Biological Activities Of Hilleria Latifolia (Lam.) H. Walt And Laportea Ovalifolia (Schumach.) Chew

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Plants have been accepted as part of human culture for the treatment of diseases and ailments, with about 80% of the populace in developing countries depending on plants for medicinal purposes. However, few plants have been scientifically proven for their folkloric uses and assessed for their quality, efficacy and toxicity. The study therefore sought to evaluate the antimicrobial, antioxidant, anti-inflammatory and wound healing activities as well as cytotoxic effects of Hilleria latifolia (Lam.) H. Walt. (Family Phytolaccaceae) and Laportea ovalifolia (Schumach.) Chew. (Family Urticaceae). These plants are used locally for the treatment of wounds, general oedema and skin diseases. The broth dilution method was used to assess the microbial susceptibility and MIC against typed and clinical strains of Gram-positive, Gram-negative bacteria and fungi. The effect of sub-inhibitory concentration on some antibiotics was also determined. The antioxidant activity was investigated employing the DPPH free radical scavenging assay, the total phenolic content as well as the total antioxidant capacity assays. The carrageenan-induced oedema model in rat was used to evaluate the anti-inflammatory activity of the plants. The wound healing activity was established using the excision wound healing model in rats. The MTT-assay for cell viability and lactate dehydrogenase (LDH) assay were used to assess the cytotoxic effect of the plant extracts. The MICs of Hilleria latifolia leaf methanol extract (HLML), Hilleria latifolia root methanol extracts (HLMR) and Laportea ovalifolia leaf methanol extract (LOML) ranged from 50 to100 mg/mL against test microorganisms. The sub-inhibitory concentration (5 mg/mL) modified the activity of amoxicillin, erythromycin, ciprofloxacin, tetracycline and ampicillin against the test microorganisms by either potentiating or reducing their antimicrobial activity. HLML, HLMR and LOML exhibited radical scavenging activity with IC50 values of 102.5 ± 1.5, 233.5 ± 0.5 and 130.8 ± 0.9 μg/mL. Total phenol content and total antioxidant capacity increased as concentration increased. The total phenol content of HLML, HLMR and LOML was calculated to be 103.0 ± 1.335, 91.32 ± 4.258 and 56.75 ± 0.3220 mg/g, respectively. The total antioxidant capacity was 410.4 ± 4.732 mg/g for HLML, 408.0 ± 18.70 mg/g for HLMR and 337.6 ± 6.961 mg/g for LOML. The anti-inflammation activity of HLML, HLMR and LOML at 300 mg/kg caused a significant (p<0.001) decrease in oedema when administered before and after inducing oedema. There was also significant (p<0.001) increase in wound contraction from days 5 to15 after injury when treated with 5 and 10% HLML, HLMR and LOML, with increased fibroblast proliferation and collagenation as well as re-epithelialisation. Treatment with 100 µg/mL of HLML (p<0.001) and HLMR (p<0.05) significantly caused a reduction in cell viability, whiles cells treated with LOML showed no significant (p>0.05) difference in viability when compared to the untreated cells. HaCaT-keratinocytes treated with HLML, HLMR and LOML (0.1, 1.0, 10.0 and 100.0 µg/mL) exhibited no significant (p>0.05) LDH release when compared with untreated cells. The study therefore indicated that HLML, HLMR and LOML possess antimicrobial, antioxidant, anti-inflammatory and wound healing activities and they did not exhibit cytotoxic activities at the concentrations used.
A thesis submitted to the department of Pharmaceutics, faculty of Pharmacy and pharmaceutical sciences, College of health science, KNUST in fulfillment of the requirements for the degree of Master of Philosophy(pharmaceutical microbiology).