Background: In the last two decades, pioneering research on anti-tumour activity of saffron has shed light on the role of crocetin, picrocrocin and safranal, as broad spectrum anti-neoplastic agents. However, the exact mechanisms have yet to be elucidated. Identification and characterization of the targets of bioactive constituents will play an imperative role in demystifying the complex anti-neoplastic machinery. Methods: In the quest of potential target identification, a dual virtual screening approach utilizing two inverse screening systems, one predicated on idTarget and the other on PharmMapper was here employed. A set of target proteins associated with multiple forms of cancer and ranked by Fit Score and Binding energy were obtained from the two independent inverse screening platforms. The validity of the results was checked by meticulously analyzing the post-docking binding pose of the picrocrocin with Hsp90 alpha in AutoDock. Results: The docking pose reveals that electrostatic and hydrogen bonds play the key role in inter-molecular interactions in ligand binding. Picrocrocin binds to the Hsp90 alpha with a definite orientation appropriate for nucleophilic attacks by several electrical residues inside the Hsp90-alpha ATPase catalytic site. Conclusion: This study reveals functional information about the anti-tumor mechanism of saffron bioactive constituents. Also, a tractable set of anti-neoplastic targets for saffron has been generated in this study which can be further authenticated by in vivo and in vitro experiments.

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Over 90% of Oral Cancers are Oral Squamous Cell Carcinomas (OSCCs). Despite having advanced treatment modalities, there is no significant improvement in the survival rate of Oral Cancer patients over the years. Thus, there arises a need for the identification of new drug targets besides development of new and effective drugs for this disease. Since Histone Deacetylase 6 (HDAC6), a class IIB member of HDAC family, is known to be upregulated in this disease in addition to being associated with tumor growth, it can be considered as a promising drug target for this disease. In this study, a structure-based virtual screening strategy was used to screen a library of 1,539 natural compounds from Naturally Occurring Plant-based Anti-cancerous Compound-Activity-Target (NPACT) database. Upon filtering and docking, top 30 hits were identified and two of them, namely Camptothecin and Diosgenin, were tested experimentally on OSCCs cell lines for anti-proliferative effects. Both of these compounds exhibited inhibitory activity against Oral Cancer cells, therefore suggesting that they can be potential HDAC6 inhibitors, which can further serve as promising leads for OSCCs.

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