Tarinee Arkaravichien

Analgesic, antipyretic, anti-inflammatory and toxic effects of andrographolide derivatives in experimental animals

Andrographolide (1) and 14-deoxy-11,12-didehydroandrographolide (2) are active constituents of Andrographis paniculata (Burm. f.), family Acanthaceae. A. paniculata extracts are reported to have antiviral, antipyretic, immunostimulant and anticancer activities. In this study, 1 and its 14-acetyl- (4) and 3,19-isopropylidenyl- (3) derivatives, as well as 2 and its 3,19-dipalmitoyl-derivative (5), were intraperitoneally tested for their analgesic, antipyretic, anti-inflammatory and acute toxicity effects in animal models. Analgesic effects were tested in mice using hot plate and writhing tests to distinguish the central and peripheral effects, respectively. The results showed that, at 4 mg/kg, all tested substances have significant analgesic effects, and the highest potency was seen with 3, 4 and 5. Increasing the dose of 3 and 5 to 8 mg/kg did not increase the analgesic effect. In the writhing test, 3 and 5, but not 1, showed significant results. In a baker’s yeast-induced fever model, 3 and 5 significantly reduced rats’ rectal temperature (p < 0.05). In a carrageenan-induced inflammation model, 1, 3 and 5 significantly reduced rats’ paw volume. Doses of 3 and 5 up to 100 mg/kg did not show any serious toxic effects. From this study, 3 and 5 are the most interesting derivatives, showing much greater potency than their parent compounds. These could be further developed as analgesic, antipyretic and anti-inflammatory agents, without any serious toxicity.

Effects of andrographolide on sexual functions, vascular reactivity and serum testosterone level in rodents

In this study, effects of andrographolide from Andrographis paniculata on sexual functions, vascular reactivity and serum testosterone level in experimental animals were observed. The suspension of andrographolide in 5% DMSO was administered orally at the dose of 50mg/kg to male ICR mice. The female mice involved in mating were made receptive by hormonal treatment. The mating behaviors, mounting latency and mounting frequency, were determined and compared with the standard reference drug sildenafil citrate. Administration of andrographolide significantly decreased the mounting latency at 120 and 180 min and increased mounting frequency at 180 min after treatment. In endothelium-intact rat aortic strips, norepineprine-induced contraction was reduced by preincubation with andrographolide. Administration of 50mg/kg andrographolide orally to male mice once daily for 2, 4, 6 or 8 weeks had no significant effects on sperm morphology and motility. Interestingly, at week 4, serum testosterone level in mice treated with andrographolide was significantly increased when compared to the control. Thus, the effects of andrographolide on vascular response to norepinephrine and testosterone level observed in this study might be contributed to the sexual enhancing properties observed.

Dose-dependent effects of glutamate in pyridoxine-induced neuropathy

In order to explore the effects of glutamate in a pyridoxine megadose-induced neuropathy, rats were received glutamate either 0.5 or 1 g/kg/day orally with or without pyridoxine 0.8 g/kg/day intraperitoneally for 14 days. The animals motor coordination, the muscle power and the thermal threshold were observed daily. The nerve conduction velocity was measured at day 0 and day 15 of the treatment. Glutamate either 0.5 or 1 g/kg/day appeared to have no effect on motor coordination, the nerve conduction velocity and the muscle power score compared with control. However, the thermal response latency was significantly decreased (from day 9) in animals treated with 1 g/kg/day glutamate. In pyridoxine-induced neuropathy rats, glutamate 0.5 g/kg/day significantly decreased the effects of pyridoxine on the sciatic nerve conduction velocity, the muscle power score and the motor coordination. Interestingly, glutamate at a dose of 1 g/kg/day worsened the neurotoxic effects cause by pyridoxine.