<![CDATA[Dry skin is a common dermatological problem that can be addressed through the application of natural-based moisturizing cosmetics. Black glutinous rice (Oryza sativa L. var. glutinosa) contains phenolic and flavonoid compounds with the potential to increase skin hydration. This study aimed to formulate an oil-in-water (O/W) cream containing 10%, 15%, and 20% ethanolic extract of black glutinous rice, evaluate its physical stability, and test its effectiveness as a skin moisturizer. A laboratory experimental study was followed by an in vivo parallel-group repeated-measures trial over 4 weeks involving 28 volunteers (7 per group) who were voluntarily divided into four groups (F0% base, F10%, F15%, F20%). The extract was obtained by remaceration of the powdered simplicia with 96% ethanol. Phytochemical screening was performed for phenolic and flavonoid compounds. Physical evaluations included organoleptic properties, homogeneity, pH, viscosity (Brookfield viscometer), spreadability, and adhesion (n=3, on days 0 and 28). Skin moisture content was measured weekly using a Skin Moisture Analyzer. Irritation testing was performed using an open patch test. Data were analyzed using the Shapiro-Wilk normality test, Levene's homogeneity test, followed by One-Way ANOVA/Kruskal-Wallis and post-hoc Tukey HSD/Mann-Whitney tests (α=0.05). The extract yield was 2.99% (w/w). All formulations were homogeneous, had a pH of 6, and met the standard ranges for spreadability (5.3–6.5 cm) and adhesion (>4 seconds). Extract concentration significantly affected viscosity and adhesion (Kruskal-Wallis, p<0.05) as well as day-0 spreadability (One-Way ANOVA, p=0.002). The increases in skin hydration from week 1 to week 4 for F0%, F10%, F15%, and F20% were 2.05%, 3.04%, 3.71%, and 4.81%, respectively. One-Way ANOVA showed significant differences in hydration efficacy between groups (p<0.001), and the Tukey HSD post-hoc test revealed that F20% was significantly different from F0% (p<0.001) and F15% (p=0.040). All formulas did not cause irritation (erythema, edema, itching, or burning sensation) during the observation period. The ethanolic extract of black glutinous rice can be formulated into a physically stable O/W cream stored at room temperature for 28 days and is safe for skin application. The formulation with 20% extract demonstrated the highest hydration efficacy within the tested concentration range.]]>
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