Lactogenic activity of Gunnera perpensa L. (Gunneraceae) from South Africa

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Date
2010
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Abstract
Gunnera perpensa L. (Gunneraceae) is a medicinal plant used by Zulu traditional healers to induce labor, expel the placenta after birth, to relieve menstrual pains, and to stimulate milk production. Phytochemical screening of the rhizomes revealed the presence of alkaloids, flavonoids, steroids, saponins, tannins and glycosides. Methanol extracts of G. perpensa exhibited strong scavenging of 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonate (ABTS), but showed poor radical scavenging of nitric oxide, superoxide and hydroxyl radicals. At a concentration of 5 mg/100 ml, the extract was able to inhibit lipid peroxidation of the whole rat brain homogenate (71%) and lipoxygenase (30%) activity. The plant extract also contained reduced form of nicotinamide adenine dinucleotide (NADH, 3.8 ρm/g), and total phenol (248.45 mg/g). The total antioxidant capacity was 36% relative to ascorbic acid (AA) and 64% relative to butylated hydroxyl toluene (BHT). The effect of an aqueous extract of the rhizome of the plant on milk production in rats was also investigated. Female lactating rats that received oral doses of aqueous extract of G perpensa produced more milk than controls (P<0·05). Pup weight gain was also significantly higher than that in the control group (P<0.05). In addition, the mammary glands of rats treated with the extract showed lobuloalveolar development. The extract of G perpensa was found to stimulate the contraction of the uterus; the highest amplitude was 5.06±08mm. G perpensa extract inhibited (23%) fish-brain acetylcholinesterase activity. The plant extract did not significantly influence prolactin, growth hormone, progesterone, cortisol, ALT, AST, and albumin levels. It is inferred that the plant extract exerts its activity on milk production and secretion by stimulating lobuloalveolar cell development and the contraction of myoepithelial cells in the alveoli. The cytotoxicity of the extract (LC50) to brine shrimp larvae was 137.62 mg/ml and to two human cell lines (HEK293 and HEPG2) it was 279.43μg/ml and 222.33μg/ml respectively. It is apparent that the antioxidant and lactogenic activity of G. perpensa contributes to its effectiveness in folk medicine.
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Dissertation submitted to the Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Zululand in Partial Fulfillment of the Requirements for the Masters (MSc) degree in Biochemistry. 2010.
Keywords
Gunnera perpensa, Gunneraceae, Antioxidant activity, Cytotoxicity, Muscle contractility, Lactation
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