Camellianols A–G, Barrigenol-like Triterpenoids with PTP1B Inhibitory Effects from the Endangered Ornamental Plant Camellia crapnelliana

Abstract

Seven new naturally occurring barrigenol-like compounds, camellianols A-G (1-7), and 10 known triterpenoids were isolated from the twigs and leaves of the cultivated endangered ornamental plant Camellia crapnelliana. According to the ECD octant rule for saturated cyclohexanones, the absolute configurations of camellianols D (4) and E (5) were defined. The backbones of the remaining new isolates are assumed to have the same absolute configuration as compounds 4, 5, and harpullone (12). Compounds 2, 3, 9, 10, 13, and 16 exhibited inhibitory effects on the protein tyrosine phosphatase 1B (PTP1B) enzyme, with IC values less than 10 μM.

Stewartiacids A–N, C-23 carboxylated triterpenoids from Chinese Stewartia and their inhibitory effects against ATP-citrate lyase and NF-κB

“…138.6 (C- 19)]. This was corroborated by the HMBC correlations from H 3 -29/H 3 -30 to C-19 and from H 3 -28 to C-18 (Fig.…”

“…Thus, the structure of 3 was dened as 3b,11a-dihydroxy-12,22-dioxo-urs-13 18-en-23-oic acid. Finally, the absolute conguration (3S,4S,5R,8R,9R,10S,11S,14S,17R,19S,20R) of 3 was unequivocally established by a single-crystal X-ray diffraction analysis [Flack parameter ¼ À0.01 (19)] using Ga Ka radiation ( Fig. 4 and Table S2 in ESI ‡).…”

Cytotoxic Polyhydroxylated Oleanane Triterpenoids from Cissampelos pareira var. hirsuta

“…The 1 H NMR spectrum (Table 1, Figure S1) showed one oxymethylene group δH 4.68 (1H, d, J = 11.0 Hz, H-28) and 4.55 (1H, d, J = 11.0 Hz, H-28), three oxymethine resonances δH 3.14 (1H, dd, J = 11.3, 4.7 Hz, H-3), 4.77 (1H, dd, J = 11.7, 5.4 Hz, H-16), and 4.32 (1H, dd, J = 12.6, 4.7 Hz, H-22), along with one nicotinoyl group δH 9.14 (1H, brs, H-3′), 8.40 (1H, dt, J = 8.0, 1.9 Hz, H-5′), 7.59 (1H, dd, J = 8.0, 5.1 Hz, H-6′), and 8.76 (1H, d, J = 3.9 Hz, H-7′) [13]. Seven tertiary methyl groups δH 0.98 (6H, s, Me-23, Me-29), 0.78 (3H, s, Me-24), 0.96 (3H, s, Me-25), 1.08 (3H, s, Me-26), 1.30 (3H, s, Me-27), and 1.03 (3H, s, Me-30), together with one olefinic proton δH 5.27 (1H, t, J = 3.4 Hz, H-12), were evidence for a characteristic olean-12-ene pentacyclic triterpenoid skeleton [14]. The 13 C-NMR and DEPT spectra (Table 1, Figure S2-S3) provided 36 carbon signals, including seven methyls, nine methylenes [one oxygenated δC 64.1 (C-28)], eleven methines [five olefinic δC 125.5 (C-12), 150.9 (C-3'), 138.8 (C-5'), 125.4 (C-6'), 154.2 (C-7'), and three oxygenated δC 79.6 (C-3), 67.5 (C-16), and 70.9…”

“…The relative configuration of the ring substituents of compound 1 was determined by analyzing the vicinal coupling constants of the key protons and NOESY spectrum (Figures 3 and S7). The proton spin-coupling constants of J H-2β/H-3 (11.3 Hz), J H-5/H6β (12.8 Hz), J H-9/H-11β (11.9 Hz), J H-18/H-19α (14.0 Hz), and J H-21α/H-22 (12.6 Hz) indicated that H-3, H-5, and H-9 were cofacial and were assigned as α-orientation [14], and this also supported the β-orientation of 3-OH. The NOESY correlations (Figure 3) from H-16 to H-27, from H-22 to H-30 and H-18 indicated that β-and α-orientations were assigned for 16-OH and 22-OH, respectively.…”

Total Synthesis of the Alleged Structure of Crenarchaeol Enables Structure Revision**

“…As ar esult of the deshielding g-gauche effect, the 13 CNMR chemical shift of axial substituents in cyclohexanes is more upfield relative to equatorial substituents. [32] In Fragment Bt he 13 Cs ignal of methyl group A20' resonates at 30.12 ppm, while the methyl group A20' of natural crenarchaeol is shifted more upfield at 22.55 ppm. This strongly suggests that the methyl group A20' in natural crenarchaeol is in axial position in contrast to the initially proposed structure.T ofurther support this,weconsidered the 13 Cc hemical shifts of A16'.I nF ragment B, the carbon atom A16' of the alkyl side-chain of the cyclohexyl ring is axially oriented.…”