ABSTRACT
BACKGROUND: Advanced glycation end products (AGEs) and free radicals are inflammatory mediators and are implicated in many diseases such as diabetes, cancer, rheumatoid arthritis etc. Multi targeted poly herbal drug systems like Nawarathne Kalka (NK) are able to quench the overall effect of these mediators as they contain good combinations of phytochemicals that have least side effects in contrast to modern medicinal drugs. The objectives of this study were to evaluate phytochemical composition, free radical scavenging activity, cytotoxicity and the inhibitory action on the formation of AGEs by aqueous extract of NK. METHODS: Total phenolic content (TPC) and total flavonoid content (TFC) were determined using Folin ciocalteu method and aluminium chloride assay respectively. Free radical scavenging activity was assessed by DPPH radical scavenging assay (DRSA), phosphomolybdenum reduction antioxidant assay (PRAA) and nitric oxide (NO) scavenging assay. Brine Shrimp Lethality (BSL) bioassay was performed as preliminary screening for cytotoxic activity. Inhibitory action on AGE formation was evaluated using fructose mediated glycation of bovine serum albumin using fluorescence spectroscopic method. RESULTS: The TPC and TFC were 75.1 ± 3.0 mg/g gallic acid equivalents and 68.7 ± 7.8 mg/g epigallocatechin gallate equivalents. The DRSA yielded EC50 of 19.15 ± 2.24 µg mL(-1) for NK. DRSA of NK extract was greater than butylated hydroxy toluene (EC50 = 96.50 ± 4.51 µg mL(-1)) but lesser than L-ascorbic acid (EC50 = 5.60 ± 0.51 µg mL(-1)). The total antioxidant capacity of NK as evidenced by PRAA was 106.4 ± 8.2 mg/g L-ascorbic acid equivalents. NK showed EC50 value of 99.3 ± 8.4 µg mL(-1) in the NO scavenging assay compared to the standard ascorbic acid (EC50 = 7.3 ± 0.3 µg mL(-1)). The extract indicated moderate cytotoxic activity in the BSL bioassay. The extract showed effective inhibitory action on the formation of AGEs with EC50 values of 116 ± 19 µg mL(-1), 125 ± 35 µg mL(-1) and 84 ± 28 µg mL(-1) in data obtained over three consecutive weeks respectively. Comparatively the reference standard, aminoguanidine at a concentration of 500 µg mL(-1) demonstrated 65 % inhibition on the formation of AGE after one week of sample incubation. CONCLUSIONS: The results proved the potential of NK as a free radical scavenger, moderate cytotoxic agent and an inhibitor on the formation of advanced glycation end-products.
