14.3.1.3 Antibacterial and Antifungal Effects
Maurya et al. isolated loganetin (69, Fig. 14.14), an iridoid from ethyl acetate
extract of A. scholaris stem barks by fast centrifugal partition chromatography
(FCPC) and evaluated for its antibacterial potential in nalidixic acid-resistant with
MTCC No. 1652 (NAREC), nalidixic acid sensitive strain CA8000 (NASEC), and
Escherichia coli strains (Maurya et al. 2014). Individually, 69 exhibited poor
activity against the selected strains (Minimum Inhibitory concentration-MIC
value-500 µg/mL). However, a combination of 69 (10 µg/mL) with nalidixic
acid exhibited a potential antibacterial activity. Individually nalidixic acid exhibited
a MIC of 6.3 and 100 µg/mL for NAREC and NASEC, while in combination, it
exhibited a MIC of 1.6 and 12.5 µg/mL with a 4- and 8-fold dose reduction of
nalidixic acid concentration, respectively.
Liu et al. isolated 16 compounds (3, 16, 18–19, 24, 27, 30–31, 70–77,
Fig. 14.15) from the methanolic extract of A. scholaris leaves (Liu et al. 2015) and
evaluated the antibacterial effects against Staphylococcus aureus (ATCC 25922),
Pseudomonas aeruginosa (ATCC 27853), Enterococcus faecalis (ATCC 10541),
Normavacurine-21-one (70)
N
N
O
HO H H
H
5-Hydroxy-19, 20-Ealschomine (71)
5-Hydroxy-19, 20-Zalschomine (72)
HN
O
N
O
O
OH
O
H
HN
O
N
O
OH
O
H
O
Strictamine N 4 oxide (73)
N
N
O
O
Vallesamine N
4 -oxide (74)
N
+
N
OH
O
O
O
-
H
19-Epischolaricine (75)
N
N
H
HO
O
O
OH
12-Methoxyechitamidine (76)
N
N
H
O
O
O
OH
Isovallesiachotamine (77)
O
N
O
O
H
N
O
Fig. 14.15 Chemical structures of various alkaloids from A. scholaris (70–77)
O
O
O
OH
OH
Loganetin (69)
Fig. 14.14 Chemical structure of loganetin (69)
478
A. T. Paul et al.