The sea buckthorn – scientific name Hippophae rhamnoides – contains compounds that may help overweight people to lose weight more easily. Taiwanese researchers suggest this after testing a sea-buckthorn extract on fattened lab animals. Sea-buckthorn extract inhibits fat from a high-calorie diet being stored and boosts sensitivity to insulin. Is the answer to the obesity epidemic just growing at the seaside?
Traditional healers in Asia have been using sea-buckthorn extracts for centuries. The active ingredients in the extracts include compounds like gallic acid, myricetin, quercetin, kaempferol and isorhamnetin, all of which are familiar to the readers of this web magazine.
Modern research received a new impetus after researchers discovered that sea-buckthorn extracts contain another compound too: the flavonoid pentamethylquercetin [structural formula shown below]. Japanese ethnopharmacologists announced in 2005 that in test tubes pentamethylquercetin inhibits the growth of human promyelotic leukaemia HL-60 cells. [Int J Mol Med. 2005 May;15(5):805-9.]
Animal studies have shown that pentamethylquercetin blocks the pathogenic enlargement of the heart muscle as a result of high blood pressure [Can J Physiol Pharmacol. 2009 Sep;87(9):720-8.], increases insulin sensitivity and reduces the concentration of triglycerides [Eur J Pharmacol. 2011 Oct 1;668(1-2):347-53.]. It looks as though pentamethylquercetin is an AMPK booster [Diabetologia. 2012 Jun;55(6):1836-46.].
One study on pentamethylquercetin that the Taiwanese refer to was done by researchers at Huazhong University of Science and Technology, in Wuhan, China [Molecules. 2011 Jul 6;16(7):5754-68.]. In that study the Chinese exposed fat cells to pentamethylquercetin, and as a result the production of PPAR-gamma increased. Production of the inflammatory factors TNF-alpha and Interleukin-6 decreased on the other hand.
This may mean that sea-buckthorn extract enhances the effect of insulin in living organisms and reduces the likelihood of diabetes type-2 developing as a result of overweight. Whether this is indeed the case you don't know until you’ve tried it out of course, so nutritionists at Chonbuk National University in Taiwan devised an animal study. They used a sea-buckthorn extract, not just pentamethylquercetin.
For their experiment they used an alcohol extract produced by the Korean Samsung Herbmedicine Corporation. made from sea-buckthorn leaves, which had been soaked in 70 percent alcohol for a week at room temperature. The manufacturer then dried the filtrate.
The Taiwanese divided their mice into four groups. The ND group were given ordinary feed; the HD group were given food enriched with bacon fat. As a result of that the mice in that group put on weight more quickly. The SL1 group also got the calorie-rich feed, but were also given 500 mg sea-buckthorn extract per kg bodyweight daily. The SL2 group got the same, but a double dose of sea-buckthorn extract. The mice were given the sea-buckthorn extract orally.
The SL1 and SL2 mice put on weight less fast than the HD mice. The fattening diet reduced insulin sensitivity, but this was partially prevented by the sea-buckthorn, which boosted the production of the fat sensors PPAR alpha and PPAR gamma in the mice's liver. These sensors mean that organs can pick up and burn more fatty acids.
"Our findings suggest that Hippophae rhamnoides may have potential as a phytochemical to manage obesity but the appropriate human studies must be conducted to continue this research", the researchers conclude.
Nutr Res. 2012 Nov;32(11):856-64.