Neopinone isomerase is involved in codeine and morphine biosynthesis in opium poppy.

The isomerization of neopinone to codeinone is a critical step in the biosynthesis of opiate alkaloids in opium poppy. Previously assumed to be spontaneous, the process is in fact catalyzed enzymatically by neopinone isomerase (NISO). Without NISO the primary metabolic products in the plant, in engineered microbes and in vitro are neopine and neomorphine, which are structural isomers of codeine and morphine, respectively. Inclusion of NISO in yeast strains engineered to convert thebaine to natural or semisynthetic opiates dramatically enhances formation of the desired products at the expense of neopine and neomorphine accumulation. Along with thebaine synthase, NISO is the second member of the pathogenesis-related 10 (PR10) protein family recently implicated in the enzymatic catalysis of a presumed spontaneous conversion in morphine biosynthesis.

Short-chain dehydrogenase/reductase catalyzing the final step of noscapine biosynthesis is localized to laticifers in opium poppy.

The final step in the biosynthesis of the phthalideisoquinoline alkaloid noscapine involves a purported dehydrogenation of the narcotinehemiacetal keto moiety. A short-chain dehydrogenase/reductase (SDR), designated noscapine synthase (NOS), that catalyzes dehydrogenation of narcotinehemiacetal to noscapine was identified in opium poppy and functionally characterized. The NOS gene was isolated using an integrated transcript and metabolite profiling strategy and subsequently expressed in Escherichia coli. Noscapine synthase is highly divergent from other characterized members of the NADPH-dependent SDR superfamily involved in benzylisoquinoline alkaloid metabolism, and it exhibits exclusive substrate specificity for narcotinehemiacetal. Kinetic analyses showed that NOS exhibits higher catalytic efficiency with NAD+ as the cofactor compared with NADP+. Suppression of NOS transcript levels in opium poppy plants subjected to virus-induced gene silencing resulted in a corresponding reduction in the accumulation of noscapine and an increase in narcotinehemiacetal levels in the latex. Noscapine and NOS transcripts were detected in all opium poppy organs, but both were most abundant in stems. Unlike other putative biosynthetic genes clustered in the opium poppy genome, and their corresponding proteins, NOS transcripts and the cognate enzyme were abundant in latex, indicating that noscapine metabolism is completed in a distinct cell type compared with the rest of the pathway.

Kochiae Fructus: Evaluation on the antioxidant properties and oral safety of its water decoction.

Kochiae Fructus (KF) was listed as 'top grade' medicinal material by the 'Shennong's Herbal Classic of Materia Medica' and has been used in traditional Chinese medicine to delay aging and treat inflammation, such as rubella, eczema, cutaneous pruritus, etc. Our research focused on the antioxidant capability of water decoction and fractions from KF based on 2,2-iphenyl-1-picrylhydrazyl (DPPH) free radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging assay, the ferric reducing antioxidant power assay, and inhibitory effects on DNA and protein oxidative damage. The results of total phenolics and flavonoids contents showed that ethyl acetate fraction (EAF) possessed the highest phenolics and flavonoids with values of 112.90 ± 9.58 mg gallic acid equivalents/g and 329.60 ± 20.93 mg rutin equivalents/g, respectively. At the same time, the results of antioxidant capacities showed that EAF possessed best antioxidant abilities. In addition, in this work, we evaluated the oral safety of the water decoction of KF (KFWD) via the 14-day acute and 28-day subacute toxicity tests. The results of in vivo toxicity assessment showed that KFWD did not cause significant changes in the general clinical symptoms, hematology and biochemical parameters, organ weights, or histopathological appearances in mice or rats. In summary, the reason why KF has the traditional effect on delaying aging may be related to the fact that its rich in flavonoids and phenolics. Simultaneously, no toxicity was detected after acute or subacute treatment of KFWD, providing valuable evidence for the traditional safe use of KF.

Polypeptide from Chlamys farreri attenuates murine thymocytes damage induced by ultraviolet B.

AIM: Polypeptide from Chlamys farreri (PCF, molecular mass is 879) is a new marine polypeptide compound isolated from Chlamys farreri. This study investigates the possible protective roles and the mechanism of PCF against ultraviolet B (UVB)-induced apoptosis in murine thymocytes. METHODS: The rate of apoptosis and caspase-3 activation was measured by flow cytometry. The expression of stress-response genes c-fos and c-jun was observed by RT-PCR. Western blot analysis was performed to determine the release of cytochrome c. RESULTS: It was found that UVB induced murine thymocyte death. The cells treated with UVB showed an increase in cytochrome c release, caspase-3 activity, as well as in the expression of c-fos and c-jun. In addition, all were involved in UVB-induced cell apoptosis. CONCLUSION: Our present observations pointed to the ability of PCF to avert UVB-induced apoptosis in thymocytes by modulating c-fos and c-jun expression, cytochrome c release, and the consequent activation of caspase-3, which were essential components of the UV-induced cell apoptotic pathway. The results suggested that PCF is a promising protective substance against UV radiation.

BmTx3B, a novel scorpion toxin from Buthus martensi Karsch, inhibits delayed rectifier potassium current in rat hippocampal neurons.

AIM: To examine the effect of BmTx3B, a novel short-chain peptide isolated from the venom of Asian scorpion Buthus martensi Karsch, on voltage-gated potassium channels. METHODS: Two types of voltage-dependent potassium currents were recorded from dissociated hippocampal neurons of neonatal rat in whole-cell voltage-clamp mode, and separated based upon their kinetic properties. RESULTS: BmTx3B (10-100 micromol/L) selectively inhibited the delayed rectifier potassium current (I(K)), without affecting the fast transient potassium current (I(A)). The inhibition of the peptide on I(K) was reversible, concentration-dependent and voltage-independent. BmTx3B did not affect the steady-state activation and inactivation kinetics of the current. CONCLUSION: The short-chain scorpion peptide BmTx3B selectively blocked the delayed rectifier potassium channel.