We aimed at reporting the chemical constituents and antimicrobial activities of
Leea aequata
L., a traditional folk medicine used in Myanmar for the treatment of wounds and skin diseases. A new neolignan, (7
S
,8
R
)-9′-
O
-acetylcedrusin (
1
), a new lactam, (3
S
,4
S
)-4-chloro-3-hydroxypiperidin-2-one (
2
), along with 21 known compounds, including five lignans (
3
–
7
), four flavonoid glycosides (
8
–
11
), and others (
12
–
23
), were isolated from the ethanoic extract of the aerial parts of
L. aequata
. The structures of the new compounds were determined by NMR, MS, and ECD spectra. For all the antimicrobial tests of the 23 compounds, only 3,4,5-trihydroxybenzoic acid ethyl ester (
17
) showed weak inhibitory activities against
Escherichia coli
and
Salmonella enterica
subsp.
enterica
.
Graphical Abstract
Electronic supplementary material
The online version of this article (10.1007/s13659-019-0209-y) contains supplementary material, which is available to authorized users.
Myanmar has a rich pool of, but less known, medicinal plants with traditional knowledge. In this study, we aimed to investigate the inhibitory activity of traditional Myanmar medicinal plants against the type III secretion system (T3SS) of Salmonella enterica serovar Typhimurium UK-1 χ8956 and the intestinal disease-caused by microbes including S. enterica serovar Typhimurium UK-1 χ8956, Proteusbacillus vulgaris CPCC 160013, Escherichia coli CICC 10003, and Staphylococcus aureus ATCC 25923. The EtOH extracts of 93 samples were used to screen the inhibitory activities against the secretion of T3SS effector proteins SipA/B/C/D of S. enterica and the antibacterial activity against S. enterica, P. vulgaris, E. coli, and S. aureus. Out of 71 crude drugs traditionally used, 18 were proofed to be effective either on the growth inhibition of tested bacteria and/or as inhibitors for the T3SS. The EtOH extracts of five plants, Luvunga scandens (Roxb.) Buch.-Ham. ex Wight & Arn. (My7), Myrica nagi Thunb. (My11), Terminalia citrina Roxb. ex Fleming (My21), Thymus vulgaris L. (My49), and Cinnamomum bejolghota (Buch.-Ham.) Sweet (My104), showed potent inhibitory activities against the secretion of T3SS proteins SipA/B/C/D of S. enterica serovar Typhimurium UK-1 χ 8956. Mansonia gagei J.R.Drumm (My3) and Mesua ferrea (Roxb.) L. (My10) showed strong antibacterial activities against P. vulgaris and S. aureus. This study provided the first scientific evidence of T3SS prohibiting and antibacterial properties for the traditional knowledge in Myanmar of using plants as medicines for treating infections and gastrointestinal disease. Further researches are proposed to discover the active chemical compounds and mechanism of L. scandens (Roxb.) Buch.-Ham. ex Wight & Arn, M. nagi Thunb., T. citrina Roxb. ex Fleming, T. vulgaris L., and C. bejolghota (Buch.-Ham.) Sweet as antivirulence drugs and the potential of M. gagei J.R.Drumm and M. ferrea L. as new broad spectrum plant antibiotics.
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