Objective: To investigate the effects of 20 methanolic extracts from Malaysian selected plants on CD18/11a expression and phagocytosis activity of leukocytes using flow cytometry analysis. Methods: The effects of methanolic extracts on CD18/11a expression and phagocytosis of leukocytes were measured by labelling the cells with CD18-fluorescein isothiocyanate and ingestion labelled with Escherichia coli-fluorescein isothiocyanate and then analyzed using flow cytometer. Results: About 12 out of 20 methanolic extracts of selected Malaysian medicinal plants significantly (P≤0.05) inhibited the CD18/11a expression of leukocytes at both concentrations of 6.25 μg/mL and 100 μg/mL in dose dependent manner. The most active inhibitory was shown in Citrus aurantifolia (Christm.) Swingle and Alpinia galangal (L.) Willd. at dosage 100 μg/mL. Moreover, the Orthosiphon aristatus (Blume) Miq (O. aristatus). showed the highest stimulatory activity at the concentration of 100 μg/mL. Other than that, four plant extracts significantly (P≤0.05) rose the phagocytosis activities of leukocytes in dose dependent manner. However, Annona muricata L. and O. aristatus showed the highest stimulated activities at the 100 μg/mL concentration. Conclusions: The results suggest that methanolic extracts of Citrus aurantifolia, Alpinia galangal, O. aristatus and Annona muricata are able to modulate innate immune system and can potentially be recognized as therapeutic agents for modulating immune system.

Objective: To evaluate the immunosuppressive effect on human phagocytes and antibacterial activity of dihydromorin and norartocarpetin isolated from Artocarpus heterophyllus heartwoods. Methods: Dihydromorin and norartocarpetin were isolated from Artocarpus heterophyllus heartwoods. A modified Boyden chamber was used to determine the chemotactic activity of human phagocyte. The respiratory burst was evaluated by chemiluminescence assay. Myeloperoxidase (MPO) activity was quantified using a colorimetric assay. The broth microdilution method was performed to assess their antibacterial activity. Results: Dihydromorin exhibited potent inhibitory effect on the chemotactic activity of polymorphonuclear neutrophils (PMNs) with an IC50 value of 5.03 μg/mL. Dihydromorin also inhibited reactive oxygen species production of whole blood cells, PMNs, and monocytes with IC50 values of 7.88, 7.59 and 7.24 μg/mL, respectively. Interestingly, dihydromorin also strongly inhibited the MPO activity of PMNs with an IC50 value of 5.24 μg/mL, which was lower than indomethacin (24.6 μg/mL). Molecular docking of dihydromorin and crystal structure of MPO showed that dihydromorin had close interaction with key amino acid residues such as Arg239 and Gln91. Antibacterial activity assay showed that only dihydromorin had a strong effect against Streptococcus pyogenes with MIC and MBC values of 15.62 and 31.25 μg/mL, respectively. Conclusions: The results suggest that dihydromorin could be developed as an anti-inflammatory and antibacterial agent.

Introduction: Inhibition of the cholinesterase’s function leads to paralysis and death. This mechanism is served as a common mode of action of insecticide. The three tropical seaweeds, namely Bryopsis pennata, Padina australis and Sargassum binderi were reported for its potential mosquito larvicidal effect. In the present study, these seaweeds were evaluated for their potential as a cholinesterase inhibitor in the mechanism of larvicidal action. Methods: Acetylcholinsterase (AChE) inhibition assay was carried out based on the colorimetric method using a microplate reader. Phytochemical content of the seaweed extracts was screened by using liquid chromatography-mass spectroscopy (LC-MS). Results: Green seaweed B. pennata showed the strongest inhibition effect towards in vitro AChE by using tissue homogenates of Aedes aegypti (IC50 value = 0.84 mg mL-1) and Aedes albopictus as the enzyme source (IC50 value = 0.92 mg mL-1). The pattern of Lineweaver-Burk plots revealed that B. pennata was a mixed type inhibitor of AChE, as the readings of Km, Vmax, Ki and Ki’, indicates that it had a strong inhibition ability with high binding affinity towards both free enzyme and enzyme-substrate complex. Conclusion: These findings suggest the compound(s) in B. pennata extract serves as a promising source that could be developed into a mosquito larvicidal agent with AChE inhibition effect.

Objective: To investigate the larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by the extracts derived from seaweeds Bryopsis pennata (B. pennata). Sargassum binderi (S. binderi) and Padina australis in Aedes aegypti (Ae. aegypti) larvae and to characterize the phytochemical components of the three seaweeds. Methods: Larvicidal activity of the seaweeds towards the larvae of Ae. aegypti was determined according to WHO. The inhibition effect of seaweeds was assessed by determining the mortality, adult emergence rate, larval and pupa duration of the treated larvae. Histopathological effect on midgut epithelium of larvae and morphological aberration induced by the methanol extracts were examined. Phytochemical analysis was done to determine the presence of alkaloids, saponins, steroids and terpenoids in the seaweeds. Results: Chloroform partition of B. pennata extract exhibited the strongest larvicidal activity (LC

Chemical constituents and biological activities of the Mitrella kentii leaf oil were investigated in this study. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to determine the chemical constituents of the oil. The oil was evaluated for its ability to inhibit prostaglandin E2 (PGE2 ) and thromboxane B2 (TXB2 ) productions in human whole blood using a radioimmunoassay technique. Its inhibitory effect on plateletactivating factor (PAF) receptor binding with rabbit platelets using 3 H-PAF as a ligand and its free radical scavenging effect on DPPH were also investigated. Caryophyllene oxide (33.8%w/w), E,Z-farnesol (6.9%), benzyl benzoate (6.5%w/w) and viridiflorol (6.5%w/w) were among the major components of the oil. Even though weak inhibitory activities were observed in both PGE2 and TXB2 assays, significant results were obtained in both PAF receptor binding inhibition and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging effect with IC50 value of 6.6 µg/mL and 155.6 µg/mL respectively. These promising activities warrant the development of the oil as an anti-inflammatory agent.