In-vitro Antioxidant, Sun Protection, Anti-inflammatory and Antibacterial Properties of F. leucopyrus, O. octandra and H. speciosa

Abstract

Rich biodiversity and strong ethnopharmacological traditional knowledge in Sri Lanka provide an opportunity to utilize highly potential medicinal plant resources for sustainable products extending from pharmacological, food/beverages to cosmetic innovation. Flueggea leucopyrus, Osbeckia octandra, and Hellenia speciosa have been a research focus due to their medicinal benefits according to ethnopharmacology. The current study investigates the beneficial bioactivities of F. leucopyrus, O. octandra, and H. speciosa in terms of their antioxidant, in-vitro sun protection, and anti-inflammatory capacities, followed by antimicrobial activity in a range of extractions. The plant leaf water, glycerine, and ethanol extracts were subjected to antioxidant assays: Total Phenol Content (TPC) as Gallic Acid Equivalent (GAE), Total Flavonoid Content (TFC) as Rutin Equivalent (RE), and DPPH free-radical scavenging percentage (DPPHfrs%) followed by in-vitro Sun Protection Factor (SPF) and egg-albumin anti-coagulation effect for in-vitro Anti-Inflammatory percentage (AI%). The antibacterial activities against Staphylococcus aureus and Pseudomonas aureoginosa strains were tested for water and ethanol extracts of the medicinal plants using disk diffusion and Resazurin assays. The TPC, TFC, and DPPHfrs% of F. leucopyrus ranged from 0.154 g/L to 0.852 g/L, 0.009 g/L to 0.455 g/L and 84.349% to 91.713%, while O. octandra ranging from 0.131 g/L to 1.113 g/L, 0.008 g/L to 0.160 g/L and 79.607% to 92.387% respectively. H. speciosa showed TPC, TFC, and DPPHfrs% ranging from 0.010 g/L to 3.024 g/L, 0.002 g/L to 0.410 g/L and 26.388% to 57.716% respectively. The SPF of F. leucopyrus, O. octandra, and H. speciosa, ranged from 33 to 40, 19 to 40, and 6 to 34 respectively. AI% of F. leucopyrus, O. octandra, and H. speciosa followed 9.037% and 11.940%, 8.418% and 11.852%, 12.515% and 12.000% respectively (water and ethanol extracts respectively). Crude ethanolic leaf extracts of F. leucopyrus and H. speciosa in a higher concentration of 50 mg/mL showed antibacterial activity against S. aureus. Thus, the current plant selection of F. leucopyrus, O. octandra, and H. speciosa can be considered as high potential resources for sustainable products with consideration on the extraction protocols as they can brighten, heal, and hydrate skin and body. 

Keywords: Medicinal plants, Antioxidant capacity, Sun protection factor, Anti-inflammatory capacity, Antibacterial activity