In-Vitro And Molecular Docking Studies Of Seven Selected Myrtaceae Plants For Neuraminidase Activity
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Date
2016-09
Authors
Abdusalsalam, Ashraf Ahmed Ali
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Abstract
Influenza A virus cause severe health problems to humans and several animal species which could result in morbidity and mortality in infected patients. Oseltamivir (Tamiflu) and zanamivir (Relenza) are two current drug used NA inhibitors that have been approved by the Food and Drug Administration (FAD, USA). However, due to the emergence of virus resistance to these drugs, there is an urgent need to discover an alternative neuraminidase inhibitors. The present study was undertaken to investigate the neuraminidase inhibition activity of seven selected plants that belong to the family of Myrtaceae; Psidium guajava, Syzygium cumini, Syzygium grande, Syzygium jambos, Syzygium malaccense cultivated jambu bol, Syzygium samaranges, and Syzygium malaccense cultivated jambu susu. The plants were extracted using methanol and fractionated using n-hexane, chloroform, ethyl acetate and butanol. Essential oils from leaves of seven selected plants were isolated by hydrodistillation and analyzed by head-space chromatography–mass spectrometry. The crude extract, fractions, compounds and essential oil were subjected to neuraminidase inhibition assay against Clostridium perfringens and H1N1 neuraminidase enzyme. Molecular docking using Autodocktools 4.2 were applied against the active site of neuraminidase H1N1 protein (PDB code: 3TI6) for the isolated and identified compounds from essential oil. The isolation was done from the ethyl acetate fraction of (leave and fruit) of P. guajava to yield one new compound 1,3-benzothiazole-oxalic acid and five
known compounds kojic acid, gallic acid, quercetin, ursolic acid and ursolic aldehyde. Good inhibition exhibited by most of the extracts, P. guajava fruit 89% and seven leaves ranging from 70 to 89% against C. perfringens. For the other fractions the inhibition ranged from 12.2 to 97% against NA from C. perfringens while 12.6-97.9% against NA from H1N1. Three essential oils showed high inhibition up to 57.8, 88.7 and 91.2% among the seven oils. The IC50 of two isolated compounds quercetin was 229 μM, gallic acid was 187 μM and DANA 4.3 μM for the bacterial NA, and quercetin was 127 μM, gallic acid was 258 μM and DANA 3.9 μM for the NA H1N1 virus. Different major compounds identified in essential oil from each variety were 20.7% α-pinene in P. guajava, 25.1% Z-β-ocimene in S. cumini, 33.1% δ-terpinene in S. samarangense, (Z)-3-hexanol (23.5%) in S. malaccense cultivated jambu susu and 62.5%, 20.5% and 23.0% β-caryophyllene in S. grande, S. malaccense cultivated jambu bol and S. Jambos, respectively. The in silico molecular docking of isolated compounds from P. guajava and identified compounds from active essential oil were correlated with the experimental results. All the compounds exhibited interactions with the target protein at two different binding sites, namely, conservative active site and adjacent pocket (150-cavity). The correlation between the in silico and experimental results revealed that the obtained activity was not due to a single compound but from a synergistic effect, where all the compounds contributed to inhibit neuraminidase. In conclusion crude extracts, fractions, three out of seven essential oils of selected plants showed good neuraminidase inhibition and could be source of neuraminidase inhibitors.
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To investigate the neuraminidase inhibition activity of , seven selected plants that belong to the family of Myrtaceae