Zi Bai Pi

A characteristic constituent of Catalpa ovata, isolated from stem bark and stems. It inhibited lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages with an IC50 of 9.80 microM, and separate work confirmed an anti-inflammatory effect in the same cell model. It also inhibited phorbol-ester-induced Epstein-Barr virus early antigen activation in Raji cells.

The most potent of the Catalpa ovata naphthoquinones tested against nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophages, with an IC50 of 2.73 microM. It was also isolated from the stem bark in antitumour-promotion work.

Inhibited lipopolysaccharide-induced nitric oxide synthesis in RAW 264.7 macrophages with an IC50 of 4.64 microM.

Biosynthetic relatives of the prenylnaphthoquinone series, with (2R)-catalponone identified as the intermediate leading to catalpalactone, catalponol and 4,9-dihydroxy-alpha-lapachone. They are markers of the naphthoquinone chemotype rather than compounds with established therapeutic activity.

Further members of the alpha-lapachone series recovered from the stem bark and stems. All the naphthoquinones isolated from the stem bark showed significant inhibitory activity against phorbol-ester-induced Epstein-Barr virus early antigen activation in Raji cells, a short-term antitumour-promotion screen.

Isolated specifically from the stem bark, which is the part used as Zi Bai Pi, in bioassay-directed fractionation against tumour promotion.

An iridoid glycoside of Catalpa ovata. In lipopolysaccharide-activated RAW 264.7 macrophages it inhibited production of TNF-alpha, IL-1beta and IL-6 and suppressed NF-kappaB activation, which is the best available mechanistic correlate for the classical use of the bark against damp-heat and heat-toxin conditions.

Lists zi bai pi in the lower class of the wood section as bitter and cold, treating heat and removing the three worms, and adds that the flowers and leaves may be pounded and applied to sores on pigs. Both of the functions attributed to the drug today, clearing heat toxin and killing intestinal parasites, come from this single line.

Zhang Zhongjing prescribes fresh zi bai pi as one of the eight ingredients of Ma Huang Lian Qiao Chi Xiao Dou Tang, for yang jaundice with an unresolved exterior presenting as fever, aversion to cold, absence of sweating, itching and generalised orange-coloured jaundice. This is the drug's only appearance in a major classical formula and the reason it survives in the literature at all.

Adds that it treats disease within the eye, and that it governs vomiting and counterflow with stomach reflux, removes the three worms, and treats heat sores in children and heat and vexation of the body and head, being used as a bath, a plaster and a dusting powder. The ophthalmic indication carried in the modern function statement traces to this entry.

Records the bark decocted as a wash for children with vigorous fever, and for all sores, scabies and itching of the skin, confirming that external use was as important as internal use.

Li Shizhen records that it treats a warm disease complicated by renewed contraction of cold evil that has turned into stomach retching, the juice being boiled and drunk.