Effects of alkaloids extracted from the stem bark of Hunteria zeylanica on acute inflammation in experimental animals

Bisnicalaterine A, a vobasine-vobasine bisindole alkaloid from Hunteria zeylanica

A new bisindole alkaloid, bisnicalaterine A (1), consisting of two vobasine-type skeletons, and 3-epivobasinol (2) and 3-O-methylepivobasinol (3), with vobasine-type skeletons, were isolated from the leaves of Hunteria zeylanica, and their structures were elucidated on the basis of spectroscopic data and chemical correlation. Bisnicalaterine A showed moderate cytotoxicity against various human cancer cell lines.

Analgesic and Antipyretic Activities of n-Butanol Alkaloids Extracted from the Stem Bark Hunteria Zeylanica and its Major Constituent, Strictosidinic Acid, in Mice

The pharmacological activities of the n -butanol alkaloids extracted from the stem bark of Hunteria zeylanica (Retz) Gardn. ex Thw. ( H. zeylanica ) and its major constituent, strictosidinic acid, on nociceptive response using writhing and hot plate tests, the antipyretic activity in yeast-induced fever, pentobarbital-induced sleep, and locomotor activity were examined in mice. Oral administration of H. zeylanica extract at 200 mg/kg significantly decreased the number of contortions and stretchings induced by acetic acid but not heat-induced pain. Strictosidinic acid (5-20 mg/kg, p.o.) also produced a similar effect but less pronounced than the extract. The antipyretic effect of strictosidinic acid (5-20 mg/kg, p.o.) was stronger than that of the extract (100-200 mg/kg, p.o.). The H. zeylanica extract dose-dependently (50-200 mg/kg, p.o.) prolonged the duration of pen-tobarbital-induced sleep but had no sign ificant effect on locomotor activity. No effect of strictosidinic acid was noted on both pentobarbital-induced sleep and locomotor activity. These results suggest that the H. zeylanica extract possesses peripheral analgesic and mild antipyretic effects and its major constituent, strictosidinic acid, exerts a similar analgesic effect with marked antipyretic activity.

Inhibitory effects of corymine, an alkaloidal component from the leaves of Hunteria zeylanica, on glycine receptors expressed in Xenopus oocytes

We previously reported that corymine, an alkaloidal compound extracted from the leaves of Hunteria zeylanica native to Thailand, potentiated convulsions induced by either picrotoxin or strychnine. Therefore, to clarify the mechanism of action of corymine, the effects of corymine on gamma-aminobutyric acid (GABA) and glycine receptors were examined. We used Xenopus oocytes expressing these receptors and the two-electrode voltage-clamp method. The receptors expressed in oocytes injected with rat brain and spinal cord RNA showed the pharmacological properties of GABAA and glycine receptors, respectively. Corymine (1-100 microM) partially (20-30%) reduced the GABA responses in oocytes injected with rat brain RNA, while marked (up to 80%) dose-dependent reductions were observed in the glycine responses in oocytes injected with rat spinal cord RNA. These observations suggest that corymine was more effective against the glycine receptors than the GABA receptors. The ED50 of corymine on the glycine response was 10.8 microM. Corymine, at 30 microM, caused a shift to the right, with a lower maximal response, of the glycine concentration-response curve. This indicated that the action of corymine on glycine receptors is neither competitive nor purely non-competitive. These observations suggest that a binding site other than the glycine recognition site of the glycine receptors is the site of action of corymine.