Triprolidine Hydrochloride

This study aimed to examine the antioxidant and antimicrobial activities and the phytochemical composition of three Parmeliaceae lichens from the western Himalayas. Three lichen species (Everniastrum cirrhatum (Fr.) Hale, Parmotrema reticulatum (Taylor) M. Choisy, and Usnea orientalis Motyka) were analyzed for antimicrobial, antioxidant assay, and chemical analyses using Gas chromatography-mass spectrometry (GC-MS). The chemical constituents were identified, and the percentage of components obtained was calculated. Antimicrobial activity was tested with the agar well diffusion method, and the total antioxidant capacity was measured using the phosphomolybdenum method (Total Antioxidant Capacity – TAC) and the hydrogen peroxide radical scavenging test. GC-MS analysis of methanol extracts from the lichens revealed 57 compounds in all three species. Methanol extracts from these lichens demonstrated strong antimicrobial activity (inhibition zones: 8.6 ± 0.09 to 28.2 ± 0.23 mm) with the highest activity against Salmonella typhi. They also exhibited low minimum inhibitory concentrations (MICs) of 0.125 mg against many microbes. The antioxidant capacity of methanol extracts ranged from 1.256 to 1.991 mg/g ascorbic acid equivalent. Interestingly, the hexane extract of E. cirrhatum showed the highest hydrogen peroxide scavenging activity at 91.13%. This study highlights the antioxidant and antimicrobial properties of these Parmeliaceae lichens, attributed to their diverse secondary metabolites. These findings suggest promising prospects for the development of novel antimicrobial and antioxidant agents from lichen extracts, warranting further exploration in pharmacological and biomedical research.

IgG can mediate murine and human systemic anaphylaxis (SA). The roles of mast cells (MCs) and histamine in IgG-mediated anaphylaxis are controversial for mice and have not been studied in vivo for humans. We are now investigating these issues.

Actively or passively sensitized wild-type and immune-deficient mice were induced to develop anaphylaxis by intravenous antigen challenge. Anaphylaxis was characterized by evaluating hypothermia, hypomobility, histamine, and MC protease responses.

In contrast to our previous results with protein-immunized mice from a conventional colony, IgG-mediated passive SA in our specific pathogen-free colony mice depended considerably on histamine produced by connective tissue MCs (CTMCs) in response to FcγRIII crosslinking. This was found for C57BL/6 and young male and female BALB/c mice, including BALB/c mice newly arrived from 3 vendors. IgG-mediated anaphylaxis was less histamine dependent in old than young mice. Although both mucosal MC (MMC) and CTMC responses were severely depleted in c-kit-deficient mice, MMC responses depended considerably more than CTMC responses on c-kit for maintenance. In immunologically naive mice, FcγRIII crosslinking strongly activated a subset of CTMCs but had little ability to activate MMCs. In vivo LPS + poly I:C treatment decreased histamine dependence of IgG-mediated anaphylaxis, while a strong T_H2 immune response increased FcγRIII crosslinking-induced MMC activation. IgG-mediated activation of human MCs in reconstituted immunodeficient mice induced histamine-dependent anaphylaxis.

IgG-dependent SA can be mediated largely by histamine released by mouse CTMCs and human MCs; histamine dependence is influenced by mouse age, sex, and immune and infectious history, as well as the anaphylaxis model studied.