Anti-angiogenic activity of Gracilaria coronopifolia J.G. Agardh extract by lowering the levels of trace metals (iron, zinc and copper) in duck chorioallantoic membrane and in vitro activation of AMP-kinase.

AMP-activated protein kinase (AMPK) is an intracellular energy sensor important in metabolic regulation, cell growth, and survival. However, the specific role of AMPK signaling pathway in the inhibition of angiogenesis remains unclear. The study highlights the activity on AMP activated protein kinase signaling pathways of a marine algae, Gracilaria coronopifolia, and its effects on angiogenesis. It was found that the most potent extract, GCD, inhibited angiogenesis significantly in the duck chorioallantoic membrane assay and also activated the enzyme AMP-kinase, in vitro. The dichloromethane extract was found most active in inhibiting angiogenesis in the duck chorioallantoic membrane (IC50 = 1.21 µg/mL) followed by GCH (IC50 = 3.08 µg/mL) (p = 0.479) and GCM (IC50 = 8.93 µg/mL) (p = 0.042). Benferroni post hoc analysis revealed that there was no significant difference between the percent inhibitions of GCH and GCM extracts (p = 0.479). Consequently, angiogenic inhibition caused lowering of iron, zinc, and copper levels in the duck CAM. Thin layer chromatography and gas chromatography-mass spectrometry revealed the components of each extracts. Notably, this is the first report on the kinase activity of a red algae G. coronopifolia extracts and a colorimetric-based quantification of angiogenesis based on metal content of CAM. Our data also suggest a novel therapeutic approach for inhibiting angiogenesis through the AMPK pathway.

Antitubercular constituents from Premna odorata Blanco.

ETHNOPHARMACOLOGICAL RELEVANCE: Premna odorata Blanco (Lamiaceae) is a medicinal plant traditionally used in Albay Province, in southeastern Luzon, Philippines to treat tuberculosis. This study aimed to determine the antitubercular property of the crude extract and sub-extracts of the leaves, and to isolate the bioactive principles from the active fractions. MATERIALS AND METHODS: Through extraction, solvent polarity-based fractionation and silica gel chromatography purification of the DCM sub-extract, compound mixtures from the bioactive fractions were isolated and screened for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv using the colorimetric Microplate Alamar Blue assay (MABA). RESULTS: The crude methanolic extract and sub-extracts showed poor inhibitory activity against Mycobacterium tuberculosis H37Rv (MIC≥128µg/mL). However, increased inhibitory potency was observed for fractions eluted from the DCM sub-extract (MIC=54 to 120µg/mL). Further purification of the most active fraction (MIC=54µg/mL) led to the isolation of a 1-heneicosyl formate (1), 4:1 mixture of ß-sitosterol (2), stigmasterol (3) and diosmetin (4), which were identified through GC-MS analysis (with dereplication) and NMR experiments. The MIC of compound 1 was 8µg/mL. CONCLUSIONS: The results of this study provide scientific basis for the traditional use of Premna odorata as treatment for tuberculosis.