Aim of the study
A number of medicinal plants are used in traditional medicine to treat erectile dysfunction. Since cyclic nucleotide PDEs inhibitors underlie several current treatments for this condition, we sought to show whether these plants might contain substantial amounts of PDE5 inhibitors.
Materials and methods
Forty one plant extracts and eight 7-methoxyflavones from Kaempferia parviflora Wall. ex Baker were screened for PDE5 and PDE6 inhibitory activities using the two-step radioactive assay. The PDE5 and PDE6 were prepared from mice lung and chicken retinas, respectively. All plant extracts were tested at 50 μg/ml whereas the pure compounds were tested at 10 μM.
Results
From forty one plant extracts tested, four showed the PDE5 inhibitory effect. The chemical constituents isolated from rhizomes of Kaempferia parviflora were further investigated on inhibitory activity against PDE5 and PDE6. The results showed that 7-methoxyflavones from this plant showed inhibition toward both enzymes. The most potent PDE5 inhibitor was 5,7-dimethoxyflavone (IC50 = 10.64 ± 2.09 μM, selectivity on PDE5 over PDE6 = 3.71). Structure activity relationship showed that the methoxyl group at C-5 position of 7-methoxyflavones was necessary for PDE5 inhibition.
Conclusions
Kaempferia parviflora rhizome extract and its 7-methoxyflavone constituents had moderate inhibitory activity against PDE5. This finding provides an explanation for enhancing sexual performance in the traditional use of Kaempferia parviflora. Moreover, 5,7-dimethoxyflavones should make a useful lead compound to further develop clinically efficacious PDE5 inhibitors.
Abstract. Inta A, Trisonthi C, Pongamornkul W, Panyadee P. 2023. Ethnobotany of Zingiberaceae in Mae Hong Son, Northern Thailand. Biodiversitas 24: 2114-2124. Zingiberaceae (ginger family) is one of the most important used plant families in Thailand. In this study, the uses of ginger species among the ethnic groups in Mae Hong Son province, northern Thailand, was investigated, which aims to answer these questions: how much diversity of ginger species is being used by the ethnicities in northern Thailand; which use categories are a most important use of ginger species? and which species or genera are the most important? The qualitative and quantitative ethnobotanical investigations were conducted with informants through semi-structured interviewing during a walk-in-the-woods in the forest around the villages and home gardens. The importance of each ginger species was compared using the ethnobotanical indices, including use-report (UR), cultural importance index (CI), fidelity level (FL), and informant agreement ratio (IAR). Therefore, 1,218 use reports of local Zingiberaceae were recorded, belonging to six use categories; 33 native ginger species of 9 genera were found. Food and medicine are the two most dominant use categories, with 572 and 446 use reports, respectively. According to the number of UR and CI, the most important local Zingiberaceae species were Zingiber purpureum, Curcuma longa, Alpinia galanga, Z. officinale, Z. ottensii, Z. rubens and Amomum siamense, respectively. About half of the ethnomedicinal ginger species found in this study were first reported for their medicinal properties.
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