Emodin – a secondary metabolite with multiple ecological functions in higher plants

Abstract

SummaryThe anthraquinone emodin, identified in 17 plant families distributed worldwide, has numerous biological activities, some of which exhibit a wide spectrum of ecological impacts by mediating biotic or abiotic interactions of plants with their environment. Here the evidence for direct and indirect effects of emodin on plant survival and reproduction is reviewed. Emodin in vegetative organs may help protect plants against herbivores, pathogens, competitors and extrinsic abiotic factors (e.g. high light intensities). In unripe fruit pulp, emodin may facilitate seed dispersal by protecting the immature fruit against predispersal seed predation whereas in ripe pulp it may deter frugivores and thus reduce the chances that seeds will be defecated beneath the parent plant. It also accelerates the passage of seeds through the digestive tract, potentially reducing dispersal distance and increasing seed viability upon dispersal. In certain circumstances both of the last two effects could also have negative fitness consequences for plants. Natural selection should favor secondary metabolites with multiple functions because they protect the plants against a variety of unpredictable biotic and abiotic environments. Such metabolites also enhance plant defenses by using different molecular targets of specific enemies through a variety of mechanisms of action. Emodin illustrates the wide and often overlooked potential for chemical multifunctionality in plant secondary metabolites.© New Phytologist (2002) 155: 205 -217

Phytochemical and antifungal activity of anthraquinones and root and leaf extracts of Coccoloba mollis on phytopathogens

“…Emodin was also found to be an efficient antifungal agent. Species of plants of the family Polygonaceae: Polygonum (rhizome, root, stem), Rheum (rhizome, leaf) and Rumex (root, seed, leaf, stem, flower) contain emodin (Izhaki, 2002 (Agarwal et al, 2000). Emodin and physcion isolated from Ventilago madraspatana showed antibacterial activity against three Bacillus sp.…”

Elucidation of cladofulvin biosynthesis reveals a cytochrome P450 monooxygenase required for anthraquinone dimerization

“…They have been largely used in both traditional Asian and modern Occidental medicines. For example, emodin is one of the most intensively studied anthraquinones because of its ubiquity and potent anticancer, antidiabetic, antiinfective, antiinflammatory, and cathartic properties as well as its cardio-, hepato-, and neuroprotective qualities (4). Anthraquinones and xanthones contain an aromatic core that serves as a scaffold for the attachment of diverse functional groups, resulting in a wide variety of molecules with distinct biological and biochemical characteristics.…”

Short communication. Insecticidal activity of different extracts of Rhamnus dispermus (Rhamnaceae) against peach trunk aphid, Pterochloroides persicae (Homoptera: Lachnidae)

“…Abu-Darwish (2000) isolated and identified 11 compounds from barks of R. This study aimed to test the insecticidal activity of R. dispermus against the PTA, since it has been shown that Rhamnus spp. may contain compounds that act as botanical pesticides, such as emodin (Trial and Dimond, 1979, Singh et al, 1992, Tsahar, 2001Izhaki, 2002) Bark of R. dispermus was collected from AshShoubak, Jordan. Its botanical identification was confirmed by Dr. Talal Abu Rjae, at the University of Jordan, who keeps voucher specimens in his laboratory.…”