Gottumukkala V. Subbaraju

Biological Screening of Medicinal Plants Collected from Eastern Ghats of India Using Artemia salina (Brine Shrimp Test)

Medicinal plants constitute important components of flora and are widely distributed in different regions of India. Based on ethnomedical significance, we have collected several medicinal plants used in traditional medicine from Eastern Ghats of India and evaluated for their biological activity. In the present study, a method utilizing brine shrimp (Artemia salina Leach) lethality was used to screen medicinal plants for their biological activity. Aqueous extracts from 118 Indian medicinal plants were screened by the brine shrimp lethality assay and found eleven out of the 118 extracts showed significant toxicity to the brine shrimp (＜60 μg/ml). Polygonum cuspidatum and Syzygium cumini extracts have exhibited potent activity with LC50 13.5 and 20, respectively. The results were analyzed within the context of the available traditional knowledge and uses for these plants. Present study could be useful in the search for new antitumor compounds from the Indian flora.

Fused tricyclic β-lactams via intramolecular aryl radical cyclization1#

Abstract Easy access to fused tricyclic β-lactams starting with o-bromobenzaldehyde and allyl amine has been devised using intramolecular aryl radical cyclization under the influence of tributyltin hydride. The major product resulted from exo cyclization leading to the formation of a 6-membered ring and thus a tricyclic β-lactam. In some cases, a minor product was a 7-membered ring-containing tricyclic β-lactam formed by endo cyclization.

An improved synthesis of (±)-dihydroactinidiolide☆

An improved synthesis of (±)-aeginetolide (2) and (±)-dihydroactinidiolide (1) from 2,6,6-trimethyl-1-cyclohexene-1-acetaldehyde (4) has been achieved.

Hispolon inhibition of inflammatory apoptosis through reduction of iNOS/NO production via HO-1 induction in macrophages

ETHNOPHARMACOLOGICAL RELEVANCE Phellinus linteus (Berkeley & Curtis), a well-known medical fungus, has long been used as a traditional medicine in Oriental countries to treat various diseases, and hispolon (HIS) is one of its bioactive components. HIS is known to possess potent antineoplastic and antiviral properties; however, its effect on inflammatory apoptosis is still undefined. MATERIALS AND METHODS RAW264.7 macrophages were incubated with HIS for 30 min followed by LPS, LTA, or PGN stimulation for 12h. The expression of indicated proteins AP-1 and NF-κB transcriptional activities was examined by Western blotting using specific antibodies. Levels of NO and ROS were examined by Griess reaction, and DCHF-DA staining via flow cytometric analysis, respectively. AP-1 and NF-κB transcriptional activities were detected by luciferase reporter assay. Knockdown of HO-1 protein expression was performed by transfection of macrophages with HO-1 siRNA. Pharmacological inhibitors including ROS scavenger NAC, JNK inhibitor SP600125, NF-κB inhibitor BAY117082 were applied for mechanism study. RESULTS HIS showed concentration-dependent inhibition of LPS, LTA, and PGN-induced iNOS protein expressions and NO production by RAW264.7 macrophages. Accordingly, HIS protected RAW264.7 cells from LPS-, LTA-, and PGN-induced apoptosis. Increased HO-1 by HIS was detected at both protein and mRNA levels along with an increase in intracellular peroxide, and this was inhibited by the translational inhibitor, cycloheximide (CHX), the transcriptional inhibitor, actinomycin D (Act D), and the reactive oxygen species scavenger, N-acetylcysteine (NAC). A mechanistic study indicated that inhibition of c-Jun N-terminal kinase (JNK) protein phosphorylation, and activator protein (AP)-1 and nuclear factor (NF)-κB activation were involved in the anti-inflammatory actions of HIS in macrophages. A structure-activity relationship analysis showed that HIS expressed the most potent effect of inhibiting iNOS and apoptosis elicited by LPS, LTA, and PGN with a significant increase in HO-1 protein in macrophages. CONCLUSIONS Evidence supporting HIS prevention of inflammatory apoptosis via blocking NO production and inducing HO-1 protein expression in macrophages is provided, and the hydroxyl at position C3 is a critical substitution for the anti-inflammatory actions of HIS.

Synthesis of kukulkanins A and B - methoxy chalcones from Mimosa tenufolia L.

Abstract Synthesis of kukulkanins A (1) and B (2) has been achieved starting from pyrogallol.

Hispolon Suppresses LPS- or LTA-Induced iNOS/NO Production and Apoptosis in BV-2 Microglial Cells

Hispolon (HIS) is an active polyphenol compound derived from Phellinus linteus (Berkeley & Curtis), and our previous study showed that HIS effectively inhibited inflammatory responses in macrophages [Yang, L.Y., S.C. Shen, K.T. Cheng, G.V. Subbaraju, C.C. Chien and Y.C. Chen. Hispolon inhibition of inflammatory apoptosis through reduction of iNOS/NO production via HO-1 induction in macrophages. J. Ethnopharmacol. 156: 61-72, 2014]; however, its effect on neuronal inflammation is still undefined. In this study, HIS concentration- and time-dependently inhibited lipopolysaccharide (LPS)- and lipoteichoic acid (LTA)-induced inducible nitric oxide (NO) synthase (iNOS)/NO production with increased heme oxygenase (HO)-1 proteins in BV-2 microglial cells. Accordingly, HIS protected BV-2 cells from LPS- or LTA-induced apoptosis, characterized by decreased DNA ladder formation, and caspase-3 and poly(ADP ribose) polymerase (PARP) protein cleavage in BV-2 cells. Similarly, the NOS inhibitor, N-nitro-L-arginine methyl ester (NAME), inhibited LPS- or LTA-induced apoptosis of BV-2 cells, but neither NAME nor HIS showed any inhibition of NO production or cell death induced by the NO donor, sodium nitroprusside (SNP), indicating the involvement of NO in the inflammatory apoptosis of microglial cells. Activation of c-Jun N-terminal kinase (JNK) and nuclear factor (NF)-[Formula: see text]B contributed to LPS- or LTA-induced iNOS/NO production and apoptosis of BV-2 cells, and that was suppressed by HIS. Additionally, HIS possesses activity to induce HO-1 protein expression via activation of extracellular signal-regulated kinase (ERK) in BV-2 cells, and application of the HO inhibitor, tin protoporphyrin (SnPP), or knockdown of HO-1 protein by HO-1 small interfering (si)RNA significantly reversed HIS inhibition of NO production and cell death in BV-2 cells stimulated by LPS. Results of an analysis of the effects of HIS and two structurally related chemicals, i.e. dehydroxy-HIS (D-HIS) and HIS-methyl ester (HIS-ME), showed that HIS expressed the most potent inhibitory effects on iNOS/NO production, JNK activation, and apoptosis in BV-2 microglial cells activated by LPS with increased HO-1 protein expression. Overall these results suggested that HIS possesses inhibitory activity against LPS- or LTA-induced inflammatory responses including iNOS/NO production and apoptosis in BV-2 microglial cells and that the mechanisms involve upregulation of the HO-1 protein and downregulation of JNK/NF-[Formula: see text]B activation. A critical role of hydroxyl at position C3 in the anti-inflammatory actions of HIS against activated BV-2 microglial cells was suggested.

Synthesis, screening and docking analysis of hispolon analogs as potential antitubercular agents

A series of 20 hispolons/dihydrohispolons were synthesized and characterized by spectral data. These compounds were subjected to in vitro antitubercular activity screening against Mycobacterium tuberculosis (H37Rv) strain. The synthesized compounds showed varied antitubercular activity ranging from 100 to 1.6μg/mL. Among the screened compounds, four compounds (H1, H2, H3 and H15) have shown moderate activity with MIC 25μg/mL. Potent activities were observed for the dihydrohispolon derivative H14 (MIC 1.6μg/mL) followed by H13 (6.25μg/mL) and H17 (12.5μg/mL), H19 (3.125μg/ML). Docking simulations gave good insights on the possible interactions between the tested compounds and β-keto acyl synthase enzyme (mtbFabH). Drug-inhibitor combination studies showed no synergism with the drugs targeting mycolic acid biosynthesis (isoniazid, ethambutol and thiolactomycin, a specific inhibitor of KAS-B enzyme) but showed significant synergism with other drugs including rifampicin and ciprofloxacin ascertaining the drug target for hispolons as inhibition of mycolic acid biosynthesis, probably via mtbFabH.

Free radical reactions of isoxazole and pyrazole derivatives of hispolon: Kinetics correlated with molecular descriptors

Abstract Hispolon (HS), a natural polyphenol found in medicinal mushrooms, and its isoxazole (HI) and pyrazole (HP) derivatives have been examined for free radical reactions and in vitro antioxidant activity. Reaction of these compounds with one-electron oxidant, azide radicals () and trichloromethyl peroxyl radicals (), model peroxyl radicals, studied by nanosecond pulse radiolysis technique, indicated formation of phenoxyl radicals absorbing at 420 nm with half life of few hundred microseconds (μs). The formation of phenoxyl radicals confirmed that the phenolic OH is the active centre for free radical reactions. Rate constant for the reaction of these radicals with these compounds were in the order kHI ≅ kHP > kHS. Further the compounds were examined for their ability to inhibit lipid peroxidation in model membranes and also for the scavenging of 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide () radicals. The results suggested that HP and HI are less efficient than HS towards these radical reactions. Quantum chemical calculations were performed on these compounds to understand the mechanism of reaction with different radicals. Lower values of adiabatic ionization potential (AIP) and elevated highest occupied molecular orbital (HOMO) for HI and HP compared with HS controlled their activity towards and radicals, whereas the contribution of overall anion concentration was responsible for higher activity of HS for DPPH, , and lipid peroxyl radical. The results confirm the role of different structural moieties on the antioxidant activity of hispolon derivatives.

Rearrangement of acyloxyoxiranes: A revised structure for the oxidation product of 5α-androst-16-ene-3α, 17-diol 3-benzoate 17-acetate

Abstract During the oxidation of conjugated enones to α-acyloxyoxiranes by m-chloroperbenzoic acid, the preferred sequence is epoxidation followed by Baeyer-Villiger oxidation. Rearrangement of acyloxyoxiranes to α-acyloxyketones, in situ, was observed. The α-ketoacetate structure assigned previously to the m-CPBA oxidation product of 5α-androst-16-ene-3α,17-diol 3-benzoate 17-acetate, has been revised to an acyloxyoxirane structure based on spectroscopic and X-ray diffraction data.

Diketo modification of curcumin affects its interaction with human serum albumin

Curcumin isoxazole (CI) and Curcumin pyrazole (CP), the diketo modified derivatives of Curcumin (CU) are metabolically more stable and are being explored for pharmacological properties. One of the requirements in such activities is their interaction with circulatory proteins like human serum albumin (HSA). To understand this, the interactions of CI and CP with HSA have been investigated employing absorption and fluorescence spectroscopy and the results are compared with that of CU. The respective binding constants of CP, CI and CU with HSA were estimated to be 9.3×105, 8.4×105 and 2.5×105M-1, which decreased with increasing salt concentration in the medium. The extent of decrease in the binding constant was the highest in CP followed by CI and CU. This revealed that along with hydrophobic interaction other binding modes like electrostatic interactions operate between CP/CI/CU with HSA. Fluorescence quenching studies of HSA with these compounds suggested that both static and dynamic quenching mechanisms operate, where the contribution of static quenching is higher for CP and CI than that for CU. From fluorescence resonance energy transfer studies, the binding site of CU, CI and CP was found to be in domain IIA of HSA. CU was found to bind in closer proximity with Trp214 as compared to CI and CP and the same was responsible for efficient energy transfer and the same was also established by fluorescence anisotropy measurements. Furthermore docking simulation complemented the experimental observation, where both electrostatic as well as hydrophobic interactions were indicated between HSA and CP, CI and CU. This study is useful in designing more stable CU derivatives having suitable binding properties with proteins like HSA.