The Diversity of Stemona Stilbenoids As a Result of Storage and Fungal Infection

Abstract

In relation to their biogenetic origin, 68 Stemona stilbenoids have been grouped into four structural types and are listed in order of increasing substitution pattern. Besides different hydroxylations and methoxylations, the rare C-methylations of the aromatic rings represent a typical chemical feature of these compounds. The formation of phenylbenzofurans constitutes another important chemical character separating Stemona species into two groups consistent with morphological and DNA data. Fungal infection leads to an increasing accumulation of stilbenes, dihydrostilbenes, and phenylbenzofurans with unsubstituted A-rings, suggesting the ecological role of these compounds as phytoalexins. Further oxygenations and methylations of both rings are interpreted as a result of aging or the drying processes. Bioautographic tests on TLC plates and germ-tube inhibition assays in microwells against four different fungi exhibited antifungal activities for almost all stilbenoids tested. Some derivatives also showed effects against yeasts and bacteria. Further activities may also be seen as dormancy-inducing factors of Stemona species occurring in periodically dry habitats. A leucotriene biosynthesis inhibition assay using 15 stilbenoids showed interesting structure-activity relationships, with more potent effects of some compounds than the commercial 5-lipoxygenase inhibitor zileuton being observed. Potential neuroprotective activities have been reported for three dihydrostilbene glucosides against 6-hydroxydopamine-induced neurotoxicity in human neuroblastoma SH-SY5Y cells.

Structural classification and biological activities of Stemona alkaloids

“…Besides highly active sulfur-containing amides from the genus Glycosmis of the Rutaceae (Greger et al 1996;Hofer and Greger 2000) and flavaglines from Aglaia of the Meliaceae (Brader et al 1998;Bacher et al 1999) we found very promising biological activities in the genus Stemona of the small monocotyledonous family Stemonaceae (Brem et al 2002;Pacher et al 2002). As reviewed previously the high insecticidal activity could be attributed to family-specific Stemona alkaloids (Greger 2006), whereas the antifungal property was caused by different groups of stilbenoids (Greger 2012). In addition, the accumulation of tocopherols with antioxidant activity was shown to represent another chemical character of that family (Brem et al 2004).…”

Selective COX-2 Inhibitory Properties of Dihydrostilbenes from Liquorice Leaves–In Vitro Assays and Structure/Activity Relationship Study

“…Dihydrostilbenes, also known as bibenzyls, are structurally characterized by a 1,2-diphenylethane scaffold; although biosynthetically strictly related to flavonoids, their presence in the plant kingdom is much more restricted. Concerning the biological function of dihydrostilbenes in plants, an increasing accumulation of these components has been observed in infected samples, thus suggesting for them a phytoalexin-like role [9].…”

“…The differences between the active sites of COX-2 and COX-1 enzymes, which are described as hydrophobic channels, are the basis for the design of COX-2 selective inhibitors. Stilbenoids act as natural protective agents to defend the plant against viral and microbial attack, excessive ultraviolet exposure, and disease [9]. More than 1,000 compounds belonging to this group have been discovered and, depending on their chemical structure, demonstrate different biological activities.…”

Stemofurans X-Y from the Roots of Stemona Species from Laos

“…Stemona species have been used as medicinal plants to treat cough and as anti-helminths in Laos, Vietnam, China, and Thailand [1]. These plants are well-known to produce various alkaloids [2,3] and stilbenoids [4][5][6], which have been reported to have antimicrobial [7], anti-inflammatory [8] and cytotoxicity activity [6]. In this paper, we report the isolation of two new phenylbenzofuran-type stilbenoids named stemofurans X-Y (1, 2), together with ten known compounds from two Stemona sp.…”