Purification and characterization of non-specific lipid transfer proteins from the leaves of Pandanus amaryllifolius (Pandanaceae)

Structural characterization and in vitro lipid binding studies of non-specific lipid transfer protein 1 (nsLTP1) from fennel (Foeniculum vulgare) seeds

Non-specific lipid transfer proteins (nsLTPs) are cationic proteins involved in intracellular lipid shuttling in growth and reproduction, as well as in defense against pathogenic microbes. Even though the primary and spatial structures of some nsLTPs from different plants indicate their similar features, they exhibit distinct lipid-binding specificities signifying their various biological roles that dictate further structural study. The present study determined the complete amino acid sequence, in silico 3D structure modeling, and the antiproliferative activity of nsLTP1 from fennel (Foeniculum vulgare) seeds. Fennel is a member of the family Umbelliferae (Apiaceae) native to southern Europe and the Mediterranean region. It is used as a spice medicine and fresh vegetable. Fennel nsLTP1 was purified using the combination of gel filtration and reverse-phase high-performance liquid chromatography (RP-HPLC). Its homogeneity was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. The purified nsLTP1 was treated with 4-vinyl pyridine, and the modified protein was then digested with trypsin. The complete amino acid sequence of nsLTP1 established by intact protein sequence up to 28 residues, overlapping tryptic peptides, and cyanogen bromide (CNBr) peptides. Hence, it is confirmed that fennel nsLTP1 is a 9433 Da single polypeptide chain consisting of 91 amino acids with eight conserved cysteines. Moreover, the 3D structure is predicted to have four α-helices interlinked by three loops and a long C-terminal tail. The lipid-binding property of fennel nsLTP1 is examined in vitro using fluorescent 2-p-toluidinonaphthalene-6-sulfonate (TNS) and validated using a molecular docking study with AutoDock Vina. Both of the binding studies confirmed the order of binding efficiency among the four studied fatty acids linoleic acid > linolenic acid > Stearic acid > Palmitic acid. A preliminary screening of fennel nsLTP1 suppressed the growth of MCF-7 human breast cancer cells in a dose-dependent manner with an IC50 value of 6.98 µM after 48 h treatment.

Cysteine-rich antimicrobial peptides from plants: The future of antimicrobial therapy

There has been a spurt in the spread of microbial resistance to antibiotics due to indiscriminate use of antimicrobial agents in human medicine, agriculture, and animal husbandry. It has been realized that conventional antibiotic therapy would be less effective in the coming decades and more emphasis should be given for the development of novel antiinfective therapies. Cysteine rich peptides (CRPs) are broad-spectrum antimicrobial agents that modulate the innate immune system of different life forms such as bacteria, protozoans, fungi, plants, insects, and animals. These are also expressed in several plant tissues in response to invasion by pathogens, and play a crucial role in the regulation of plant growth and development. The present work explores the importance of CRPs as potent antimicrobial agents, which can supplement and/or replace the conventional antibiotics. Different plant parts of diverse plant species showed the presence of antimicrobial peptides (AMPs), which had significant structural and functional diversity. The plant-derived AMPs exhibited potent activity toward a range of plant and animal pathogens, protozoans, insects, and even against cancer cells. The cysteine-rich AMPs have opened new avenues for the use of plants as biofactories for the production of antimicrobials and can be considered as promising antimicrobial drugs in biotherapeutics.

Alkaloids from Pandanus amaryllifolius: Isolation and Their Plausible Biosynthetic Formation

Pandanus amaryllifolius Roxb. (Pandanaceae) is used as a flavor and in folk medicine in Southeast Asia. The ethanolic crude extract of the aerial parts of P. amaryllifolius exhibited antioxidant, antibiofilm, and anti-inflammatory activities in previous studies. In the current investigation, the purification of the ethanolic extract yielded nine new compounds, including N-acetylnorpandamarilactonines A (1) and B (2); pandalizines A (3) and B (4); pandanmenyamine (5); pandamarilactones 2 (6) and 3 (7), and 5(E)-pandamarilactonine-32 (8); and pandalactonine (9). The isolated alkaloids, with either a γ-alkylidene-α,β-unsaturated-γ-lactone or γ-alkylidene-α,β-unsaturated-γ-lactam system, can be classified into five skeletons including norpandamarilactonine, indolizinone, pandanamine, pandamarilactone, and pandamarilactonine. A plausible biosynthetic route toward 1-5, 7, and 9 is proposed.

Isolation, characterization and mechanism of action of an antimicrobial peptide from Lecythis pisonis seeds with inhibitory activity against Candida albicans

Antimicrobial peptides (AMPs) are produced by a range of organisms as a first line of defense against invaders or competitors. Owing to their broad antimicrobial activity, AMPs have attracted attention as a potential source of chemotherapeutic drugs. The increasing prevalence of infections caused by Candida species as opportunistic pathogens in immunocompromised patients requires new drugs. Lecythis pisonis is a Lecythydaceae tree that grows in Brazil. The AMPs produced by this tree have not been described previously. We describe the isolation of 12 fractions enriched in peptides from L. pisonis seeds. Of the 12 fractions, at 10 μg/ml, the F4 fraction had the strongest growth inhibitory effect (53.7%) in Candida albicans, in addition to a loss of viability of 94.9%. The F4 fraction was separated into seven sub-fractions by reversed-phase chromatography. The F4.7' fraction had the strongest activity at 10 μg/ml, inhibiting C. albicans growth by 38.5% and a 69.3% loss of viability. The peptide in F4.7' was sequenced and was found to be similar to plant defensins. For this reason, the peptide was named L. pisonis defensin 1 (Lp-Def1). The mechanism of action that is responsible for C. albicans inhibition by Lp-Def1 includes a slight increase of reactive oxygen species induction and a significant loss of mitochondrial function. The results described here support the future development of plant defensins, specifically Lp-Def1, as new therapeutic substances against fungi, especially C. albicans.

Purification and characterization of a novel antifungal protein with antiproliferation and anti-HIV-1 reverse transcriptase activities from Peganum harmala seeds

A novel antifungal protein, designated as PHP, was isolated from the seeds of Peganum harmala, by cationic exchange chromatography on Resource S column and gel filtration on Sephadex 75 10/300 GL column. PHP was found to form a homodimer of about 16 kDa. Isoelectric focusing polyacrylamide gel electrophoresis analysis showed that the isoelectric point of PHP was ∼8.4. The N-terminal 20-amino acid sequence of PHP, ITCPQVTQSLAPCVPYLISG, resembles the non-specific lipid transfer proteins in certain plants. PHP exhibited lipid-binding activity. Furthermore, PHP exerted antifungal activity against Alternaria alternate, Penicillium degitatum, Rhizopus stuolonifer, and Magnaporthe grisea, and its antifungal activity was stable in the temperature range 4-60°C, and in the pH range 4-10. It inhibited the mycelial growth in A. alternate, P. degitatum, R. stuolonifer, and M. grisea with 50% inhibitory concentration (IC(50)) of 1.5, 37.5, 8.44, and 12.19 μM, respectively. PHP was also able to inhibit the proliferation of esophagus carcinoma (Eca-109), cervical carcinoma (HeLa), gastric carcinoma (MGC-7), and melanoma (B16) cells with IC(50) of 0.7, 2.74, 3.13, and 1.47 μM, respectively. Moreover, PHP significantly inhibited HIV-1 reverse transcriptase (RT) with an IC(50) of 1.26 μM. It did not have hemagglutinating and antibacterial activities. In conclusion, a novel antifungal protein with antiproliferation and anti-HIV-1 RT activities was obtained from P. harmala seeds.

Recent advances in leishmaniasis treatment

About 1.5 million new cases of cutaneous leishmaniasis and 500,000 new cases of visceral leishmaniasis occur each year around the world. For over half a century, the clinical forms of the disease have been treated almost exclusively with pentavalent antimonial compounds. In this review, we describe the arsenal available for treating Leishmania infections, as well as recent advances from research on plants and synthetic compounds as source drugs for treating the disease. We also review some new drug-delivery systems for the development of novel chemotherapeutics. We observe that the pharmaceutical industry should employ its modern technologies, which could lead to better use of plants and their extracts, as well as to the development of synthetic and semi-synthetic compounds. New studies have highlighted some biopharmaceutical technologies in the design of the delivery strategy, such as nanoparticles, liposomes, cochleates, and non-specific lipid transfer proteins. These observations serve as a basis to indicate novel routes for the development and design of effective anti-Leishmania drugs.

Isolation, characterization, molecular cloning and modeling of a new lipid transfer protein with antiviral and antiproliferative activities from Narcissus tazetta

A fetuin-binding peptide with a molecular mass of about 9kDa (designated NTP) was isolated and purified from the bulbs of Chinese daffodil, Narcissus tazetta var. chinensis L., by gel filtration and high-performance liquid chromatography, after removing the mannose-binding proteins by mannose-agarose column. Molecular cloning revealed that NTP contained an open reading frame of 354bp encoding a polypeptide of 118 amino acids which included a 26-amino-acid signal peptide. An analysis of the deduced amino acid sequence of NTP shows considerable sequence homology to the non-specific lipid transfer proteins (nsLTPs) of certain plants. Model of the three-dimensional (3D) structure of NTP exhibits an internal hydrophobic cavity which can bind lipid-like molecules and transfer a wide range of ligands. As a member of the putative non-specific lipid transfer protein of N. tazetta, NTP did not possess hemagglutinating activity toward rabbit erythrocytes. In a cell-free system, it could arrest the protein synthesis of rabbit reticulocytes. Using the in vitro antiviral assays, NTP could significantly inhibit the plaque formation by respiratory syncytial virus (RSV) and the cytopathic effect induced by influenza A (H1N1) virus, as well as the proliferation of human acute promyelocytic leukemia cells (HL-60).

Role of plant lipid transfer proteins in plant cell physiology-a concise review

Plant lipid transfer proteins (LTP) are cationic peptides, subdivided into two families, which present molecular masses of around 7 and 10 kDa. The peptides were, thus, denominated due to their ability to reversibly bind and transport hydrophobic molecules in vitro. Both subfamilies possess conserved patterns of eight cysteine residues and the three-dimensional structure reveals an internal hydrophobic cavity that comprises the lipid binding site. Based on the growing knowledge regarding structure, gene expression and regulation and in vitro activity, LTPs are likely to play a role in key processes of plant physiology. Although the roles of plant LTPs have not yet been fully determined. This review aims to present comprehensive information of recent topics, cover new additional data, and present new perspectives on these families of peptides.