Abstract:
Background: Traditional Sri Lankan medicine have been serving as a cornerstone of healthcare
for approximately 70% of our rural population. In traditional Sri Lankan medicine, formulations
combine multiple plants, with a few main components and others act as supportive agents to
enhance their effectiveness. Azadirachta indica (AI) and Oroxylum indicum (OI) are components
of Denabadiya Kasaya, which traditional healers use to treat viral infections.
Objective: To assess the bioactivity of AI and OI bark extracts using in vitro bioassays
Methods: Hot water extracts (100°C) of the barks of AI and OI were prepared by boiling 30 g of
powdered bark material with 1940 mL of distilled water and condensed to 240 mL. Subsequently,
the Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were determined.
Antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl DPPH assay and anti-inflammatory activity
by human red blood cell (HRBC) assay were carried out. Finally, cytotoxicity was assessed by (3
(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) MTT assay at 24 and 120 h, with
Vero cells
cultured in DMEM complete media at 37°C in 5% CO2.
Results: TPC of AI and OI were recorded as 15.6 and 20.2 mg/g GAE, respectively. TFC of AI
and OI were 40.0 and 15.1 mg/g QE. For DPPH assay, IC50 was 0.4 mg/mL for both samples,
while standard ascorbic acid showed an IC50 of 0.016 mg/mL. HRBC depicted an IC50 of <0.0625
mg/mL for both AI and OI, while ibuprofen showed an IC50 of <0.0625 mg/mL. Finally,
cytotoxicity of AI and OI were recorded as CC50 0.60 and 0.80 mg/mL for 24 h and >1 and 0.62
mg/mL for 120 h.
Conclusions: AI showed a remarkably higher TFC value, while both plant extracts depicted
moderate antioxidant activity. Both extracts also showed potent anti-inflammatory activity which
can help mitigate the detrimental effects of DENV infection by reducing oxidative stress and
protecting host cells. However, among the two plants tested AI showed a slightly high CC50 value
which might be a more promising candidate for further research as a potential anti-viral therapy.
