Boehmeria cylindrica

False nettle Boehmeria cylindrica (L.) Dicot, angiosperm... 

A cytotoxic alkaloid from Boehmeria cylindrica (Urticaceae), active in cell cultures against Eagle s K.B. carcinoma of the nasopharynx, but inactive against sarcoma 180, adenocarcinoma 755, L-1210 leukaemia, and Walker carcinosarcoma, was identified as cryptopleurine (61) (67) is a close relative of tylocrebrine (68), from Tylophora crebrifolia (Asclepiadaceae), whose high activity against lymphoid leukaemia L-1210 in mice had been observed. ... 

Phenanthroindolizidine and phenanthroquinolizidine alkaloids have similar pentacyclic structures however, the latter compounds contain a 6-membered piperidine E ring rather than the 5-membered pyrrolidine E ring found in the former compounds. Cryptopleurine (5), Fig. (2), is a representative and important phenanthroquinolizidine alkaloid. It is isolated primarily from Cryptocarya pleurosperma [20], but also from Cryptocarya laevigata [21], Boehmeria cylindrica [22, 23], Boehmeria platyphylla [24], Boehmeria caudate [21], and Cissus rheifolia [25], and is known as a highly toxic skin irritant and vesicant. 

Phenanthroauinozolizidine Boehmeria cylindrica HSV Cytotoxic/ cell protein synthesis [37]... 

Method 6. This synthesis is biomimetic (52), and the product of the first reaction, 33, occurs naturally along with oyptopleurine (18) in Boehmeria platyphylla and B. cylindrica (26,27). The penultimate stage is the alkaloid julandine (24), which also occurs in these two plants (26,27). The synthesis can be modified (52) to afford tylophorine (13) through the secophenanthro-indolizidine alkaloid septidne (30) (27,33,56). 

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