Abstract:
A remarkable research interest has been shown on phytochemicals in spices and their bioactivities
during the last decade. Nitric oxide (NO) radical scavenging potential is one of the assays used in the
determination of in vitro antioxidant activity. The study aims to determine NO radical scavenging
potential of the aqueous extracts of ten selected Sri Lankan spices and a mixture of spices made from
five selected spices with high NO scavenging potential. The spices were randomly collected within
the areas of Sabaragamuwa and Southern provinces from their natural habitats. L-ascorbic acid was
used as the reference compound in the assay. The NO radical scavenging potential were estimated
following the standard protocol using a spectrophotometric assay. The half maximal inhibitory
concentration (IC50) was calculated using regression analysis and the values were expressed as mean
± standard deviation (SD) of the three analytical triplicates. IC50 values of the selected spices were
269.33 ± 2.21 μg/mL (Piper nigrum), 270.24 ± 4.23 μg/mL (Curcuma domestica), 279.85 ± 1.62 μg/
mL (Elettaria repens), 288.88 ± 0.87 μg/mL (Myristica fragrans), 292.59 ± 11.83 μg/mL (Zingiber
officinale), 322.05 ± 2.13 μg/mL (Eugenia caryophyllata), 341.11 ± 1.39 μg/mL (Cinnamomum verum),
355.94 ± 2.98 μg/mL (Cymbopogon citratus), 356.32 ± 1.31 μg/mL (Brassica integrifolia) and 394.19 ±
3.87 μg/mL (Capsicum frutescens). There was a statistically significant difference in between ten spices
(p<0.05). The spices which showed the highest NO radical scavenging potential (lowest IC50) were
selected for the mixture. Accordingly, P. nigrum, C. domestica, E. repens, M. fragrans and Z. officinale
were selected. The mixture showed the highest NO radical scavenging potential with the lowest value
of IC50 (256.42 ± 0.22 μg/mL) compared to the individual spices. Based on the results, all selected
extracts of spices possess NO scavenging potential and the mixture showed the highest activity.
