New Dihydrobenzofurans and Triterpenoids from Roots of Microglossa pyrifolia

Abstract

From the roots of Microglossa pyrifolia (Lam.) Kuntze (Asteraceae, tribe Astereae), used in East African traditional Medicine to treat a variety of ailments, seven dihydrobenzofurans and seven triterpenoids (five dammaranes and two 28-nor-oleanenes) were isolated. Their structures were elucidated by spectroscopic (UV, MS and NMR) means. With the exception of the tremetone derivative 1, all of the dihydrobenzofurans found in this drug possess the rare 6-acetyl-5-hydroxy substitution pattern. Dihydrobenzofurans 1 [methyl 2-(5-acetyl-2,3-dihydrobenzo[β]furan-2-yl)propenoate], 3 (methyl2-(6-acetyl-5-hydroxy-2,3-dihydrobenzofuran-2-yl)propenoate] and 7 (6-acetyl-5-hydroxy-2-(1-hydroxy-2-propenyl)-3-methoxy-2,3-dihydrobenzofuran) as well as the triterpenes 3β-acetoxy-25-hydroxydammara-20,23-diene (9), 3β-acetoxy-24-oxo-dammara-20,25-diene (11), 17β-hydroxy-3,16-dioxo-28-norolean-12-ene (12) and 17β-hydroxy-3,11,16-trioxo-28-norolean-12-ene (13) are new natural products, to the best of our knowledge.

Microglossa pyrifolia - Asteraceae - Astereae - Dihydrobenzofurans - Triterpenes - Structure elucidation

References

• 1 Neuwinger H D. Afrikanische Arzneipflanzen und Pfeilgifte. Stuttgart; Wissenschaftliche Verlagsgesellschaft 1994
• 2 Zdero C, Ahmed A A, Bohlmann F, Mungai G M. Diterpenes and sequiterpene xylosides from east african conyza species.  Phytochemistry. 1990;  29 3167-72
• 3 Ruecker G, Kehrbaum S, Sakulas H, Lawong B, Goeltenboth F. Acetyenic glucosides from Microglossa pyrifolia .  Planta Med.. 1992;  58 266-9
• 4 Bohlmann F, Buehmann U. Synthesis of naturally occurring hydroxyacetophenone derivatives.  Chem Ber. 1972;  105 863-73
• 5 Valverde Lopez S, Rodriguez Gonzalez B. Benzofuran derivative isolated from Helichrysum stoechas .  An Quim. 1971;  67 879-85
• 6 Buckingham J. et al (eds) .Dictionary of Natural Products on CD-ROM. Boca Raton, FL; Chapman & Hall 2001
• 7 Le-Van N, Pham T VC. An unusual m-hydroxyacetophenone and three new chromanone derivatives from Chrysothamnus viscidiflorus .  Phytochemistry. 1981;  20 485-7
• 8 Hyperchem v. 5.1 is a product of Hypercube Inc., http://www.hyper.com/. 
• 9 Bohlmann F, Kramp W, Grenz M, Robinson H, King R M. Diterpenes from Baccharis species.  Phytochemistry. 1981;  20 1907-13
• 10 Alarcon S R, De la Fuente J R, Novara L, Sosa V E. Un Benzofurano y Cumarinas en Trichocline reptans WEDD.  An Asoc Quim Argent. 1998;  86 248-51
• 11 Bohlmann F, Zdero C, Gupta R K, King R M, Robinson H. Diterpenes and Tetranorditerpenes from Acritopappus species.  Phytochemistry. 1980;  19 2695-705
• 12 Bremer K . (ed) .Asteraceae Cladistics ( Classifications. Portland, Oregon; Timber press 1994
• 13 Proksch P, Rodriguez E. Review Chromenes and benzofurans of the Asteraceae, their chemistry and biological significance.  Phytochemistry. 1983;  22 2335-48
• 14 De Pascual Teresa J, Bellido I S, Gonzales M S, Vicente S. Tetracyclic triterpenes and nerolidol derivatives from Santolina oblongifolia .  Phytochemistry. 1986;  25 85-190
• 15 Grande M, Torres P, Piera F, Bellido I S. Triterpenoids from Dittrichia viscosa .  Phytochemistry . 1992;  31 1826-8
• 16 Daryl D R, Newman R H. Noroleane saponins from Celmisia petriei .  Phytochemistry. 1984;  23 639-44

1 Assignments interchangeable within each row for 10a/10b.