Chemical Constituents of Plants from the Genus Rhododendron

Grayanotoxin Poisoning: ‘Mad Honey Disease’ and Beyond

“…Its chemical structure has been fully elucidated as a diterpene, a polyhydroxylated cyclic hydrocarbon with a 5/7/6/5 ring structure that does not contain nitrogen [9]. More than 25 grayanotoxin isoforms have been isolated from Rhododendron [10]. Three members of the large grayanotoxin family (Fig.…”

“…A possible explanation could be the grayanotoxin-mediated stimulation of the parasympatic nervous system or the M 2 -muscarinic receptors causing increased insulin secretion [58]. Species of the Rhododendron genus have been shown to possess many bioactive compounds [10]. Although the number of studies on biological actions, such as anti-viral or anti-bacterial, of various Rhododendron preparations is increasing, it is largely unknown whether grayanotoxin is the active compound.…”

Grayanane and leucothane diterpenoids from the leaves of Rhododendron micranthum

“…Many Rhododendron species have been used as traditional medicines in Asia, North America, and Europe to treat asthma, common cold, gastro-intestinal disorders, inflammation, pain, and skin disease (Popescu and Kopp, 2013). Phytochemical studies on the genus of Rhododendron established the presence of flavonoids, phenolic compounds, diterpenoids, triterpenoids, iridoid glycosides, and magestigmane sesquiterpenoids, and some isolates showed acetylcholinestherase inhibitory, anti-HIV, antiinflammatory, antimicrobial, antinociceptive, antiprotozoal, antiviral, immunomodulatory, and tyrosinase inhibitory activities Popescu and Kopp, 2013;Qiang et al 2011). …”

A case of human poisoning by grayanotoxins following honey ingestion: elucidation of the toxin profile by mass spectrometry

“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Introduction Grayanotoxins (GrTx) are formed by the plant family Ericaceae, for instance by genera of Rhododendron, Pieris (Andromeda), Leucothoe, Craibiodendron, Lyonia or Kalmia (Scott et al 1971;Burke & Doskotch 1990;Teuscher & Lindequist 1994;Kron et al 2002;Qiang et al 2011;Li et al 2013). These secondary metabolites are diterpenes with a tetracyclic A-nor-B-homo-ent-kaurane skeleton called grayanane or andromedane, a polyhydroxylated cyclic hydrocarbon with a 5/7/6/5 ring structure (Wood et al 1954;Tallent et al 1957;Narayanan et al 1970;Burke & Doskotch 1990;Li et al 2013) (Figure 1).…”