New flavonoidsC-glycosides fromRhabdophyllum arnoldianum

Abstract

Two new flavone glycosides, 3″-O-acetyl-7-O-methylvitexin (1) and 6″-α-rhamnopyranosyl-7-O-methylvitexin (2), along with nine known compounds (3-11) were isolated from the leaves of Rhabdophyllum arnoldianum (Ochnaceae). The structures of the new compounds were established by detailed spectroscopic studies and mass spectrometry, while known compounds were characterised by direct comparison of their reported NMR data with those found in the literature. All these compounds were the first reported from Rhabdophyllum genus. The biological assays on crude extracts and compounds of this plant demonstrated that the crude extracts possess significant antimicrobial activity against Gram-positive bacteria.

A new procyanidin B from Campylospermum zenkeri (Ochnaceae) and antiplasmodial activity of two derivatives of (±)-serotobenine

“…Several species belonging to this genus are reported in folk medicine in the treatment of various diseases such as gastric pains, gonorrhoea, icterus, whitlow, malaria and aphrodisiac matter (Bouquet 1969;Ngono et al 2011Ngono et al , 2015. Previous reports indicated that the genus and many others belonging to Ochnaceae family are a rich source of compounds with wide variety of structures (Abouem à Zintchem et al 2008;Abouem et al 2014;Bayiha Ba Njock et al 2013;Ghogomu et al 1990;Ndongo et al 2010Ndongo et al , 2015Ngo Mbing et al 2014;Ngono Bikobo et al 2011. Hence, this study was carried out to isolate and elucidate the structure of constituents from stem bark extract of C. zenkeri, then to perform few chemical transformations on an isolated one serotobenine (which is the marker of the genus) in order to evaluate the potent bioactive derivative for antiplasmodial activity.…”

Three new compounds with nitric oxide inhibitory activity from Tirpitzia sinensis, an ethnomedicinal plant from Southwest China

“…The 13 C NMR data showed 25 carbon signals of compound 1 , including 2 methyls, 4 methylenes, 11 methines, and 8 quaternary carbons in the DEPT experiment. The presence of an apiofuranosyl unit was suggested by two oxygenated methylene carbons at δ C 75.1 and 65.6, one oxygenated methine carbon at δ C 70.7, one quaternary carbon at δ C 80.6 and one anomeric carbon at δ C 111.1 (Table 1), which were identified as α configuration based on the J value-coupling constant of H-1′′ ( J = 2.6 Hz) [21]. The HMBC correlations from proton at H-7′ ( δ H 4.62) to the carbons C-1′ ( δ C 136.9), C-2′ ( δ C 112.7), and C-6′ ( δ C 117.0) indicated that the group of C-7′/C-8′/C-9′ was attached to C-1′ of lignan skeleton (Fig.…”

“…The IR spectrum of 2 showed hydroxyl groups, methoxy groups and aromatic rings respectively at 3347, 2945, 2832, 1451 and 1030 cm −1 . The 1 H NMR spectrum (Table 1) of 2 revealed an ABX system at δ H 7.51 (1H, dd, J = 8.4, 1.4 Hz, H-6′), 7.48 (1H, d, J = 1.4 Hz, H-2′) and 6.94 (1H, d, J = 8.3 Hz, H-5′), and an olefinic signal at δ H 6.65 assigned to H-3 position, which indicated it is a flavone skeleton [21]. Additionally, one aromatic singlet signal at δ H 6.53, one methoxyl signal at δ H 3.96 (3H, s), one doublet methyl signal at δ H 0.75 (3H, d, overlapped), two anomeric proton signals at δ H 5.23 (1H, s) and δ H 4.95 (1H, d, J = 11.3 Hz) were observed as well.…”

“…The NOESY correlations for H-1′′′/H-2′′′, H-2′′′/H-3′′′, H-3′′′/H-5′′′, and H-4′′′/H-6′′′ indicated that H-1′′, H-3′′ and H-5′′ were α -oriented, and H-4′′′, H-6′′′ were β -oriented. Furthermore, the obvious downfield shift of glucose methylene carbon (C-6′′) at δ C 69.8 indicated the effect of glycosidation, which suggested anomeric proton of rhamnose δ H 5.23 (s) was located at C-6′′ hydroxyl group of the glucosyl moiety with α configuration and 6 → 1 sequence linkage [21, 26], also supported by the NOESY correlations of H-5′′/H-6′′β ( δ H 3.87) and H-1′′′/H-6′′α ( δ H 3.89). On the basis of these combined data, compound 2 was identified as 3′- O -methylluteolin-6- C -[1′′- β - d -glucopyranosyl (6 → 1)- α - l -rhamnoside].…”