Xian Ren Zhang

Three polysaccharide fractions were separated from Opuntia dillenii by ultrasonic extraction and DEAE-Sepharose chromatography and screened in streptozotocin-diabetic mice over three weeks. ODP-Ia significantly lowered fasting blood glucose, total cholesterol, triglycerides, plasma urea nitrogen, malondialdehyde and glucose-6-phosphatase activity, and raised body weight, hepatic glycogen, HDL cholesterol and hepatic superoxide dismutase and glutathione peroxidase, without significantly raising insulin. A mouse study of an isolated fraction, not of a cladode preparation as used clinically.

The formal toxicology study for this species. Cladode methanol extract, its fractions and the pyrones opuntiol and opuntioside were non-cytotoxic to HEK-293 cells and rat neutrophils, did not fragment genomic DNA, and did not induce micronuclei in human lymphocytes or in rat bone marrow. Oral extract at 5 g/kg for seven days in mice produced no significant change in relative organ weights, blood, liver or kidney biochemistry, or liver and kidney histology. This is the best available support for the oral safety of the cladode, and it is why O. dillenii is treated as low-toxicity in contrast to several other herbs in the clearing-heat category.

Opuntiol and opuntioside from O. dillenii cladode attenuated inflammation mediated by cytokines and eicosanoids in experimental models, giving a defined chemical basis for the traditional use of the cladode as a poultice and internal remedy for swelling and heat toxin. Preclinical work on isolated compounds; it does not establish an effective oral dose of the crude drug.

Chemical profiling of O. dillenii fruit pulp and peel extracts with measurement of antihyperglycaemic activity and inhibition of carbohydrate-digesting enzymes. It locates part of the species' glucose-lowering activity in alpha-amylase and alpha-glucosidase inhibition — the acarbose mechanism — and so underpins the theoretical additive effect with antidiabetic drugs. It concerns fruit extracts rather than the cladode that constitutes the medicinal drug.

A PRISMA-guided review of 45 studies of O. dillenii phytochemistry and biological activity. It identifies betalains, polyphenols, flavonoids and polysaccharides as the active classes and reports anti-inflammatory, antiproliferative, antiatherogenic, hypotensive, hypolipidaemic, antidiabetic and antimicrobial activities with a low toxicity profile. The authors' own conclusion is the important one for practice: the evidence base is preclinical and human clinical trials are still needed.

A controlled clinical study in patients with non-insulin-dependent diabetes showing that ingestion of broiled prickly pear cladode lowered serum glucose and insulin. It is included here because it is routinely cited as the human evidence for cactus in diabetes, and it is important to be clear that it used Opuntia streptacantha, a different species from the O. dillenii of this monograph. No equivalent controlled human trial exists for O. dillenii.

A systematic review of human studies of prickly pear cactus and its products on blood glucose and insulin. It is the appropriate reference point for what is and is not established in people — the included human work is dominated by Opuntia ficus-indica and Opuntia streptacantha, and the review does not supply human glucose evidence specific to Opuntia dillenii.