请帮分析这个英语句子The effects of B on phenolic metabolism have been

请帮分析这个英语句子
The effects of B on phenolic metabolism have been proposed to be indirect,due to its structural role in
the plant cell wall or cell membrane rather than its primary role in regulation of phenolic metabolism by
non-specific B complexation
请帮忙翻译,分析下这个英语句子结构,这里rather than
关于rather than 而不是 “与其说……不如说”怎么区分

这句话的意思是
B对酚类代谢有了间接的的影响,
是因为其（指B）在植物细胞壁或细胞膜结构
而不是因为其在主要酚类代谢的调节作用和其非特异性络合的作用.
rather than
与would 连用时,构成“would rather...than...”句式,意思是“宁愿……而不愿……”,表示主观愿望,即在两者之中选择其一.
例如：
She'd rather die than lose the children.
她宁愿死也不愿失去孩子们.
2.
rather than 不与would连用时,表示客观事实,意为“是……而不是……；与其…不如……”
前者表主观愿望后者陈述事实
rather than在上文中是‘是.而不是.’的意思
望阁下纳之,若有不懂,余在此静候、