Neuroprotective activity of galloylated cyanogenic glucosides and hydrolysable tannins isolated from leaves of Phyllagathis rotundifolia.
The galloylated cyanogenic glucosides based on prunasin (1-7), gallotannins (8-14), ellagitannins (15-17), ellagic acid derivatives (18, 19) and gallic acid (20) isolated from the leaves of Phyllagathis rotundifolia (Melastomataceae) were investigated for their neuroprotective activity against hydrogen peroxide (H(2)O(2))-induced oxidative damage in NG108-15 hybridoma cell line. Among these compounds, the gallotannins and ellagitannins exhibited remarkable neuroprotective activities against oxidative damage in vitro as compared to galloylated cyanogenic glucosides and ellagic acid derivatives in a dose-dependent manner. They could be explored further as potential natural neuroprotectors in various remedies of neurodegenerative diseases.
Tan HP
，Wong DZ
，Ling SK
，Chuah CH
，Kadir HA
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Characterisation of galloylated cyanogenic glucosides and hydrolysable tannins from leaves of Phyllagathis rotundifolia by LC-ESI-MS/MS.
Phyllagathis rotundifolia (Jack) Bl. (Melastomataceae) is a creeping herb found in Peninsular Malaysia and Sumatra. Traditionally, a decoction of the leaves is used in the treatment of malaria, fever and stomach ache.
To provide ESI-MS(n) data which are applicable for chemical fingerprinting of P. rotundifolia to obviate laborious isolation and purification steps.
The mass spectral data for the compounds isolated from the leaves of P. rotundifolia were obtained by liquid chromatography-electrospray ionisation tandem mass spectrometry.
The MS fragmentation patterns were obtained for galloylated cyanogenic glucosides based on prunasin (prunasin 6′‐O‐gallate 1, prunasin 2′,6′‐di‐O‐gallate 2, prunasin 3′,6′‐di‐O‐gallate 3, prunasin 4′,6′‐di‐O‐gallate 4, prunasin 2′,3′,6′‐tri‐Ogallate 5, prunasin 3′,4′,6′‐tri‐O‐gallate 6 and prunasin 2′,3′,4′,6′‐tetra‐O‐gallate 7), gallotannins (6‐O‐galloyl‐D‐glucose 8, 3,6‐di‐O‐galloyl‐D‐glucose 9, 1,2,3‐tri‐O‐galloyl‐β‐D‐glucose 10, 1,4,6‐tri‐O‐galloyl‐β‐D‐glucose 11, 3,4,6‐tri‐O‐galloyl‐D‐glucose 12, 1,2,3,6‐tetra‐O‐galloyl‐β‐D‐glucose 13 and 1,2,3,4,6‐penta‐O‐galloyl‐β‐D‐glucose 14), ellagitannins [6‐O‐galloyl‐2,3‐O‐(S)‐hexahydroxy‐diphenoyl‐D‐glucose 15, praecoxin B 16 and pterocarinin C 17], ellagic acid derivatives (3′‐O‐methyl‐3,4‐methylenedioxyellagic acid 4′‐O‐β‐D‐glucopyranoside 18 and 3,3′,4‐tri‐O‐methylellagic acid 4′‐O‐β‐D‐glucopyranoside 19) and gallic acid 20 that were isolated from the leaves of P. rotundifolia.
The ESI-MS(n) technique facilitates identification of galloylated cyanogenic glucosides, hydrolysable tannins and ellagic acid derivatives that were isolated from the leaves of P. rotundifolia. It yields MS(n) spectra that are useful for identification of these compounds in complex samples and permit more complete fingerprinting of plant materials.
Hooi Poay T
，Sui Kiong L
，Cheng Hock C
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Bioassay-guided isolation of neuroprotective compounds from Loranthus parasiticus against H₂O₂-induced oxidative damage in NG108-15 cells.
A parasite plant, Loranthus parasiticus (Loranthaceae), which is generally known as benalu teh (in Malay), Sang Ji Sheng (in Chinese), and baso-kisei (in Japan) distributed in south and southwest part of China, has been used as a folk medicine for the treatment of schizophrenia in southwest China. Loranthus parasiticus has various uses in folk and traditional medicines for bone, brain, kidney, liver, expels wind-damp, and prevents miscarriage.
The current study was designed to evaluate the neuroprotective activity of Loranthus parasiticus against hydrogen peroxide (H(2)O(2))-induced oxidative damage in NG108-15 hybridoma cells, so as to present evidence for the traditional use of this parasite plant in the treatment of oxidative stress related neurodegenerative diseases.
Dried and ground leaves of Loranthus parasiticus were extracted and fractionated into Loranthus parasiticus ethanol extract (LPEE), Loranthus parasiticus ethyl acetate fraction (LPEAF), and Loranthus parasiticus aqueous fraction (LPAF), which were subjected to neuroprotective activity assessment by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. Bioassay-guided fractionation and isolation was performed subsequently to identify the most neuroactive compound. Mechanism studies underlying the present neuroprotection model of the isolated neuroactive compound was evaluated by employing 2,7-dichlorofluorescein diacetate (DCFH-DA) for intracellular reactive oxygen species (ROS) measurement, annexin V/propidium iodide (PI) for translocation of membrane phosphatidyleserine to identify cells undergo apoptosis, 5,5',6,6'-tetrachloro-1,1',3,3' tetraethylbenzimidazolylcarbocyanine iodide (JC-1) for mitochondrial membrane potential (MMP) detection, and PI for cell cycle events analysis.
Among those tested extract and fractions (LPEE, LPEAF, and LPAF) in our previous screening, LPAF significantly (P<0.01) yielded the highest neuroprotective activity with 78.00±1.85% cell viability in a dose dependent manner, supporting a neuroprotective role for LPAF in vitro. AC trimer and (+)-catechin have been isolated from LPAF successfully through bioassay-guided fractionation and isolation approach and (+)-catechin exhibited stronger neuroprotective activity as compared with AC trimer. (+)-Catechin increased cell viability and decreased the level of intracellular reactive oxygen species (ROS) in a dose-dependent manner against H(2)O(2)-induced oxidative stress in NG108-15 cells. Moreover, (+)-catechin reduced total annexin V positive cells (early and late apoptotic cells), attenuated the collapsed of MMP, and inhibited cell cycle arrested at sub-G(1) population following H(2)O(2) insult.
Collectively, the use of Loranthus parasiticus as folk medicine in the treatment of mental disorder was attributed to the presence of proanthocyanidins in this parasite plant. These findings support the traditional use of Loranthus parasiticus which is capable in managing neurological disorder where oxidative stress is implicated.
Wong DZ
，Kadir HA
，Ling SK
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