Antibacterial and Synergistic Activity of Pentacyclic Triterpenoids Isolated from Alstonia scholaris

Abstract

(1) Background: Alstonia scholaris (Apocynaceae) is an important medicinal plant that has been historically used in "Dai" ethnopharmacy to treat infectious diseases in China. Although various pharmacological activities have been reported, the antimicrobial constitutes of A. scholaris have not yet been identified. The objective of this study is to evaluate the antibacterial constitutes from the leaf extract of A. scholaris and to assess the synergistic effects of isolated compounds with antibiotics against bacterial pathogens.; (2) Methods: The chemical constitutes isolated from the leaf extract of A. scholaris were structurally identified by NMR. The antibacterial and synergistic effect of compounds was assessed by calculating the minimal inhibitory concentration (MIC), checkerboard dilution test, and time-kill assay.; (3) Results: Six pentacyclic triterpenoids were structurally identified as (1) lupeol, (2) betulin, (3) 3-hydroxy-11-ursen-28,13-olide, (4) betulinic acid, (5) oleanolic acid and (6) ursolic acid. Both oleanolic and ursolic acid showed antibacterial activity but were limited to Gram-positive bacteria. Ursolic acid showed a synergistic effect with ampicillin and tetracycline against both Bacillus cereus and S. aureus.; (4) Conclusion: These findings reflect that pentacyclic triterpenoids are the antibacterial chemicals in A. scholaris. The ability of ursolic acid to enhance the activity of antibiotics can constitute a valuable group of therapeutic agents in the future.

Comparison of antimicrobial properties of two spices commonly consumed in Nigeria and effect of temperature on their antioxidant properties

“…EOs are complex mixtures of a wide variety of components. Thus, their antimicrobial activity is related to their configuration, composition, amount and possible interaction which could be additive, antagonist or synergetic (Lis-Balchin et al, 1998;Wang et al, 2016). Inactivity of the EOs and other extracts of plants may be due to age of plant, extracting solvent, method of extraction and time of harvesting of plant materials (Okigbo et al, 2005;Okigbo and Ajalie, 2005).…”

Preliminary study on the chemical constituents of the leaves of Macaranga balansae Gagnep.

“…The NMR data is in agreement with those reported in the literature. [4] Compound 2 was obtained as a colorless oil. The ESI-MS revealed molecular ion peak m/z 297 suggested the molecular formula of 2 is C 20 H 40 O.…”

A New C-methyl Isoflavone and Other Compounds from the Roots of Amphiblemma monticola(Melastomataceae)

“…The known compounds were identified as 3,4'-di-O-methylellagic acid (2) [9], dimethyl 4,4',5,5',6,6'-hexahydroxybiphenyl-2,2'dicarboxylate (3) [10], lupeol (4) [11], ellagic acid 5 [13] and a mixture of oleanolic acid (10) [2,12] and ursolic acid (11) [2,12] (Figure S1).…”