Chromatographic Analysis and In Vitro Cytotoxic Properties of Different Root Extracts of <I>Hermannia geniculata</I> Eckl. & Zeyh on Vero, HepG2 And RAW 264.7 Macrophage

Abstract

Hermannia geniculata is widely used in the management of several illnesses in South African traditional medicine. Chromatographic analysis, in vitro cytotoxicity, and biological activities of secondary metabolites present in Hermannia geniculata root extracts were investigated. Vero monkey kidney cells, human hepatocellular carcinoma (HepG2) cells, and RAW 264.7 macrophage cell lines were used to determine the cytotoxicity of the extracts using MTT assay. The capabilities of the plant extracts to inhibit 5-lipoxygenase enzyme activities, the overproduction of nitric oxide (NO) following lipopolysaccharide (LPS)-activated RAW 264.7 macrophages by the ethanol extract was evaluated. Results showed selective toxicity of the extracts with LC₅₀ values of Vero cells ranging from (0.40-0.57 mg/mL) while the LC₅₀ value of HepG2 cells varies between (0.016-0.136 mg/mL). The selectivity indexes (SI) were recorded (31.87, 18.87, 33.33, and 13.52) for ethanol, hydro-ethanol, decoction, and aqueous extracts respectively. The ethanol extract inhibited NO production in a concentration-dependent manner showing a decrease of 82% at a concentration of 0.1 mg/mL. Its LC₅₀ value (3.64  mg/mL) is lower and significantly different (p<0.05) compared to quercetin (standard) with an LC₅₀ (8.28 mg/mL). Similarly, the ethanol extract is a potent inhibitor of 5-lipoxygenase enzyme with the lowest IC₅₀ value of 0.14 mg/mL which is significantly different (p<0.05) from other extracts and indomethacin (standard). The GC-MS chromatograms of the ethanol extract revealed five principal compounds that have been reported to have antioxidant, anti-inflammatory, and antifungal properties. This result indicated that Hermannia  geniculata root extracts is not toxic to Vero and RAW 264.7 macrophage cell lines and toxic to HepG2 cell lines used in this experiment, it may also possesses antiiflammatory and antiploriferative activities which could be exploited in the development of new, safer, and efficacious drugs.

Keywords: Cytotoxicity; Nitric oxide; 5-lipoxygenase; Hermannia geniculata, Antioxidant GCMS.