Annona

Abstract: Bioassay-guided fractionation of the bark extract of Annona foetida afforded a new antileishmanial pyrimidine-beta-carboline alkaloid, N-hydroxyannomontine (1), together with the previously reported annomontine (2), O-methylmoschatoline (3), and liriodenine (4). The structure of compound 1 was established on the basis of extensive 1D and 2D NMR and MS analyses. This is the third reported pyrimidine-beta-carboline-type alkaloid and is particularly important for Annona genus chemotaxonomy. In addition, all compounds exhibit in vitro antileishmanial activity against promastigote forms of Leishmania braziliensis. Compounds 2 and 4 showed better activity than compounds 1 and 3 against L. braziliensis. Compound 2 was not active against L. guyanensis.

Abstract: Background: Nearly all cultures from ancient times to the present day have used plants as a source of medicines. As a result, different remedies tended to develop in different parts of the world. Current strategies to overcome the global problem of antimicrobial resistance include research in finding new and innovative antimicrobials from plants. Objectives: To determine the antibacterial activity of extracts of Annona senegalensis, Securidacca longipendiculata and Steganotaenia araliacea, plants which are used in Eastern Uganda for the treatment of diarrhea and wound infections. Methods: The root barks of these plants were collected, sun-dried, pounded using pestles and wooden mortars. Water and methanol extracts were derived and screened. Standard cultures of E. coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923 were used in the study. The antibacterial tests used were the agar well diffusion assays. The minimum inhibitory concentrations (MIC) were determined by cylinder plate technique. Results: Extracts of Annona senegalensis, Steganotaenia araliacea and Securidaca longipendiculata showed activity against Staphylococcus aureus. The methanol extract of Securidaca longipediculata was not inhibitory to S.aureus. Steganotaenia araliacea and Securidaca longipediculata (water) extracts were active against all the bacteria tested. The water and methanol extracts of Annona senegalensis did not show inhibitory activity against E. coli. Of the three bacteria studied, Staphylococcus aureus was the most susceptible to the extracts followed by P. aeruginosa. E. coli was least sensitive to the plant extracts. Annona senegalensis had the lowest MIC against Staphylococcus aureus (62.5mg/ml); while Steganotaenia araliacea had the highest MIC (250mg/ml) signifying lower activity. Conclusions: The root bark extracts of the three plants showed antibacterial activity, justifying their continued use in treatment of bacterial infections. Recommendations: Further studies are required to isolate and characterise the active phytochemical constituents in the plants. Toxicity studies should be done to determine their safety. African Health Sciences 2006; 6(1): 31-35

Abstract: Annona species have been a valuable source of anti-infective and anticancer agents. However, only limited evaluations of their alkaloids have been carried out. This review collates and evaluates the biological data from extracts and purified isolates for their anti-infective and anti-cancer activities. An isoquinoline backbone is a major structural alkaloid moiety of the Annona genus, and more than 83 alkaloids have been isolated from this genus alone. Crude extracts of Annona genus are reported with moderate activities against Plasmodium falciparum showing larvicidal activities. However, no pure compounds from the Annona genus were tested against the parasite. The methanol extract of Annona muricata showed apparent antimicrobial activities. The isolated alkaloids from this genus including liriodenine, anonaine, asimilobine showed sensitivity against Staphylococcus epidermidis. Other alkaloids such as (+)-Xylopine and isocoreximine indicated significant anti-cancer activity against A549 and K-562 cell lines, respectively. This review revealed that the alkaloids from Annona genus are rich in structural diversity and pharmacological activities. Further exploration of this genus and their alkaloids has potential for developing novel anti-infective and anticancer drugs.