Gunjan Biswas

Leishmanicidal and Anticandidal Activity of Constituents of Indian Edible Mushroom Astraeus hygrometricus

Two new lanostane‐type triterpenes, 1 and 2, were isolated from Astraeus hygrometricus. The structures were established by IR, 1H‐ and 13C‐NMR, MS, and X‐ray crystallographic experiments. The triterpenes exhibited excellent in vitro toxicities against Candida albicans, comparable to standard antifungal antibiotics. The triterpene 2 significantly inhibited the growth of Leishmania donovani promastigotes in vitro. The triterpene skeleton may be considered a template structure in search for new compounds with anticandidal and leishmanicidal activity.

Apoptogenic effects of Tricholoma giganteum on Ehrlich's ascites carcinoma cell

This study explored the efficacy of Fa fraction of Tricholoma giganteum against Ehrlich’s ascites carcinoma (EAC). Mechanisms of apoptogenic effect of the fraction were delineated. The flow cytometric analysis of EAC cells, showed an increase in number of cells in sub-G0/G1 population and reduction in the G2/M phase due to the treatment thus suggesting apoptosis. The induction of apoptosis has also been confirmed by nuclear staining that demonstrated distinctive morphological features of apoptosis. Our data also revealed an increase in the expression of pro-apoptotic protein p53 in EAC and induced factors contributing to apoptosis. Pro-apoptotic gene Bax was up-regulated during p53-mediated apoptosis. No significant change in the expression of anti-apoptotic protein Bcl-2 was observed ensuing in decrease of the Bcl-2/Bax ratio. p53-mediated growth arrest involves p21 as a major effecter, which interestingly showed moderate elevation. All these observations indicate that Fa fraction of T. giganteum induces apoptogenic signal in EAC.

A novel triterpene from Astraeus hygrometricus induces reactive oxygen species leading to death in Leishmania donovani

AIM The effect of astrakurkurone, a novel triterpene, isolated from Indian mushroom Astraeus hygrometricus has been investigated to elucidate the mechanisms involved in selective cell death of Leishmania donovani. MATERIALS & METHODS The hypotheses were investigated using flow-cytometry, scanning electron microscopy and confocal microscopy. RESULTS The time dependent elevation of astrakurkurone-induced reactive oxygen species (ROS) was found intimately associated with apoptosis. The involvement of ROS in promastigote death was found confirmed as NAC and GSH could decrease the ROS level and restored the mitochondrial membrane potential (ΔΨ(m)). It also inhibited the intracellular amastigotes. CONCLUSION We claim the present invention as substantial in depth evidences that mushroom derived active molecules can be exploited as target specific, comparatively nontoxic leads for antileishmanial therapy.

Successful Therapy of Murine Visceral Leishmaniasis with Astrakurkurone, a Triterpene Isolated from the Mushroom Astraeus hygrometricus, Involves the Induction of Protective Cell-Mediated Immunity and TLR9

ABSTRACT In our previous report, we showed that astrakurkurone, a triterpene isolated from the Indian mushroom Astraeus hygrometricus (Pers.) Morgan, induced reactive oxygen species, leading to apoptosis in Leishmania donovani promastigotes, and also was effective in inhibiting intracellular amastigotes at the 50% inhibitory concentration of 2.5 μg/ml. The aim of the present study is to characterize the associated immunomodulatory potentials and cellular activation provided by astrakurkurone, leading to effective antileishmanial activity in vitro and in vivo. Astrakurkurone-mediated antileishmanial activity was evaluated by real-time PCR and flow cytometry. The involvement of Toll-like receptor 9 (TLR9) was studied by in vitro assay in the presence of a TLR9 agonist and antagonist and by in silico modeling of a three-dimensional structure of the ectodomain of TLR9 and its interaction with astrakurkurone. Astrakurkurone caused a significant increase in TLR9 expression of L. donovani-infected macrophages along with the activation of proinflammatory responses. The involvement of TLR9 in astrakurkurone-mediated amastigote killing has been evidenced from the fact that a TLR9 agonist (CpG, ODN 1826) in combination with astrakurkurone enhanced the amastigote killing, while a TLR9 antagonist (bafilomycin A1) alone or in combination with astrakurkurone curbed the amastigote killing, which could be further justified by in silico evidence of docking between mouse TLR9 and astrakurkurone. Astrakurkurone was found to reduce the parasite burden in vivo by inducing protective cytokines, gamma interferon and interleukin 17. Moreover, astrakurkurone was nontoxic toward peripheral blood mononuclear cells of immunocompromised patients with visceral leishmaniasis. Astrakurkurone, a nontoxic antileishmanial, enhances the immune efficiency of host cells, leading to parasite clearance in vitro and in vivo.