Antioxidant and antimicrobial properties of Litsea elliptica Blume and Litsea resinosa Blume (Lauraceae).

OBJECTIVE: To investigate antioxidant and antimicrobial activities of two plant species, Litsea elliptica (L. elliptica) and Litsea resinosa (L. resinosa). METHODS: In vitro method-2,2-diphenyl-1-picrylhydrazyl radical scavenging assay was conducted for antioxidant activity determination while antimicrobial assay consisted of agar well diffusion assay and mycelial radial growth assay. RESULTS: Methanol extracts of root and stem of L. elliptica and L. resinosa exhibited the highest antioxidant activity with EC50 of 23.99, 41.69, 11.22 and 35.48 mg/L respectively. All methanol extracts of L. resinosa as well as root extracts from L. elliptica showed significant scavenging activity. Hexane extract from stem of L. resinosa presented the largest inhibition zone in Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli while chloroform extract from inner bark of L. resinosa showed major inhibition towards Gram-positive bacteria Bacillus subtilis. Essential oils from the root of both species showed significant antifungal activities which are 80.11% and 66.85% respectively. CONCLUSIONS: Overall, methanol extracts from root and stem of both species showed antioxidant activity comparable to standard butylated hydroxytoluene. Extracts from L. resinosa demonstrated stronger antimicrobial properties compared to that from L. elliptica.

Antiplatelet aggregation and platelet activating factor (PAF) receptor antagonistic activities of the essential oils of five Goniothalamus species.

Nine essential oils, hydrodistilled from different parts of five Goniothalamus species (G. velutinus Airy-Shaw, G. woodii Merr., G. clemensii Ban, G. tapis Miq. and G. tapisoides Mat Salleh) were evaluated for their ability to inhibit platelet aggregation in human whole blood using an electrical impedance method and their inhibitory effects on platelet activating factor (PAF) receptor binding with rabbit platelets using 3H-PAF as a ligand. The chemical composition of the oils was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The bark oil of G. velutinus was the most effective sample as it inhibited both arachidonic acid (AA) and ADP-induced platelet aggregation with IC(50) values of 93.6 and 87.7 microg/mL, respectively. Among the studied oils, the bark oils of G. clemensii, G. woodii, G. velutinus and the root oil of G. tapis showed significant inhibitory effects on PAF receptor binding, with IC(50 )values ranging from 3.5 to 10.5 microg/mL. The strong PAF antagonistic activity of the active oils is related to their high contents of sesquiterpenes and sesquiterpenoids, and the individual components in the oils could possibly produce a synergistic effect in the overall antiplatelet activity of the oils.