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Hexane, chloroform, ethyl acetate and methanolic extracts from leaves and stem-bark of Rhamnus prinoides were evaluated for their antioxidant activity by DPPH radical scavenging assay. The leaves extracts showed scavenging activity ranging from 03.33±0.89 to 55.03±3.40 µg mL-1 while the stem-bark extracts showed relatively strong scavenging activity ranging from 03.65±1.02 to 59.55±2.27 µg mL-1. The IC 50 values of R. prinoides hexane leaves extract (RPHELS), R. prinoides chloroform leaves extract (RPCHLS), R. prinoides ethyl acetate leaves extract (RPEALS), R. prinoides methanolic leaves extract (RPMELS), R. prinoides hexane stem-bark extract (RPHESB), R. prinoides chloroform stem-bark extract (RPCHSB), R. prinoides ethyl acetate stem-bark extract (RPEASB) and R. prinoides methanolic stembark extract (RPMESB) were found to be >3000, >3000, >3000, 950.42, ~1500, 710.50, ~1000 and 902.78 µg mL-1 , respectively. The positive control ascorbic acid showed an IC 50 value of <200 µg mL-1. From this study, we concluded that the extracts from R. prinoides showed promising antioxidant activity. R. prinoides finds therapeutic applications in the traditional medicine. Further research is required to commercialize products from this plant.

Aims: Rosehip seed press cake is a waste material in the industrial extraction of rosehip seed oil using cold press process. The current study seeks to evaluate the phytochemical profile, total phenolic content, total flavonoid content and DPPH radical scavenging activity of the ethanolic extract of rosehip seed press cake using standard methods and DPPH assay. Study Design:  This is an experimental laboratory report on the phytochemical properties and antioxidant potential of the ethanolic semi-solid extract (ESE) of rosehip seed press cake in order to assess its commercial viability as a food supplement. Place and Duration of Study:  The work was conducted in the Department of Chemistry, National University of Lesotho, from August 2019 to March 2020.  Methodology: Ethanol was used for the extraction of the semi-solid extract (ESE) from the rosehip seed press cake. The ESE was analysed for phytochemical constituents using standard methods. In vitro antioxidant activity of the ESE was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. For data analysis, mean and standard deviation were computed for each parameter that was quantitatively determined. Results: Presence of flavonoids, alkaloids, terpenoids, sterols, glycosides, reducing sugars, proteins, amino acids, fatty acids, phenols and polyphenols in the ESE was confirmed. Total phenolics and flavonoids content were found to be 134.44 mg GAE/g DW and 73.23 mg QE/g DW, in the range of 200 to 3000 µg/ml respectively. The DPPH radical scavenging activity of the extract was found to be in the range 10.32±3.89 and 76.06±3.48% within the concentration range and was very close to the scavenging activity of DPPH at concentrations ≥ 1500 µg/ml. The ESE showed an IC50 value of 1367.06 µg/ml relative to that of the positive control, ascorbic acid, being <200 µg/ml. Conclusion: The ESE from the rosehip seed press cake was found to be very promising as a food supplement since 50% of the 16 screened phyto-constituents were present in high concentrations; 6.25% were detected in moderate concentrations and another 6.25% were present in low concentrations. Furthermore, the ESE exhibited antioxidant properties. Further studies are recommended to obtain more information on its composition and suitability additive in animal feed or as a food supplement.