The flavonoid Oroxylin A (6‐methoxychrysin or 5,7‐dihydroxy‐6‐methoxy‐2‐phenyl‐4H‐chromen‐4‐one, C₁₆H₁₂O₅) and its regioisomers are of increasing interest for a variety of bioactive functions and their pharmaceutical formulation is of importance. Previous difficulties in the separation and misidentification of Oroxylin A from its regioisomers Wogonin (8‐methoxychrysin or 5,7‐dihydroxy‐8‐methoxy‐2‐phenyl‐4H‐chromen‐4‐one) and Negletein (5,6‐dihydroxy‐7‐methoxyflavone or 5,6‐dihydroxy‐7‐methoxy‐2‐phenyl‐4H‐chromen‐4‐one) render its full structural and powder X‐ray characterization highly desirable. The low‐temperature (100 K) crystal structures of Oroxylin A, Negletein and Wogonin sesquihydrate are reported for the first time. Wogonin crystallizes in two related but distinct hydrated forms. These have very similar powder diffractograms, indicating that such issues need to be addressed for its pharmaceutical formulation.

中文翻译：

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类黄酮Oroxylin A和区域异构体Negletein和Wogonin的晶体结构。

类黄酮Oroxylin A（6-甲氧基酪蛋白或5,7-二羟基-6-甲氧基-2-苯基-4 H-铬4-4-酮，C ₁₆ H ₁₂ O ₅）及其区域异构体对于各种生物活性功能及其药物配方非常重要。从其区域异构体沃贡宁（8-甲氧基白or或5,7-二羟基-8-甲氧基-2-苯基-4 H-铬n-4-1）和神经钙蛋白（5,6-二羟基-7-甲氧基黄酮或5,6-二羟基-7-甲氧基-2-苯基-4 H-chromen-4-one）使其具有完整的结构和粉末X射线表征非常可取。首次报道了Oroxylin A，Negletein和Wogonin倍半水合物的低温（100 K）晶体结构。沃戈宁以两种相关但不同的水合形式结晶。这些具有非常相似的粉末衍射图，表明其药物制剂需要解决这些问题。