds exert antinutritional effects in animals there is also substantial evidence that they are the principal source of anticarcinogenic activity in Brassica vegetables, and this provides a strong motive for the manipulation of glucosinolate levels in vegetables for human consumption. This review provides an overview of the evidence for a beneficial role for glucosinolates in human health, and describes the current state of knowledge regarding the genetics and biosynthesis of glucosinolates, their chemical analysis, their behaviour during cooking and processing, and their bioavailability to humans. As the genetic basis of glucosinolate biosynthesis becomes more apparent, and tools for marker-assisted plant breeding become more available, the selective breeding of horticultural brassicas with different levels and types of glucosinolates, whether by conventional means or genetic manipulation, is becoming a practical possibility. However before this strategy becomes commercially viable, the health benefits of glucosinolates for human beings must be unequivocally established.

© 2000 Society of Chemical Industry

The nutritional significance, biosynthesis and bioavailability of glucosinolates in human foods

Montmorillonite KSF as an Inorganic, Water Stable, and Reusable Catalyst for the Knoevenagel Synthesis of Coumarin-3-carboxylic Acids.

Freshly extracted oil from a sample of kenaf seed, var.Cubano, was found to contain an appreciable amount of epoxy acid as glyceride;cis-12,13-epoxyoleic acid was isolated. Its identity was confirmed by analysis and by conversion to threo-12,13-dihydroxyoleic acid. The remaining fatty acids were esterified, distilled, and identified by the usual procedures. The percentage composition of the fatty acids was estimated from the data as follows: 9-hexadecenoic 1, palmitic 19, linoleic 41, oleic 30, stearic 2, arachidic (trace), 12,13-epoxyoleic 5, undetermined 2.

Fatty acids of kenaf seed oil

Seed oils were hydrolyzed under mild conditions and the major conjugated fatty acid of each oil was isolated and identified. In two families, species which were closely related botanically contained different but isomeric acids. Thus, in the Bignoniaceae, Jacaranda chelonia had cis trans,cis-8,10,12-octadecatrienoic acid as a major acid while Catalpa speciosa had trans,trans,cis-9,11,13-octadecatrienoic acid. In the Cucurbitaceae, Momordica charantia had the ordinary cis,trans,trans-9,11,13-octadecatrienoic (α-eleostearic) acid while M. balsamina had cis,trans,cis-9,11,13-octadecatrienoic (punicic) acid. M. balsamina is a new and convenient source of punicic acid. α-Eleostearic acid was identified as a major acid in examples of Valerianaceae and Rosaceae. Further proof was obtained that the fatty acid of Calendula officinalis (Compositae) is trans,trans,cis-8,10,12-octadecatrienoic acid.

Identification of conjugated triene fatty acids in certain seed oils

The following fatty acids were identified in the respective seed oils; α-eleostearic in Kentranthus macrosiphon; trans-8,trans-10,cis-12-octadecatrienoic in Osteospermum hyoseroides; 9-hydroxy-10,12- and 13-hydroxy-9,11-octadecadienoic in Tagetes erecta. Dimorphecolic acid was obtained from Osteospermum ecklonis in pure crystalline form. It gave 9-D-hydroxystearic acid on hydrogenation, thus establishing the D-configuration of the parent acid. Dehydration of dimorphecolic acid gave a mixture of all-trans-8,10,12- and all-trans-9,11,13-octadecatrienoic acids.

Occurrence in seed oils of some fatty acids with conjugated unsaturation

Punicic acid was identified as a component of the seed oils of Cyclanthera explodens (26%) and Cayaponia africana (38%). α-Eleostearic acid was identified in Momordica dioica (55%) and its occurrence in Telfairia occidentalis (7 and 12%) was confirmed. Evidence of conjugated acids was noted in Fevillea peruviana and Bryonia alba. The oils of four other species of Cucurbitaceae had no conjugated acids. The distribution pattern of fatty acids in this family is discussed.

Mary J. Chisholm

Papers

Fatty acids of kenaf seed oil

Identification of conjugated triene fatty acids in certain seed oils

Occurrence in seed oils of some fatty acids with conjugated unsaturation

Conjugated fatty acids in some cucurbitaceae seed oils

Fatty acid components of some Santalaceae seed oils