A new bioactive thiophenolic glycoside from the leaf of Massularia acuminata (g. Don Bullock) ex Hoyle (Rubiaceae).

BACKGROUND: Massularia acuminata is a small tree or shrub of tropical rainforest. The leaves are used in Nigerian ethno-medicine for the treatment of microbial infections and pharmacological report suggested the leaf extract as possessing antioxidant activity. This study was therefore carried out to determine the most antioxidant and antimicrobial active fraction(s) of Massularia acuminata leaf and the constituent(s) responsible for the activities. MATHERIALS AND METHODS: The leaf of Massularia acuminata was investigated for in vitro antioxidant and antimicrobial activities, using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and agar dilution method respectively. RESULTS: The ethyl acetate fraction demonstrated the best activities among the partitioned fractions tested. Bioassay guided purification of the most active ethyl acetate fraction led to isolation of a new thiophenolic glycoside, characterized as 4-(3',3'-dihydroxy-1-mercaptopropyl)phenyl glycosylpyranoside. CONCLUSION: The isolated compound from the leaf of Massularia acuminata demonstrated antioxidant and antimicrobial activities and may be responsible for the activities of leaf extract and its ethyl acetate fraction, hence this may justify its ethnomedicinal use.

Antimicrobial and Antioxidant Activities of Some Nigerian Medicinal Plants

Ten Nigerian plants suggested from their ethnomedical uses to possess antimicrobial and antioxidant activities were studied for their anti-microbial and anti-oxidant properties. Antimicrobial activity was tested against Escherichia coli NCTC 10418, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Candida pseudotropicalis and Trichophyton rubrum (clinical isolate). Trichilia heudelotti leaf extract showed both antibacterial and antifungal activities and was the most active against all the strains of bacteria tested. Boerhavia diffusa, Markhamia tomentosa and T. heudelotti leaf extracts inhibited the gram negative bacteria E.coli and P. aeruginosa strains whereas those of M. tomentosa, T. heudelotti and Sphenoceutrum jollyamum root inhibited at least one of the fungi tested. At a concentration of 312 µg/ml, hexane and chloroform fractions of T. heudelotti extract inhibited 6 and 14% of the fifty mult-idrug resistant bacteria isolates from clinical infectins, respectively. At ≤ 5mg/ml, the CHCl3 (64%) and aqueous (22%) fractions of T. heudelotti and those of CHCl3 (34%) and EtOAC (48%) of M. tomentosa gave the highest inhibition that was stronger than their corresponding methanol extracts. The corresponding EC50 of the extracts on M. acuminata, T. heudelotti, E. senegalensis and M. tomentosa were 4.00, 6.50, 13.33, and 16.50 ig/ml using the TLC staining and 1,1-dipheyl-2-picry-hydrazyl (DPPH) free radical scavenging assay. Therefore, leaf extracts of M. tomentosa and T. heudelotti, especially the latter, possess strong antimicrobial and antioxidant activities and should be further investigated. These activities justified the ethnomedical uses of these plants

Antimicrobial and antioxidant activities of some Nigerian medicinal plants.

Ten Nigerian plants suggested from their ethnomedical uses to possess antimicrobial and antioxidant activities were studied for their anti-microbial and anti-oxidant properties. Antimicrobial activity was tested against Escherichia coli NCTC 10418, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Candida pseudotropicalis and Trichophyton rubrum (clinical isolate). Trichilia heudelotti leaf extract showed both antibacterial and antifungal activities and was the most active against all the strains of bacteria tested. Boerhavia diffusa, Markhamia tomentosa and T. heudelotti leaf extracts inhibited the gram negative bacteria E. coli and P. aeruginosa strains whereas those of M. tomentosa, T. heudelotti and Sphenoceutrum jollyamum root inhibited at least one of the fungi tested. At a concentration of 312 microg/ml, hexane and chloroform fractions of T. heudelotti extract inhibited 6 and 14% of the fifty multi-drug resistant bacteria isolates from clinical infections, respectively. At < or = 5 mg/ml, the CHCl(3) (64%) and aqueous (22%) fractions of T. heudelotti and those of CHCl(3) (34%) and EtOAC (48%) of M. tomentosa gave the highest inhibition that was stronger than their corresponding methanol extracts. The corresponding EC(50) of the extracts on M. acuminata, T. heudelotti, E. senegalensis and M. tomentosa were 4.00, 6.50, 13.33, and 16.50 ig/ml using the TLC staining and 1,1-dipheyl-2-picry-hydrazyl (DPPH) free radical scavenging assay. Therefore, leaf extracts of M. tomentosa and T. heudelotti, especially the latter, possess strong antimicrobial and antioxidant activities and should be further investigated. These activities justified the ethnomedical uses of these plants.

Ethno-veterinary medicine: screening of Nigerian medicinal plants for trypanocidal properties.

Trypanosoma congolense and T. brucei bloodstream form parasites were propagated axenically in suitable standard media at 34 degrees C. The effects of 33 plant extracts, fractions and pure compounds were evaluated on two clones of T. brucei and drug-sensitive and multi-drug-resistant clones of T. congolense. The cytotoxic activity of the trypanocidal extracts was also evaluated on calf aorta endothelial cells in vitro. Of the extracts tested, 22% killed T. congolense IL 1180 at a concentration of 100 microg/ml while 18% killed 90-100% of T. brucei ILTat 1.4 at the same concentration. However, 6% of the active extracts killed 93% of a dyskinetoplastid form of T. brucei IL Tat 1.1, indicating that the intact kinetoplast is a target of some of the compounds tested. Of the 12 extracts that displayed activity against drug sensitive trypanosomes, 66.7% had trypanocidal activity on a multi-drug-resistant clone, T. congolense IL 3338. The extracts of Eugenia uniflora, Acacia artaxacantha, Terminalia ivorensis, T. superba and Alchornea cordifolia had median lethal concentrations of between 13 and 69 microg/ml on both the drug-sensitive, IL 1180 and multi-drug-resistant clone, IL 3338. The median lethal doses of the active plant extracts on the calf aorta endothelial cells varied between 112 and 13750 microg/ml while the calculated selective indices ranged between 0.71 and 246.8 indicating bright prospects for the development of some of these extracts as potential trypanocidal agents.

Antimicrobial activity of Trichilia heudelotti leaves.

Diterpenes and phenolic acids, including the new compounds 12 beta-hydroxysandaracopimar-15-ene (4) and 2-propionoxy-beta-resorcylic acid (8) have been isolated from Trichilia heudelotti leaves. The methanol extract showed antimicrobial activity concentrated in the ethyl acetate fraction and some of its constituents.

New pyrazole alkaloids from the root bark of Newbouldia laevis.

The root bark of Newbouldia laevis afforded withasomnine, 4'-hydroxywithasomnine, 4'-methoxywithasomnine, newbouldine, 4'-hydroxynewbouldine, and 4'-methoxynewbouldine. 4'-Methoxywithasomnine and 4'-methoxynewbouldine are new natural products.

Phytochemical and pharmacological investigation of the cardioactive constituents of the leaf of Dysoxylum lenticellare.

The cardiac effects of the leaf extract and 11 isolated pure compounds have been examined on isolated, spontaneously beating, atrial muscles of the rat. Using nor-adrenaline (8 X 10(-7)M) and acetylcholine (4 X 10(-8)M) as reference drugs and normal saline (equivalent volume) as control, the crude extract of Dysoxylum lenticellare (8 X 10(-4) g/ml) induced negative chronotropic and positive inotropic responses on the isolated cardiac muscle preparations. The extract demonstrated significant (p less than 0.05-0.01) cardioactivity as attested to by its positive inotropic and/or negative chronotropic activities on the rat atrial preparations. Of the pure isolates tested, 7, 8, and 9 demonstrated significant cardiac effects. Although the precise mechanism of action of the extract or pure isolates on the atrial myocardium has not been fully determined, available experimental data suggest that the extract and pure isolates act directly on the cardiac muscle. Alkaloids 7, 8, and 9 manifest cardiac effects similar to that of the crude extract but of lesser magnitude. Some indirect effects of these isolates may, however, be associated with the manifested activities.