A lupeol derivative and other isolates with antiplasmodial activity from the stem root of Rauvolfia mannii Stapf. (Apocynaceae).

Rauvolfia mannii is a plant from western and eastern areas of African continent and is widely used in folk medicine for the treatment of various diseases including malaria. Herein, one previously undescribed acylated triterpene (1), together with five already published natural products (2-6) were removed from its roots. The chemical structures of these compounds were determined by spectroscopic and spectrometric means (NMR, HRESIMS, IR and UV). In addition to the isolated triterpenoids, components 5 and 6 are also newly reported from the genus Rauvolfia. Moreover, some constituents were further tested against the chloroquine-sensitive strain of P. falciparum (3D7). It has been found that 3 and 4 showed a moderate antiplasmodial activity with IC50 values of 46.25 and 39.79 µM respectively.

Antimicrobial and cytotoxic activities of indole alkaloids and other constituents from the stem barks of Rauvolfia caffra Sond (Apocynaceae).

Twenty indole alkaloids, among which two undescribed ones named rauvolfianoids A (1) and B (2), were isolated from the stem barks of Rauvolfia caffra Sond along with eight other compounds from other biosynthetic pathways. The structures were elucidated by analysis of spectroscopic data, including 1 D and 2 D NMR; absolute configurations of 1 and 2 were determined by CD exciton chirality method. Compounds 1 and 2 were evaluated for antimicrobial and anticancer activities against three bacterial strains (Escherichia coli, Shigella sp and Salmonella sp) and CRC-related opportunistic pathogens. 1 showed moderate antibacterial activity against Salmonella sp with the MIC value of 25 µg/ml, while 2 exhibited weak selective activity against all tested pathogens. In addition, these alkaloids were characterized as weak apoptosis inducers in HCT116 human colon carcinoma cell line.

Antiplasmodial activities of indole alkaloids from Tabernaemontana penduliflora K. Schum (Apocynaceae).

Five undescribed carboxy-indole alkaloids with corynanthe skeleton, penduflorines A-E (1-3) as well as a voacangine-N-oxide alkaloid, tabernaemontine (4), were isolated along with eight other known compounds (5-12) from the trunk bark of Tabernaemontana penduliflora K. Schum (Apocynaceae). Their structures were determined by means of spectroscopic and spectrometric methods such as UV, IR, NMR and HR-ESI-MS. Antiplasmodial activities of new isolates were evaluated against two strains of Plasmodium falciparum 3D7 and Dd2 by the Sybr green I-based fluorescence assay setup. Those compounds showed good in vitro activities. Among them, penduflorines A and B (1a and 1b) as well as tabernaemontine (4) showed significant inhibitory activities against the two strains with IC50 values ranged between 1.85 and 7.88 µg/mL. This is the first report of quaternary-N-indole alkaloids (1a, 1b, 2, 3a, 3b and 4) occurring in the form of zwitterion from Tabernaemontana genus.

Isolation, characterization and in vitro anti-salmonellal activity of compounds from stem bark extract of Canarium schweinfurthii.

BACKGROUND: Bacteria belonging to the Salmonella genus are major concern for health, as they are widely reported in many cases of food poisoning. The use of antibiotics remains a main stream control strategy for avian salmonellosis as well as typhoid and paratyphoid fevers in humans. Due to the growing awareness about drug resistance and toxicities, the use of antibiotics is being discouraged in many countries whilst advocating potent benign alternatives such as phyto-based medicine. The objective of this work was to isolate, characterise the bioactive compounds of Canarium schweinfurthii; and evaluate their anti-salmonellal activity. METHODS: The hydro-ethanolic extract of Canarium schweinfurthii was fractionated and tested for their anti-salmonellal activity. The most active fractions (i.e. chloroform and ethyl acetate partition fractions) were then explored for their phytochemical constituents. Fractionation on normal phase silica gel column chromatography and size exclusion chromatography on Sephadex LH-20 led to the isolation of four compounds (maniladiol, scopoletin, ethyl gallate and gallic acid) reported for the first time in Canarium schweinfurthii. RESULTS: Result indicated that scopoletin and gallic acid had greater activity than the crude extracts and partition fractions. Among the isolated compounds, scopoletin showed the highest inhibitory activity with a MIC of 16 µg/ml against Salmonella Typhimurium and Salmonella Enteritidis. CONCLUSIONS: The overall results of this study indicates that the hydro-ethanolic extract as well as some of isolated compounds have interesting anti-salmonellal activities that could be further explored for the development of potent therapy for salmonellosis. Furthermore, the study adds credence to the folkloric applications of the plant.