ABSTRACT
The preliminary α-glucosidase inhibitory activity of the methanol extract of the leaves of Sandoricum koetjape Merr. exhibited promising results. The leaves was extracted with methanol to obtain the methanol extract that was continuedly partitioned with hexane and ethyl acetate. Those fractions were further purified by various chromatographic techniques. The isolation of the potent fractions furnished two new cycloartane-type triterpenoids (1 and 2) along with ten known compounds (3-12). Their chemical structures were unambiguously established by interpretation of NMR (1 D & 2 D) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Furthermore, the configurations of two new compounds were determined by using NOESY spectrum as well as comparing their NMR data to the reference. These compounds were evaluated against α-glucosidase. All tested compounds revealed potent activity with IC50 value in the range of 2.17-49.2 µM compared to that of acarbose (IC50 100.6 µM). Compound 10 showed the lowest IC50 value. This compound was reported as a mixed-type inhibitor. Compound 3 possessed the second strong activity with an IC50 value of 14.0 µM and was further investigated on kinetic analysis which revealed as a mixed-type inhibitor with Ki and Ki' values of 59.1 and 155.2 µM, respectively.
Subject(s)
Glycoside Hydrolase Inhibitors , Plant Extracts , Plant Leaves , Triterpenes , alpha-Glucosidases , Glycoside Hydrolase Inhibitors/pharmacology , Glycoside Hydrolase Inhibitors/chemistry , Glycoside Hydrolase Inhibitors/isolation & purification , Triterpenes/chemistry , Triterpenes/pharmacology , Triterpenes/isolation & purification , Plant Leaves/chemistry , alpha-Glucosidases/metabolism , Plant Extracts/chemistry , Plant Extracts/pharmacology , Molecular Structure , Magnetic Resonance Spectroscopy , Spectrometry, Mass, Electrospray IonizationABSTRACT
Chemical investigation of the lichen Parmotrema tsavoense led to the isolation of 5 new depsidones, parmosidones Fâ-âJ (1: â-â5: ). These compounds were structurally elucidated using spectroscopic methods including HRESIMS and 2D NMR data. Compounds 1, 3: , and 4: were evaluated for their inhibition of α-glucosidase. All exhibited potent α-glucosidase inhibitory activity with IC50 values ranging from 10.7 to 17.6 µM, which was much lower than that of the positive control acarbose (IC50 449 µM).
