β-Orcinol depsidones from the lichenUsneasp. from Sri Lanka

Abstract

Two beta-orcinol depsidone lactones, the methyl ethers of menegazziaic acid and stictic acid were isolated along with glyceryl trilinolate and usnic acid from an Usnea sp. new to Sri Lanka growing on rotting trees of Acacia decurrans. Usnic acid exhibited potent antitermite activity against a common pest of tea, Glyptotermes dilatatus, at low elevations.

Enantioselective activity of usnic acid: a comprehensive review and future perspectives

“…The starved insects were administered 10 mg of the tested compound. This caused a significant, 80% mortality of the termites after 23 days of the exposure (Kathirgamanathar et al 2005).…”

β-Orcinol Metabolites from the Lichen Hypotrachyna revoluta

“…All spectra, of the minor metabolite 4, were supportive of being the 8΄-methyl analogue of constictic acid or the oxidation derivative of metabolite 5 on C-9΄. The chemical shifts of proton and carbon resonances for metabolite 5 are reported along with the new compounds in Table 1, since careful spectral analyses revealed some erroneous assignments in the previous literature report [13].…”

“…It is important to mention that these metabolites are the first examples of depsides (compound 1) and depsidones (compounds 2, 3) with a non functionalized α-carbon on the lactone ring. Along with the new molecules, the previously described metabolites 8΄-methylstictic acid (5) [13][14], 8΄-methylmenegazziaic acid (6) [13], stictic acid (7) [15][16], 8΄-ethylstictic acid (8) [16] and atranorin (9) [7] were isolated from the same extract. Metabolite 6 has been isolated previously from an unidentified Usnea species collected in Sri Lanka [13].…”

“…Along with the new molecules, the previously described metabolites 8΄-methylstictic acid (5) [13][14], 8΄-methylmenegazziaic acid (6) [13], stictic acid (7) [15][16], 8΄-ethylstictic acid (8) [16] and atranorin (9) [7] were isolated from the same extract. Metabolite 6 has been isolated previously from an unidentified Usnea species collected in Sri Lanka [13]. It is noteworthy that compounds 1 -8 are reported for the first time as metabolites of H. revoluta, since the only study on the chemistry of this species,reported the presence of atranorin and gyrophoric acid in a sample collected in New Zealand [17].…”

Extraction, isolation and characterization of depsidones from Usnea baileyi (Stirt.) Zahlbr collected from tree barks in Tam Bo Mountain of Di Linh, Lam Dong Province, Viet Nam

“…In addition, the HMBC correlations between H-9' and C-7' (δ C 165.9) and 8'-O-Me (δ C 56.3) led to deduction of the five-member ring lactone in the B-ring. The comparison of NMR data of 1 and those of methylstictic acid Ramesh and Baig (1994); Kathirgamanathar et al (2005) showed that they were identical. Thus, 1 was elucidated as 8'-O-methylstictic acid.…”