4α-6α-Dihydroxy-A-homoazadiron, ein neues tetranortriterpenoid aus azadirachta indica a. juss (meliaceae)

Tetracyclic Triterpenoids and Their Derivatives from Azadirachta indica

“…Compound 40 obtained earlier through the alkaline hydrolysis of salannin [10] followed by methylation (34) has now also been isolated from a natural source (51). 2',3'-Dehydrosalannol [45] isolated from the leaves (65); desacetylnimbin [46] obtained from the seeds, bark, and twigs (66,67); nimbolide [8] (32) from fresh leaves; and nimbolin B [47] from trunk wood ( 48) are all related to nimbin [1] and represent various stages in the biosynthetic pathway. Nimbolide [8] is the only compound from neem possessing a lactone ring between C-6 and C-28.…”

Constituents of Azadirachta indica: Isolation and Structure Elucidation of a New Antibacterial Tetranortriterpenoid, Mahmoodin, and a New Protolimonoid, Naheedin

“…Another ion at m/z 137.0967 arises from the cleav- age of ring A. Thus the structure of naheedin was established as 20,22-dihydroazadirachtol [3], which was confirmed through formation of the diacetyl derivative 4, the 'H-nmr spectrum of which showed a shifting of resonance of -11 from 3.51 to 4.95 and that of H-21 from 5.50 to 6.20, while the signals for the two hydroxyl groups at 3.90 and 2.81 were replaced by two sharp singlets of the acetoxy methyls at 2.05 and 2.10 in addition to a singlet at 1.93 present in 3-13C-nmr chemical shifts (Table 2) further confirmed the structure as 3, the assignments of which have been made through comparison with those of azadirachtol (24) and other model compounds (17,25,26).…”

“…Assignments of various protons, particularly in the upfield region, were made through double resonance and 2D nmr experiments (COSY-45, NOESY,_/-resolved and hetero-COSY). The 13C-nmr spectral assignments have been made partly through a comparison of the chemical shifts with the published data for similar compounds (9,17,19,20,(24)(25)(26), and partly through the appearance of signals in DEPT and hetero-COSY spectra. For naheedin, *H and I3C-nmr (BB and off-resonance) spectra were run in CDC13 on a Bruker WP-100-SY Ft-nmr spectrometer.…”

Azadirachta indica

“…Compounds isolated from the leaves included the following: nimbolide, a meliacin (Ekong 1967 ); meliantriol (Lavie et al 1967 ); quercetin and isorhamnetin (Basak and Chakraborty 1968 ); β-sitosterol-β-D -glucoside, n -hexacosanol and β-carotene (Awasthi and Mitra 1971 ); a hexacyclic tetranortriterpenoid, vilasinin, a biogenetic precursor of salannin and nimbin isolated from fruits (Pachapurkar et al 1974 ); quercetin glycosides, quercetin 3-O -L -rhamnoside and quercetin 3-O -B-rutinoside (rutin) (Nair and Subramaniam 1975 ); pentanortriterpenoids, nimbinene, 6-deacetylnimbinene, 6-O -acetylnimbandiol and nimbandiol (Kraus and Cramer 1981b ); an isoprenylated fl avanone, 8,3′-di-isoprenyl-5, 7-dihydroxy-4′-methoxyfl avanone (Garg and Bhakuni 1984a ); a tetranorterpenoid, 4α-6α-dihydroxy-A-homoazadiron (Bruhn et al 1984 ); a tetranortriterpenoid, nimocinol (Siddiqui et al 1984b ); a limonoid, azadirachtin (Podder and Mahato 1985 ); 2′,3′-dehydrosalannol, a meliacin related to salannin (Garg and Bhakuni 1985 ); a γ-hydroxybutenolide tetranortriterpenoid named as isonimbocinolide (Siddiqui et al 1986a ); two bitter meliacins, nimocinolide and isonimocinolide (Siddiqui et al 1986c ); a triterpenoid nimbocinone and the two sterols sitosterol and stigmasterol (Siddiqui et al 1986e ); a ring C-seco-tetranortriterpenoid γ-hydroxybutenolide named as isoazadirolide, and a coumarin identifi ed as scopoletin (Siddiqui et al 1986g ); two fl avonol diglycosides (quercetin 3-O -β-rutinoside (rutin) and kaempferol 3-O -β-rutinoside) (Marco et al 1986 ); cyclic trisulphide and cyclic tetrasulphide (Pant et al 1986 ); nimbolide and 28-deoxonimbolide (Kigodi et al 1989 ); two tetranortriterpenoids, 6-deacetylnimbinal and 28-deoxonimbolide (Bokel et al 1990 ); an isoprenylated fl avanone, 8-prenyl-5,7-dihydroxy-3′-(3-hydroxy-3, 3 -d i m e t h y l bu t y l ) -4 ′ -m e t h o x y f l ava n o n e (Balasubramanian et al 1993 ); two tetranortriterpenoids (azadirachtolide and deoxyazadirachtolide) (Ragasa et al 1997 ); limonoids, nimbolide and 28-deoxonimbolide and α-linolenic acid (Nair et al 1997 ), nimocinol, nimonol, 6-acetylnimonol identifi ed as 6-acetoxyazadirone and dihydronimonol identical to isomeldenin …”