Dian Di Mei

One of four saxifragifolin saponins isolated by cytotoxicity-guided fractionation of the methanol extract of the whole plant. Together with saxifragifolins B, C and D it was cytotoxic to a panel of human tumour cell lines with IC50 values of 0.19-2.37 microM, and induced Annexin V binding and nuclear condensation consistent with apoptosis.

Cytotoxic in the same sub-micromolar to low-micromolar range as the other saxifragifolins. Notably, multidrug-resistant cell lines (MES-SA/DX5, HCT15/CLO2) were no less sensitive than their parent lines, although they were highly resistant to doxorubicin, suggesting these saponins are not P-glycoprotein substrates.

The major cytotoxic saponin recovered from the n-butanol soluble fraction. Like related Primulaceae saponins it is surface-active, which is the usual explanation for the irritancy of saponin-rich crude extracts applied to mucosa.

Cytotoxic against both drug-sensitive and multidrug-resistant human tumour lines and, with saxifragifolin B, one of the two compounds shown to produce apoptotic nuclear condensation in RAW 264.7 macrophages.

One of two saponins first described from the ethanol extract of the whole plant; reported cytotoxic to human hepatoma cells. Structurally it belongs to the same 13beta,28-epoxy oleanane series as the saxifragifolins.

One of ten flavonol glycosides characterised from the whole plant, alongside several 2-O- and 3-O-acetylated rhamnosides and 3,7-di-rhamnosides of kaempferol. These are the plant's main polar phenolics; no specific pharmacology has been reported for them in this species.

Reported from the whole plant together with quercetin 3-O-alpha-L-rhamnopyranoside and myricetin 3-O-beta-D-glucopyranoside. Contributes to the antioxidant character of aqueous-alcoholic extracts.

Dian Di Mei has no entry in the classical materia medica; it is a folk drug of the lower Yangtze and southwest China that entered the printed literature only in modern regional handbooks. Modern Chinese reference works describe the dried whole plant as bitter and acrid, cold, clearing heat and resolving toxicity and reducing swelling and pain, used for sore swollen throat, mouth sores, toothache, red eyes, wind-damp painful obstruction, wheezing, and topically for sores, burns, snakebite and traumatic injury; the usual internal dose is 9-15 g in decoction. Regional names include hou long cao (throat herb, Jiangsu and Zhejiang) and bai hua zhen zhu cao.