1.Kavalactones, a novel class of protein glycation and lipid peroxidation inhibitors.
Upadhyay A1, Tuenter E1, Ahmad R1, Amin A1, Exarchou V1, Apers S1, Hermans N1, Pieters L1. Planta Med. 2014 Aug;80(12):1001-8. doi: 10.1055/s-0034-1382949. Epub 2014 Aug 6.
Both advanced glycation endproducts and advanced lipoxidation endproducts are implicated in many age-related chronic diseases and in protein ageing. In this study, kawain, methysticin, and dihydromethysticin, all belonging to the group of kavalactones, were identified as advanced glycation endproduct inhibitors. With IC50 values of 43.5 ± 1.2 µM and 45.0 ± 1.3 µM for kawain and methysticin, respectively, the compounds inhibited the in vitro protein glycation significantly better than aminoguanidine (IC50 = 231.0 ± 11.5 µM; p = 0.01), an established reference compound. Kawain and methysticin also inhibited the formation of dicarbonyl compounds, which are intermediates in the process of advanced glycation endproduct formation. Similarly, kawain and aminoguanidine prevented the formation of thiobarbituric reactive substances in both low-density lipoprotein and linoleic acid oxidation. Moreover, kawain and aminoguanidine prevented advanced glycation endproduct formation by chelating Fe(3+) and Cu(2+) two to three times better than aminoguanidine.
2.Kavalactone content and chemotype of kava beverages prepared from roots and rhizomes of Isa and Mahakea varieties and extraction efficiency of kavalactones using different solvents.
Wang J1, Qu W2, Bittenbender HC3, Li QX4. J Food Sci Technol. 2015 Feb;52(2):1164-9. doi: 10.1007/s13197-013-1047-2. Epub 2013 Jun 25.
The South Pacific islanders have consumed kava beverage for thousands of years. The quality of kava and kava beverage is evaluated through determination of the content of six major kavalactones including methysticin, dihydromethysticin, kavain, dihydrokavain, yangonin and desmethoxyyangonin. In this study, we determined contents of kavalactones in and chemotype of kava beverages prepared from roots and rhizomes of Isa and Mahakea varieties and extraction efficiency of five different solvents including hexane, acetone, methanol, ethanol and ethyl acetate. The six major kavalactones were detected in all kava beverages with these five solvents. Different solvents had different extraction efficiencies for kavalactones from the lyophilized kava preparations. The contents of kavalactones in the extracts with acetone, ethanol, and methanol did not differ significantly. Ethanol had the highest extraction efficiency for the six major kavalactones whereas hexane gave the lowest extraction efficiency.
3.Phototoxicity of kava - formation of reactive oxygen species leading to lipid peroxidation and DNA damage.
Xia Q1, Chiang HM, Zhou YT, Yin JJ, Liu F, Wang C, Guo L, Fu PP. Am J Chin Med. 2012;40(6):1271-88. doi: 10.1142/S0192415X12500942.
Kava is one of the most widely sold herbal dietary supplements in the United States. It has been reported that, besides exhibiting hepatotoxicity, kava also possesses photosensitivity and induces dermopathy in humans. In this study, we determined that UVA irradiation of kava in the presence of a lipid, methyl linoleate, generated lipid peroxidation which was mediated by singlet oxygen generated during photoirradiation. The six major kavalactones(yangonin, 7,8-dihydrokawa in, kawain, 7,8-dihydromethysticin, methysticin, and 5,6-dehydrokawain) were also studied in parallel; only 5,6-dehydrokawain and yangonin-induced a low level of lipid peroxidation. UVA irradiation of kava in human HaCaT skin keratinocytes induced cytotoxicity which was mediated by oxidative stress, led to DNA strand cleavage, and produced 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct. Study by the electron spin resonance (ESR) method revealed that UVA irradiation of kava produced singlet oxygen and carbon-centered radicals.
4.Pacific island 'Awa (Kava) extracts, but not isolated kavalactones, promote proinflammatory responses in model mast cells.
Shimoda LM1, Park C, Stokes AJ, Gomes HH, Turner H. Phytother Res. 2012 Dec;26(12):1934-41. doi: 10.1002/ptr.4652. Epub 2012 Apr 4.
Kava ('Awa) is a traditional water-based beverage in Pacific island communities, prepared from the ground root and stems of Piper methysticum. Kava use is associated with an ichthyotic dermatitis and delayed type hypersensitivity reactions. In the current study we collated preparative methodologies from cultural practitioners and recreational kava users in various Pacific communities. We standardized culturally informed aqueous extraction methods and prepared extracts that were subjected to basic physicochemical analysis. Mast cells exposed to these extracts displayed robust intracellular free calcium responses, and concomitant release of proinflammatory mediators. In contrast, mast cells were refractory to single or combinatorial stimulation with kavalactones, including methysticin, dihydromethysticin and kavain. Moreover, we reproduced a traditional modification of the kava preparation methodology, pre-mixing with the mucilage of Hibiscus tiliaceus, and observed its potentiating effect on the activity of aqueous extracts in mast cells.