Effects of aqueous and methanolic solvent systems on phytochemical and antioxidant extraction from two varieties of Roselle (Hibiscus sabdariffa L.) var. sabdariffa plant from Central Malawi

Abstract

The extraction efficiency of aqueous and 80 % methanolic solvent systems on phytochemicals and antioxidant capacity from two varieties of Roselle (Hibiscus sabdariffa var.) was evaluated for ethno-medicinal and nutritional purposes. Phytochemical screening revealed the presence of tannins, phenols, saponins, flavonoids, cardiac glycosides and carbohydrates from both extractions. Methanolic extracts had high (P < 0.05) total phenolic compound in both red and dark red calyx H. sabdariffa, compared to aqueous extracts which ranged from 17.97 ± 0.08–258.06 ± 0.17 for dark red calyx leaf and methanolic red calyx calyces respectively. However, the study showed that red calyx H. sabdariffa had high (P < 0.05) concentration of total phenolic content compared to dark red calyx H. sabdariffa irrespective of the effect of solvent systems. In this study, aqueous extracts exhibited higher TAC than methanolic extracts but aqueous dark red calyx H. sabdariffa had high (P < 0.05) TAC compared to red calyx H. sabdariffa extracts. In methanol, red calyx H. sabdariffa exhibited high (P < 0.05) TAC compared to dark red calyx sabdariffa extracts. Anthocyanins content was high (P < 0.05) in methanol compared to aqueous extracts which ranged from 4.1562 ± 0.0742–315.460 ± 0.428 for aqueous dark red calyx fruit and dark red calyx calyces respectively. The type and polarity of solvent had a significant effect on both the quality and quantity of the extracts, phytochemicals and antioxidants of the extracts from the two H. sabdariffa varieties. The study revealed that methanolic extracts had high antioxidants, phytochemicals and anthocyanins compared to aqueous extracts. Therefore consumption and use of H. sabdariffa extracts could improve human health by either reducing or delaying the development of cell degenerative diseases like cancer and diabetes mellitus.