Molecular characterization of Trimeresurus stejnegeri venom L-amino acid oxidase with potential anti-HIV activity

A novel L-amino acid oxidase, named TSV-LAO, has been purified and cloned from the snake Trimeresurus stejnegeri. Fifty percentage cytotoxic concentrations (CC50) of TSV-LAO on C8166 cells were 24 and 390 nM in the absence or presence of catalase (400nM), respectively. However, at concentrations that showed little effect on cell viability, TSV-LAO displayed dose dependent inhibition on HIV-1 infection and replication. The antiviral selectivity indexes (CC50/EC50) were 16 and 6, respectively, corresponding to the measurements of syncytium formation and HIV-1 p24 antigen expression. Interestingly, the presence of catalase resulted in an increase of its antiviral selectivity to 52 and 38. Under the same conditions, no anti-HIV-1 activity was observed by exogenous addition of H2O2. The complete amino acid sequence of TSV-LAO, as deduced from its cDNA, exhibits a high degree of sequence identity with other snake venom LAOs. (C) 2003 Elsevier Inc. All rights reserved.

Site-directed PEGylation of trichosanthin retained its anti-HIV activity with reduced potency in vitro

Trichosanthin (TCS) was the first ribosome inactivating protein found to possess anti-HIV-1 activity. Phase I/II clinical trial of this compound had been done. Antigenicity and short plasma half-life were the major side effects preventing further clinical trial. Modification of TCS is therefore necessary to revive the interest to develop this compound as an anti-HIV agent. Three potential antigenic sites (Ser-7, Lys-173, and Gln-219) were identified by computer modeling. Through site-directed mutagenesis, these three antigenic amino acids were mutated to a cysteine residue resulting in 3 TCS mutants, namely S7C, K173C, and Q219C. These mutants were further coupled to polyethylene glycol with a molecular size of 20 kDa (PEG) via the cysteine residue. This produced another three TCS derivatives, namely PEG(20)k-S7C, PEG(20)k-K173C, and PEG(20)k-Q219C. PEGylation had been widely used recently to decrease immunogenicity by masking the antigenic sites and prolong plasma half-life by expanding the molecular size. The in vitro anti-HIV-1 activity of these mutants and derivatives was tested. Results showed that the anti-HIV-1 activity of S7C, K173C, and Q219C was decreased by about 1.5- to 5.5-fold with slightly lower cytotoxicity. On the other hand, PEGylation produced larger decrease (20- to 30-fold) in anti-HIV activity. Cytotoxicity was, however, weakened only slightly by about 3-fold. The in vitro study showed that the anti-HIV activity of PEGylated TCS was retained with reduced potency. The in vivo activity is expected to have only slightly changed due to other beneficial effects like prolonged half-life. (C) 2004 Elsevier Inc. All rights reserved.

Structure and anti-HIV activity of micrandilactones B and C, new nortriterpenoids possessing a unique skeleton from Schisandra micrantha

Two new highly oxygenated nortriterpenoids with a unique norcycloartane skeleton, micrandilactones B and C (1-2), were isolated from Schisandra micrantha; micrandilactone C ( 2) exhibited an EC50 value of 7.71 mu g/mL (SI > 25.94) against HIV-1 replication with minimal cytotoxicity, and the potent anti-HIV-1 activity and unique structural features of 2 make it a promising lead for therapeutic development of a new generation of anti-HIV drug.

Lancifodilactone G: A unique nortriterpenoid isolated from Schisandra lancifolia and its anti-HIV activity

Lancifodilactone G (1), a novel, highly oxygenated nortriterpenoid featuring a partial enol structure and a spirocyclic moiety, was isolated from the medicinal plant Schisandra lancifolia. Its structure and stereochemistry were determined from extensive one- and two-dimensional NMR and mass spectral data, coupled with single-crystal X-ray analysis. Compound 1 exerted minimal cytotoxicity against C8166 cells (CC50 > 200 mu g/mL) and showed anti-HIV activity with EC50 = 95.47 +/- 14.19 mu g/mL and a selectivity index in the range of 1.82-2.46.

Lancifodilactone F: A novel nortriterpenoid possessing a unique skeleton from Schisandra lancifolia and its anti-HIV activity

Lancifodilactone F (1), possessing an unprecedented rearranged pentanortriterpenoid backbone derived from cycloartane, was isolated from the leaves and stems of Schisandra lancifolia (Rehd. et Wils) A. C. Smith. Its structure was established by comprehensive NMR and MS spectroscopic analysis, coupled with single-crystal X-ray experiment. Compound 1 exerted minimal cytotoxicity against C8166 cells (CC50 > 200 mu g/mL) and showed anti-HIV activity with EC50 = 20.69 +/- 3.31 mu g/mL and a selectivity index > 6.62.

A new lectin from the sea worm Serpula vermicularis: Isolation, characterization and anti-HIV activity

A GlcNAc-specific lectin was isolated from the sea worm Serpula vermicularis (SVL) (Annelida) and purified by ion-exchange, affinity and gel permeation chromatography. SVL was a homotetrameric protein with native molecular mass of about 50 kDa, and consis

Symmetrical 1-pyrrolidineacetamide showing anti-HIV activity through a new binding site on HIV-1 integrase

Aim: To characterize the functional and pharmacological features of a symmetrical 1-pyrrolidineacetamide, N,N'-(methylene-di-4,1-phenylene) bis-1-pyrrolidineacetamide, as a new anti-HIV compound which could competitively inhibit HIV-1 integrase (IN) bindi

Compounds from Kadsura heteroclita and related anti-HIV activity

Phytochemical investigation of the stems of Kadsura heteroclita led to isolation of 16 compounds, including the triterpenoid named longipcdlactone J (2), and two dibenzocyclooctadiene type lignans named heteroclitin I and J (3, 4). Compounds 8-10, 14, and

Lignans with Anti-HIV Activity from Schisandra propinqua var. sinensis

Fourteen new lignans, tiegusanins A-N (1-14), together with 13 known compounds were isolated from the aerial parts of Schisandra propinqua var. sinensis. The structures and absolute configurations of 1-13 were established using a combination of spectrosco

Tetra-end-linked oligonucleotides forming DNA G-quadruplexes: a new class of aptamers showing anti-HIV activity.

The biophysical and biological properties of unprecedented anti-HIV aptamers are presented. The most active aptamer (1L) shows a significant affinity to the HIV protein gp120.

New anti-HIV aptamers based on tetra-end-linked DNA G-quadruplexes: effect of the base sequence on anti-HIV activity.

This communication reports on the synthesis and biophysical, biological and SAR studies of a small library of new anti-HIV aptamers based on the tetra-end-linked G-quadruplex structure. The new aptamers showed EC(50) values against HIV-1 in the range of 0.04-0.15 µM as well as affinities for the HIV-1 gp120 envelope in the same order of magnitude

Triterpenes from Maytenus macrocarpa and evaluation of their anti-HIV activity

A set of pentacyclic triterpenes has been isolated from the bark of Maytenus macrocarpa (Celastraceae). It includes two new olean-12-ene derivatives, namely 3 beta, 22(alpha-dihydroxy-olean-12-en-30-oic acid (1) and 22 alpha-hydroxy-olean-12-en-3-oxo-30-oic acid (2), and the new urs-12-ene derivative 3-(E)-coumaroyluvaol (7), along with 10 known compounds possessing olean-12ene, urs-12-ene, lupane and friedelane skeletons. The structures have been elucidated by extensive spectroscopic methods including ID- and 2D-NMR experiments, as well as ESI-MS analysis. All isolated compounds were tested for anti-HIV activity in C8166 cells infected with HIV-1(MN), the most active compound was 22(alpha-hydroxy-12-en-3-oxo-29-oic acid (triterpenonic acid A, 4), with an EC50 value of I mu g/mL and a selectivity index of 35.

The in vitro ejection of zinc from human immunodeficiency virus (HIV) type 1 nucleocapsid protein by disulfide benzamides with cellular anti-HIV activity.

Several disulfide benzamides have been shown to possess wide-spectrum antiretroviral activity in cell culture at low micromolar to submicromolar concentrations, inhibiting human immunodeficiency virus (HIV) type 1 (HIV-1) clinical and drug-resistant strains along with HIV-2 and simian immunodeficiency virus [Rice, W. G., Supko, J. G., Malspeis, L., Buckheit, R. W., Jr., Clanton, D., Bu, M., Graham, L., Schaeffer, C. A., Turpin, J. A., Domagala, J., Gogliotti, R., Bader, J. P., Halliday, S. M., Coren, L., Sowder, R. C., II, Arthur, L. O. & Henderson, L. E. (1995) Science 270, 1194-1197]. Rice and coworkers have proposed that the compounds act by "attacking" the two zinc fingers of HIV nucleocapsid protein. Shown here is evidence that low micromolar concentrations of the anti-HIV disulfide benzamides eject zinc from HIV nucleocapsid protein (NCp7) in vitro, as monitored by the zinc-specific fluorescent probe N-(6-methoxy-8-quinoyl)-p-toluenesulfonamide (TSQ). Structurally similar disulfide benzamides that do not inhibit HIV-1 in culture do not eject zinc, nor do analogs of the antiviral compounds with the disulfide replaced with a methylene sulfide. The kinetics of NCp7 zinc ejection by disulfide benzamides were found to be nonsaturable and biexponential, with the rate of ejection from the C-terminal zinc finger 7-fold faster than that from the N-terminal. The antiviral compounds were found to inhibit the zinc-dependent binding of NCp7 to HIV psi RNA, as studied by gel-shift assays, and the data correlated well with the zinc ejection data. Anti-HIV disulfide benzamides specifically eject NCp7 zinc and abolish the protein's ability to bind psi RNA in vitro, providing evidence for a possible antiretroviral mechanism of action of these compounds. Congeners of this class are under advanced preclinical evaluation as a potential chemotherapy for acquired immunodeficiency syndrome.

The role of the cyclic peptide backbone in the anti-HIV activity of the cyclotide kalata B1

The plant cyclotides, the largest known family of circular proteins, have tightly folded structures and a range of biological activities that lend themselves to potential pharmaceutical and agricultural applications. Based on sequence homology, they are classified into the bracelet and Mobius subfamilies. The bracelet subfamily has previously been shown to display anti-HIV activity. We show here that a member of the Mobius subfamily, kalata B1, also exhibits anti-HIV activity despite extensive sequence differences between the subfamilies. In addition, acyclic permutants of kalata B1 displayed no anti-HIV activity, suggesting that this activity is critically dependent on an intact circular backbone. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Isolation and characterization of novel cyclotides from Viola hederaceae - Solution structure and anti-HIV activity of vhl-1, a leaf-specific expressed cyclotide

Based on a newly established sequencing strategy featured by its efficiency, simplicity, and easy manipulation, the sequences of four novel cyclotides (macrocyclic knotted proteins) isolated from an Australian plant Viola hederaceae were determined. The three-dimensional solution structure of V. hederaceae leaf cyclotide-1 ( vhl-1), a leaf-specific expressed 31-residue cyclotide, has been determined using two-dimensional H-1 NMR spectroscopy. vhl-1 adopts a compact and well defined structure including a distorted triple-stranded β- sheet, a short 310 helical segment and several turns. It is stabilized by three disulfide bonds, which, together with backbone segments, form a cyclic cystine knot motif. The three-disulfide bonds are almost completely buried into the protein core, and the six cysteines contribute only 3.8% to the molecular surface. A pH titration experiment revealed that the folding of vhl-1 shows little pH dependence and allowed the pK(a) of 3.0 for Glu(3) and ∼ 5.0 for Glu(14) to be determined. Met(7) was found to be oxidized in the native form, consistent with the fact that its side chain protrudes into the solvent, occupying 7.5% of the molecular surface. vhl-1 shows anti-HIV activity with an EC50 value of 0.87 μ m.