Effect of solvents of extreme polarities on the antioxidative and cytotoxic profiles of single and combined tropical spices

Abstract

Objective: To assess the possible augmented phytochemical constituents, antioxidant and cytotoxicity activities of hexane and hydroethanol extracts of five combined tropical spices. Methods: Powdered samples from five dried tropical spices [Zingiber officinale Rosc., Xylopia aethiopica (Dun.) A. Rich, Piper guineense Schum & Thonn, Myristica fragrans Houtt. and Allium sativum L.] were separately and in combination extracted with hexane (HX) and hydroethanol (50:50) (HE). Both extracts of the single spices (Ssp) and mixed spices (Mxsp) were evaluated for total phenolic content (TPC), total flavonoid content (TFC) and estimation of antioxidant activities through 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-Azino-bis (3-ethylbenzothiazoline-6)-sulphonic acid (ABTS), hydroxyl radical (HR) scavenging and reducing power (RP) assays as well as metal chelating (MC) capability. The tetrazolium-based colorimetric cellular (MTT) assay was utilized to assess their possible cytotoxic effect on Vero cells. Results: The study revealed that the HX (75.28 ± 10.07 mggallic acid equivalent/mL) and HE (19.00±3.21 mg quercetin equivalent/g) extracts of Mxsp had the highest TPC and TFC respectively when compared with corresponding extracts of Ssp. The antioxidant efficacy revealed that the HE extract of Mxsp depicted the highest DPPH (median inhibitory concentration (IC50): 0.09 ± 0.03 mg/mL), ABTS (IC50: 0.21 ± 0.03 mg/mL) and HR (IC50: 0.63 ± 0.92 mg/mL) scavenging activities respectively. The best MC effect and potent RP activity were observed in the HX extracts of ginger (IC50: 0.11 ± 0.03 mg/mL) and Mxsp (2.85 ± 0.11 mg/mL) respectively. The MTT assay revealed that Ssp and Mxsp were not cytotoxic to Vero cells with median lethal concentration (LC50) values ranging from 0.13-0.48 mg/mL. Conclusion: This study suggests that Mxsp contains more phytochemical compounds and exhibits better antioxidant activity than Ssp. Moreover, both extracts of Ssp and Mxsp may be considered safe for consumption at specified concentrations.