WHO prescribed shelf life assessment of Syzygium cumini extract through chromatographic and biological activity analyses

BACKGROUND: Regulatory guidelines recommend shelf life of herbal products to be established through systematic stability studies. OBJECTIVE: The study was designed to establish shelf life of Syzygium cumini extract through accelerated and long-term stability testing as per WHO guidelines. MATERIAL AND METHODS: The extract was stored under accelerated (40°C/75 %RH) and long-term (25°C/60 %RH) stability conditions for 6 and 30 months, respectively. Samples were withdrawn at periodic intervals and analysed through two validated HPLC-UV methods (I and II) for fingerprint and quantitative analysis of markers. Antidiabetic activity of control and stability samples was evaluated by α-glucosidase inhibitory model. RESULTS: Method I generated a well resolved fingerprint of the control sample that was found to contain gallic acid (GA, 1.45 % w/w) and ellagic acid (EA, 3.97 % w/w). The content of GA did not change under both the stability conditions, but that of EA varied insignificantly (3.97–4.77 % w/w) under long-term conditions up to 24 months and subsequently decrease to 3.15 % w/w after 30 months. There was no visible change in LC-UV fingerprint of any stability sample with respect to control. α-Glucosidase inhibitory activity of all stability samples also remained unaltered as compared to control sample (IC(50) 1.48 mg/mL). GA and EA did not elicit any activity at the concentrations present in the extract. CONCLUSION: Phytochemical composition and antidiabetic efficacy of S. cumini extract remain unchanged during its storage under both accelerated and long-term stability conditions, which suggest its shelf life to be 30 months. Also, GA and EA are not appropriate anti-diabetic markers.