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Melatonin’s role in circadian rhythm is well documented, as are its’ anti-oxidant, oncostatic and anti-inflammatory properties. Poor sleep quality has been associated as a potential risk factor for several malignancies, including head and neck cancers. The purpose of this study is to determine salivary melatonin (MLT) levels in oral squamous cell carcinoma (OSCC) patients, compare the salivary MLT levels with those in healthy individuals and compare the salivary and serum levels in OSCC patients. Furthermore, the aim is to investigate the potential relationship between sleep quality and salivary MLT levels in OSCC patients. Unstimulated (UWS) and stimulated (SWS) whole saliva was sampled from patients with T1N0M0 and T2N0M0 OSCC (N = 34) and 33 sex and age matched healthy subjects. Serum samples were taken from 11 OSCC patients. Sleep quality was measured using Pittsburgh Sleep Quality Index (PSQI) questionnaire. Melatonin levels in UWS and SWS were significantly higher in the OSCC group. Sleep quality was significantly lower in patients with OSCC (P = 0.0001). ROC analysis was found to be significant (P < 0.001) in evaluating MLT concentration limit in diagnosing OSCC. The expected relationship between sleep quality and salivary MLT levels in OSCC patients was not observed. Our results suggest salivary MLT as a potential biomarker that might facilitate non-invasive detection of early stage OSCC.

An alkaline 5'-phosphodiesterase (5'-PDE) from barley (Hordeum distichum) malt sprouts was partially purified by thermal treatment and acetone precipitation to diminish phosphomonoesterase (PME) activity. 5'-PDE was purified 40-fold to a specific activity of 30 U mg(-1) protein with a final yield of about 32%. With synthetic substrate, the enzyme had an optimum pH of 8.9, maximum activity at 70 degrees C over 10 min, and a Km of 0.26 mM. The partially purified enzyme was activated by 10 mM Mg2+ up to 168% of the original activity, while Zn2+, Mn2+ and Cu2+ ions, chelating agent (EDTA) and NaN3 (1-10 mM), and 5'-ribonucleotides (1-5 mM) were inhibitory. Final enzyme preparation was stable over 8 d at 4 degrees C), at 70 degrees C for up to 120 min and without loss of activity over 90 d at -18 degrees C.

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