Peptides (v.25, #7)

In vitro activity of protegrin-1 and beta-defensin-1, alone and in combination with isoniazid, against Mycobacterium tuberculosis by Lanfranco Fattorini; Renato Gennaro; Margherita Zanetti; Dejiang Tan; Lara Brunori; Federico Giannoni; Manuela Pardini; Graziella Orefici (1075-1077).
The antimicrobial peptide protegrin-1 (PG-1) inhibited the growth in vitro of drug-susceptible and multidrug-resistant Mycobacterium tuberculosis; a lower activity was shown by human beta-defensin-1 (HBD-1) against both strains. The combination of PG-1 or HBD-1 with isoniazid significantly reduced M. tuberculosis growth in comparison with the peptides or isoniazid alone.
Keywords: Mycobacterium tuberculosis; Protegrin-1; Human beta-defensin-1; Isoniazid; Activity in vitro;

Parabutoporin—an antibiotic peptide from scorpion venom—can both induce activation and inhibition of granulocyte cell functions by Jean Willems; Leentje Moerman; Suzanne Bosteels; Erik Bruyneel; Filip Ryniers; Fons Verdonck (1079-1084).
Parabutoporin (PP) affects motility and NADPH oxidase activity in normal human polymorphonuclear neutrophils and in granulocytic HL-60 cells. These PP-induced interactions utilize a Rac activation pathway. PP induces chemotaxis of neutrophils and HL-60 cells via a pertussis toxin-sensitive way, thus using trimeric G-proteins. The enhanced chemotaxis is also apparent in undifferentiated HL-60 cells which lack functional formyl peptide receptors. On the other hand, PP strongly reduces the superoxide production by the NADPH oxidase complex after either PMA or fMLP activation of granulocytes. These combined results strongly suggest a direct activation of G-proteins and subsequent Rac activation as the basis for the observed effects. The unexpected inhibitory effect of PP, despite Rac activation, on superoxide production in granulocytes is explained by the direct interaction of membrane localized PP which prevents the formation of a functional NADPH oxidase complex.
Keywords: Parabutoporin; Granulocytes; Superoxide; Chemotaxis;

Identification of five new bradykinin potentiating peptides (BPPs) from Bothrops jararaca crude venom by using electrospray ionization tandem mass spectrometry after a two-step liquid chromatography by Danielle Ianzer; Katsuhiro Konno; Rafael Marques-Porto; Fernanda Calheta Vieira Portaro; Reto Stöcklin; Antônio Carlos Martins de Camargo; Daniel Carvalho Pimenta (1085-1092).
Bradykinin potentiating peptides (BPPs) from Bothrops jararaca venom were described in the middle of 1960s and were the first natural inhibitors of the angiotensin-converting enzyme displaying strong anti-hypertensive effects in human subjects. The BPPs can be recognized by their typical pyroglutamyl proline-rich oligopeptide sequences presenting invariably a proline residue at the C-terminus. In the present study, we identified 18 BPPs, most of them already described for the B. jararaca venom. We isolated and sequenced new peptides ranging from 5 to 14 amino acid residues exhibiting similar amino acid sequence features. The applied methodology consisted of a strait two-step liquid chromatography, followed by mass spectrometry analysis. Besides the amino acid sequence homology, the corresponding synthetic peptides were able to potentiate bradykinin on the isolated guinea-pig ileum.
Keywords: Bradykinin potentiating peptide; Bothrops jararaca; Bradykinin; Mass spectrometry; De novo sequencing; ACE inhibitors;

An antifungal protein designated actinchinin, with an N-terminal sequence different from that of the thaumatin-like antifungal protein from green kiwi fruit, was isolated from the gold kiwi fruit. The antifungal protein, unlike its counterpart from green kiwi fruit, did not exert antifungal activity against Botrytis cinerea, but was active against Fusarium oxysporum which was unresponsive to thaumatin-like protein from green kiwi fruit. Actinchinin was isolated using a protocol that comprised ion exchange chromatography on CM-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono S, and gel filtration by FPLC on Superdex 75. Actinchinin was adsorbed on CM-cellulose, Affi-gel blue gel and Mono S. It was devoid of mitogenic activity toward mouse splenocytes. In contrast to thaumatin-like protein from green kiwi fruit, actinchinin lacked HIV-1 reverse transcriptase inhibiting activity.
Keywords: Gold kiwi fruit; Antifungal protein; Isolation;

We have cloned the diapause hormone (DH)–pheromone biosynthesis activating neuropeptide (PBAN) cDNA from the suboesophageal ganglion (SG) of Manduca sexta pupae using rapid amplification of cDNA ends. The Mas-DH-PBAN cDNA encodes a preprohormone of 194 amino acids that contains five peptides (PBAN, DH-like, and α-, β-, γ-SGNP), all of which share a common FXPRL sequence at the C-terminus. Yet, the sequences are rather distinct from those reported from other species: Mas-α-SGNP has a unique C-terminal FXPEL (the arginine or lysine at FXPR(or K)L is replaced by glutamic acid), Mas-γ-SGNP is one amino acid shorter than its counterpart in other species, and Mas-PBAN contains two extra residues not seen in other species. Mas-DH-like peptide has the highest homology (83%) to Bombyx mori DH. Northern blot analysis shows a single mRNA corresponding in size to the Mas-DH-PBAN cDNA detected in brain-SG samples of pupae and adults, suggesting that these peptides are derived from a precursor through posttranslational processing. Using the more sensitive method of RT-PCR, DH-PBAN mRNA is also detectable in thoracic ganglia, although the expression is much lower than in the SG. Developmental profiles of DH-PBAN transcripts in the early pupal stage reveal different patterns in diapause and nondiapause individuals. While a conspicuous drop in expression of the DH-PBAN gene is noted in diapausing pupae 9 days after pupation, high expression persists in nondiapausing individuals. At earlier stages (wandering larva and day 3 pupae) expression is high in diapausing individuals but low in nondiapausing individuals. These observations suggest a possible contribution of the DH-like peptide to the induction phase of diapause in M. sexta.
Keywords: Diapause hormone; Pheromone biosynthesis activating neuropeptide; FXPRL family peptides; Expression pattern; Manduca sexta;

Differential gene expression of adrenomedullin receptors in pressure- and volume-overloaded heart—role of angiotensin II by Hisamitsu Onitsuka; Takuroh Imamura; Kaoru Ito; Kenji Kuwasako; Hiroshi Yamakawa; Shuji Hirano; Kazuo Kitamura; Tanenao Eto (1107-1114).
Left ventricular (LV) adrenomedullin (AM) gene expression differs between pressure overload (POL) and volume overload (VOL) and angiotensin II could be a critical stimulator of AM gene expression in POL and VOL models. Calcitonin receptor-like receptor (CRLR) co-expressed with receptor activity modifying protein 2 (RAMP2) or RAMP3 functions as an AM receptor. Levels of CRLR, RAMP2 and RAMP3 mRNA that were significantly increased within 24 h returned to the basal level at 5 days after the imposition of POL in the present study. In contrast, mRNA levels of CRLR and RAMP2 gradually increased over 6 weeks after the imposition of VOL. Continuous infusion of angiotensin II stimulated LV AM gene and AM receptor gene expression independently of LV peak-systolic and LV end-diastolic pressure. The gene expression of LV AM receptors increased in different types of cardiac overload. The present study revealed an intimate association between the AM signaling system and angiotensin II.
Keywords: Adrenomedullin receptor; Adrenomedullin signaling system; Angiotensin II; Calcitonin receptor-like receptor; Receptor activity-modifying protein;

Tumor necrosis factor-α downregulates adrenomedullin receptors in human coronary artery smooth muscle cells by Yasuko Nagoshi; Kenji Kuwasako; Yuan-Ning Cao; Takuroh Imamura; Kazuo Kitamura; Tanenao Eto (1115-1121).
We examined the effects of tumor necrosis factor (TNF)-α on the expression and functionality of adrenomedullin (AM) receptors in cultured human coronary artery smooth muscle cells. Analysis of real-time quantitative polymerase chain reactions showed that these cells abundantly express two AM receptors comprised of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying protein 1 (RAMP1) or RAMP2. TNF-α induced time- and dose-dependent decreases in the expression of CRLR and RAMP1/2 mRNAs, thereby diminishing AM-evoked cAMP production. The suppression of these three mRNAs was unaffected by inhibiting NOS, protein kinase G, protein kinase A, superoxide formation or NF-κB activation.
Keywords: Adrenomedullin; Receptor; Tumor necrosis factor-α; Downregulation; Coronary artery smooth muscle cells;

The interaction between human interleukin-6 (hIL-6) and human interleukin-6 receptor (hIL-6R) is the initial and most specific step in the hIL-6 signaling pathway. Understanding its binding core and interaction mechanism at amino acid level is the basis for designing small IL-6 inhibiting molecules, such as peptides or lead compounds. With Docking method, the complex structure composed of hIL-6 and its α-subunit receptor (hIL-6R) was analyzed theoretically. By using structure-based analysis and phage display methods, the loop AB (from Lys67 to Glu81) of hIL-6 was found to be the important binding epitope of hIL-6R. By means of computer-aided design, the mimic antagonist peptide (14 residues) was designed and synthesized. Using multiple myeloma cell line (XG7), IL-6 dependent cell line, as test model, the influence of antagonist peptides on the proliferation of XG7 cells was investigated. The results showed that the synthetic peptide could be competitive to bind to hIL-6R with hIL-6, and the effect was concentration dependent. The theoretical design approach is a powerful alternative to phage peptide library for protein mimics. Such mini-peptide is more amenable to synthetic chemistry and thus may be useful starting points for the design of small organic mimics.
Keywords: Mimic antagonist peptide; Epitope; Computer-aided design; Computer modeling;

Endothelin 1 and 3 enhance neuronal nitric oxide synthase activity through ETB receptors involving multiple signaling pathways in the rat anterior hypothalamus by Marı́a S. Jaureguiberry; Andrea S. di Nunzio; Melina A. Dattilo; Liliana G. Bianciotti; Marcelo S. Vatta (1133-1138).
We have previously reported that endothelin 1 and 3 (ET-1, ET-3) through the ETB receptor decrease norepinephrine release in the anterior hypothalamus and activate the nitric oxide (NO) pathway. In the present work we sought to establish the receptors and intracellular mechanisms underlying the increase in nitric oxide synthase (NOS) activity stimulated by ET-1 and ET-3 in the rat anterior hypothalamus. Results showed that ETs-stimulated NOS activity was inhibited by a selective ETB antagonist (BQ-788), but not by a selective ETA antagonist (BQ-610). In addition, NOS activity was not altered in the presence of an ETA agonist (sarafotoxin 6b), but it was enhanced in the presence of a ETB agonist (IRL-1620). Both N ω-nitro-l-arginine methyl ester (NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) diminished ETs-stimulated NOS activity. The stimulatory effect of ETs on NOS activity was inhibited in the presence of PLC, PKC, PKA and CaMK-II inhibitors (U-73122, GF-109203X, H-89 and KN-62, respectively), and the IP3 receptor selective antagonist, 2-APB. Our results showed that both ET-1 and ET-3 modulate neuronal NOS activity through the ETB receptor in the rat anterior hypothalamus involving the participation of the PLC-PKC/IP3 pathway as well as PKA and CaMK-II.
Keywords: Endothelin 1; Endothelin 3; ETB receptor; Neuronal NOS; Anterior hypothalamus; PKA; PKC; PLC; CaMK-II; IP3 receptor;

Facilitative effect of a novel AVP fragment analog, NC-1900, on memory retention and recall in mice by Tomoaki Sato; Koh-ichi Tanaka; Toyonori Teramoto; Yoshiko Ohnishi; Kenji Hirate; Masahiro Irifune; Takashige Nishikawa (1139-1146).
In order to determine the mechanism of action of a new AVP4–9 analog, NC-1900, on memory processes, memory retention and retrieval tests were conducted in a step-through passive avoidance (PA) task in mice. The administration of NC-1900 facilitated memory retention and retrieval in the PA task through vasopressin1A (V1A) receptors but not V2 receptors. The effect of NC-1900 on memory retention test performance appeared to be due to activation of the protein kinase C (PKC) signaling pathway via V1A receptors; however, the modulation of PKC was not essential for the facilitative effect of the new peptide in the retrieval test. The facilitation of memory retrieval by NC-1900 may also be mediated by other non-PKC-dependent signaling pathways, such as the phospholipase C-inositol trisphosphate pathway.
Keywords: NC-1900; Retention; Retrieval; AVP4–9; V1A receptor; Protein kinase C;

Effects of peptide YY3–36 on PRL secretion: pituitary and extra-pituitary actions in the rat by E Aguilar; R Fernandez-Fernandez; M Tena-Sempere; L Pinilla (1147-1152).
Polypeptide YY3–36 (PYY3–36) is a gastrointestinal secreted molecule, agonist of neuropeptide Y (NPY) receptor subtypes Y2 and Y5, that has been recently involved as anorexigenic signal in the network controlling food intake. Notably, several factors primarily involved in food intake control and energy homeostasis (as leptin, orexins, ghrelin and NPY) have been linked also to the regulation of anterior pituitary hormone secretion and carry out pleiotropic effects upon the reproductive axis. However, whether similar actions are conducted by PYY3–36 remains so far largely unexplored. Present studies were undertaken to analyze the potential effects of PYY3–36 in the control of prolactin (PRL) secretion in the rat. To this end, responses to PYY3–36 in terms of PRL secretion were monitored in vitro, after pituitary exposure to 10−8 to 10−6  M concentrations, and in vivo, after i.p. administration of different doses of PYY3–36 (3, 10 and 30 μg/kg) to prepubertal male and female rats. In addition, the in vivo effects of PYY3–36 were tested after central (i.c.v.) administration of 3 nmol of the peptide to prepubertal rats, and in hyperprolactinaemic aged females. PYY3–36 stimulated, in a dose-dependent manner, in vitro PRL secretion by pituitaries from prepubertal male and female rats. In contrast, systemic administration of PYY3–36 failed to modify serum PRL levels, whereas central infusion of PYY3–36 significantly inhibited PRL secretion in prepubertal rats. Finally, PRL secretion was stimulated in aged hyperprolactinaemic female rats by systemic administration of PYY3–36. In conclusion, the anorexigenic peptide PYY3–36 may participate in the control of PRL secretion in the prepubertal rat, acting at pituitary (stimulatory effect) and extra-pituitary (likely inhibitory action at the hypothalamus) sites of the lactotrope axis. Moreover, net actions of PYY3–36 on PRL secretion may depend on the age and prevailing PRL levels.
Keywords: PYY3–36; NPY; PRL; Pituitary; Puberty; Ageing;

This study investigates the release characteristics of neuropeptide Y (NPY) from young (10 weeks) and old (22 months) rat atrium. Levels of NPY release from samples of atrium were studied by organ perifusion. Rats were exposed to light:dark (LD) cycles of 12:12 or 18:6 and sacrificed at different circadian stages: 0, 4, 7, 12, 18, and 20 h after dark onset (HADO) for LD 12:12 or 0, 2, 3.5, 6, 15, and 22 HADO for LD 18:6. The heart was collected, and the right atrium was removed, weighed, and perifused with Krebs-bicarbonate buffer for 100 min, including a period of 50 min for stabilization of secretion rate. NPY concentrations released by atrium did not differ between the two age groups. NPY exhibited daily variations in concentrations in LD 12:12, with a peak during the end of scotophase, at 12 HADO, in both the young and old rats. These variations were strongly modified in LD 18:6, where the pattern of the release exhibited two peaks occurring during the two thirds of dark (3.5 HADO) and light (22 HADO) periods. This strongly suggests that the NPY rhythm is dependent on the environmental light:dark cycle. In this paper we show that NPY concentrations in the rat atrium exhibit daily variations, which are maintained with ageing. Moreover, photoperiod greatly influences NPY levels in the atrium.
Keywords: Neuropeptide Y; Atrium; Perifusion; Rat; Ageing; Photoperiod;

The effect of neurotensin on insulin-induced proliferation of human fibroblasts by Richard C. Scarpa; Robert E. Carraway; David E. Cochrane (1159-1169).
Neurotensin has been shown to influence growth in a number of cancerous and non-cancerous cells and to enhance the proliferative effects of growth factors without itself inducing proliferation. Here we show that neurotensin potentiates the proliferative effects of insulin on IMR90 human fibroblasts in a concentration and neurotensin receptor type 1-dependent manner. This potentiating effect of neurotensin was blocked by inhibitors of phospholipase C and protein kinase C, was accompanied by an increase in the level of soluble inositol phosphates and did not involve an autocrine factor. These results show that neurotensin can enhance insulin-dependent proliferation of human fibroblasts and suggest a possible role for neurotensin in tissue growth and repair.
Keywords: Neurotensin; Insulin; Proliferation; IMR90 cells;

Cloning and characterization of the glucagon receptor from cynomologous monkey by Teresa McNally; Nelson D. Grihalde; Terry M. Pederson; Christopher A. Ogiela; Stevan W. Djuric; Christine A. Collins; Chun W. Lin; Regina M. Reilly (1171-1178).
The glucagon receptor was cloned from cynolomologous monkey. A frame-shift mutation at the 3′ end of the monkey transcript results in a C-terminal extension of 14 amino acids. This extension is not observed in either the human or rodent glucagon receptors. Monkey glucagon receptor was expressed in CHO cells, either with (mkGCGR) or without (mkGCGRΔ14) the 14-amino acid C-terminal extension to approximate the human receptor. Both forms of the monkey receptor bound glucagon with similar affinity and showed glucagon-stimulated cAMP production, however the full-length form of the monkey receptor (mkGCGR) was less sensitive to glucagon in its ability to stimulate cAMP than the shortened form (mkGCGRΔ14). PCR of genomic DNA from baboon and rhesus monkeys suggests that they express a form of the receptor similar to that of cynomologous monkey, while in chimpanzee, the receptor is similar to the human form.
Keywords: GCGR; Glucagon receptor; G-protein coupled receptor; Cynomologous monkey; Intracellular signaling; Amino acid sequence; Nucleic acid sequence;

Glucagon-like peptide-1 (GLP-1) is accepted to be a peptide involved in the central regulation of gastrointestinal function, but its potential gastroprotective effect is not clear. The aim of this study was to investigate whether intracerebroventricularly injected GLP-1 has protective effects on gastric mucosal lesions induced by several models, and if yes, whether these effects are due to the gastric antisecretory effect of the peptide. GLP-1 which was injected in three different doses (1, 10, 100 ng/10 μl; i.c.v.) to conscious rats prevented the mucosal lesions induced by reserpine and ethanol, but did not prevent the gastric mucosal lesions induced by pyloric ligation. In addition, 1 ng/10 μl dose of centrally injected GLP-1 inhibited gastric acid secretion in pylorus-ligated rats. As a result, we conclude that intracerebroventricularly injected GLP-1 may play a role in the prevention of gastric mucosal lesions induced by certain experimental models and this gastroprotective effect may be independent from its antisecretory effect.
Keywords: GLP-1; Gastric mucosal damage; i.c.v.;

Exogeneous and endogenous CCK inhibit ethanol ingestion in Sardinian alcohol-preferring rats by Nori Geary; Amy Wolfe; Carlo Polidori; Federica Policani; Maurizio Massi (1185-1194).
Ethanol ingestion, like food ingestion, stimulates release of the signaling molecule cholecystokinin (CCK) from the small intestine. Here, we investigated the possibility that ethanol-induced CCK release might be a negative-feedback control of ethanol ingestion, similar to its function as part of the mechanism by which ingested food produces meal-ending satiation. We used Sardinian alcohol-preferring (sP) and Marchesian Sardinian (msP) alcohol-preferring rats, two apparently identical substrains that spontaneously ingest pharmacologically relevant amounts of ethanol, as well as their background strain, Wistar (W) rats. We demonstrated that: (1) intraperitoneal (IP), but not intracerebroventricular, injections of 0.5–4 μg/kg CCK-8 produced transient, dose-related reductions in 10% ethanol ingestion; (2) this inhibitory effect of CCK-8 on ethanol intake appeared behaviorally similar to its inhibitory action on ingestion of sucrose solutions; (3) the inhibitory effect of IP CCK-8 on ethanol ingestion occurred without evidence of tolerance when tests were repeated on consecutive days; (4) IP CCK-8 reduced ethanol intake despite simultaneously reducing blood ethanol levels (BALs); and (5) antagonism of CCK1 receptors with devazepide increased ethanol intake, indicating that endogenous CCK normally limits the size of bouts of ethanol ingestion. These results implicate peripheral CCK in the control of ethanol ingestion in sP and msP alcohol-preferring rats.
Keywords: Alcohol; Cholecystokinin; Devazepide; Satiation; Marchesian Sardinian alcohol-preferring rats; Reward;

An important role for angiotensin IV (Ang IV) in the processes of learning and memory has now been well established. We have previously found that intracerebroventricular (ICV) administration of Ang IV as well as des-Phe6-Ang IV enhances learning of conditioned avoidance responses (CARs), facilitates recall of a passive avoidance (PA) task, and improves object recognition (OR) in rats. Since the dopaminergic system is crucial for the cognitive processes, in this study our aim was to determine the dopaminergic D1 mediation of these effects using SCH 23390 as a selective D1 receptor antagonist. Male Wistar rats (180–200 g), pretreated with SCH 23390 (R-[+]-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) 0.05 mg/kg intraperitoneally (IP), were given Ang IV or des-Phe6-Ang IV (1 nmol ICV) 1 h later and then tested in the above cognitive paradigms, as well as in the open field and an elevated ‘plus’ maze to control for the unspecific, respectively, motor and emotional, effects of our treatments. Both, Ang IV and des-Phe6-Ang IV effectively enhanced learning of CARs (P < 0.05), recall of PA (P < 0.001), and improved OR (P < 0.001). Pretreatment with SCH 23390 abolished the cognitive effects of both peptides. SCH 23390, Ang IV, and des-Phe6-Ang IV, given at the same doses and routes as in the cognitive tests, did not significantly influence crossings, rearings and bar approaches in the open field, nor the parameters measured in the elevated ‘plus’ maze, thus making a major contribution of the unspecific effects of our treatments to the results of the memory tests improbable. In conclusion, these results indicate that the functional dopaminergic D1 receptors are necessary for the Ang IV and des-Phe6-Ang IV cognitive effects to occur.
Keywords: Angiotensin IV; Des-Phe6-Angiotensin IV; Dopamine D1 receptors; Learning and memory; Locomotor activity; Anxiety;

Role of substance P in hypersensitivity reactions induced by paclitaxel, an anticancer agent by Toshiaki Sendo; Yoshinori Itoh; Takeshi Goromaru; Toshio Hirakawa; Mawako Ishida; Hitoo Nakano; Ryozo Oishi (1205-1208).
The role of substance P in adverse pulmonary reactions induced by an anticancer agent paclitaxel was investigated in rats and humans who undertook post-operative chemotherapy for ovarian cancer. In rats, paclitaxel caused a marked plasma extravasation and edema in lungs with a concomitant decrease in arterial partial oxygen pressure, which were reversed by an NK1 antagonist LY303870. Substance P level in rat plasma and bronchoalveolar lavage fluid increased after paclitaxel injection. In 13 patients, plasma level of substance P but not histamine significantly (P<0.05) increased during paclitaxel infusion. Therefore, substance P rather than histamine may be involved in paclitaxel hypersensitivity.
Keywords: Paclitaxel; Hypersensitivity; Acute lung injury; Plasma extravasation; Substance P; Histamine; NK1 antagonist;

Two antifungal peptides (designated α- and β-basrubrins) with molecular masses of 4–5 kDa and distinct N-terminal sequences, and a peptide and a protein with N-terminal sequences resembling heat shock protein (hsp) and serine–threonine kinase, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure entailed saline extraction, (NH4)2SO4 precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and FPLC–gel filtration on a Superdex peptide column. α- and β-basrubrins inhibited mycelial growth in Botrytis cirerea with an IC50 value of 7.5 and 14.7 μM, respectively, Mycosphaerella arachidicola with an IC50 of 12.4 and 6.9 μM, and Fusarium oxysporum with an IC50 of 5.8 and 6.2 μM. Neither α-basrubrin nor β-basrubin exhibited DNase, RNase, lectin or protease activity, indicating that their antifungal action is not due to these activities. HIV-1 reverse transcriptase was inhibited by α- and β-basrubrins with an IC50 of 246 and 370 μM, respectively. Translation in rabbit reticulocyte lysate was inhibited by α- and β-basrubrins with an IC50 of 400 and 100 nM. The heat shock protein-like peptide and serine–threonine kinase-like protein exhibited a molecular mass of 3 and 30 kDa, respectively. They inhibited neither translation in a rabbit reticulocyte system at concentrations up to 50 μM nor HIV-1 reverse transcriptase activity at concentrations up to 400 μM. They did not exert antifungal activity toward B. cinerea, M. arachidicola, and F. oxysporum when tested up to 16 μg. None of the aforementioned proteins demonstrated DNase, RNase, protease or lectin activity.
Keywords: Ceylon spinach; Peptides; Seeds; Antifungal;

Antifungal proteins and peptides, as their names imply, serve a protective function against fungal invasion. They are produced by a multitude of organisms including leguminous flowering plants, non-leguminous flowering plants, gymnosperms, fungi, bacteria, insects and mammals. The intent of the present review is to focus on the structural and functional characteristics of leguminous, as well as non-leguminous, antifungal proteins and peptides. A spectacular diversity of amino acid sequences has been reported. Some of the antifungal proteins and peptides are classified, based on their structures and/or functions, into groups including chitinases, glucanases, thaumatin-like proteins, thionins, and cyclophilin-like proteins. Some of the well-known proteins such as lectins, ribosome inactivating proteins, ribonucleases, deoxyribonucleases, peroxidases, and protease inhibitors exhibit antifungal activity. Different antifungal proteins may demonstrate different fungal specificities. The mechanisms of antifungal action of only some antifungal proteins including thaumatin-like proteins and chitinases have been elucidated.
Keywords: Antifungal peptides; Antifungal proteins; Leguminous plants; Non-leguminous plants;