Maculosin,a non-toxic antioxidant compound isolated from Streptomyces sp. KTM18

ContextStreptomyces species are prolific sources of bioactive secondary metabolites known especially for their antimicrobial and anticancer activities.ObjectiveThis study sought to isolate and characterize antioxidant molecules biosynthesized by Streptomyces sp. KTM18. The antioxidant potential of an isolated compound and its toxicity were accessed.Materials and methodsThe compound was purified using bioassay-guided chromatography techniques. Nuclear magnetic resonance (NMR) experiments were carried out for structure elucidation. The antioxidant potential of the isolated compound was determined using DPPH free radical scavenging assay. The toxicity of the isolated compound was measured using a brine shrimp lethality (BSL) assay.ResultsEthyl acetate extract of Streptomyces sp. KTM18 showed more than 90% inhibition of DPPH free radical at 50 µg/mL of the test concentration. These data were the strongest among 13 Streptomyces isolates (KTM12–KTM24). The active molecule was isolated and characterized as maculosin (molecular formula, C₁₄H₁₆N₂O₃ as determined by the [M + H]⁺ peak at 261.1259). The DPPH free radical scavenging activity of pure maculosin was higher (IC₅₀, 2.16 ± 0.05 µg/mL) than that of commercial butylated hydroxyanisole (BHA) (IC₅₀, 4.8 ± 0.05 µg/mL). No toxicity was observed for maculosin (LD₅₀, <128 µg/mL) in brine shrimp lethality assay (BSLA) up to the compound’s antioxidant activity (IC₅₀) concentration range. The commercial standard, berberine chloride, showed toxicity in BSLA with an LD₅₀ value of 8.63 ± 0.15 µg/mL.ConclusionsMaculosin may be a leading drug candidate in various cosmetic and therapeutic applications owing to its strong antioxidant and non-toxic properties.     

Spontaneous chemical degradation of substance P in the solid phase and in solution

The instability of the undecapeptide substance P (SP), a neuropeptide implicated in several physiological processes, was occasionally observed when the peptide was stored in the solid state or in solution. The aim of the present study was to identify the decomposition products of SP stored as lyophilized peptide or in aqueous neutral solution. The main pathway of the decomposition of SP acetate consists of the subsequent release of N-terminal dipeptides via their diketopiperazines. cyclo(Arg-Pro) and cyclo(Lyys-Pro). In contrast to the decomposition of the acetate of SP, the hydrochloride and trifluoroacetate salts were found to be considerably more stable. Under the studied conditions the release of N-terminal dipeptides dominates over other possible routes of spontaneous modifications, such as S-oxidation and deamidation.     

The effects of peptides on the stimulus properties of ethanol

Male Sprague-Dawley rats were trained to discriminate ethanol (2 g/kg, PO: EtOH) from saline (10 ml/kg, PO: SAL) in a two-bar positively reinforced operant task on a VI 15 sec schedule. After the rats reached criterion performance (greater than 90% correct responses on the appropriate lever), thyrotropin releasing hormone (pyroGlu-His-Pro-NH2: TRH), a metabolite of TRH (His-Pro diketopiperazine: HP), and a structural analog of TRH (HPCA-His-ThiaPro-NH2: OHT) were tested for their ability to antagonize the EtOH cue. These peptides were chosen for their reported ability to reverse ethanol-induced narcosis. However, at doses that did not disrupt performance, TRH, HP, and OHT did not affect the stimulus properties of ethanol at any dose tested, nor did they change the stimulus properties of saline. Naloxone and ACTH(1-10)-NH2 were also tested as ethanol antagonists of the training dose. Pretreatment with either of these compounds failed to alter ethanol-appropriate responding. In addition, (DA1a2-Met5)-enkephalin-ol, (DAla2-Met(O)5)-enkephalin-ol, substance P, delta sleep-inducing peptide, and bombesin were tested for their ability to elicit ethanol appropriate responding. The EtOH cue generalized to none of these peptides.     

Peptidergic regulation of norepinephrine induced feeding

The inhibitory effect of a variety of substances on feeding induced by norepinephrine (20 μg ICV) was studied. Subcutaneous administration of the opiate antagonist, naloxone, inhibited norepinephrine-induced eating at 10 and 5 mg/kg, but not a 1 mg/kg. Intraventricular administration of the GABA antagonist, bicuculline, produced a dose related decrease in food ingestion. The putative satiety hormones, bombesin (10 μg/kg; subcutaneously) and cholecystokinin octapeptide ( 10 gmg/kg; subcutaneously) also reduced norepinephrine induced eating, as did ICV administration of calcitonin (2 units). Neither thyrotropin-releasing hormone (1 μg ICV) nor its metabolits, histidyl-proline diketopiperazine (1 μg ICV) altered norepinephrine-induced feeding. The studies reported here suggest a neuromodulatory role of peptides in the central regulation of norepinephrine-induced feeding.     

Technosphere? Insulin: Defining the Role of Technosphere Particles at the Cellular Level

Background

Technosphere^® Insulin (TI) is a novel inhalation powder for the treatment of diabetes mellitus. Technosphere Insulin delivers insulin with an ultra rapid pharmacokinetic profile that is distinctly different from all other insulin products but similar to natural insulin release. Such rapid absorption is often associated with penetration enhancers that disrupt cellular integrity.

Methods

Technosphere Insulin was compared to a panel of known penetration enhancers in vitro using the Calu-3 lung cell line to investigate the effects of TI on insulin transport.

Results

Measures of tight junction integrity such as transepithelial electrical resistance, Lucifer yellow permeability, and F-actin staining patterns were all unaffected by TI. Cell viability and plasma membrane integrity were also not affected by TI. In contrast, cells treated with comparable (or lower) concentrations of penetration enhancers showed elevated Lucifer yellow permeability, disruption of the F-actin network, reduced cell viability, and compromised plasma membranes.

Conclusions

These results demonstrate that TI is not cytotoxic in an in vitro human lung cell model and does not function as a penetration enhancer. Furthermore, TI does not appear to affect the transport of insulin across cellular barriers.     

无花果内生真菌FL10中吲哚二酮哌嗪类生物碱的研究

目的:研究无花果内生真菌FL10的次级代谢产物成分.方法:采用反复硅胶柱色谱法、Sephadex LH-20凝胶色谱法等进行分离纯化,从无花果内生真菌FL10的发酵液中分离得到6个吲哚二酮哌嗪类生物碱.结果:通过理化常数测定和光谱分析,6个吲哚二酮哌嗪类生物碱鉴定分别为verruculogen(1),cyclotryprostatins B(2),fumitremorgin C(3),cyclotryprostatin A(4),tryprostatin A(5),tryprostatin B(6).结论:这6个吲哚二酮哌嗪类生物碱是首次从无花果内生真菌中分离得到,目前研究表明,无花果内生真菌Aspergillus tamarii可以作为一种可产生吲哚二酮哌嗪类生物碱的新来源.     

Pharmaceutical strategies to extend pulmonary exposure of inhaled medicines

Pulmonary administration route has been extensively exploited for the treatment of local lung diseases such as asthma, chronic obstructive pulmonary diseases and respiratory infections, and systemic diseases such as diabetes. Most inhaled medicines could be cleared rapidly from the lungs and their therapeutic effects are transit. The inhaled medicines with extended pulmonary exposure may not only improve the patient compliance by reducing the frequency of drug administration, but also enhance the clinical benefits to the patients with improved therapeutic outcomes. This article systematically reviews the physical and chemical strategies to extend the pulmonary exposure of the inhaled medicines. It starts with an introduction of various physiological and pathophysiological barriers for designing inhaled medicines with extended lung exposure, which is followed by recent advances in various strategies to overcome these barriers. Finally, the applications of the inhaled medicines with extended lung exposure for the treatment of various diseases and the safety concerns associated to various strategies to extend the pulmonary exposure of the inhaled medicines are summarized.     

Diketopiperazine formation and N-terminal degradation in recombinant human growth hormone

A new degradation process has been identified that occurs in recombinant DNA-derived human growth hormone. Non-enzymatic cyclization of the first two amino acids from the N-terminus and subsequent cleavage results in the formation of a diketopiperazine and a truncated variant of rhGH. The truncated protein was separated using hydrophobic interaction chromatography and identified as desPhe¹Pro²-rhGH using N-terminal sequence analysis, tryptic mapping, and mass spectrometry.     

Coordination chemistry of peptides

The structure of the title compound displays a nearly planar diketopiperazine ring. The side chain is folded on the ring, the S atom making a significantly short contact with the methionine carbonyl atom. The crystal packing shows an unusual assembly of alternating layers of peptide and crystallization water molecules. The side chain sulfur atom is found to be the primary site for metal coordination of the ligand, while in some systems there is evidence of additional coordination through deprotonated amide nitrogens.