Phytochemistry Reviews (v.14, #5)

Exposure to physical or psychological stimuli perceived to be threatening activates the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS) resulting in a classical stress response. Prolonged activation of the HPA and SNS is associated with many adverse physiological changes, most notable the development of anxiety and depression. Recently, a number of plant-derived aliphatic alcohols and aldehydes, termed ‘green odors,’ have demonstrated stress-alleviating properties. This novel method of stress-alleviation has been shown using a number of different animal and stress models utilizing numerous experimental techniques. The object of this review is to present a balanced and critical overview of the present literature on the mammalian effects of exposure to these odors. These findings will be discussed in terms of ongoing trends in the field and possible experimental outcomes will be suggested.
Keywords: Anxiety; Depression; Green odor; Olfaction; Stress

Nutritionally important carotenoids as consumer products by Judit Berman; Uxue Zorrilla-López; Gemma Farré; Changfu Zhu; Gerhard Sandmann; Richard M. Twyman; Teresa Capell; Paul Christou (727-743).
Carotenoids are nutritionally-beneficial organic tetraterpenoid pigments synthesized mainly by plants, bacteria and fungi. Although research has focused on the production of carotenoids in staple crops to improve nutritional welfare in developing countries, there is also an enormous market for carotenoids in the industrialized world, where they are produced both as commodities and luxury goods targeted at the pharmaceutical, nutraceutical, food/feed additive, cosmetics and fine chemicals sectors. Carotenoids are economically valuable because they have diverse bioactive and chemical properties. Some are essential nutrients (e.g. β-carotene), others are antioxidants with specific roles (e.g. lutein and zeaxanthin) or general health-promoting roles that reduce the risk or progression of diseases associated with oxidative stress (e.g. lycopene), and still others are natural pigments (e.g. astaxanthin, which is added to fish feed to impart a desirable pink flesh color). Even carotenoid degradation products, such as damascones and damascenones, are used as fragrances in the perfumes industry. Here we discuss the importance of carotenoids in different market sectors, review current methods for commercial production and its regulation, summarize the most relevant patents and consider evidence supporting the health claims made by different industry sectors, focusing on case studies representing the most commercially valuable carotenoids on the market: β-carotene, lycopene, lutein, zeaxanthin and astaxanthin.
Keywords: Health claims; Intellectual property; Market production; Nutraceuticals; Regulation

Non-terpenoid biotransformations by Mucor species by Eliane de Oliveira Silva; Niege Araçari Jacometti Cardoso Furtado; Josefina Aleu; Isidro González Collado (745-764).
Biotransformation is an important tool for the structural modification of organic compounds, especially natural products with complex structures, which are difficult to achieve using ordinary methods. It is also useful as a model for mammalian metabolism due to similarities between mammalian and microbial enzyme systems. The development of novel biocatalytic methods is a continuously growing area of chemistry, microbiology, and genetic engineering, and novel microorganisms and/or their enzymes are being screened intensively. This review covers the transformation of non-terpenoid compounds such as steroids, coumarins, flavonoids, drugs, pesticides and others by Mucor spp. up to the end of 2012.
Keywords: Biotransformation; Mucor sp.; Non-terpenoid

Trigonelline and related nicotinic acid metabolites: occurrence, biosynthesis, taxonomic considerations, and their roles in planta and in human health by Hiroshi Ashihara; Iziar A. Ludwig; Riko Katahira; Takao Yokota; Tatsuhito Fujimura; Alan Crozier (765-798).
This review describes the occurrence and biosynthesis of trigonelline (N-methylnicotinic acid) and related nicotinic acid metabolites. High concentrations of trigonelline are found in seeds of coffee, and some members of the Fabaceae, while trace amounts occur in many other species. In contrast, the occurrence of other pyridine alkaloids derived from nicotinic acid is limited. Nicotinic acid, a precursor of the secondary pyridine metabolites, is derived from pyridine nucleotides. In planta, pyridine nucleotide biosynthesis de novo is initiated from aspartic acid. The degradation of NAD and its regeneration from the catabolites is called the pyridine nucleotide cycle (PNC). Isotopic labelling and enzymatic studies indicate a seven-component PNC VII pathway is the major route. All plants examined convert exogenous nicotinic acid to trigonelline and/or nicotinic acid N-glucoside (NaG). In general, NaG formation is restricted to ferns and selected orders of angiosperms, whereas other plants produce trigonelline. The biosynthesis of other pyridine alkaloids, of which many details remain to be resolved, is discussed briefly. The potential in planta roles of trigonelline, including detoxification, nyctinasty and host selection are discussed. Coffee beverage is the major food containing trigonelline and some vegetables also contain trigonelline. The possible effects of trigonelline on health mediated via hypoglycaemic, neuroprotective, anti-cancer, estrogenic, and antibacterial activities are reviewed. Finally, potential genetic manipulation of biosynthetic pathways to create trigonelline- and vitamin B3-rich plants and agricultural uses of trigonelline-rich genetically modified crops and trees are discussed.
Keywords: Pyridine alkaloids; Occurrence; Biosynthesis; Pyridine nucleotide cycle; Coffee

Phytochemical profile of Paulownia tomentosa (Thunb). Steud. by Kristýna Schneiderová; Karel Šmejkal (799-833).
Paulownia tomentosa, a member of the plant family Paulowniaceae and a rich source of biologically active secondary metabolites, is traditionally used in Chinese herbal medicine. Flavonoids, lignans, phenolic glycosides, quinones, terpenoids, glycerides, phenolic acids, and miscellaneous other compounds have been isolated from different parts of P. tomentosa plant. Recent interest in this species has focused on isolating and identifying of prenylated flavonoids, that exhibit potent antioxidant, antibacterial, and antiphlogistic activities and inhibit severe acute respiratory syndrome coronavirus papain-like protease. They show cytotoxic activity against various human cancer cell lines and inhibit the effects of human cholinesterase, butyrylcholinesterase, and bacterial neuraminidases. Most of the compounds considered here have never been isolated from any other species of plant. This review summarizes the information about the isolated compounds that are active, their bioactivities, and the structure–activity relationships that have been worked out for them.
Keywords: Bignonia tomentosa ; Flavonoid; Lignan; Paulownia tomentosa ; Paulowniaceae; Phenolic glycosides

The genuine structure of alectrol: end of a long controversy by Kotomi Ueno; Yukihiro Sugimoto; Binne Zwanenburg (835-847).
Alectrol was first isolated from root exudates of cowpea (Vigna unguiculata), a genuine host of a root parasitic weed Striga gesnerioides, as a germination stimulant for seeds of the parasite. The proposed structure, an isomer of strigol, was disproven by chemical synthesis. Recently, another structure, namely orobanchyl acetate, was proposed. Surprisingly, however, the synthetic compound having this proposed structure for alectrol was not active in inducing germination of S. gesnerioides seeds although it was active toward seeds of other root parasitic weeds such as S. hermonthica and Orobanche minor. Detailed studies on 1H NMR, mass and CD spectra of naturally occurring alectrol, re-isolated from cowpea root exudates, revealed that the genuine structure of the germination stimulant is not orobanchyl acetate but its stereoisomer ent-2′-epi-orobanchyl acetate. Accordingly, the structure of natural orobanchol was revised to ent-2′-epi-orobanchol 12 years after a tentative structure of orobanchol was proposed. Strict stereochemical requirements of strigolactones for germination induction of S. gesnerioides seeds, authentic samples of synthetic strigolactones and advanced analytical instruments made the structural assignment possible, thus ending a 20 years controversy concerning the true structure of alectrol.
Keywords: Cowpea; Germination; Stereochemistry; Striga gesnerioides ; Strigolactone

Bioactive soy isoflavones: extraction and purification procedures, potential dermal use and nanotechnology-based delivery systems by Marina Cardoso Nemitz; Renata Cougo Moraes; Letícia Scherer Koester; Valquiria Linck Bassani; Gilsane Lino von Poser; Helder Ferreira Teixeira (849-869).
Isoflavones are polyphenol compounds found mainly in legumes such as soybeans (Glycine max (L.) Merrill). These compounds can be found in different chemical forms; however, the beneficial effects for skin care have been mainly credited to their free forms. This manuscript claims to review the main effects of isoflavone aglycones on the skin, the different techniques for obtaining bioactive forms from soybeans, and the interest in incorporating them into topical systems. The benefits of dermatological application of isoflavones, as anti-aging action, estrogenic activity, wound healing properties, and antiphotocarcinogenic effects are highlighted. Moreover, the advantages and drawbacks of the extraction techniques of soybeans, methods for converting glucosides into aglycones, and purification procedures are described. Different strategies to incorporate these poorly soluble compounds in conventional or nanostructured delivery systems are also discussed. Illustrative examples especially for genistein-loaded liposomes, nanoemulsions, nanocapsules and cyclodextrin complexation are reported.
Keywords: Dermatological application; Extraction techniques; Nanostructured delivery systems; Skin care; Soybean isoflavones