Further Mulinane and Azorellane Diterpenoids Isolated from Mulinum crassifolium and Azorella compacta

Abstract

Abstract:The new mulinane diterpenoids 1 and 2 were isolated from the EtOAc extract of Mulinum crassifolium, while the rearranged mulinane 5, which was isolated for the first time from a natural source, was isolated from Azorella compacta. Compounds 1-2 were prepared by semi-synthesis thorough acetylation of the diterpene 17-acetoxymulinic acid (3). A mechanism of reaction was proposed, while the structures of the new compounds were elucidated on the basis of comprehensive spectroscopic analysis and computational methods.

Crystal structure of 5-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3,7,8-trimethoxy-4H-chromen-4-one, C19H18O8

“…The title compound was isolated using medium pressure column chromatography (MPCC) from Parastrephia quadrangularis, a medicinal plant used by the Aymara Amerindians [6,7], a known producer of several flavonoids and benzoic acid derivatives with antioxidant activity [8][9][10][11]. Following our program to isolate interesting metabolites from the Atacama Desert Flora, Northern Chile [12][13][14][15][16][17][18], dried aerial parts of P. quadrangularis (1622 g) collected in april 2015 in "El Tatio", Andean mountain range of the of Atacama Desert, II Region, Northern Chile, were defatted with hexane (3 liters, 3 times in the dark, 24 hours each time) and 54.82 g were obtained after evaporation of the solvent. Then the plant material was extracted with ethyl acetate (3 liters, 3 times in the dark, 24 hours each time.…”

7-6-5 Tricarbocyclic Diterpenes

“…Mulinanes [15][16][17][18][19][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Structurally, these compounds (or nearly of all them) are characterized by having an acid group in C-20, and a seven-member ring C functionalized. They show a wide variety of biological activities, such as antituberculosis, antimalaric, antibacterial, spermatostatic, and antihyperglycemic effects ( Table 5.3).…”

“…madreporica Antibacterial [34] Mulinone A, 50 M. crassifolium [35] Mulinone B, 51 M. crassifolium [35] biological activities, including trypanocidal, analgesic, antiinflammatory, anti-NF-kB (antinuclear factor kappa-light-chain-enhancer of activated B cells), and antituberculosis (Fig. madreporica Antibacterial [34] Mulinone A, 50 M. crassifolium [35] Mulinone B, 51 M. crassifolium [35] biological activities, including trypanocidal, analgesic, antiinflammatory, anti-NF-kB (antinuclear factor kappa-light-chain-enhancer of activated B cells), and antituberculosis (Fig.…”

Absolute Configuration of Mulinolic Acid

“…Bitter tasting infusions of the whole plant are used widely in folk medicine, principally in the treatment of diabetes, and bronchial and intestinal disorders 1 . This plant is well recognized as an important source of diterpenes bearing the mulinane skeleton with interesting biological activities 2 . The relative stereochemistry of the title compound was assigned by spectroscopic data and by chemical transformations 3 .…”