Physicochemical investigation of the red alga Acanthophora spicifera (Vahl) Borgesen, collected from Al-Shoaiba coast, Red Sea, Saudi Arabia, led to the isolation of a flavone from the algal tissue with acetone. Preparative chromatography on silica gel thin-layer chromatography was used for the separation of the flavone and eluted with the methanol:chloroform:ethyl acetate (1:7:2) solvent system. The physicochemical analyses infrared, mass spectra, and ultraviolet spectra in addition to shift reagents (NaOMe, NaOAc, NaOAc + H3BO3, AlCl3, and AlCl3 + HCl) were used for the identification and elucidation of the structure of the flavone compound (4,5,7-trihydroxy flavonoids). The flavone compound was identified as apigenin bycomparing its physicochemical data with those in the literature. Analgesic and anti-inflammatory activities of apigenin were evaluated. Apigenin showed promising analgesic and anti-inflammatory activities in the hot plate test and writhing test in mice as well as tail-immersion tests and carrageenan-induced paw edema and cotton pellet-induced granuloma formation in rats. It is concluded that apigenin possesses potent analgesic, anti-inflammatory, and antiproliferative activities, which might be due to the inhibition of PGE2 as well as proinflammatory cytokines such as interleukin-1β, interleukin-6, and tumor necrosis factor-α.

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This paper presents an experimental investigation of adsorption equilibrium characteristics of natural gas onto granular activated carbon (GAC). Experiments have been conducted at adsorption temperatures ranging from 20 °C to 50 °C and pressures up to 10 bar. The measurements are based on measuring the adsorption uptake difference between two equilibrium adsorption states. Experimental data have been correlated using four adsorption isotherm models, namely, Langmuir, Tóth, Dubinin–Astakhov (D–A), with and without volume correction. The proposed method reduces the time required to conduct the experiments significantly. It is found that 1 kg of GAC can adsorb about 77 g of natural gas at adsorption temperature of 20 °C and equilibrium pressure of 10 bar. Isosteric heat of adsorption of natural gas/GAC pair has been estimated using Clausius–Clapeyron equation. Comparison between storage capacities of adsorbed natural gas and compressed natural gas has also been discussed. Results extracted from the present study are useful for developing efficient adsorbed natural gas storage systems.