Ethnobotanical survey, phytoconstituents and antibacterial investigation of Rapanea melanophloeos (L.) Mez. bark, fruit and leaf extracts

Rapanea melanophloeos is traditionally used in South Africa in the treatment of ailments of the skin, pulmonary and gastro intestinal tract. This study was aimed at giving an overview of these traditional uses and comparing the phytochemicals and antibacterial activities of various crude extracts of the leaves, fruits and bark in order to validate these uses. The three plant parts were extracted using petroleum ether (PE), ethyl acetate (EtOAc), methanol (MeOH) and water. Various phytochemicals were compared using TLC, while alcohol precipitable solids (APS), non-polar terpenes and amino acids were analysed by GC-MS. Antibacterial activity was determined against three Gram-positive and three Gram-negative strains by microdilution assays. Caryophyllene oxides, α-cadinol and (−)-spathulenol were identified in the PE extracts. All nine essential amino acids were present in fruit extracts in significantly higher levels than in the leaves and bark; 255.1, 23.4 and 21.3 mg/g respectively. Most of the extracts showed good antibacterial activity, especially against the Gram-positive pathogens (MIC of ≤1 mg/mL), the EtOAc extracts exhibited the best activity with the fruit having an MIC values of 0.1 ± 0.2 mg/mL against Staphylococcus epidermidis and Enterococcus faecalis, 0.05 mg/mL against Bacillus cereus. Results from this study validate the ethnomedicinal uses of R. melanophloeos extracts for ailments of bacterial etiology. The plant had a rich supply of secondary metabolites, APS and amino acids and TLC and antibacterial activities of the extracts showed slight variations in chemical composition due to geographic distribution.

Experimental validation and computational modeling of anti-influenza effects of quercetin-3-O-α-L-rhamnopyranoside from indigenous south African medicinal plant Rapanea melanophloeos

Background Influenza A virus (IAV) is still a major health threat. The clinical manifestations of this infection are related to immune dysregulation, which causes morbidity and mortality. The usage of traditional medication with immunomodulatory properties against influenza infection has been increased recently. Our previous study showed antiviral activity of quercetin-3-O-α-L-rhamnopyranoside (Q3R) isolated from Rapanea melanophloeos (RM) (L.) Mez (family Myrsinaceae) against H1N1 (A/PR/8/34) infection. This study aimed to confirm the wider range of immunomodulatory effect of Q3R on selective pro- and anti-inflammatory cytokines against IAV in vitro, to evaluate the effect of Q3R on apoptosis pathway in combination with H1N1, also to assess the physical interaction of Q3R with virus glycoproteins and RhoA protein using computational docking. Methods MDCK cells were exposed to Q3R and 100CCID50/100 μl of H1N1 in combined treatments (co-, pre- and post-penetration treatments). The treatments were tested for the cytokines evaluation at RNA and protein levels by qPCR and ELISA, respectively. In another set of treatment, apoptosis was examined by detecting RhoA GTPase protein and caspase-3 activity. Molecular docking was used as a tool for evaluation of the potential anti-influenza activity of Q3R. Results The expressions of cytokines in both genome and protein levels were significantly affected by Q3R treatment. It was shown that Q3R was much more effective against influenza when it was applied in co-penetration treatment. Q3R in combination with H1N1 increased caspase-3 activity while decreasing RhoA activation. The molecular docking results showed strong binding ability of Q3R with M2 transmembrane, Neuraminidase of 2009 pandemic H1N1, N1 and H1 of PR/8/1934 and Human RhoA proteins, with docking energy of − 10.81, − 10.47, − 9.52, − 9.24 and − 8.78 Kcal/mol, respectively. Conclusions Quercetin-3-O-α-L-rhamnopyranoside from RM was significantly effective against influenza infection by immunomodulatory properties, affecting the apoptosis pathway and binding ability to viral receptors M2 transmembrane and Neuraminidase of 2009 pandemic H1N1 and human RhoA cellular protein. Further research will focus on detecting the detailed specific mechanism of Q3R in virus-host interactions.

Anthelmintic efficacy and safety of selected medicinal plants against mixed gastrointestinal nematodes in artificially infected sheep

There has been widespread resistance to anthelmintics by pathogenic helminths to an extent where there is multi-drug resistance against all major classes of conventional anthelmintics. This world-wide phenomenon calls for urgent search for different approaches to the control of helminthosis including novel anthelmintic products. The purpose of the study was to determine the efficacy and safety of selected plants, which are frequently used in the treatment and control of helminthosis, in artificially infected sheep under controlled laboratory conditions. The selected plant species were, Albizia anthelmintica Brongn, Embelia schimperi L., Myrsine africana L. and Rapanea melanophloeos (L.) Mez. Thirty six male Dorper lambs, aged between 6 and 8 months, artificially infected with mixed gastrointestinal nematodes (GIN) under controlled laboratory conditions, were used for the study. Efficacy was determined using percentage fecal egg count reduction test (FECRT %) and percentage total worm count reduction (TWCR %). Safety of the remedies was assessed using health, hematological and biochemical parameters. The FECR % against the mixed gastrointestinal nematodes was -55, 7.6, 34.2, 69.3 and 83.3% for Albizia anthelmintica, Embelia schimperi, Rapanea melanophloeos, albendazole and Myrsine africana respectively. TWCR% of 60.7, 44.6, 66, 69.7 and 35.6 percent were recorded for Albizia anthelmintica, Embelia schimperi, Myrsine Africana, Rapanea melanophloeos, and albendazole groups respectively. It was concluded that some of the remedies like M. africana have good efficacy at safe levels and should further be evaluated to determine the most optimum dosages. The gastrointestinal nematodes used in this study were resistant to albendazole