TY - JOUR
T1 - Antibacterial compounds from the Australian native plant Eremophila glabra
AU - Algreiby, Azizah A.
AU - Hammer, Katherine A.
AU - Durmic, Zoey
AU - Vercoe, Phil
AU - Flematti, Gavin R.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Recent reports of Eremophila glabra (R.Br.) Ostenf. (Scrophulariaceae) displaying antibacterial activity has led us to investigate the bioactive secondary metabolites responsible for this activity. Bioassay-directed fractionation of solvent extracts prepared from the leaves of E. glabra led to the isolation of seven serrulatane diterpenes, three flavonoids and the caffeoyl ester disaccharide verbascoside. Among these, four serrulatanes, namely 18-acetoxy-8, 20-dihydroxyserrulat-14-en-19-oic acid (14), 18,20-diacetoxy-8-hydroxyserrulat-14-en-19-oic acid (16), 8,18,20-triacetoxyserrulat-14-en-19-oic acid (17) and 18-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (18) are described for the first time, while 8,20-diacetoxyserrulat-14-en-19-oic acid (3), 8,18,20-trihydroxyserrulat-14-en-19-oic acid (5) and 20-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (19) were previously reported. All three flavonoids hispidulin (12), jaceosidin (13) and cirsimaritin (15) are known but reported for the first time in E. glabra. All compounds were tested in an agar diffusion antimicrobial assay against Staphylococcus aureus (NCTC 10442) and Staphylococcus epidermidis (ATCC 14990). Compounds 12, 13, 17, 18 and 19 exhibited moderate activity, with minimum inhibitory concentrations (MICs) ranging from 32 to 512 μg/mL. Compound 19 demonstrated the highest activity against S. epidermidis ATCC 14990 with MIC of 32 μg/mL, while 13 demonstrated the highest activity against S. aureus NCTC 10442 with MIC of 128 μg/mL.
AB - Recent reports of Eremophila glabra (R.Br.) Ostenf. (Scrophulariaceae) displaying antibacterial activity has led us to investigate the bioactive secondary metabolites responsible for this activity. Bioassay-directed fractionation of solvent extracts prepared from the leaves of E. glabra led to the isolation of seven serrulatane diterpenes, three flavonoids and the caffeoyl ester disaccharide verbascoside. Among these, four serrulatanes, namely 18-acetoxy-8, 20-dihydroxyserrulat-14-en-19-oic acid (14), 18,20-diacetoxy-8-hydroxyserrulat-14-en-19-oic acid (16), 8,18,20-triacetoxyserrulat-14-en-19-oic acid (17) and 18-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (18) are described for the first time, while 8,20-diacetoxyserrulat-14-en-19-oic acid (3), 8,18,20-trihydroxyserrulat-14-en-19-oic acid (5) and 20-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (19) were previously reported. All three flavonoids hispidulin (12), jaceosidin (13) and cirsimaritin (15) are known but reported for the first time in E. glabra. All compounds were tested in an agar diffusion antimicrobial assay against Staphylococcus aureus (NCTC 10442) and Staphylococcus epidermidis (ATCC 14990). Compounds 12, 13, 17, 18 and 19 exhibited moderate activity, with minimum inhibitory concentrations (MICs) ranging from 32 to 512 μg/mL. Compound 19 demonstrated the highest activity against S. epidermidis ATCC 14990 with MIC of 32 μg/mL, while 13 demonstrated the highest activity against S. aureus NCTC 10442 with MIC of 128 μg/mL.
KW - Antimicrobial
KW - Diterpene
KW - Eremophila glabra
KW - Flavonoids
KW - Serrulatane
KW - Staphylococcus
UR - http://www.scopus.com/inward/record.url?scp=85034991435&partnerID=8YFLogxK
U2 - 10.1016/j.fitote.2017.11.008
DO - 10.1016/j.fitote.2017.11.008
M3 - Article
C2 - 29155275
AN - SCOPUS:85034991435
SN - 0367-326X
VL - 126
SP - 45
EP - 52
JO - Fitoterapia
JF - Fitoterapia
ER -