Novel Saponins from Zizyphus spina-christi growing in Egypt.

From the butanol extract of the leaves of Zizyphus spina-christi (L.) Willd. (Rhamnaceae), four saponin glycosides were isolated: Christinin A (1), B (2), C (3), and D (4). Their structures were determined by chemical and spectroscopic evidence. Compound 1, was found to be 3-O-[alpha-L-fucopyranosyl (1 -> 2)-beta-D-glucopyranosyl(1 ->3)-alpha-L-arabinopyranosyl]jujubogenin; the others are the new, 2 being 3-O-[alpha-D-fucopyranosyl(1 -> 2)-¿beta-D- glucopyranosyl-4-sulphate(1 ->3)¿-alpha-L-arabinopyranosyl]jujubogenin, 3 being 3-O-beta-glucopyranosyl(1 -> 2)-alpha-L-rhamnopyranosyl (1 -> 3)-alpha- L-arabinopyranosyl]jujubogenin, and 4 being 3-O-[alpha-L-fucopyranosyl(1 -> 2) -¿beta-D-arabinopyranosyl(1 -> 3)-beta-D-glucopyranosyl(1 -> 3)¿-alpha-L- arabinopyranosy]jujubogenin.

Alectosarmentin, a new antimicrobial dibenzofuranoid lactol from the lichen, Alectoria sarmentosa.

From the alcoholic extract of the lichen Alectoria sarmentosa, four compounds showing antimicrobial activity were isolated. Of these, (-)-usnic acid and physodic acid are well known lichen products, 8'-O-ethyl-beta-alectoronic acid [2] is believed to be an artifact formed during isolation and fractionation, and alectosarmentin [1] is a new natural product whose structure was shown, by spectroscopy and chemical transformations, to be that of a dibenzofuranoid lactol. The antimicrobial activity of these substances accounts for the activity of the lichen.

Hypoglycemic and antihyperglycemic effects of Zizyphus spina-christi in rats.

Zizyphus is one of the plants commonly used in Egyptian folk medicine for the treatment of different diseases. The present study aims to investigate the effect of the butanol extract of Zizyphus spina-christi leaves as well as christinin-A, its principle saponin glycoside, in normal and streptozotocin-diabetic rats. In normal rats, treatment in both cases for one and four weeks produced insignificant changes in all studied parameters. However, in diabetic rats, both treatments significantly reduced serum glucose level, liver phosphorylase and glucose-6-phosphatase (G-6-pase) activities, and significantly increased serum pyruvate level and liver glycogen content after 4 weeks treatment. There was also marked improvement in glucose utilization in diabetic rats in both cases. Serum insulin and pancreatic cAMP levels showed significant increases in diabetic rats treated for a period of 4 weeks with the butanol extract.

Study into wild Egyptian plants of potential medicinal activity. Ninth communication: hypoglycaemic activity of some selected plants in normal fasting and alloxanised rats.

31 desert plants belonging to 17 families were collected from different Egyptian localities. 21 plants extracts were orally given to normal rats, and 15 were tested on fasted and to alloxanised rats. The results were compared with a standard oral hypoglycaemic drug (Daonil, Hoechst) used as a positive control. The following findings were obtained: 8 plants exhibited persistent hypoglycaemic effects, Lycium shawii, Salvia (S.) aegyptiaca, Pergularia tomentosa, Convolvulus (C.) althaeoides, Haloxylon salicornicum, Ephedra alata, Scrophularia deserti, and Crotalaria aegyptiaca. Transient hypoglycaemic effects appeared only 1 hour after administration in response to 4 plants, Silena succulenta, Lygos raetam, C. lanatus, and Pulicaria incisa. In the cases of Ochradenus baccatus and Zygophyllum album, slow hypoglycaemic activity was produced and appeared 3 hours after administration. 5 plants showed hypoglycaemic effects viz, Thymus capitatus, Launaea nudicaulis, Conyza dioscorides, Nitraria retusa, and Limonium tubiflorum. Among the 15 plant extracts tested on alloxanised diabetic rats only 4 showed hypoglycaemic effects more potent than those of the administered dose of Daonil. These were Matthiola livida, S. aegyptiaca, Astragalus species, and Arthrocnemum glaucum. The hypoglycaemic effect of S. aegyptiaca in fasting rats has been confirmed also in alloxanised diabetic animals. This emphasises the importance of conducting both experiments in order to obtain a reliable conclusion.