Parvaxanthines D–F and Asponguanosines C and D, Racemic Natural Hybrids from the Insect Cyclopelta parva

Abstract

Five new compounds including three pairs of enantiomeric xanthine analogues, parvaxanthines D–F (1–3), two new guanosine derivatives, asponguanosines C and D (6 and 7), along with two known adenine derivatives were isolated from the insect Cyclopelta parva. Racemic 1–3 were further separated by chiral HPLC. Their absolute configurations were assigned by spectroscopic and computational methods. It is interesting that all of these isolates are natural product hybrids. Antiviral, immunosuppressive, antitumor and anti-inflammatory properties of all the isolates were evaluated.

Non-peptide compounds from Kromopolites svenhedini (Verhoeff) and their anti-tumor and iNOS inhibitory activities

“…and they share the same 7-hydroxyflavan skeleton. The difference in 4 is an additional methoxy group, which is connected to C-5' supported by the HMBC correlation (Figure 2 Compound 7, light yellow gum, has the molecular formula C16H28O3 (three degrees of unsaturation) deduced from its HRESIMS [M + H] + ion at m/z 251.1274 (calcd for C16H29O3, 251.1278), 13 C NMR, and DEPT data. The 1 H NMR spectrum (Table 4 and However, the signals of H2-5 and H2-8 overlap so badly that we cannot determine the geometry of the ∆ 6,7 by the same way.…”

“…Compound 1, yellow gum, has the molecular formula C14H18O4 (six degrees of unsaturation) deduced from its HRESIMS [M + H] + ion at m/z 251.1274 (calcd for C14H19O4, 257.1278), 13 C NMR, and DEPT data. The 1 H NMR data (Table 1 and 1 and Figure S2 in Supporting Information File 1) contain 14 resonances attributable to two methyls, two methoxy carbons, one methylene, three 4 methines (one sp 2 and one oxygenated), one ketone, and five sp 2 carbons (two oxygenated).…”

“…Compound 2, brown solid, has the molecular formula C17H16O6 (ten degrees of unsaturation) deduced from its HRESIMS [M + H] + ion at m/z 317.1008 (calcd for C17H17O6, 317.1020), 13 C NMR, and DEPT data. The 1 H NMR data (Table 2 and disclosed that the hydroxy group and the methyl group are positioned at C-2 and C-4, respectively, by the literature [17][18][19][20].…”

“…The two methoxy groups are positioned at C-3 and C-5 according to the HMBC correlations (Figure 2 Compound 4, brown solid, has the molecular formula C21H24O5 (six degrees of unsaturation) deduced from its HRESIMS [M + H] + ion at m/z 357.1680 (calcd for C21H25O5, 357.1697), 13 C NMR, and DEPT data. The 1 H NMR data (Table 3 and 3 and Figure S21 in Supporting Information File 1) contain 21 resonances attributable to two methyls, one methoxy carbon, three methylenes, seven methines (five sp 2 and two oxygenated), one oxygenated proton, and seven sp 2 carbons (four oxygenated).…”

“…According to very few studies on the chemical composition and biological activity about millipede, we can find that it contains antimicrobial peptides [6], defensive alkaloids [7], and defensive long chain alcohol acetates [8]. In our studies of arthropods and insects over the years, we have found that non-peptide small molecules play an important part in chemical structures and biological activities [9][10][11][12][13][14].…”