Chemical fingerprinting, comparative in vitro antioxidant properties, and biochemical effects of ginger and bitterleaf infusion

Abstract

Botanicals with remarkable pharmacological properties include Zingiber officinale Roscoe [Zingiberaceae] (ginger) and Gymnanthemum amygdalinum (Delie) Sch. Bip [Asteraceae] (bitterleaf). The plants are frequently used as teas and decoctions, and have been studied in the treatment of various illnesses. Thus, this study investigated the in vitro antioxidant activities and chemical fingerprints of ginger and bitter leaf infusions separately and as a combination. In addition, we assessed the effects of the tea infusions on rat liver and kidney indices. The findings from this study showed that the bitterleaf infusion had the highest phenolic content (21.77 ± 3.140 µg gallic acid equivalent/mg) in comparison with that of ginger (15.17 ± 1.50 µg gallic acid equivalent/mg) and their combination (8.81 ± 0.48 µg gallic acid equivalent/mg). The ginger infusion had the highest flavonoid content (547.15 ± 1.17 µg quercetin equivalent/mg), which was preceded by bitterleaf (473.02 ± 10.48 µg quercetin equivalent/mg) and the ginger and bitterleaf infusion (415.08 ± 4.15 µg quercetin equivalent/mg). Furthermore, our results showed that the tea infusions had no significant effect on the liver function indices (ALT and AST) compared to the control. In contrast, the rat plasma urea significantly increased in the groups given bitterleaf and a combination of ginger and bitterleaf infusions, while creatinine significantly decreased in the group that received the combined form of the infusion. The GC-MS analysis of ginger and bitterleaf infusions revealed that n-hexadecanoic acid, oleic acid, and ergosterol were most abundant in the bitterleaf infusion. At the same time, gingerol, 2-butanone, and 4-(4-hydroxy-3-methoxyphenyl) were the most abundant in the ginger infusion. Together, the findings are not only evidence in support of the medicinal value of these plants but also reinforce their prospects as nutriceuticals.

Keywords: Botanical drugs; Gymnanthemum amygdalinum (delie); Medicinal biochemistry; Phytochemical analysis; Tea infusion; Zingiber officinale Roscoe.