In vitro biological assessment of Homalium zeylanicum and isolation of lucidenic acid A triterpenoid

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Current investigation supports antioxidant, anti-diabetic activities of H. zeylanicum.

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Current investigation also supports anti-inflammatory activity of H. zeylanicum.

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The research successfully isolated and analysed structure of lucidenic acid A.

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Lucidenic acid A reported first time in the bark of H. zeylanicum.

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Lucidenic acid A produces a significant anti-inflammatory activity.

Homalium zeylanicum (Gardner) Benth. (Flacourtiaceae) is a medicinal plant useful in controlling rheumatism, inflammation and diabetes. The objective of this work evaluates in vitro antioxidant, antidiabetic, and antiinflammatory properties of hydroalcohol extract of bark of H. zeylanicum (HAHZ). It also describes isolation and structure determination of lucidenic acid A, which is the first report in this plant. In order to explain the role of antioxidant principles, DPPH, nitric oxide, hydroxyl, superoxide and metal chelating assays were performed. Antidiabetic and anti-inflammatory activities were investigated by quantifying α-amylase, α-glucosidase and protein denaturation inhibitory activities of HAHZ. Biochemical estimations were performed. The chemical structure of the triterpenoid was elucidated using ¹H, ¹³C NMR and high resolution-MS. IC₅₀ of DPPH, nitric oxide, hydroxyl, superoxide and metal chelating activities were of 36.23 ± 0.27, 40.11 ± 0.32, 35.23 ± 0.57, 43.34 ± 0.22 and 11.54 ± 0.08 μg/mL, respectively. IC₅₀ of α-amylase and α-glucosidase activities were 29.12 ± 0.54, and 18.55 ± 0.15 μg/mL. Total phenolic and total flavonoid contents were recorded at 233.65 mg/g GAE and 172.7 mg/g QE. Regarding kinetic behaviour, HAHZ showed competitive inhibition on α-glucosidase and mixed competitive inhibition on α-amylase. Lucidenic acid A was confirmed by spectroscopic studies. Anti-inflammatory activity of lucidenic acid A was determined by using protein denaturation assay with IC₅₀ 13 μg/mL but HAHZ showed 30.34 ± 0.13 μg/mL. Phenols and flavonoids could be attributed to inhibition of intestinal carbohydrases for anti-diabetic activities whereas triterpenoids could be responsible for anti-inflammatory activity of H. zeylanicum.