Antibacterial secotirucallane triterpenes from the stem bark of Pseudocedrela kotschyi.

The antibacterial-guided investigation of the stem bark extract of Pseudocedrela kotschyi led to the isolation of a new secotirucallane triterpene derivative: 4-hydroxy-3,4-secotirucalla-7,24-dien-3,21-dioic acid (1), together with the known one: 3,4-secotirucalla-4(28),7,24-trien-3,21-dioic acid (2) and 3-methyl ester 3,4-secotirucalla-4(28),7,24-trien-3,21-dioic (3). The structures of the isolated compounds were elucidated on the basis of extensive 1D- and 2D-NMR spectroscopy. Extracts, fractions and compounds (1-3) were tested in vitro for antibacterial activity against two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus ATCC 25923), and two Gram negative bacteria (Escherichia coli S2(1) and Pseudomonas aeruginosa). The MeOH extract and the Hex/CH2Cl2 (70:30) fraction showed significant levels of activity (MIC=64- 256 µg/mL) compared with the two reference drugs [ciprofloxacin: MIC (0.5-1 µg/mL) and amoxicillin: MIC (1-128 µg/mL)]. Moreover, the compound 2 isolated from this Hex/CH2Cl2 (70:30) fraction had the greatest potential value against S. aureus, E. coli and P. aeruginosa, with minimum inhibitory concentrations (MIC) ranging from 4-16 µg/mL.

Constituents of the Stem Bark of Trichilia monadelpha (Thonn.) J. J. De Wilde (Meliaceae) and Their Antibacterial and Antiplasmodial Activities.

The chemical investigation of the EtOH extract from the stem bark of Trichilia monadelpha (Thonn.) J. J. De Wilde afforded two new limonoids (1 and 2): 24-acetoxy-21,25-dihydroxy-21,23-epoxytirucall-7-en-3-one (1) and (6R)-1-O-deacetylkhayanolide E (2), together with eleven known compounds (3-13), including additional limonoids, flavonoids, triterpenoids, steroids, and fatty acid. Their structures were determined using 1D- and 2D-NMR experiments, ESI mass spectrometry, and single crystal X-ray diffraction analysis. The antibacterial and antiplasmodial activities of the extracts, sub-extracts, fractions, and some of the isolated compounds were evaluated in known pathogenic strains, including Staphylococcus aureus and Plasmodium falciparum. Fraction E (n-Hex/EtOAc 30:70, v/v) showed significant activity against S. aureus ATCC 25923 with a MIC value of 3.90 µg/mL, while one of its constituents (epicatechin (9)) exhibited significant activity with MIC values of 7.80 µg/mL. Interestingly, grandifotane A (6) (IC50 = 1.37 µM) and khayanolide D (5) (IC50 = 1.68 µM) were highly active against the chloroquine-sensitive/sulfadoxine-resistant plasmodium falciparum 3D7 strain, unlike their corresponding plant extract and fractions.

Antioxidant and cytotoxicity activities of δ-tocotrienol from the seeds of Allophylus africanus.

Chemical investigation of Allophylus africanus P. Beauv fruits led to the isolation of a new δ-tocotrienol, 3α-hydroxy-δ-tocotrienol (1) together with eight known compounds (2-9). Compound (1) was allylated (1a) and prenylated (1 b and 1c) to give three new semi-synthesized derivatives which were fully characterized as: 6-O-allyl-3α-hydroxy-δ-tocotrienol (1a), 6-O-prenyl-3α-hydroxy-δ-tocotrienol (1 b) and 6-O,5-C-diprenyl-3α-hydroxy-δ-tocotrienol (1c). The structures of compounds were established using comprehensive spectroscopic analysis including UV, MS, 1 D NMR, 2 D NMR and by comparison with the corresponding literature data. Compound (1) and its semi-synthetic derivatives (1a-c) were tested for their antioxydant activity using DPPH radical scavenging assay and also for their cytotoxicity using human cervix carcinoma KB-3-1 cell lines. The results showed that compound (1) exhibited antioxidant activity with an IC50 value of 0.25 µM compared to the reference control trolox (26 µM); and good cytotoxic activity with IC50 values of 97 µM compared to the reference (+)-griseofulvin (IC50 between17-21 µM).

Phytochemical, antibacterial, antioxidant and cytoxicity investigation of Tarenna grandiflora.

The phytochemical investigation of Tarenna grandiflora led to the isolation of 18 known compounds of which were four flavones, three anthraquinones, one phenyl propanoic derivative, five triterpenoids, four steroids and a mixture of glucose. Luteolin (1) and soranjidiol (6) were allylated and/or prenylated to give four new semisynthesized derivatives which were fully characterized as 7,3',4'-O-triallylluteolin (1a), luteolin-7,3',4'-O-triprenyls (1b), luteolin-5,7,3',4'-O-tetraprenyls (1c) and 6-O-allylsoranjidiol (6a). Their structures were established using spectroscopic analysis including 1D, 2D NMR and MS data. The cytotoxic, antioxidant and antimicrobial activities of extracts, fractions, isolated compounds and semi-synthesized derivatives were evaluated. The petroleum ether and EtOAc extracts exhibited good cytotoxic potency on KB-3-1 cell line with IC50 of >0.1 and 0.025 mg/mL respectively, while compounds 1b and 11 were the most active (IC50 > 0.0001 M). Compounds 1 and 3 showed the best antioxidant activities (45.5 and 55.8 µM); while compounds 9 and 12 showed the best antibacterial activities with MICs values ranges from 8.55 to 132 µM.