K. alvarezii is an algae specie cultivated for its nutrients and nutraceutical uses in South East Asia. It is an important source of kappa carrageenan, a hydrocolloid used as food additive – acting as a gelling, emulsifying, thickening and stabilising agent in both pharmaceutical and nutraceutical products.
The red seaweed has significant amounts of protein, vitamins, trace elements and a wide range of second metabolites not found in other organisms. Most importantly, it has antiproliferative properties or the ability to inhibit cell growth.
To determine if k. alvarezii extract can slow down growth of cancer cells, researchers from the USCI University in Malaysia tested it on rats induced with mammary tumour by using DMBA, a powerful organ-specific laboratory carcinogen.
Twenty rats were in three groups: experimental, untreated, and normal plus control groups. Both experimental and untreated groups received DMBA, with the experimental group receiving k. alvarezii crude extracts orally, and only after tumours developed.
An MTT assay determined if the cancer cells induced in the rats would be able to survive following treatment of various concentration of k.alvarezii.
The concentrations of k. alvarezii extract used during the study were 1.0 mg/mL, 3.0 mg/mL, 5.0 mg/mL, 7.0 mg/mL, 9.0 mg/mL, 12.0 mg/mL and 15.0 mg/mL respectively.
Researchers noted that k.alvarezii administered at 1.0mg/mL started inhibiting cell growth, and showed a reduction of cells compared to the solvent control.
Tumour growth rate
“The percentage of cell viability of MCF-7 (breast cancer cells) was reduced from 84.91% to 0.81% which showed a significant reduction of cell viability when the concentration of K. alvarezii extract is increased,” they wrote. “Based on the observation, K. alvarezii extract is able to induce the apoptosis of the MCF-7.”
Other findings showed that tumour growth rate and tumour sizes differed between the untreated and experimental groups.
“The specific growth rate of tumour for untreated group is 1.580 ± 0.270 mm3/t and treated group is 0.097 ± 0.060 mm3/t. This indicate that specific growth rate of tumour in untreated group is significantly higher than treated [experimental] group.”
While the study determined the compounds found in k. alvarezii namely chlorophyll d, pycobiliproteins, allophycocyanin, C-phycocyanin, R-phycocanin, B-phycoerythrin, β-carotene, α-carotene, sterols, unsaturated C20 fatty acid, vitamin B12 and taurine; it also discovered that k.alvarezii has six unknown compounds.
Since the researchers cannot find any match of the compounds in their existing database library, the samples need to be purified and further analysis carried out, they said.
Over-all k. alvarezii showed a good cytotoxic effect on MCF-7 cell line. “The good cytotoxic effect of K. alvarezii shows that K. alvarezii is a potential natural product of cancer treatment,” the researchers concluded.
Source: Biomedicine and Pharmacotherapy
“The properties of red seaweed (Kappaphycus alvarezii) and its effect on mammary carcinogenesis”
Authors: Vi-Sion Chang, Patrick N Okechukwu et al