I.M.S. Eldeen

In vitro biological activities of niloticane, a new bioactive cassane diterpene from the bark of Acacia nilotica subsp. kraussiana

ETHNOPHARMACOLOGICAL RELEVANCE Acacia nilotica subsp. kraussiana was reported in African traditional medicine for the treatment of various ailments. Isolation of an active compound in this study from the bark extract may lead to the validation of its efficiency as a traditional crude drug. AIMS OF THE STUDY This study aimed to isolate active compound(s) from an ethyl acetate bark extract of Acacia nilotica subsp. kraussiana and to investigate some of its biological activity. MATERIALS AND METHODS The isolation process was carried out using bioassay-guided fractionation. The isolated compound was tested for antibacterial activity using the micro-dilution assay; anti-inflammatory activity using the COX-1 and COX-2 assays and investigated for inhibitory effect against acetylcholinesterase using the microplate assay. RESULTS A new bioactive compound was isolated and identified as a cassane diterpene, niloticane. Niloticane showed antibacterial activity against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus with MIC values of 4 and 8microg/mL, respectively. With Gram-negative bacteria, niloticane showed weak activity. MIC values obtained were 16 and 33microg/mL against Klebsiella pneumonia and Escherichia coli, respectively. In the cyclooxygenase test, niloticane possessed activity with IC50 values of 28 and 210microM against COX-1 and COX-2, respectively. IC50 values observed with indomethacin (positive control) were 3.6microM for COX-1 and 189microM for COX-2. In the acetylcholinesterase test, niloticane showed anti-cholinesterase activity with an IC50 value of 4microM. IC50 values obtained by the galanthamine (positive control) was 2.0microM. CONCLUSION The results obtained support the traditional uses of the bark of Acacia nilotica subsp. kraussiana in African traditional medicine for the treatment of some ailments that relate to microbial diseases, inflammation and central nervous system disorders.

Isolation and Biological Activities of Termilignan B and Arjunic Acid from Terminalia sericea Roots

Bioassay-guided fractionation of ethyl acetate root extracts of Terminalia sericea yielded a new compound, termilignan B, and the known arjunic acid. Both compounds showed activity against Gram-positive and Gram-negative bacteria with MIC values ranging between 1.9 and 15.6 microg/mL. The lowest MIC value (1.9 microg/mL) was observed with termilignan B against Bacillus subtilis. Neither of the compounds showed significant activity against Mycobacterium aurum A+. In the cyclooxygenase assays, the compounds showed weak inhibitory activity with IC (50) values of 78 microM (COX-1) and 156 microM (COX-2) (termilignan B) and 36 microM (COX-1) and 253 microM (COX-2) (arjunic acid). No potential mutagenic effects were observed with the two compounds in the Salmonella microsome assay (TA 98).

A new sesquiterpenoid from the rhizomes of Homalomena sagittifolia

A new sesquiterpenoid, 1α,4β,7β-eudesmanetriol (1), was isolated together with the known compounds 1β,4β,7β-eudesmanetriol (2) and oplopanone (3) from the rhizomes of Homalomena sagittifolia. The structures of these compounds were determined by extensive spectral analyses. The compounds 1 and 2 inhibited growth of Pseudomonas stutzeri with a MIC value of 117 µM when evaluated for antibacterial activity using the minimum concentration assay. Both these compounds showed remarkable activities against acetylcholinesterase enzyme with IC50 values ranging between 25 and 26 µM. The isolation of these sesquiterpenoids and their biological activities observed in this study support the reported traditional uses of H. sagittifolia for the treatment of microbial related diseases and central nervous system disorders.