Persimmons are cultivated mainly in Asian countries such as Korea, Japan, and China. The Astringent persimmons are wild species and have astringent taste until they have ripened. Kaki Calyx is a type of traditional Korean medicine (TKM) containing persimmons. In TKM, the stalks of astringent persimmons are known to be effective for the treatment of bed-wetting, vomiting, and hiccupping.
This study has investigated microbial identification, tannic acid content, and anti-inflammatory activities of astringent persimmons (Diospyros kaki Thunb.) stalks based on the cultivar types and stages of maturity in the Gyeongnam province to suggest the optimal harvesting time based on the efficacy as herb medicine and also to provided basic information of identified the microbial organisms by hanging season. The three stalks of immature astringent persimmon from Hamyang (Gojongsi), Hamyang (Danseongsi), and Miryang (Bansi); the three stalks of mature astringent persimmon from Hamyang (Gojongsi), Hamyang (Danseongsi), and Miryang (Bansi); the three stalks of immature astringent persimmon from Hamyang (Gojongsi), Hamyang (Danseongsi), and Miryang (Bansi); the three stalks of dried astringent persimmon from Hamyang (Gojongsi), Hamyang (Danseongsi), and Miryang (Bansi) were used for this study based on seasonal ripening [Stage 1: August-September (8-9 months), Stage 2: October–November (10-11 months), and Stage 3: December–January (12–1 months)]. Identification of microorganisms showed that Metschnikowia sp. was identified only in the stalks of immature astringent persimmon regardless of the cultivars. It has been identified that various useful microorganism candidates appeared such as Bacillus thuringensis, Rhodotorula flutinis. Tannic acid contents in Astringent persimmon can be converted during ripening. We analyzed contents of tannic acid for several selected cultivars of astringent persimmons from various regions and at different mature stages. All the samples analyzed were found to contain tannic acid and the stage 1 (8-9 month) from stalks of all samples had highest percentage of tannic acid content compared with the tannic acid contents obtained in other samples. especially the stalk of immature astringent persimmon from Gojongsi (Hamyang) had the highest tannic acid content (2.597 mg/g). In addition, anti-inflammatory effects of extractions of stalks of astringent persimmon showed that anti-inflammatory effects were confirmed by reducing anti-inflammatory factors such as iNOS, phosphorylated p65 and phosphorylated IkBα and their effects decreased according to maturity Respectively. This study provides basic information on useful microorganisms and tannic acid content changes in astringent persimmon on maturity. The anti-inflammatory effect of extracts are expected to be helpful for the verification of efficacy of oriental medicine and the timing of proper harvest.