The Royal King Culinary-Medicinal Mushroom, Pleurotus tuber-regium Sclerotium (Agaricomycetes), a Potential Source of Drug for Interocular Pressure Management.

Pleurotus tuber-regium has been reported to lower dexamethasone-induced ocular hypertension. Effects of P. tuber-regium and 0.005% latanoprost on the circadian intraocular pressure (IOP) cycle in cats were investigated for a possible phase difference. The research was conducted in three phases. In phase 1, the baseline diurnal IOP of 12 cats was determined. In phase 2, the cats were divided into two groups (X and Y). Group Y was left untreated, while group X was treated with 0.1% dexamethasone topically. In phase 3, group X was further divided into two subgroups (X1 and X2). One eye of each cat in subgroup X1 was treated with 0.005% latanoprost; at the same time, one eye of each cat in subgroup X2 received P. tuber-regium topically. IOP was measured at 3-h intervals for 24 h, after 2 weeks of treatment. The mean baseline IOP was 12.8 mm Hg. After 2 weeks, both P. tuber-regium and latanoprost significantly (P < 0.0001) reduced ocular hypertension induced (mean of 23.2 mm Hg) in the right eye of subgroups X1 and X2 to 15.6 and 14.4 mm Hg, respectively. Their mean dark phases were 15.8 and 14.2 mm Hg, while their mean light phases were 15.5 and 14.6 mm Hg, respectively. Control group Y had a mean IOP of 13.2 mm Hg. Both P. tuber-regium and latanoprost lower dexamethasone-induced ocular hypertension significantly. While P. tuber-regium is more effective in the light phase, latanoprost is more effective in the dark phase; however, the difference is not significant. This work further confirms P. tuber-regium as a candidate to study for a source of drug that could be useful in IOP management in clinical practice.

Report: The effects of topical pleurotus tuberregium (PT) aqueous extract on intraocular pressure in monkeys.

PURPOSE: In earlier experiments in Nigeria, aqueous extract of Pleurotus tuber-regium (PT) had been shown to lower intra ocular pressure (IOP) in a feline model. The aim of the current study was to determine whether PT had the same or a similar IOP-lowering effect in ocularly normal non-human primates. METHODS: Four monkeys were treated twice daily for 4 days with 2 x 20 µl drops of 50 mg/ml PT (pH = 4.3). The monkeys were sedated with 5-10 mg/kg ketamine HCl IM. PT was administered to the right eye and BSS to the left eye. Baseline IOP was measured just prior to beginning treatment, and on day 5 before treatment and then hourly for 3 hours, beginning 1 hour after treatment. SLEs were performed at baseline and on day 5 pre- and 3 hours post-treatment. RESULTS: There was no significant difference between IOP in treated vs control eyes in the protocol. There were no adverse effects or toxicity as seen by SLE. CONCLUSIONS: The inability of the extract to lower IOP in monkeys, in contrast to ocular hypertensive cats in an earlier study, could be due to species differences or duration of treatment. Since no adverse effects were observed in the monkeys, further studies with varying durations and dosages are recommended.

Contractile effect of aqueous Pleurotus tuberregium extract on the isolated bovine iris.

BACKGROUND: Aqueous extract of Pleurotus tuberregium (PT) has been shown to reduce intraocular pressure (IOP) but the underlying mechanism has not been explained. PURPOSE: To investigate the effect of PT on the bovine iris in vitro in comparison with acetylcholine (ACh). METHOD: Strips of the iris were mounted in 10 ml organ baths and exposed to increasing concentrations of PT, ACh and a combination of both agents. The effect of atropine on the responses to the agents was also investigated. RESULTS: PT and ACh separately caused contractile responses on the iris, but their effect reduced with higher concentrations. Combination of PT and ACh did not significantly alter the reduced responses seen with high concentrations of either agent. Atropine completely abolished the contractile responses of the agents. CONCLUSION: The contractile effect of PT on muscarinic receptor-containing iris muscle may explain its IOP reducing property.