Chemical Constituents of the Flowers of Azadirachta indica

Abstract

Studies on the chemical constituents of the flowers of Azadirachta indica have led to the isolation of two new flavanones, flowerine (=5‐hydroxy‐7,4′‐dimethoxy‐8‐(3‐methylbut‐2‐enyl)flavan‐4‐one; 1) and flowerone (=5,7,8,4′‐tetrahydroxy‐3′‐(3‐methylbut‐3‐enyl)flavan‐4‐one; 2), and two new triterpenoids, O‐methylazadironolide (=7α‐(acetoxy)‐23ξ‐methoxy‐21,23‐epoxy‐24,25,26,27‐tetranorapotirucalla‐1,14,20(22)‐trien‐3,21‐dione; 3) and diepoxyazadirol (=(20S,23S,24R)‐7‐α‐(acetoxy)‐25‐hydroxy‐21,24 : 23,24‐diepoxyapotirucalla‐1,14‐dien‐3‐one; 4) along with the known triterpenoid trichilenone acetate (=7α‐(acetoxy)‐14,15 : 21,23‐diepoxy‐24,25,26,27‐tetranorapotirucalla‐1,20,22‐trien‐3‐one; 5), two known flavanones, nimbaflavone (=5,7‐dihydroxy‐4′‐methoxy‐8,3′‐bis(3‐methylbut‐2‐enyl)‐flavan‐4‐one; 6) and 3′‐prenylnaringenin (=5,7,4′‐trihydroxy‐3′‐(3‐methylbut‐2‐enyl) flavan‐4‐one; 7), and 4‐(2‐hydroxyethyl)phenol (8). Their structures have been elucidated through spectral studies, including 2D‐NMR experiments, and chemical transformation. Compounds 5, 7 and 8 are heretofore unreported from any part of tree, while 6 has been isolated earlier from leaves.

Antiproliferative activity and synthesis of 8-prenylnaringenin derivatives by demethylation of 7-O- and 4′-O-substituted isoxanthohumols

“…The 1 H NMR and IR spectroscopic data were in agreement with those reported in the literature (Cano et al , 2006; Siddiqui et al , 2003). …”

“…When the spectrum was accumulated on the next day or later the signals for the hydroxyl protons disappeared because of the hydrogen deuterium exchange. Compound ( 11 ) was also isolated from Azadirachta indica (Siddiqui et al , 2003) and Esenbeckia berlandieri ssp. Acapulcensis (Cano et al , 2006).…”

Omani propolis: chemical profiling, antibacterial activity and new propolis plant sources

“…By comparison of their spectral properties (NMR spectra, MS) with literature data [16], these compounds were identified as 7-O-methyl-8-prenylnaringenin 1 and 3’,8-diprenylnaringenin 2 (Figure 3). Both compounds are new propolis constituents and have been isolated previously from the neem tree Azadiracta indica [16,17]. For this reason we consider this tree as a likely major plant source of the samples OM-2, OM-6 and OM-7.…”

Synthesis, crystal structures and antibacterial activity studies of aza-derivatives of phytoalexin from cotton plant – gossypol

“…In the spectrum of GOS the signal of C(7) carbon atom was found at 155.6 ppm in CDCl 3 [54] and at 151.4 ppm in CD 3 CN [55], whereas the signal of C(7) carbon atom in the spectra of 19-27 was in the range 150.1-157.3 ppm ( Table 5). The chemical shift of the C(7) signals of gossypol hydrazones (19)(20)(21)(22)(23)(24)(25)(26)(27), similar to those of GOS, are in the range characteristic of the C-OH carbon atoms of phenols [46,[56][57][58][59]. This result shows clearly that gossypol hydrazones are present in the N-imine-N-imine tautomeric form, which is analogous to the aldehyde-aldehyde form of GOS (Scheme 1).…”