Chemical profiling, in vitro antioxidant and antidiabetic assessment of flavonoids from the ethanol extract of Hermannia geniculata root

Determination of the in vitro antioxidant and the inhibitory potential of flavonoids from Hermannia geniculata (FHG) roots on diabetes-linked enzymes was carried out. The chemical profiling of FHG roots extract was investigated using High Pressure Thin Layer Chromatography (HPTLC) fingerprint analysis. The reactive oxygen scavenging potential of the extract was analyzed. Starch solution (1%) was reacted with different concentrations of FHG extract to determine the α-amylase inhibitory potential of the extract while α- glucosidase inhibition assay was carried out through incubation of different concentrations of the extract followed by addition of p-ntrophenyl-α-Dglucopyranoside solution. HPTLC results indicated the presence of flavonoids/ phenolcarboxylic acid, and Kaemferol (Rf 0.80) were detected in the extract with retention factor Rf. ranging from 0.08 to 0.95. FHG extract showed commendable antioxidant properties with IC50 values (3.07± 0.12, 2.13± 0.67) µg/mL for 1, 1-diphenyl-2- picrylhydrazyl (DPPH) and 2, 2-azino-bis (3- ethylbenzothiazoline-6-sulphonic) acid (ABTS) radicals which were lower and significantly different (p<0.05) compared to standard silymarin with IC50: (3.55± 0.10, 2.77± 0.75) µg/mL for DPPH and ABTS respectively. The results indicated mild inhibition of α-amylase with IC50: (5.55± 0.37) µg/mL which was higher and significantly different (p<0.05) from acarbose with IC50: (3.81± 0.29) µg/mL. Moreover, the extract showed 73% inhibition of α-glucosidase. Kinetic studies of FHG extract revealed competitive and mixed non-competitive inhibition of α- amylase and α-glucosidase respectively. This study indicated FHG capabilities of scavenging reactive oxygen species and reducing hydrolysis of starch responsible for post-prandial hyperglyceamia seen in type 2 diabetes mellitus. Keywords: Antidiabetic, Antioxidant, Flavonoids, Hermannia geniculate, HPTL

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

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

In Vitro Antioxidant Activity Of Extracts From The Leaves Of Felicia Muricata Thunb. An Underutilized Medicinal Plant In The Eastern Cape Province, South Africa

Felicia muricata is a medicinal plant used for the management of different human and livestock diseases in the Eastern Cape Province of South Africa. The antioxidant potential of the leaves from this herb was investigated using its water, methanol, acetone and ethanol extracts. All the extracts were rich in phenols, proanthocyanidins and flavonols but low in flavonoids. The water extract exhibited low DPPH scavenging activity while the methanol, acetone and ethanol extracts showed higher activities. Again all the extracts showed high ABTS scavenging activity with a correlation between total phenolic content (R2=0.9965), DPPH (R2 =0.982) and ABTS (R2=0.927). Traditionally, however, plant extracts are prepared with water as infusions, decoction and poultice. Our results have shown that both the water and ethanol extracts from Felicia muricata displayed strong antioxidant activity. Therefore, it would seem likely that both solvents were able to extract those compounds which are responsible for the antioxidant activity of F. muricata