No abstract

β-Caryophyllene (trans-4,11,11-trimethyl-8-methylenebicyclo[7,2,0]undec-4-ene), found in various plants, is a natural bicyclic sesquiterpene with a low toxicity. Here, we show that a single intraperitoneal injection of β-caryophyllene (10 mg/kg) significantly reduced the cortical infarct volume by 67% when given immediately before middle cerebral artery occlusion (MCAO). Neurological deficits caused by MCAO were also significantly decreased by β-caryophyllene. β-Caryophyllene treatment of cortical cells exposed to oxygen-glucose deprivation revealed a significant protection in a dose-dependent manner. However, β-caryophyllene neither suppressed N-methyl-D-aspartate excitotoxicity in cultured cortical cells nor markedly decreased the oxidative stress measured in the cellular or acellular systems. By contrast, treatments with β-caryophyllene dose-dependently inhibited mRNA expression of inducible nitric oxide synthetase, interleukin (IL)-1β, IL-6, and cyclooxygenase 2 in C6 microglial cells, and decreased the level of nitric oxide and prostaglandin E₂ at a 100 μM concentration. All of these findings suggest that β-caryophyllene has a potent neuroprotective activity, and its neuroprotection may be partly related to the modulation of inflammatory mediators.

The neuroprotective and antioxidative activities of five organosulfur compounds with a thioallyl structure (-S-CH2CH=CH2) were characterized in terms of structure-activity relationships. Among five organosulfur compounds, only S-allyl-L-cysteine (SAC) having the alanyl group (-CH2CH-NH2-COOH) and lacking the oxo (O=) group with in between molecular properties, was effective in protecting cell death induced by both oxygen glucose deprivation and global cerebral ischemia. Conversely, lipophillic organosulfur compounds including diallyl sulfide, diallyl disulfide, and diallyl trisulfide were devoid of in vitro and in vivo neuroprotective activities. Furthermore, a significant correlation was only found between the in vivo neuroprotective activity and the OH- scavenging activity (gamma = 0.55 and p = 0.032) among reactive oxygen species scavenging activities. These results indicate that the presence of the alanyl group and the absence of the oxo group are essential for the manifestation of neuroprotective activity against ischemic insults and scavenging of OH radical, with SAC surfacing as a potent neuroprotectant.

The authors report low-power optical bistability under continuous wave pumping conditions in five-cell photonic crystal linear resonators containing InGaAsP quantum wells, by employing the fiber-coupling technique. The threshold bistable power is measured to be 35μW at the normalized detuning of −1.724. Owing to the high band-edge nonlinearities of quantum wells and the efficient fiber coupling, minimal instability is observed. In addition, all-optical switching is demonstrated with switching energy less than 75.4fJ.