Antimicrobial clerodane diterpenoids from Microglossa angolensis Oliv. et Hiern.

OBJECTIVE: To identify the antimicrobial components present in Microglossa angolensis following fractionation of the methylene chloride extract of the aerial part of this plant. MATERIALS AND METHODS: The plant was dried and extracted by percolation with methylene chloride. The dry extract was fractionated and purified by silica gel column chromatography. The isolated compounds were identified by comparison of their Nuclear Magnetic Resonance (NMR) spectral data with those reported in the literature. Antimicrobial activity was assayed by broth macro dilution method. RESULTS: The crude extract of M. angolensis displayed significant antifungal and antibacterial activities (MIC = 312.50-1250mug/ml). 6beta-(2-methylbut-2(Z)-enoyl)-3alpha,4alpha,15,16-bis-epoxy-8beta,10betaH-ent-cleroda-13(16),14-dien-20,12-olide and spinasterol were the most active compounds (MIC = 1.56-100mug/ml) and the most sensitive microorganisms were Enterococcus faecalis and Candida tropicalis for bacteria and yeasts respectively. CONCLUSION: The isolation of these active antibacterial and antifungal principles supports the use of M. angolensis in traditional medicine for the treatment of gastro-intestinal disorders.

Antibacterial agents from the leaves of Crinum purpurascens herb (Amaryllidaceae).

BACKGROUND: Typhoid fevers and urogenital infections continue to be serious health problems in developing countries. In our search for therapeutic agents from natural sources with potential for the treatment of typhoid fevers and urogenital infections, extract and compounds were obtained from Crinum purpurascens and tested. METHODS: Two alkaloids (4,5-ethano-9,10-methylenedioxy-7-phenanthridone or hippadine (1) and 4,5-ethano-9-hydroxy-10-methoxy-7-phenanthridone or pratorimine (2)) and one steroid (â-D-glucopyranoside of sitosterol (3)) were isolated from the CH(2)Cl(2)/MeOH (1:1) leaf extract of Crinum purpurascens and screened for antibacterial activity using both agar diffusion and broth dilution techniques. RESULTS: For the CH(2)Cl(2)/MeOH extract, the MIC values obtained were 3 mg/ml (against P. aeruginosa), 4 mg/ml (against E. coli, K. pneumoniae and S. aureus) and 6 mg/ml (against S. typhi and S. paratyphi B), whereas the MBC values varied between 7 and 12 mg/ml. For compound 1, the MIC values varied between 200 and 250 µg/ml, whereas the MBC value was 300 µg/ml against all the bacteria strains used. Compound 2 did not show any antimicrobial activity against these bacteria strains. For compound 3, the MIC values varied between 250 and 300 µg/ml, whereas the MBC values were 300 µg/ml (against S. typhi and S. paratyphi B) and > 300 µg/ml (against the other bacteria strains). CONCLUSION: These data suggest that C. purpurascens leaf extract contains antibacterial agents which could be used in the treatment of typhoid fevers and urogenital infections.

Millaurine A, a new guanidine alkaloid from seeds of Millettia laurentii.

A new guanidine alkaloid, millaurine A (1), was isolated from the methanol extract of the seeds of Millettia laurentii. The structure of the new compound was elucidated on the basis of spectral analysis.

Piptaderol from Piptadenia africana.

A new glyceryl derivative (Glyceryl-1-hexacosanoate) and a flavone derivative (methyletherapigenin) were isolated from the stem bark extract of Piptadenia africana, a western Cameroonian plant species. Common terpenes like sitosterol, beta-amyrin and eicosane were also isolated. These compounds were identified using physical and spectroscopic methods including mp, IR, (1)H and (13)C-NMR, DEPT, COSY, HMQC, HMBC, EI MS, HREI MS as well as some chemical transformations. The antibacterial activity of the extract, the fractions and the pure compounds is also discussed.

Diarylheptanoids from Myrica arborea.

Investigations of the stem and root bark of Myrica arborea (Myricaceae) have yielded two novel diarylheptanoids, myricarborin and 11-O-beta-D-xylopyranosylmyricanol along with the known myricanol and 5-O-beta-D-glucopyranosylmyricanol. The structures of the novel compounds were determined by spectroscopic methods.

Chromone glycosides from Schumanniophyton magnificum.

Two new chromone glycosides, schumanniofiosides A and B have been isolated from the root bark of Schumanniophyton magnificum and their structures shown to be 2-methyl-5,7-dihydroxychromone 5-O-beta-D-glucopyranoside and 2-methyl-5,7-dihydroxychromone 7-O-beta-D-glucopyranosyl-(1----2)-apiofuranoside, respectively. The structures were elucidated by a combination of spectral data and chemical degradation.