Bhahwal Ali Shah

Boswellic acids: a group of medicinally important compounds

This review, containing over 276 references, covers the progress made in the chemistry and bioactivity of this important group of triterpenoids. Though initially known for their anti-inflammatory and anti-arthritic activities through a unique 5-LO inhibition mechanism, boswellic acids have recently attained significance due to their anti-cancer properties. The phytochemistry and chemical modifications, including mechanism of action, are discussed.

Identification and bioactive potential of endophytic fungi isolated from selected plants of the Western Himalayas

This study was conducted to characterize and explore the endophytic fungi of selected plants from the Western Himalayas for their bioactive potential. A total of 72 strains of endophytic fungi were isolated and characterized morphologically as well as on the basis of ITS1-5.8S-ITS2 ribosomal gene sequence acquisition and analyses. The fungi represented 27 genera of which two belonged to Basidiomycota, each representing a single isolate, while the rest of the isolates comprised of Ascomycetous fungi. Among the isolated strains, ten isolates could not be assigned to a genus as they displayed a maximum sequence similarity of 95% or less with taxonomically characterized organisms. Among the host plants, the conifers, Cedrus deodara, Pinus roxburgii and Abies pindrow harbored the most diverse fungi, belonging to 13 different genera, which represented almost half of the total genera isolated. Several extracts prepared from the fermented broth of these fungi demonstrated strong bioactivity against E. coli and S. aureus with the lowest IC50 of 18 μg/ml obtained with the extract of Trichophaea abundans inhabiting Pinus sp. In comparison, extracts from only three endophytes were significantly inhibitory to Candida albicans, an important fungal pathogen. Further, 24 endophytes inhibited three or more phytopathogens by at least 50% in co-culture, among a panel of seven test organisms. Extracts from 17 fungi possessed immuno-modulatory activities with five of them showing significant immune suppression as demonstrated by the in vitro lymphocyte proliferation assay. This study is an important step towards tapping the endophytic fungal diversity from the Western Himalayas and assessing their bioactive potential. Further studies on the selected endophytes may lead to the isolation of novel natural products for use in medicine, industry and agriculture.

A propionyloxy derivative of 11-keto-β-boswellic acid induces apoptosis in HL-60 cells mediated through topoisomerase I & II inhibition

Boswellic acids have invariably been reported for their antiproliferative potential in various cell systems. In the present study the growth inhibitory effect of propionyloxy derivative of 11-keto-β-boswellic acid (PKBA; a semisynthetic analogue of 11-keto-β-boswellic acid) on HL-60 promyelocytic leukemia cells is being reported for the first time. In the preliminary studies, in vitro cytotoxicity of PKBA was investigated against eight human cancer cell lines viz., IMR-32, SF-295 (both neuroblastoma), PC-3 (prostate), Colo-205 (colon), MCF-7 (breast), OVCAR-5 (ovary), HL-60, Molt-4 (both leukemia) and their respective IC(50) values were found to be 5.95, 7.11, 15.2, 14.5, 15, 15.9, 8.7 & 9.5μg/ml, respectively. For determining the mechanism of cell death in HL-60 cells, PKBA was subjected to different mechanistic studies. DNA relaxation assay of PKBA revealed inhibition of both topoisomerases I & II. The fragmentation analysis of DNA revealed typical ladders indicating the cytotoxic effect to be mediated by induction of apoptosis. The morphologic studies of PKBA showed the presence of true apoptotic bodies. Apoptosis was confirmed further by flow-cytometric detection of sub-G(1) peaks and enhanced annexin-V-FITC binding of the cells. The activation of apoptotic cascade by PKBA in HL-60 cells was found to be associated with the loss of mitochondrial membrane potential, release of cytochrome c, activation of initiator and executioner caspases and cleavage of poly ADP ribose polymerase (PARP). In vivo studies of PKBA revealed anti-tumoral activity against both ascitic and solid murine tumor models. These studies thus demonstrate PKBA to induce apoptosis in HL-60 cells due to the inhibition of topoisomerases I and II.

Antistaphylococcal and biofilm inhibitory activities of acetyl-11-keto-β-boswellic acid from Boswellia serrata

BackgroundBoswellic acids are pentacyclic triterpenes, which are produced in plants belonging to the genus Boswellia. Boswellic acids appear in the resin exudates of the plant and it makes up 25-35% of the resin. β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid have been implicated in apoptosis of cancer cells, particularly that of brain tumors and cells affected by leukemia or colon cancer. These molecules are also associated with potent antimicrobial activities. The present study describes the antimicrobial activities of boswellic acid molecules against 112 pathogenic bacterial isolates including ATCC strains. Acetyl-11-keto-β-boswellic acid (AKBA), which exhibited the most potent antibacterial activity, was further evaluated in time kill studies, postantibiotic effect (PAE) and biofilm susceptibility assay. The mechanism of action of AKBA was investigated by propidium iodide uptake, leakage of 260 and 280 nm absorbing material assays.ResultsAKBA was found to be the most active compound showing an MIC range of 2-8 μg/ml against the entire gram positive bacterial pathogens tested. It exhibited concentration dependent killing of Staphylococcus aureus ATCC 29213 up to 8 × MIC and also demonstrated postantibiotic effect (PAE) of 4.8 h at 2 × MIC. Furthermore, AKBA inhibited the formation of biofilms generated by S. aureus and Staphylococcus epidermidis and also reduced the preformed biofilms by these bacteria. Increased uptake of propidium iodide and leakage of 260 and 280 nm absorbing material by AKBA treated cells of S aureus indicating that the antibacterial mode of action of AKBA probably occurred via disruption of microbial membrane structure.ConclusionsThis study supported the potential use of AKBA in treating S. aureus infections. AKBA can be further exploited to evolve potential lead compounds in the discovery of new anti-Gram-positive and anti-biofilm agents.

Capsaicin production by Alternaria alternata, an endophytic fungus from Capsicum annum; LC-ESI-MS/MS analysis

Alternaria alternata, an endophytic fungus capable of producing capsaicin (1) was isolated from Capsicum annum. The endophyte was found to produce capsaicin upto three generations. Upscaling of the fermentation broth led to the isolation of one known and one compound characterized as 2,4-di-tert-butyl phenol (2) and alternariol-10-methyl ether (3) respectively. Compound 1 and 3 were identified and quantified using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) system through multiple reaction monitoring (MRM). Furthermore, compound 3 displayed a range of cytotoxicity against a panel of human cancer cell lines and was found to induce apoptosis evidenced by Hoechst staining and loss of mitochondrial-membrane potential in HL-60 cells.

Nuclear blebbing of biologically active organoselenium compound towards human cervical cancer cell (HeLa): in vitro DNA/HSA binding, cleavage and cell imaging studies.

New pharmacophore organoselenium compound (1) was designed, synthesized and characterized by various spectroscopic methods (IR, ESI-MS, (1)H, (13)C and (77)Se NMR) and further confirmed by X-ray crystallography. Compound 1 consists of two 3,5-bis(trifluoromethyl)phenyl units which are connected to the selenium atom via the organometallic C-Se bond. In vitro DNA binding studies of 1 was investigated by absorption and emission titration methods which revealed that 1 recognizes the minor groove of DNA in accordance with molecular docking studies with the DNA duplex. Gel electrophoretic assay demonstrates the ability of 1 to cleave pBR322 DNA through hydrolytic process which was further validated by T4 religation assay. To understand the drug-protein interaction of which ultimate molecular target was DNA, the affinity of 1 towards HSA was also investigated by the spectroscopic and molecular modeling techniques which showed hydrophobic interaction in the subdomain IIA of HSA. Furthermore, the intracellular localization of 1 was evidenced by cell imaging studies using HeLa cells.

Acyl derivatives of boswellic acids as inhibitors of NF-κB and STATs

Boswellic acid acylates including their epimers were synthesized and screened against a panel of human cancer cell lines. They exhibited a range of cytotoxicity against various human cancer cell lines thereby leading to the development of a possible SAR. One of the identified lead compounds was found to be an inhibitor of the NF-κB and STAT proteins, warranting further investigations to be developed into a potential anticancer lead.

Secalonic Acid-D Represses HIF1α/VEGF-Mediated Angiogenesis by Regulating the Akt/mTOR/p70S6K Signaling Cascade

Tumor angiogenesis is a validated target for therapeutic intervention, but agents that are more disease selective are needed. Here, we report the isolation of secalonic acid-D (SAD), a mycotoxin from a novel source that exhibits potent antiangiogenic antitumor activity. SAD inhibited multiple HIF1α/VEGF-arbitrated angiogenesis dynamics as scored in human umbilical vascular endothelial cells and human MCF-7 breast tumor xenografts. Similarly, SAD suppressed VEGF-induced microvessel sprouting from rat aortic ring and blood vessel formation in the Matrigel plug assay in C57/BL6J mice. Under normoxic or hypoxic conditions, SAD inhibited cell survival through the Akt/mTOR/p70S6K pathway, with attendant effects on key proangiogenesis factors, including HIF1α, VEGFR, and MMP-2/MMP-9. These effects were reversed by cotreatment with the Akt inhibitors perifosine and GSK69069 or by the addition of neutralizing VEGF antibodies. The apoptotic properties of SAD were determined to be both extrinsic and intrinsic in nature, whereas the cell-cycle inhibitory effects were mediated by altering the level of key G1-S transition-phase proteins. In experimental mouse models of breast cancer, SAD dosing produced no apparent toxicities (either orally or intraperitoneal) at levels that yielded antitumor effects. Taken together, our findings offered a preclinical validation and mechanistic definition of the antiangiogenic activity of a novel mycotoxin, with potential application as a cancer-selective therapeutic agent.

A comparative study of proapoptotic potential of cyano analogues of boswellic acid and 11-keto-boswellic acid

Semi-synthetic analogues of β-boswellic acid (BA) and 11-keto-β-boswellic acid (KBA) were comparatively evaluated for in vitro cytotoxicity against human myeloid leukaemia (HL-60) and human cervical carcinoma (HeLa) cells. 2-Cyano analogues of both the triterpenes were observed to have significant cytotoxicity against both the cells, displaying cytotoxicity in HL-60 cells at low concentrations. Further investigations suggested the proapoptotic potential associated with the two molecules to induce cytotoxicity in HL-60 cells, where one of them showed early proapoptotic effect as evidenced by several biological end-points of the apoptosis such as annexinV binding, DNA fragmentation and increase in sub-G0 DNA fraction and apoptotic bodies formation (Hoechst 33258 staining and SEM studies).

Saponins as novel TNF-α inhibitors: isolation of saponins and a nor-pseudoguaianolide from Parthenium hysterophorus

Two novel saponins and a 13-nor-pseudoguaianolide designated as hysterolactone were isolated from Parthenium hysterophorus. The two saponins were found to be potent inhibitors of TNF-alpha. Their mode of inhibition was studied through molecular modeling. The wet lab results were in concordance with the data obtained from docking experiments.