Toxicity screening and in vitro antioxidant activities of aqueous extracts of Morinda lucida and Saccharum officinarum leaves

The use of medicinal plants as natural antioxidants in the treatment of diabetes and cardiovascular diseases is on the increase. However, toxicity of the plants is also a major concern. Hence, this present study investigated the toxic and in vitro antioxidant activities of aqueous extracts of Morinda lucida and Saccharum officinarum leaves. Brine shrimp lethality assay for larvae nauplii was used to evaluate the toxicity of the two plant extracts. The antioxidant potential of the plant extracts was examined by determining tannin content, total flavonoid content, total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, in vitro lipid peroxidation, and nitric oxide (NO) scavenging assay. Both Morinda lucida and Saccharum officinarum showed the presence of tannin and flavonoids; additional presence of saponin, alkaloid and phenol were confirmed in Morinda lucida while the presence of steroids was shown in Saccharum officinarum. Brine shrimp toxicity test revealed LC50 of 112.2 µg/ml, 44,668.3 µg/ml, and 14.12 µg/ml for Morinda lucida, Saccharum officinarum, and the standard (Potassium dichromate) respectively. The amount of total flavonoid content was 23.08 mg per 100 g and 5.28 mg per 100 g for M. lucida and S. officinarum respectively. Total antioxidant capacity assay showed 83.15 mg per 100 g for M. lucida and 27.56 mg per 100 g for S. officinarum. Morinda lucida and Saccharum officinarum showed IC50 values of 31.25 µg/ml and 68.75 µg/ml for DPPH free radical respectively. In Nitric oxide scavenging activities, IC50 values of Morinda lucida and Saccharum officinarum were 22.50 µg/ml and 21.88 µg/ml. It can be concluded that M. lucida and S. officinarum are not toxic and possess antioxidant activities.