Secondary metabolites from the leaves and stem of the Nigerian mangrove plant -Acrostichum aureum possess wound healing and antimicrobial properties

Abstract

Acrostichum aureum is a medicinal plant used for the treatment of several disease conditions and infections. In Nigeria, its use is limited to the management of stomach pain and skin infections. This research aims to evaluate the wound healing and antimicrobial properties of the secondary metabolites from the stem and leaf of Acrostichum aureum. The crude extract was subjected to liquid- liquid partitioning successively with n-hexane, ethylacetate, butanol and water.  Wound healing activity was determined using wound excision model while the antimicrobial activity was evaluated using the Inhibition Zone Diameter (IZD) model. Metabolomics was carried out using High performance Liquid Chromatography coupled with Diode Array Detector (HPLC-DAD). Result from the study revealed that the crude extract and butanol fractions of both stem and leaves of Acrostichum aureum elicited significant (p<0.05) reduction in wound size on progressive administration of the extract at all doses when compared to the controls. From the result, models treated with 2% AAL-BF, 6% AAS-BF and povidone had at least 94% wound contraction on day 12 respectively, while models treated with 2% AAS-BF and 6% AAL-BF had 89.5% and 85.0% wound contraction respectively on the 12^th day. The crude extract and fractions of Acrostichum aureum showed a dose dependent response against the pathogens. The crude extract of both AAS and AAL showed the best antibacterial activities. AAL showed an IZD of 10.0 ± 0.7, 6.00 ± 0 and 12.0 ± 0 for Staphylococcus aureus, Pseudomonas aereginosa, and Escherichia coli respectively at the highest dose (1 mg/mL), while AAS showed an IZD of 10.0 ± 0.7, 7.0 ± 0 for Staphylococcus aureus and Pseudomonas aereginosa respectively at dose of 1.0 mg/mL. Fractions of AAL also showed activity against Staphylococcus aureus and Escherichia coli.  The HPLC-DAD identified compounds; quercetin-3-galactoside, rocaglamide, palitantin and isorhamnetin diglycoside proposed to be responsible for the bioactivities observed. In conclusion, the secondary metabolites from the leaf and stem part of Acrostichum aureum growing in Nigeria possess wound healing and antibacterial properties and can be optimized for the development of potent therapeutic agents.